Transcript
TR41.3.10-09-02-004
PN-3-4350.120-RV3 (to become ANSI/TIA-470.120-C) Draft 18 (Includes Costa Mesa November 4, 2008 meeting edits)
Telecommunications Telephone Terminal Equipment Transmission Requirements for Analog Speakerphones
Formulated under the cognizance of TIA Subcommittee TR-41.3, Analog and Digital Wireline Terminals
With the approval of TIA Engineering Committee TR-41, User Premises Telecommunications Requirements
PN-3-4350.120-RV3
DRAFT 18
TIA-470.120-C
1 2
TABLE OF CONTENTS
3
FOREWORD ___________________________________________________________________ 8
4
INTRODUCTION _______________________________________________________________ 9
5
1
SCOPE __________________________________________________________________ 10
6
2
NORMATIVE REFERENCES ______________________________________________ 11
7
3
ABBREVIATIONS, ACRONYMS, AND DEFINITIONS ________________________ 12
8
3.1 ABBREVIATIONS AND ACRONYMS...................................................................12
9
3.2 DEFINITIONS ...........................................................................................................13
10
4
TECHNICAL REQUIREMENTS ____________________________________________ 14
11
4.1 CATEGORIES OF CRITERIA..................................................................................14
12
4.2 TEST CIRCUITS .......................................................................................................15
13
4.2.1
SEND TESTING WITH ARTIFICIAL LINES .........................................................15
14
4.2.2
RECEIVE TESTING WITH ARTIFICIAL LINES....................................................16
15
4.2.3
DOUBLE-TALK TESTING WITH ARTIFICIAL LINES .........................................16
16
4.2.4
DC FEED CIRCUIT ............................................................................................17
17
4.2.5
TERMINATION IMPEDANCE .............................................................................18
18
4.2.6
ARTIFICIAL LINES ............................................................................................18
19 20 21
4.3 TRANSMISSION PERFORMANCE ........................................................................19 4.3.1
SEND PERFORMANCE.......................................................................................19 4.3.1.1
SEND FREQUENCY RESPONSE ...............................................................19
22
4.3.1.1.1
Requirement ............................................................................................................ 19
23
4.3.1.1.2
Method of Measurement.......................................................................................... 21
24
4.3.1.2
25 26
SEND LOUDNESS RATING (SLR) ..........................................................21 4.3.1.2.1
4.3.1.3
Requirement ............................................................................................................ 21
SEND LOUDNESS RATING DIRECTIONALITY (SLRD) ..........................22
27
4.3.1.3.1
Requirement ............................................................................................................ 22
28
4.3.1.3.2
Method of Measurement.......................................................................................... 22
29 30
4.3.1.4
SEND DISTORTION AND NOISE .............................................................22 4.3.1.4.1
Requirement ............................................................................................................ 22
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4.3.1.5
32
TIA-470.120-C
Method of Measurement...........................................................................................23
SEND OFF-HOOK NOISE ........................................................................24
33
4.3.1.5.1
Requirement .............................................................................................................24
34
4.3.1.5.2
Method of Measurement...........................................................................................24
4.3.1.6
35
SEND ON-HOOK NOISE .........................................................................24
36
4.3.1.6.1
Requirement .............................................................................................................24
37
4.3.1.6.2
Method of Measurement...........................................................................................24
4.3.1.7
38
OFF-HOOK SEND SINGLE FREQUENCY INTERFERENCE .......................24
39
4.3.1.7.1
General .....................................................................................................................24
40
4.3.1.7.2
Requirement .............................................................................................................24
41
4.3.1.7.3
Method of Measurement...........................................................................................24
4.3.1.8
42
SEND MUTING .......................................................................................25
43
4.3.1.8.1
Requirement .............................................................................................................25
44
4.3.1.8.2
Method of Measurement...........................................................................................25
4.3.1.9
45 46 47
4.3.2
DYNAMIC SEND BACKGROUND NOISE SUPPRESSION .........................25
RECEIVE PERFORMANCE ..........................................................................26 4.3.2.1
RECEIVE LEVEL .....................................................................................26
48
4.3.2.1.1
Requirement .............................................................................................................26
49
4.3.2.1.2
Method of Measurement...........................................................................................26
50
4.3.2.2
RECEIVE FREQUENCY RESPONSE .........................................................28
51
4.3.2.2.1
Requirement .............................................................................................................28
52
4.3.2.2.2
Method of Measurement...........................................................................................30
53
4.3.2.3
54 55
RECEIVE LOUDNESS RATING (RLR)ERROR! BOOKMARK NOT DEFINED. 4.3.2.3.1
4.3.2.4
Requirement ............................................................. Error! Bookmark not defined.
RECEIVE LOUDNESS RATING DIRECTIONALITY (RLRD)ERROR! BOOKMARK NOT DEFIN
56
4.3.2.4.1
Requirement ............................................................. Error! Bookmark not defined.
57
4.3.2.4.2
Method of Measurement........................................... Error! Bookmark not defined.
58
4.3.2.5
RECEIVE DISTORTION AND NOISE ........................................................31
59
4.3.2.5.1
Requirement .............................................................................................................31
60
4.3.2.5.2
Method of Measurement...........................................................................................31
61
4.3.2.6
OFF-HOOK NOISE ..................................................................................32
62
4.3.2.6.1
Requirement .............................................................................................................32
63
4.3.2.6.2
Method of Measurement...........................................................................................32
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OFF-HOOK RECEIVE SINGLE FREQUENCY INTERFERENCE .................32
65
4.3.2.7.1
General .................................................................................................................... 32
66
4.3.2.7.2
Requirement ............................................................................................................ 32
67
4.3.2.7.3
Method of Measurement.......................................................................................... 32
4.3.2.8
68
RECEIVE VOLUME DYNAMIC RANGE ...................................................32
69
4.3.2.8.1
Requirement ............................................................................................................ 32
70
4.3.2.8.2
Method of Measurement.......................................................................................... 33
71 72
4.4 VOICE SWITCHING PERFORMANCE ..................................................................33 4.4.1
SINGLE TALK PERFORMANCE .................................................................33 4.4.1.1
73
SEND BUILD-UP TIME ...........................................................................33
74
4.4.1.1.1
Requirement ............................................................................................................ 33
75
4.4.1.1.2
Method..................................................................................................................... 33
4.4.1.2
76
RECEIVE BUILD-UP TIME .....................................................................33
77
4.4.1.2.1
Requirement ............................................................................................................ 33
78
4.4.1.2.2
Method..................................................................................................................... 33
79 80
4.4.2
DOUBLE-TALK PERFORMANCE ...............................................................34 4.4.2.1
RECEIVE TO SEND SWITCHING TIME (SEND SWITCHING TIME)..........34
81
4.4.2.1.1
Requirement ............................................................................................................ 34
82
4.4.2.1.2
Method..................................................................................................................... 34
83
4.4.2.2
RECEIVE TO SEND SWITCHING THRESHOLD LEVEL ............................34
84
4.4.2.2.1
Requirement ............................................................................................................ 34
85
4.4.2.2.2
Method..................................................................................................................... 34
86
4.4.2.3
SEND TO RECEIVE SWITCHING TIME (RECEIVE SWITCHING TIME) ....34
87
4.4.2.3.1
Requirement ............................................................................................................ 34
88
4.4.2.3.2
Method..................................................................................................................... 34
89
4.4.2.4
SEND TO RECEIVE SWITCHING THRESHOLD LEVEL ............................35
90
4.4.2.4.1
Requirement ............................................................................................................ 35
91
4.4.2.4.2
Method..................................................................................................................... 35
92
4.4.2.5
ATTENUATION RANGE ..........................................................................35
93
4.4.2.5.1
Requirement ............................................................................................................ 35
94
4.4.2.5.2
Method..................................................................................................................... 35
95
4.4.2.6
RECEIVE TO SEND TAKE-OVER TIME (SEND TAKE-OVER TIME)........36
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4.4.2.6.1
Requirement .............................................................................................................36
97
4.4.2.6.2
Method .....................................................................................................................36
4.4.2.7
98
SEND TO RECEIVE TAKE-OVER TIME (RECEIVE TAKE-OVER TIME) ..36
99
4.4.2.7.1
Requirement .............................................................................................................36
100
4.4.2.7.2
Method .....................................................................................................................36
101
ANNEX A
(NORMATIVE) – NOISE CURVES ____________________________________ 37
102
A.1 SEND NOISE CURVES ............................................................................................37
103
A.2 RECEIVE NOISE CURVE........................................................................................39
104
ANNEX B
(NORMATIVE) – CALCULATION OF LOUDNESS RATINGS ____________ 40
105
B.1 SEND LOUDNESS RATING (HANDSET): ............................................................41
106
B.2 RECEIVE LOUDNESS RATING (HANDSET):......................................................41
107
B.3 SIDETONE MASKING RATING (HANDSET): .....................................................42
108
ANNEX C
(NORMATIVE) – ISO R-40 FREQUENCIES ____________________________ 44
109
ANNEX D
(INFORMATIVE) – LOSS PLAN AND LOUDNESS RATING REFERENCES
110 111
AND HIERARCHY __________________________________________________ 46 ANNEX E
112 113
(INFORMATIVE) – NOMINAL FREQUENCY RESPONSE CHARACTERISTICS AND LOUDNESS RATING CALCULATIONS _______ 47
ANNEX F
114
(INFORMATIVE) – USE OF THE FREE FIELD AS THE TELEPHONOMETRIC REFERENCE POINT ___________________________ 51
115
ANNEX G
(INFORMATIVE) - BIBLIOGRAPHY __________________________________ 54
116
ANNEX H
(INFORMATIVE) – ITEMS FOR FUTURE CONSIDERATION ____________ 55
117
H.1 SEND THRESHOLD LEVEL ...................................................................................55
118
H.2 SEND HANG-OVER TIME ......................................................................................55
119
H.3 SEND NOISE GUARD..............................................................................................55
120
H.4 RECEIVE THRESHOLD LEVEL.............................................................................56
121
H.5 RECEIVE HANG-OVER TIME................................................................................56
122
H.6 RECEIVE NOISE GUARD .......................................................................................56
123
H.7 ACOUSTIC ECHO CANCELLER PERFORMANCE .............................................57
124
H.7.1
ROUND TRIP ECHO PATH DELAY ....................................................................57
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H.7.2
TCL SINGLE TALK ...........................................................................................57
126
H.7.3
CONVERGENCE TIME .......................................................................................57
127
H.7.4
TCL TEMPORALLY WEIGHTED COUPLING LOSS - DOUBLE TALK ................57
128
H.7.5
SEND SPEECH ATTENUATION DURING DOUBLE TALK ..................................57
129
H.7.6
RECEIVE SPEECH ATTENUATION DURING DOUBLE TALK .............................57
130
H.7.7
SEND SPEECH FRONT-END CLIPPING TIME DURING DOUBLE TALK .............57
131
H.7.8
RECEIVE SPEECH FRONT-END CLIPPING TIME DURING DOUBLE TALK ........57
132
H.7.9
ACOUSTIC STABILITY (TCL: TERMINAL COUPLING LOSS)............................57 H.7.9.1 STABILITY RELATED TO LOW LEVEL STIMULUS .................................57
133
H.8 SWITCHING OPERATION BETWEEN SPEAKERPHONE & HANDSET MODE57
134 135
ANNEX I
(INFORMATIVE) – BNR STUDY _____________________________________ 58
136
4.4.3
OBJECTIVES .....................................................................................................58
137
4.4.4
APPARATUS......................................................................................................59
138
4.4.5
PROCEDURE .....................................................................................................59
139
4.4.6
PRELIMINARY RESULTS...................................................................................59
140
5
TABLE OF RESULTS _____________________________________________________ 61
141
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142
Table of Figures
143
Figure 1 – Test circuit for send measurements .................................................................................... 15
144
Figure 2 – Test circuit for receive measurements ................................................................................ 16
145
Figure 3 – Test circuit for double-talk measurements ......................................................................... 16
146
Figure 4 – One possible dc feed circuit................................................................................................ 17
147
Figure 5 – Artificial line segment ........................................................................................................ 18
148
Figure 6 – Send frequency response limits .......................................................................................... 20
149
Figure 7 – Receive frequency response limits ..................................................................................... 30
150
Figure A.1 – Psophometric and C-Message noise weighting curves comparison ............................... 38
151
Figure A.2 – A-weighting noise weighting curve................................................................................ 39
152
Figure D.1 – Hierarchical Relationship between Loudness Rating and Loss Plan Standards ............. 46
153
Figure E.1 – Nominal send frequency response .................................................................................. 49
154
Figure E.2 – Nominal receive frequency response .............................................................................. 49
155
Figure F.1 – Flat free field loudspeaker response ................................................................................ 51
156
Figure F.2 – HATS measurement of same loudspeaker....................................................................... 51
157
Figure F.3 – HATS measurement of handset telephone ...................................................................... 52
158
Figure F.4 – Type 1 ear simulator measurement of handset telephone................................................ 52
159
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160
Table of Tables
161
Table 1 – Artificial line segment component values ............................................................................ 18
162
Table 2 – Send frequency response limits ............................................................................................ 20
163
Table 3 – Send loudness rating limits................................................................................................... 21
164
Table 4 – Send Loudness Rating Directionality Limits. ...................................................................... 22
165
Table 5 – Send Signal-to-Total Distortion and Noise Ratio Limits. .................................................... 23
166
Table 6 – Mandatory Receive frequency response limits..................................................................... 28
167
Table 7 – Desired Receive frequency response limits.......................................................................... 29
168
Table 8 – Receive loudness rating limits.............................................. Error! Bookmark not defined.
169
Table 9 – Receive Loudness Rating Directionality Limits................... Error! Bookmark not defined.
170
Table 10 – Receive Signal-to-Total Distortion and Noise Ratio Limits. ............................................. 31
171
Table 11 – Speakerphone Duplex Capability and Classification ......................................................... 35
172
Table A.1 – Psophometric weighting curve
173
Table A.3 – A-weighting curve ............................................................................................................ 39
174
Table B.1 – ITU-T P.79 Tables 1, 2 and 3, Weighting factors for calculating loudness ratings.......... 43
175
Table C.1 – ISO R-40, ISO R-10,1/12th Octave and 1/3rd Octave Frequencies.................................... 44
176
Table C.2 – ISO R-40, ISO R-10,1/12th Octave and 1/3rd Octave Frequencies (Continued) ............. 44
177
Table E.1 – Nominal Frequency Response Characteristics and Loudness Ratings Calculations......... 50
Table A.2 – C-Message weighting curve .................... 37
178
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FOREWORD
180 181 182 183 184 185 186 187 188 189 190 191 192 193
(This foreword is not part of this Standard.) This document is a TIA Telecommunications standard produced by Working Group TR-41.3.10 of Committee TR-41. This standard was developed in accordance with TIA procedural guidelines, and represents the consensus position of the Working Group and its parent Subcommittee TR-41.3, which served as the formulating group. There are nine annexes in this Standard. Annexes A, B, and C are normative and are considered part of this Standard; Annexes D, E, F, G, H, and I are informative and are not considered part of this Standard. The TR-41.3.10 Working Group acknowledges the contributions and leadership provided by the following individuals in the development of this standard. Organization
Representative
TIA-470.120-C 9 Chair, Editor
Uniden.
Al Baum
Acoustics for Communications
Ron Magnuson
9
Advent Instruments
Dave Stenner
9
Atlinks
Fred Bonhomme
9
Consultant in Electroacoustics
John Bareham
9
Embarq Corporation
Amar Ray
9
Listen Inc.
Dan Foley
9
MWM Acoustics
Glenn Hess
9
Nortel
Miguel DeAraujo
9
Texas Instruments
Tom Harley
9
VTech Communications
Steve Whitesell
9
194 195 196
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DRAFT 18
INTRODUCTION @@@ Wording needed here.
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PN-3-4350.120-RV3 203 204
Telephone Terminal Speakerphones
205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227
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Equipment
–
Transmission
TIA-470.120-C
Requirements
for
Analog
SCOPE
This standard provides speakerphone acoustic performance requirements for Customer Premises Equipment (CPE) intended for analog connection to the Public Switched Telephone Network (PSTN). These requirements should ensure compatibility and satisfactory performance to the user in a high percentage of installations. Test measurement methods reference procedures in IEEE Std 1329 where applicable. These requirements apply to measurements made in a laboratory consisting of an anechoic chamber, and possibly a test table and/or a test wall and that can be repeated from lab to lab. These requirements do not apply to measurements made in a real room with environmental reflections. These measurements shall be performed with a free field microphone and artificial mouth in accordance with IEEE-1329. If the device under test includes multiple housings (excluding cordless phones) or inherently involves environmental reflections other than a test table or test wall (e.g. office cubicle) then a HATS shall be used in accordance with IEEE-1329. This document proposes or references at least one measurement procedure for each technical requirement. However, these procedures are not exclusive. Any measurement procedure and equipment that can result in an identical measurement is considered valid. While the procedures may call out specific test points within the requirements, the full range of the requirements take precedent. This standard is primarily intended to be used for evaluating single user speakerphones normally used at a distance of one half meter or closer.
10
PN-3-4350.120-RV3 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248
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TIA-470.120-C
NORMATIVE REFERENCES
The following standards contain provisions, which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. ANSI and TIA maintain registers of currently valid national standards. ANSI/IEEE Std 1329-1999 – Standard method for measuring transmission performance of handsfree telephone sets ANSI/IEEE Std 269-2002 – Standard methods for measuring transmission performance of analog and digital telephone sets, handsets and headsets ANSI S1.4-1983 (Reaff. 2006) – Specification for sound level meters ITU-T Recommendation O.41 (10/94) –Psophometer for use on telephone-type circuits ITU-T Recommendation P.57 (10/05) – Artificial ears ITU-T Recommendation P.79 (11/07) – Calculation of loudness ratings for telephone sets
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249
3
250 251 252
3.1
253
CPE
Customer Premises Equipment
254
DLC
Digital Loop Carrier
255
DRP
Drum Reference Point
256
ERP
Ear Reference Point
257
HATS
Head And Torso Simulator
258
MRP
Mouth Reference Point
259
OLR
Objective Loudness Rating
260
PSTN
Public Switched Telephone Network
261
PBX
Private Branch Exchange
262
RETP
Receive Electrical Test Point
263
RLR
Receive Loudness Rating
264
ROLR
Receive Objective Loudness Rating
265
SETP
Send Electrical Test Point
266
SLR
Send Loudness Rating
267
SOLR
Send Objective Loudness Rating
268
TOLR
Transmit Objective Loudness Rating
TIA-470.120-C
ABBREVIATIONS, ACRONYMS, AND DEFINITIONS ABBREVIATIONS AND ACRONYMS
For the purposes of this standard, the following abbreviations and acronyms apply. AWG American Wire Gauge
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269 270 271
3.2
272 273
dBA:
Sound pressure level in decibels, relative to 2×10-5 Pa, using A-weighting. (See Annex A)
274
dBm:
Power level in decibels, relative to a power of 1 mW (milliwatt).
275 276
dBmp
Power level in decibels, relative to a power of 1 mW, using psophometric weighting. (See Annex A)
277
dBPa:
Sound pressure level in decibels, relative to a sound pressure of 1 Pa (pascal).
278
dBV:
Voltage level in decibels, relative to 1 volt rms.
279 280
Mouth Reference Point (MRP): A point on the axis of the mouth simulator, 25 mm in front of the center of the equivalent lip plane.
281 282
Off-Hook:
The state of the CPE when the hook-switch is closed. Refers to the state of a particular CPE rather than the line state.
283 284
On-Hook:
The state of the CPE when the hook-switch is open. Refers to the state of a particular CPE rather than the line state.
285 286 287
Off-hook noise:
The internally generated noise of the telephone set. It is the psophometric weighted signal power delivered to a specified termination (SETP) in the absence of an acoustic input into the telephone set.
288 289 290
Reference Volume Control Setting: The quietest volume control setting that produces a receive level of at least 65dBSPL with a P.50 test level of -25dBV with a 2.7km artificial line.
291 292
Speakerphone:
DEFINITIONS
For the purposes of this standard, the following definitions apply. Central Office: Used broadly to describe the switch connected to a subscriber’s line.
A device that facilitates two-way voice communication between persons over the public switched telephone network without contacting the user’s head.
293
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4
295 296 297 298 299
4.1
300 301 302
Recommended requirements are designated by the terms “should” and “should not.” These requirements generally relate to compatibility or performance advantages towards which future designs should strive.
303 304
Permissive requirements are designated by the terms “may” and “may not.” These requirements are used to indicate an action that is permitted within the limits of the standard.
305 306 307 308 309
Advisory requirements are designated by the term “desirable.” Advisory criteria represent product goals or are included in an effort to ensure universal product compatibility and may be used instead of a Recommended requirement. If both a mandatory and an advisory level are specified for the same criterion, the advisory level represents a goal currently identifiable as having distinct compatibility or performance advantages toward which future designs should strive.
TECHNICAL REQUIREMENTS CATEGORIES OF CRITERIA
Four types of requirements are specified in this standard: Mandatory, Recommended, Permissive and Advisory: Mandatory requirements are designated by the terms “shall” and “shall not.” These requirements are used to indicate conformity in which no deviation is permitted.
310
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4.2
313
4.2.1
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TEST CIRCUITS
The following test circuits are referenced in this document: SEND TESTING WITH ARTIFICIAL LINES
314
Tx
Ring
315 316 317
Figure 1 – Test circuit for send measurements
318
15
SETP
900 Ω termination
DC Feed Circuit
Rx
Telephone set speech network
Apply Mouth Sound Pressure at MRP
Artificial line No.26 AWG non-loaded cable
Tip
dB Meter or level recorder
PN-3-4350.120-RV3 319 320
4.2.2
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RECEIVE TESTING WITH ARTIFICIAL LINES
Telephone set speech network
Artificial line No.26 AW G non-loaded cable
DC Feed Circuit
RETP
900 Ω
G enerator
Tip
Rx
Ear Sound Pressure at ERP
Tx
Ring
321 322 323 324 325 326 327
Figure 2 – Test circuit for receive measurements
4.2.3
DOUBLE-TALK TESTING WITH ARTIFICIAL LINES
Ear Sound Pressure at ERP Telephone set speech network
Artificial line No.26 AWG non-loaded cable
DC Feed Circuit
900 Ω termination
Tip
Ring 328 329 330
Figure 3 – Test circuit for double-talk measurements
331
16
Rx Apply Mouth Sound Pressure at MRP Tx
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332 333 334 335 336 337
4.2.4 DC FEED CIRCUIT The dc feed circuit must supply the CPE power and interface to test equipment such that the required parameters may be measured without introducing any significant error. The dc feed shall provide the following: • 50 Vdc in series with 400 ohms +/- 1% • less than 0.1 dB insertion loss over the 100 Hz to 10 kHz range
338 339 340 341
NOTE:See IEEE-269 for the procedure to follow when determining feed circuit loss. • At least 30 dB return loss with respect to 900 ohms over the 300 Hz to 10 kHz range One possible implementation of the dc Feed is shown in Figure 4.
C R
fromsource or totermination
L
50 V
R
to CPE
L
C NOTES: 1.C >=100 uF 2. L >= 5 H 3.R=200 ohms (including resistanceofL) 4. V= 50 Vdc 5.This is asimplified DC feed circuit.It does not implement the current limit characteristicofmodern end offices,which typically limit themaximumcurrent supplied by theoffice.
342 343
Figure 4 – One possible dc feed circuit
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344 345 346 347
4.2.5 TERMINATION IMPEDANCE The termination impedance shall be a resistive load of 900 ohms with a tolerance of +/- 1 %.
348 349 350 351 352 353
4.2.6 ARTIFICIAL LINES This standard has transmission requirements for CPE when connected to 0 km, 2.7 km and 4.6 km artificial lines. These lines may be assembled using combinations of artificial line segments shown in Figure 5 with component values selected from Table 1. These artificial line segments represent 26 AWG non-loaded cable.
R1
L1
C2
R2
C4
C1
R3
C3
L2
R4
354 355 356
Figure 5 – Artificial line segment
357 358
Table 1 – Artificial line segment component values Component
0.305 km (1 kft)
0.914 km (3 kft)
1.83 km (6 kft)
R1, R4
41.7 Ω
124 Ω
249 Ω
R2, R3
109 Ω
174 Ω
312 Ω
C1, C4
3.77 nF
11.3 nF
22.6 nF
C2, C3
4.02 nF
12.2 nF
25.5 nF
L1, L2
96.0 μH
336 μH
983 μH
NOTES: (1) All values are ± 1 %. (2) 2.7 km (9 kft) and 4.6 km (15 kft) can be made up of cascaded sections of the above.
359 360
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361 362 363 364 365 366 367 368 369 370 371 372 373 374 375
4.3
376 377 378 379 380 381
4.3.1 SEND PERFORMANCE The send performance of a speakerphone is determined by its acoustical-to-electrical transfer characteristics. To determine the send performance, requirements for frequency response, Send Loudness Rating (SLR), directionality (SLRD), linearity, distortion, noise and, if supported, muting are specified.
382 383 384 385 386 387
4.3.1.1 SEND FREQUENCY RESPONSE 4.3.1.1.1 Requirement The send frequency response for a 2.7 km artificial line shall fall within the upper and lower limits in Table 2 (shown in Figure 6). These are floating limits, which are positioned vertically for the best fit to the actual measurement.
TRANSMISSION PERFORMANCE
The transmission performance of a speakerphone is determined by its acoustical-to-electrical and electrical-to-acoustical transfer characteristics. A free field microphone and P.51 compliant mouth simulator or a Head and Torso Simulator (HATS) with a Type 3.3 or a Type 3.4 ear simulator (see ITU-T Recommendation P.57) shall be used for all transmission performance measurements. If a HATS is used it shall be equipped with both a right and left ear simulator. Mouth and ear simulator calibration shall be performed according to IEEE Std 1329. The measuring equipment and the speakerphone shall be positioned as described in IEEE Std 1329 . The Test Table used shall meet the requirements of IEEE Std 1329. The default test signal for speakerphones shall be the ITU-T Recommendation P.50 male. The long term spectral average of P.50 Artificial Speech is very similar to real speech. Any test signal that produces identical results is considered an acceptable test signal. In the rare case that it can be shown that P.50 is not an appropriate test signal for a specific device, a real speech test signal may be used.
19
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Table 2 – Send frequency response limits
389 Limit Curve
Nominal 1/3 Octave Band (Hz)
Lower Band Mask Limit
Upper Band Mask Limit
Send Response Limit
(Hz)
(Hz)
(dB)
Upper Limit
100 125 160 to 1000 1250 1600 2000 to 3150 4000
89.1 112 141 1122 1413 1778 3548
112 141 1122 1413 1778 3548 4467
-3.5 0.5 3.5 5.5 7.5 8.5 3.5
Lower Limit
315 400 500 630 800 1000 to 2000 2500 3150
282 356 447 562 708 891 2239 2818
356 447 562 708 891 2239 2818 3548
-9.5 -8.5 -7.5 -6.5 -5.5 -3.5 -6.5 -9.5
390 15
Arbitrary Level (dB)
10 5 12 dB
0 -5 -10 -15 -20 100
391 392 393
1000 Frequency (Hz)
Figure 6 – Send frequency response limits
394
20
10000
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395 396 397 398 399 400 401 402 403 404 405
4.3.1.1.2 Method of Measurement 1. The send frequency response shall be measured using 0 km, 2.7 km, and 4.6 km artificial lines using the test circuit shown in Figure 1. 2. The nominal test signal level shall be 0 dBPa at the MRP. 3. The test signal for this test shall be the ITU-T Recommendation P.50 male artificial speech signal. 4. The measurement shall be made over a minimum range of 100 Hz through 8000 Hz using realtime analysis with 1/3 octave or smaller bands averaged over the entire duration of the test signal. If smaller bands are used then the response shall be band averaged to 1/3 octave before applying the mask. 5. The send sensitivity is expressed in terms of dBV/Pa.
406 407 408 409 410 411
4.3.1.2 SEND LOUDNESS RATING (SLR) 4.3.1.2.1 Requirement The SLR values for 0 km, 2.7 km, and 4.6 km artificial lines shall be calculated from the send frequency response measurements (4.3.1.1) as described in Annex B and shall fall within the ranges given in Table 3.
412
Table 3 – Send loudness rating limits Send Loudness Rating (SLR) Nominal Artificial line, km dB
Mandatory Range, dB
0
11
22 to 6
2.7
13
24 to 8
4.6
15
26 to 10
413 414 415
NOTES: 1. Loudness rating values represent system losses. More positive values of SLR represent quieter send levels.
416
2. The nominal SLR values are based on ITU-T P.340. (See also TIA-810-B, and TIA-920.)
417 418
3. Send Automatic Gain Control (AGC) is a subject for further study which may be addressed in the next revision of this standard.
419
21
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4.3.1.3 SEND LOUDNESS RATING DIRECTIONALITY (SLRD) 4.3.1.3.1 Requirement The SLRD values should be less than the limits given in Table 4. Table 4 – Send Loudness Rating Directionality Limits. Angle Degrees CCW
SLRD (dB)
30
+/- 3
60
< -3
90
< -3
120
< -3
150
< -3
180
< -3
210
< -3
240
< -3
270
< -3
300
< -3
330
+/- 3
Notes: 1. The intent is to have consistent loudness when the talker is +/- 30 degrees from the center axis. 2. The intent is to ensure that there is no more than 3dB gain from the 0 degree axis when measured at any other angle.
430 431 432 433 434 435 436 437 438 439 440 441
4.3.1.3.2 Method of Measurement 1. The send frequency response shall be measured according to 4.3.1.1 at the 0 degree angle with a 2.7 km artificial line and the Send Loudness Rating calculated from the data. 2. The speakerphone is then rotated about its physical center 30 degrees counter-clockwise. Take care to keep the center of the lip ring of the mouth simulator at a constant distance from the physical center of the speakerphone. 3. A second frequency response measurement shall be made and the Send Loudness Rating calculated. 4. This process is continued for the remaining positions listed in Table 4. 5. The SLRD for each angle is the difference between the SLR at the angle and the SLR at 0 degrees.
442 443 444 445 446 447 448
4.3.1.4 SEND DISTORTION AND NOISE 4.3.1.4.1 Requirement The ratio of the signal power to the total distortion and noise power of the signal output shall be above the limits given in Table 5. Use IEEE-269 to determine if the product is activated for each test point, especially at lower test levels. Activation threshold is dependent on both level and frequency. For any point that is not activated this requirement does not apply. It is recommended that the send distortion and noise performance also be confirmed using subjective listening tests.
22
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DRAFT 18
4.3.1.4.2 Method of Measurement 1. Send distortion and noise is measured according to IEEE Std 1329. 2. The test stimulus is white noise band limited to 1/3rd octave and pulsed 250ms ON, 150ms OFF. 3. Apply the test signal at the MRP, at the levels given in Table 5 using the center frequencies and band limits specified below: Stimulus Center Freq 500 800 1000
455 456 457 458 459 460
TIA-470.120-C
Band Limits (Hz) 450 710 900
560 900 1120
4. Process the measured data using Hanning Windowing with 10Hz (@@@ask Glenn why 10Hz and not 31Hz) resolution FFT. After time averaging, remove the data within the notch frequency band specified below: (@@@ Editor’s Note: We need to specify a frequency range for the FFT analysis – possibly 25Hz to 6000Hz per IEEE 269A-2006.) @@@ need to harmonize with 1329/269 Stimulus Center Analysis Notch Freq (Hz) Freq 500 350 650 800 650 950 1000 850 1150
461 462 463
5. Calculate the ratio of the signal power to the total Psophometric-weighted distortion and noise power of the signal output.
464
Table 5 – Send Signal-to-Total Distortion and Noise Ratio Limits.
465
Send Level at the MRP (dBPa)
Send Ratio (dB) @ 500 to 1000 Hz
-10
26
-5
26
0
26
+5
26
+10
24
Note: 26 dB = 5%, 30 dB = 3.2%
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466 467 468 469 470 471 472
4.3.1.5 SEND OFF-HOOK NOISE 4.3.1.5.1 Requirement The psophometric-weighted telephone set noise (see Annex A) shall not exceed -69 dBmp when measured with 0 km, 2.7 km and 4.6 km artificial lines over a minimum period of 5 seconds.
473 474 475 476 477 478 479 480 481 482 483 484
4.3.1.5.2 Method of Measurement The send off-hook noise measurement shall be made as described in IEEE Std 1329. The speakerphone noise shall be measured using the test circuit shown in Figure 1 except no signal shall be applied at the MRP. The noise shall be measured under the following conditions: 1. The measurements shall be made in the Off-Hook mode with 0 km, 2.7 km, and 4.6 km artificial lines. 2. The microphone shall be isolated from sound input and mechanical disturbances. The background noise level shall be less than 29 dBA. 3. The measurement shall be taken over a minimum period of 5 seconds. 4. Microphone Muting shall not be used to provide room noise isolation. 5. Steps should be taken to ensure the speakerphone is fully operating in the send mode.
485 486 487 488 489
4.3.1.6 SEND ON-HOOK NOISE 4.3.1.6.1 Requirement The telephone set noise shall not exceed -80 dBmp with a 0 km artificial line measured over a minimum period of 5 seconds.
490 491 492 493
4.3.1.6.2 Method of Measurement The telephone set noise shall be measured using the test circuit shown in Figure 1 except no signal shall be applied at the MRP.
494 495 496 497 498 499
4.3.1.7 OFF-HOOK SEND SINGLE FREQUENCY INTERFERENCE 4.3.1.7.1 General Narrow-Band noise, including single frequency interference, is an impairment that can be perceived as a tone depending on its level relative to the overall weighted noise level. This test measures the weighted noise level characteristics in narrow bands of not more than 31 Hz.
500 501 502 503
4.3.1.7.2 Requirement The send single frequency interference shall not exceed -78 dBmp with 0 km, 2.7 km and 4.6 km artificial lines when measured over a minimum period of 5 seconds.
504 505 506 507 508 509 510 511
4.3.1.7.3 Method of Measurement The speakerphone noise shall be measured using the test circuit shown in Figure 1 except no signal shall be applied at the MRP. The noise shall be measured under the following conditions: 1. The measurements shall be made in the Off-Hook mode with 0 km, 2.7 km, and 4.6 km artificial lines. 2. The microphone shall be isolated from sound input and mechanical disturbances. The background noise level shall be less than 29 dBA (as specified in IEEE Std 1329). 3. Measure the psophometric-weighted noise level with a selective voltmeter or spectrum analyzer 24
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with an effective bandwidth of not more than 31 Hz, over the frequency range of 100 to 3500 Hz. 4. If FFT analysis is used, then “Flat Top” windowing shall be employed. 5. Microphone Muting shall not be used to provide room noise isolation. 4.3.1.8 SEND MUTING 4.3.1.8.1 Requirement If supported, the send muting (i.e., manual mute mode selection) shall be determined over the frequency range of 100 Hz to 8000 Hz. During muting, any transmitted signal in the frequency range for 0 km, 2.7 km, and 4.6 km artificial lines shall not exceed -80 dBV at the SETP.
522 523 524
4.3.1.8.2 Method of Measurement The send muting shall be measured using the test circuit shown in Figure 1. 1. Set the Mouth simulator level to 0 dBPa.
525
2. The Send Muting measurement shall be made with 0 km, 2.7 km and 4.6 km artificial lines.
526 527
3. This measurement should be done with a narrow band meter that has a noise floor less than –86 dBV.
528 529 530 531 532 533 534 535
4.3.1.9 DYNAMIC SEND BACKGROUND NOISE SUPPRESSION Attenuation of transmit noise (dynamic mute or squelch). The purpose of this test is to check the background noise attenuation performance. @@@ We need to review the switching requirements then re-visit this test to determine if it is necessary. (This test was intended to confirm that the UUT will identify the 1kHz tone as noise and then attenuate it within a specified period of time.) @@@ this test is only applicable to Type 2 and Type 3, if consistent with P.340. The following five steps need to be followed in order to check this feature.
536
1. Line feed 48 Vdc, No current limit, 2 x 200 ohms, 2 x 20 μF, 600 ohm termination.
537
2. Apply sound source (Loudspeaker) output of 65 dBSPL (1 kHz) to Hands-free unit.
538
3. Measure T-R level at 400 ms intervals, from time = 0.0 to 20 seconds.
539
4. Check that transmit level at 1.2 second is ±2dB from the transmit level at 400 ms.
540
5. Check that the transmit level at 18seconds is attenuated by at least 12 dB from the transmit level
541 542
at 400ms.
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543 544 545 546 547 548 549 550 551 552 553 554
4.3.2 RECEIVE PERFORMANCE The receive performance of a speakerphone is determined by its electrical-to-acoustical transfer characteristics. To determine the receive performance, requirements for frequency response, Receive Loudness Rating (RLR), Receive Loudness Rating Directionality (RLRD), linearity, distortion, noise and volume control are specified. The speakerphone receive volume control shall be set to the Reference Volume Control Setting when checking for compliance with the requirements for receive characteristics, unless specifically stated otherwise. The stimulus levels specified for receive tests are specified as 900 ohm nominally loaded (one-half of the open circuit voltage). Following a calibration, the resistive load is removed and the source is connected to the speakerphone without further adjustment.
555
4.3.2.1
556
The CPE is expected to receive a wide dynamic range of input speech levels. A speaker volume
557 558
control (manual or automatic or both) provides a means to compensate for this variable input level.
559 560 561 562
4.3.2.1.1 Requirement 1. The CPE shall meet the Mandatory requirements and should meet the Recommended requirements in Table X. Different volume control settings may be used to meet the requirements at the different input levels.
563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587
RECEIVE LEVEL
Test Condition
Mandatory
Recommended
–18 dBV into a 0 km loop
≥ 65 dB SPL
≥70 dB SPL
–25 dBV into a 2.7 km loop
≥ 65 dB SPL
≥70 dB SPL
–32 dBV into a 4.6 km loop
≥ 62 dB SPL
≥70 dB SPL
Note: The test signal input levels were derived as follows: 1. High Level (-18dBV): Highest level possible for using P.50 without the PSTN clipping the test signal. 2. Medium Level (-25dBV): Represents the mean Far-End Active Speech Level (ASL) (28dBm) at the CPE recorded in Bellcore SR-2476 Annex B. 3. Low Level (-32dBV): Represents two standard deviations (2 x 4.5dB = 9dB) from the mean Far-End Active Speech Level (ASL) at the CPE recorded in Bellcore SR-2476 Annex B. Switched loss (for echo suppression) may squelch lower levels. 2. The CPE shall have a volume control setting that will produce a receive level of less than 60dBSPL with a test level of -18dBV (0km loop). 4.3.2.1.2 Method of Measurement 1. Perform a power sum over the entire range of the test signal (see IEEE-269-2002 Annex G.6).
26
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4.3.2.2 RECEIVE LEVEL DIRECTIONALITY (RLD) @@@NEEDS WORK 4.3.2.2.1 Requirement The RLD values should be less than the limits given in Error! Reference source not found.. Table 6 – Receive Level Directionality Limits. Angle Degrees CCW
RLD (dB)
30
5
60
5
90
10
120
15
150
15
180
15
210
15
240
15
270
10
300
5
330
5
593 594 595 596 597 598 599 600 601 602 603 604 605
4.3.2.2.2 Method of Measurement 1. The receive level shall be measured according to 4.3.2.1 at the 0 degree angle at -25dBV with a 2.7 km artificial line. 2. The speakerphone is then rotated about its physical center 30 degrees counter-clockwise. Take care to keep the center of the lip ring of the mouth simulator at a constant distance from the physical center of the speakerphone. 3. A second receive level measurement shall be made. 4. This process is continued for the remaining positions listed in Error! Reference source not found.. 5. The RLD for each angle is the absolute value of the difference between the Receive Level at the angle and the Receive Level at 0 degrees.
606 607 608
27
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609 610 611 612 613 614 615
4.3.2.3 RECEIVE FREQUENCY RESPONSE 4.3.2.3.1 Requirement The receive frequency response recorded for a 2.7 km artificial line shall fall within the upper and lower limits in Table 7 (shown in Figure 7) between 100 Hz and 8 kHz. These are floating limits, which are positioned vertically for the best fit to the actual measurement.
616
Table 7 – Mandatory Receive frequency response limits Limit Curve
1/3 Octave Band (Hz)
Lower Band Mask Edge
Upper Band Mask Edge
Receive Response Limit (dB)
Upper Limit
100 125 160 200 to 4000 5000 6300 8000
89.1 112 141 178 4467 5623 7079
112 141 178 4467 5623 7079 8913
-4 -1 2 5 -2 -9 -15
Lower Limit
400 500 to 2000 2500 3150
355 447 2239 2818
447 2239 2818 3548
-6 -5 -8 -11
617
28
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Table 8 – Desired Receive frequency response limits Limit Curve
1/3 Octave Band (Hz)
Lower Band Mask Edge
Upper Band Mask Edge
Receive Response Limit (dB)
Upper Limit
100 125 160 200 to 4000 5000 6300 8000
89.1 112 141 178 4467 5623 7079
112 141 178 4467 5623 7079 8913
-4 -1 2 5 -2 -9 -15
Lower Limit
315 400 500 to 2000 2500 3150
282 355 447 2239 2818
355 447 2239 2818 3548
-7 -6 -5 -8 -11
29
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619 620 15 Arbitrary Level (dB)
10 5 10 dB
0 -5 -10 -15 -20 100
621 622 623
1000 Frequency (Hz)
10000
Figure 7 – Receive frequency response limits
624 625 626 627 628 629 630 631 632 633 634 635 636
4.3.2.3.2 Method of Measurement 1. The receive frequency response shall be measured using 0 km, 2.7 km, and 4.6 km artificial lines using the test circuit shown in Figure 2 with the generator level set for a nominally loaded level of –16 dBV with the CPE at the Reference Volume Control Setting. 2. The measurement shall be made over a minimum range of 100 Hz through 8000 Hz using realtime analysis with 1/3 octave or smaller bands averaged over the entire duration of the test signal. If smaller bands are used then the response shall be band averaged to 1/3 octave before applying the mask. 3. If a HATS is used, after correction to the ERP, the measured receive frequency responses for the right and left ears are summed on a voltage basis. 4. The receive sensitivity is expressed in terms of dBPa/V.
30
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637 638 639 640
4.3.2.4 RECEIVE DISTORTION AND NOISE 4.3.2.4.1 Requirement The ratio of the signal power to the total A-weighted distortion and noise power should be above the limits given in Table 9, unless the measured sound pressure is less than –50 dBPa.
641 642 643 644 645 646 647
4.3.2.4.2 Method of Measurement 1. Receive distortion and noise is measured according to IEEE Std 1329 (clause 9.4.6) with the speakerphone at the Reference Volume Control Setting. 2. The test stimulus is white noise band limited to 1/3rd octave and pulsed 250ms ON, 150ms OFF. 3. Apply the test signal at the levels given in Table 9 using the center frequencies and Band Limits specified below: Stimulus Center Freq 500 800 1000
648 649 650 651 652 653
Band Limits (Hz) 450 710 900
560 900 1120
4. Process the measured data using Hanning Windowing with 10Hz resolution FFT. After time averaging, remove the data within the notch frequency band specified below: (@@@ Editor’s Note: We need to specify a frequency range for the FFT analysis – possibly 25Hz to 8500Hz per IEEE 269A-2006.) Stimulus Center Freq 500 800 1000
Analysis Notch Freq (Hz) 350 650 850
650 950 1150
654 655 656
5. Calculate the ratio of the signal power to the total A-weighted distortion and noise power of the signal output.
657
Table 9 – Receive Signal-to-Total Distortion and Noise Ratio Limits.
658
Receive Level (dBV)
Receive Ratio (dB) @ 500 to 1000 Hz
-30
26
-23
26
-16
26
-8
26
0
24
Note: 24 dB = 6.3%, 28 dB = 4%, 30 dB = 3.2%
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659 660 661 662 663 664 665
4.3.2.5 OFF-HOOK NOISE 4.3.2.5.1 Requirement The acoustic noise level from the speakerphone at the Reference Volume Control Setting shall not exceed 40 dBA for 0 km, 2.7 km, and 4.6 km artificial lines when measured over a minimum period of 5 seconds.
666 667 668 669 670 671 672 673 674 675 676 677
4.3.2.5.2 Method of Measurement The measurement shall be made as described in IEEE Std 1329, clause 9.4.4. The speakerphone noise shall be measured using the test circuit shown in Figure 2 except no signal shall be applied at the RETP. The noise shall be measured under the following conditions: 1. The measurements shall be made in the Off-Hook mode with 0 km, 2.7 km, and 4.6 km artificial lines. 2. The microphone shall be isolated from sound input and mechanical disturbances. The background noise level shall be less than 29 dBA (as specified in IEEE Std 1329). 3. The measurement shall be taken over a minimum period of 5 seconds. 4. Microphone Muting shall not be used to provide room noise isolation. 5. The receive noise measurements shall be referenced to the ERP.
678 679 680 681 682 683 684
4.3.2.6 OFF-HOOK RECEIVE SINGLE FREQUENCY INTERFERENCE 4.3.2.6.1 General Narrow-Band noise, including single frequency interference, is an impairment that can be perceived as a tone depending on its level relative to the overall weighted noise level. This test measures the weighted noise level characteristics in narrow bands of not more than 31 Hz, which can then be compared to the overall weighted background noise level.
685 686 687 688 689
4.3.2.6.2 Requirement The receive A-weighted single frequency interference at the Reference Volume Control Setting shall be 10 dB quieter than the A-weighted broadband noise floor when measured over a minimum period of 5 seconds.
690 691 692 693 694 695 696 697
4.3.2.6.3 Method of Measurement 1. Receive noise is measured according to IEEE Std 1329, (clause 9.4.4) using the test circuit shown in Figure 2 except no signal shall be applied at the RETP. 2. The A-weighted noise level is measured with a selective voltmeter or spectrum analyzer having an effective bandwidth of not more than 31 Hz, over the frequency range of 100 to 8000 Hz. 3. If FFT analysis is used, then “Flat Top” windowing shall be employed. 4. The ambient noise for this measurement shall not exceed 29 dBA.
698 699 700 701 702 703 704
4.3.2.7
RECEIVE VOLUME DYNAMIC RANGE @@@NEEDS WORK IN LIGHT OF NEW RECEIVE LEVEL REQUIREMENT 4.3.2.7.1 Requirement 1. The speakerphone receive volume control shall provide greater than or equal to 8 dB of gain relative to the Reference Volume Control Setting. 2. The volume control should provide at least 16 dB of attenuation relative to the Reference Volume Control Setting.
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705 706 707 708 709 710 711
4.3.2.7.2 Method of Measurement 1. The receive level is measured according to 4.3.2.1 with the volume control at the minimum and maximum volume control setting using 0 km, 2.7 km, and 4.6 km artificial lines. 2. Calculate the RLR from the measured responses as described in Annex B. A correction factor of 8dB shall then be subtracted per ITU-T P.581, clause 5.4. @@@ needs to be re-written based on mic/mouth method.
712 713 714 715 716 717 718
4.4
719 720
4.4.1
721 722
4.4.1.1 SEND BUILD-UP TIME Descriptions of timings and levels refer to IEEE-1329 Figure 12.
723 724 725 726
4.4.1.1.1 Requirement The Send Build-Up Time shall be < 50 ms. preferably below 10 ms.)
727 728 729 730 731 732
4.4.1.1.2 Method 1. Adjust the test signal for L1_MRP = 0dBPa, T1 = 100ms 2. Apply the test signal to the speakerphone and measure the time from the start of L1_MRP until the time at which the output level at the SETP reaches 3dB below complete removal of the insertion loss in the send direction.
733 734
4.4.1.2 RECEIVE BUILD-UP TIME Descriptions of timings and levels refer to IEEE-1329 Figure 13.
735 736 737 738
4.4.1.2.1 Requirement The Receive Build-Up Time shall be < 50 ms. (@@@ Note: P.340 = Should be less than 15 ms and preferably below 10 ms.)
739 740 741 742 743
4.4.1.2.2 Method 1. Adjust the test signal for L1_RETP = –30dBV, T1 = 100ms. 2. Apply the test signal to the speakerphone and measure the time from the start of L1_RETP until the time at which the output level reaches 3dB below complete removal of the insertion loss in the receive direction.
VOICE SWITCHING PERFORMANCE
The test setup for voice switching performance testing shall be the same as that used for speakerphone transmission testing except that a receiving test microphone shall be placed 1cm from the center of the speakerphone loudspeaker along the axis of the speaker (the Near Field Test Point per IEEE-1329 clause 3.28). A periodic 1004 Hz tone burst test signal shall be used to perform these tests. SINGLE TALK PERFORMANCE
(@@@ Note: P.340 = Should be less than 15 ms and
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744 745 746 747
4.4.2 DOUBLE-TALK PERFORMANCE 4.4.2.1 RECEIVE TO SEND SWITCHING TIME (SEND SWITCHING TIME) Descriptions of timings and levels refer to IEEE-1329 Figure 14.
748 749 750 751
4.4.2.1.1 Requirement The Receive to Send Switching Time shall be <150 ms . and >50ms. This is not applicable to Full Duplex. (@@@ P.340 says: Switching time TS – Should be approximately 100 ms.)
752 753 754 755 756 757 758 759 760
4.4.2.1.2 Method 1. Adjust the send test signal for L1_MRP = 0dBPa, T1 = 300ms. 2. Adjust the receive test signal for L0_RETP = –30dBV, T0 = 200ms. 3. Synchronize the two test signals so that L1_MRP begins 20ms (+/-1ms) before the end of L0_RETP. 4. Apply the synchronized test signals to the speakerphone and measure the time from the end of L0_RETP until the time at which the send output level at the SETP reaches 3dB below complete removal of the insertion loss.
761 762
4.4.2.2 RECEIVE TO SEND SWITCHING THRESHOLD LEVEL Descriptions of timings and levels refer to IEEE-1329 Figure 14.
763 764 765
4.4.2.2.1 Requirement The Receive to Send Switching Threshold Level shall be <-10 dBPa
766 767 768 769 770 771 772 773
4.4.2.2.2 Method 1. Adjust the send test signal for L1_MRP = –20dBPa, T1 = 300ms. 2. Adjust the receive test signal for L0_RETP = –30dBV, T1 = 200ms. 3. Synchronize the two test signals so that L1_MRP begins 20ms (+/-1ms) before the end of L0_RETP. 4. Apply the synchronized test signals to the speakerphone. Increase the level of L1_MRP to determine the threshold level where full transmission direction change occurs.
774 775
4.4.2.3 SEND TO RECEIVE SWITCHING TIME (RECEIVE SWITCHING TIME) Descriptions of timings and levels refer to IEEE-1329 Figure 15.
776 777 778 779
4.4.2.3.1 Requirement The Send to Receive Switching Time shall be <150 ms and >50ms. This is not applicable to Full Duplex. (@@@ P.340 says: Switching time TS – Should be approximately 100 ms.)
780 781 782 783 784 785 786 787
4.4.2.3.2 Method 1. Adjust the send test signal for L0_MRP = 0dBPa, T0 = 200ms. 2. Adjust the receive test signal for L1_RETP = –30dBV, T1 = 300ms. 3. Synchronize the two test signals so that L1_RETP begins 20ms (+/-1ms) before the end of L0_MRP. 4. Apply the synchronized test signals to the speakerphone and measure the time from the end of L0_MRP until the time at which the receive output level at the NFTP reaches 3dB below complete removal of the insertion loss.
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788 789 790
4.4.2.4 SEND TO RECEIVE SWITCHING THRESHOLD LEVEL Descriptions of timings and levels refer to IEEE-1329 Figure 15.
791 792 793
4.4.2.4.1 Requirement The Send to Receive Switching Threshold Level shall be <-12 dBV.
794 795 796 797 798 799 800 801 802
4.4.2.4.2 Method 1. Adjust the send test signal for L0_MRP = 0dBPa, T0 = 200ms. 2. Adjust the receive test signal for L1_RETP = –55dBV, T1 = 300ms. 3. Synchronize the two test signals so that L1_RETP begins 20ms +/-10ms before the end of L0_MRP. 4. Apply the synchronized test signals to the speakerphone. 5. Increase the level of L1_RETP to determine the threshold level where full transmission direction change occurs.
803 804 805
4.4.2.5 ATTENUATION RANGE 4.4.2.5.1 Requirement Based on the measured Attenuation Range, the speakerphone shall be classified as follows:
806
Table 10 – Speakerphone Duplex Capability and Classification Attenuation Range < 3dB ≥ 3dB, ≤ 20dB > 20dB
Classification Type 1 Type 2 Type 3
Duplex Capability Full Duplex Partial Duplex No Duplex
807 808 809 810 811 812 813 814 815 816
4.4.2.5.2 Method 1. Use the procedure for “Receive to Send Switching Time” to measure the difference between the minimum send level at full loss insertion (period ΔT in IEEE-1329 Figure 14) and the maximum send level obtained after transmission reversal. 2. Use the procedure for “Send to Receive Switching Time” to measure the difference between the minimum receive level at full loss insertion (period ΔT in IEEE-1329 Figure 15) and the maximum receive level obtained after transmission reversal. 3. The larger of the two measurements is the attenuation range.
35
PN-3-4350.120-RV3
DRAFT 18
TIA-470.120-C
817 818
4.4.2.6 RECEIVE TO SEND TAKE-OVER TIME (SEND TAKE-OVER TIME) Descriptions of timings and levels refer to IEEE-1329 Figure 16.
819 820 821
4.4.2.6.1 Requirement The Receive to Send Take-Over Time shall be <200 ms.
822 823 824 825 826 827 828 829 830
4.4.2.6.2 Method 1. Adjust the send test signal for L1_MRP = 0dBPa, T1 = 300ms. 2. Adjust the receive test signal for L0_RETP = –30dBV, T1 = 500ms. 3. Synchronize the two test signals so that L1_MRP begins 200ms +/-10ms after the start of L0_RETP. 4. Apply the synchronized test signals to the speakerphone and measure the time from the start of L1_MRP until the time at which the send output level at the SETP reaches 3dB below complete removal of the insertion loss.
831 832
4.4.2.7 SEND TO RECEIVE TAKE-OVER TIME (RECEIVE TAKE-OVER TIME) Descriptions of timings and levels refer to IEEE-1329 Figure 17.
833 834 835
4.4.2.7.1 Requirement The Send to Receive Take-Over Time shall be <300 ms.
836 837 838 839 840 841 842 843 844 845 846
4.4.2.7.2 Method 1. Adjust the send test signal for L0_MRP = 0dBPa, T1 = 500ms. 2. Adjust the receive test signal for L1_RETP = –30dBV, T1 = 300ms. 3. Synchronize the two test signals so that L1_RETP begins 200ms +/-10ms after the start of L0_MRP. 4. Apply the synchronized test signals to the speakerphone and measure the time from the start of L1_RETP until the time at which the receive output level at the NFTP reaches 3dB below complete removal of the insertion loss.
847 848 849 850 851 852 853 854 855 856
@@@ FYI - The following info is from Advent’s contribution (TR41.3.10-06-11-006-L) regarding P.340: •
Hang-over time TH – The parameter is broken down to three different performance levels. Behaviour 1 (full duplex) has no specified requirement.
Behaviour 2 (partial duplex) Should be greater than 50 ms and preferably more than 100 ms Behaviour 3 (no duplex) Should be greater than 250 ms
36
PN-3-4350.120-RV3
DRAFT 18
TIA-470.120-C
857 858
Annex A (Normative) – Noise Curves
859
A.1
860 861 862 863
Psophometric weighting is now being used for send noise measurements in the interest of harmonization with other standards. The psophometric weighting is defined in ITU-T Recommendation O.41 (94). The previously used C-message weighting (defined in IEEE Std 7431995) is also shown for comparison purposes.
864
Table A.1 – Psophometric weighting curve
The send and receive noise weighting curves are shown for reference. Send Noise Curves
Table A.2 – C-Message weighting curve
Frequency (Hz)
Relative weight (dB)
Tolerance (± dB)
Frequency (Hz)
Relative weight (dB)
Tolerance (± dB)
16.66
-85.0
–
60
-55.7
2
50
-63.0
2
100
-42.5
2
100
-41.0
2
200
-25.1
2
200
-21.0
2
300
-16.3
2
300
-10.6
1
400
-11.2
1
400
-6.3
1
500
-7.7
1
500
-3.6
1
600
-5.0
1
600
-2.0
1
700
-2.8
1
700
-0.9
1
800
-1.3
1
800
–0.0
0 (reference)
900
-0.3
1
900
0.6
1
1000
0.0
0 (reference)
1000
1.0
1
1200
-0.4
1
1200
–0.0
1
1300
-0.7
1
1400
-0.9
1
1500
-1.2
1
1600
-1.7
1
1800
-1.3
1
1800
-2.4
1
2000
-1.1
1
2000
-3.0
1
2500
-1.1
1
2500
-4.2
1
2800
-2.0
1
3000
-5.6
1
3000
-3.0
1
3500
-8.5
2
3300
-5.1
2
4000
-15.0
3
3500
-7.1
2
4500
-25.0
3
4000
-14.6
3
5000
-36.0
3
4500
-22.3
3
6000
-43.0
–
5000
> -28.7
865
37
PN-3-4350.120-RV3
DRAFT 18
TIA-470.120-C
866
Send Noise Weighting Curves Comparison Psophometric
C-Message
5 -5 -15
dB
-25 -35 -45 -55 -65 -75 -85 10
100
1000
10000
Frequency (Hz)
867 868
Figure A.1 – Psophometric and C-Message noise weighting curves comparison
869
38
PN-3-4350.120-RV3
DRAFT 18
TIA-470.120-C
870
A.2
871 872
The A-weighting curve is defined in ANSI S1.4-1983 (Reaff. 2001)
873
Table A.3 – A-weighting curve
Receive Noise Curve
874 Frequency (Hz) A-Weighting Frequency (Hz) A-Weighting Frequency (Hz) A-Weighting 12.5
-63.4
125
-16.1
1250
0.6
16
-56.7
160
-13.4
1600
1.0
20
-50.5
200
-10.9
2000
1.2
25
-44.7
250
-8.6
2500
1.3
31.5
-39.4
315
-6.6
3150
1.2
40
-34.6
400
-4.8
4000
1.0
50
-30.2
500
-3.2
5000
0.5
63
-26.2
630
-1.9
6300
-0.1
80
-22.5
800
-0.8
8000
-1.1
100
-19.1
1000
0.0
10000
-2.5
12000
-4.3
16000
-6.6
20000
-9.3
875
Receive Noise Weighting Curve A-Weighting 5.0 -5.0 -15.0
dB
-25.0 -35.0 -45.0 -55.0 -65.0 -75.0 -85.0 10
100
1000 Frequency (Hz)
876 877
Figure A.2 – A-weighting noise weighting curve
39
10000
PN-3-4350.120-RV3
878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893
This Annex details the loudness rating calculations and weighting factors relevant to this document. Loudness ratings are used to insure that the loudness of a connection from the Mouth Reference Point (MRP) of the talker to the Ear Reference Point (ERP) of the far end listener is at a satisfactory level. The loudness of the complete path is designated as the Overall Loudness Rating (OLR). The MRP to electrical component is referred to as the Send Loudness Rating (SLR). The electrical to ERP component is the Receive Loudness Rating (RLR). The loudness of the sidetone path of handsets and headsets is referred to as the Sidetone Masking Rating (STMR). Loudness ratings are used rather than simple level measurements because of better subjective correlation. Loudness ratings more closely account for changes in the ear’s sensitivity at different frequencies and its nonlinear response to varying sound levels. The following calculations are based on the 1999 revision of ITU-T Recommendation P.79. Older versions of P.79 should not be used. ITU-T P.79 provides information on the derivation of the loudness rating algorithm. For use in these loudness ratings formulae, frequency response measurements shall be converted to the R10 format, by using band averaging according to IEEE Std 269. At each ISO R10 preferred frequency
⎡1 H ′( f ) = 10 log 10 ⎢ ⎣N
N
∑ 10 i =1
Hi 10
⎤ ⎥ ⎦
where
H’(f) f N i Hi
= response at the new preferred ISO R10 frequency = preferred ISO R10 frequency = number of response values within the 1/3 octave band centered at f = index for each response value within the 1/3 octave band = measured response value (in dB)
For the lowest frequency within the band, i = 1. For the highest included frequency, i = N. The 1/3 octave pass band limit frequencies can be calculated according as:
f = 10( n /10) ± 0.05
904 905
TIA-470.120-C
Annex B (Normative) – Calculation of Loudness Ratings
894 895 896 897 898 899 900 901 902 903
DRAFT 18
Where n is the band number.
40
PN-3-4350.120-RV3
906
B.1
914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933
TIA-470.120-C
Send Loudness Rating (Handset):
Band 17 SLR = - 57.1 log10 ∑ 10(0.1 * 0.175 * (SMJ – Wsi – Ks )) i = Band 4
907 908 909 910 911 912 913
DRAFT 18
where: i Frequency bands from Table 1 of ITU-T P.79 (1999), bands 4-17. SMJ Send frequency response data (Sensitivity, Mouth-to-Junction) in dB(V/Pa). Wsi Send weighting factor from Table 1 of ITU-T P.79 (1999), see Table B.1 Ks Impedance sensitivity correction = 1.76 dB when 900 ohm termination is used in the measurement.
B.2
Receive Loudness Rating (Handset):
Band 17 RLR = - 57.1 log10 ∑ 10(0.1 * 0.175 * (SJE – Wri – LE + KR )) i = Band 4
where: i Frequency bands from Table 1 of ITU-T P.79 (1999), bands 4-17. SJE Receive frequency response data (Sensitivity, Junction-to-Ear) in dB(Pa/V). Wri Receive weighting factor from Table 1 of ITU-T P.79 (1999), see Table B.1 LE Leakage correction is not used when using ear simulators that include leakage such as HATS. (Leakage correction is only used when the handset is sealed to a Type 1 ear. Leakage correction from Table 2 of ITU-T P.79 (1999), see Table B.1 KR Impedance sensitivity correction = 1.76 dB when 900 ohm termination is used in the measurement.
41
PN-3-4350.120-RV3
934 935 936 937 938 939 940 941 942 943 944 945
B.3
DRAFT 18
TIA-470.120-C
Sidetone Masking Rating (Handset):
Band 20 STMR = - 44.4 log10 ∑ 10(0.1 * 0.225 * (SmeST – WMSi)) i = Band 1
where: i Frequency bands from Table 3 of ITU-T P.79 (1999), bands 1-20. SmeST Sidetone frequency response data (Sensitivity, mouth-to-ear) in dB(Pa/Pa). WMSi Sidetone weighting factor from Table 3 of ITU-T P.79 (1999), see Table B.1.
42
PN-3-4350.120-RV3 946
DRAFT 18
TIA-470.120-C
Table B.1 – ITU-T P.79 Tables 1, 2 and 3, Weighting factors for calculating loudness ratings Receive Wri
Send Wsi
Receive LE (dB)
Sidetone WMSi
Band No.
Midfrequency (Hz)
1
100
110.4
2
125
107.7
3
160
104.6
4
200
76.9
85.0
8.4
98.4
5
250
62.6
74.7
4.9
94.0
6
315
62.0
79.0
1.0
89.8
7
400
44.7
63.7
-0.7
84.8
8
500
53.1
73.5
-2.2
75.5
9
630
48.5
69.1
-2.6
66.0
10
800
47.6
68.0
-3.2
57.1
11
1000
50.1
68.7
-2.3
49.1
12
1250
59.1
75.1
-1.2
50.6
13
1600
56.7
70.4
-0.1
51.0
14
2000
72.2
81.4
3.6
51.9
15
2500
72.6
76.5
7.4
51.3
16
3150
89.2
93.3
6.7
50.6
17
4000
117.0
113.8
8.8
51.0
18
5000
49.7
19
6300
50.0
20
8000
52.8
947
43
PN-3-4350.120-RV3
948 949 950
DRAFT 18
TIA-470.120-C
Annex C (Normative) – ISO R-40 Frequencies Table C.1 – ISO R-40, ISO R-10,1/12th Octave and 1/3rd Octave Frequencies
R40 Preferred Frequencies, Hz. 90 95 100 106 112 118 125 132 140 150 160 170 180 190 200 212 224 236 250 265 280 300 315 335 355 375 400 425 450 475 500 530 560 600 630 670 710 750 800 850 900 950 1000 1060 1120
1/12 Oct. Band Center Freq, Hz.
1/3 Oct. Band Center Freq, Hz.
91.73 97.16 102.92 109.02 115.48 122.32 129.57 137.25 145.38 153.99 163.12 172.78 183.02 193.87 205.35 217.52 230.41 244.06 258.52 273.84 290.07 307.26 325.46 344.75 365.17 386.81 409.73 434.01 459.73 486.97 515.82 546.39 578.76 613.06 649.38 687.86 728.62 771.79 817.52 865.96 917.28 971.63 1029.20 1090.18
R10 Preferred Frequencies, Hz.
100.00
100
125.89
125
158.49
160
199.53
200
251.19
250
316.23
315
398.11
400
501.19
500
630.96
630
794.33
800
1000.00
1000
951 952
Table C.2 – ISO R-40, ISO R-10,1/12th Octave and 1/3rd Octave Frequencies (Continued)
44
PN-3-4350.120-RV3
DRAFT 18
R40 Preferred Frequencies, Hz.
1/12 Oct. Band Center Freq, Hz.
1120 1180 1250 1320 1400 1500 1600 1700 1800 1900 2000 2120 2240 2360 2500 2650 2800 3000 3150 3350 3550 3750 4000 4250 4500 4750 5000 5300 5600 6000 6300 6700 7100 7500 8000 8500 9000 9500 10000 10600 11200
1154.78 1223.21 1295.69 1372.46 1453.78 1539.93 1631.17 1727.83 1830.21 1938.65 2053.53 2175.20 2304.09 2440.62 2585.23 2738.42 2900.68 3072.56 3254.62 3447.47 3651.74 3868.12 4097.32 4340.10 4597.27 4869.68 5158.22 5463.87 5787.62 6130.56 6493.82 6878.60 7286.18 7717.92 8175.23 8659.64 9172.76 9716.28 10292.01 10901.84
TIA-470.120-C
1/3 Oct. Band Center Freq, Hz
953 954
45
R10 Preferred Frequencies, Hz.
1258.93
1250
1584.89
1600
1995.26
2000
2511.89
2500
3162.28
3150
3981.07
4000
5011.87
5000
6309.57
6300
7943.28
8000
10000.00
10000
PN-3-4350.120-RV3
955 956 957 958 959
DRAFT 18
TIA-470.120-C
Annex D (Informative) – Loss Plan and Loudness Rating References and Hierarchy
G.101 SLR 8 dB RLR 2 dB OLR 10 dB Digital
Analog
TIA-810-A SLR 8 dB RLR 2 dB
TIA-470.110-C SLR 8 dB RLR -3 dB @ 2.7 km
T1.508 Loss A/D 0 dB Loss D/A 6 dB
TIA-912-A Loss A/D 0 dB Loss D/A 6 dB
TIA-464-C TIA-464-C-1 Loss A/D 0 dB Loss D/A 6 dB
ESLR = SLR + Loss A/D = 8 + 0 = 8 dB ERLR = RLR + Loss D/A = -3 + 6 = 3 dB OLR = SLR + Loss A/D + Loss D/D + Loss D/A + RLR = 8 + 0 + 0 + 6 - 3 = 11 dB
T1.508 Loss D/D 0 dB Loss D/D 0 dB
TIA-920 SLR 8 dB RLR 2 dB
TIA-912-A Loss D/D 0 dB Loss D/D 0 dB
TIA-464-C TIA-464-C-1 Loss D/D 0 dB Loss D/D 0 dB
ESLR = SLR + Loss D/D = 8 + 0 = 8 dB ERLR = RLR + Loss D/D = 2 + 0 = 2 dB OLR = SLR + Loss D/D + RLR = 8 + 0 + 2 = 10 dB
Where: ESLR and ERLR are the “Equivalent” SLR and RLR at the 0 dBr point.
960 961
Figure D.1 – Hierarchical Relationship between Loudness Rating and Loss Plan Standards
962
46
PN-3-4350.120-RV3
963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005
DRAFT 18
TIA-470.120-C
Annex E (Informative) – Nominal Frequency Response Characteristics and Loudness Rating Calculations This standard specifies the send and receive loudness ratings, as well as the sidetone loudness, using ITU-T Recommendation P.79. Previous revisions of this standard used the methodology of IEEE Std 661. The intent of this annex is to provide information on the approximate relationship between the loudness ratings obtained using the two methods. In order to accomplish this, nearly ideal send and receive response curves were drawn through the specified frequency response templates. The overall levels of the curves were adjusted to produce the specified nominal loudness rating values of SLR = 8 dB and RLR = 2 dB. The corresponding IEEE Std 661 objective loudness rating parameters, TOLR = -49.4 dB and ROLR = 52.7 dB, were then calculated from the same frequency response curves, taking into account the correction from 600 ohm to 900 ohm impedances. For sidetone, the send and receive frequency response curves were added together and an appropriate overall level shift was made to provide the nominal sidetone masking rating value of STMR = 15 dB. This simulates a design in which a part of the send signal is fed to the receive path via a frequency independent loss path to produce the sidetone signal. The corresponding IEEE Std 661 sidetone loudness rating parameter, SOLR = 5.5 dB, was then calculated from the response curve. Figure E.1and Figure E.2 show the send and receive sensitivity curves, and Table E.1 provides the details of the various loudness rating calculations. The first column of the table lists the ISO preferred 1/3 octave frequencies from 100 to 8000 Hz; it also includes the frequencies 300 Hz and 3300 Hz that are the endpoints of the IEEE loudness rating calculation bandwidth. The next three columns of the table list the nominal send, receive, and sidetone sensitivities at each of the specified frequencies. There are then seven columns in the table associated with the P.79 loudness rating calculations. The first three of these columns provide the W-weights for send, receive and masked sidetone used in the P.79 calculation algorithm. The fourth column is the LE factor included in the receive calculation to take account of acoustic leakage between the ear and the handset. Finally, there are three columns providing the SLR, RLR, and STMR calculations. The table entries at each frequency indicate the relative weight that frequency has on the overall loudness, taking into account the frequency response, the W-weight, and (for receive) the LE factor. The send and receive loudness ratings are calculated over the frequency range from 200 to 4000 Hz, whereas the sidetone masking rating is calculated over the range from 100 to 8000 Hz, both in keeping with the latest version of P.79. The actual loudness rating is shown in the last row of the table. The final three columns of the table are associated with the IEEE Std 661 loudness ratings. Since this method uses a flat weighting in which equally spaced intervals on a logarithmic frequency scale receive equal weight, no separate column of weights is necessary. Neither is any The final three columns of the table are associated with the IEEE Std 661 loudness ratings. Since this method uses a flat weighting in which equally spaced intervals on a logarithmic frequency scale receive equal weight, no separate column of weights is necessary. Neither is any allowance made for acoustic leakage between the ear and the handset in the receive calculation. The table entries in each column represent the relative contribution made by the frequency interval from the frequency just above the entry in the table to the frequency of the entry in the table. The actual loudness ratings again appear in the last row of the table.
47
PN-3-4350.120-RV3 1006 1007 1008 1009
TIA-470.120-C
The exact calculations in the table give the following relationships between P.79 and IEEE Std 661 loudness ratings: SLR (P.79) = TOLR (IEEE) + 57.4 dB
1010
RLR (P.79) = ROLR (IEEE) - 50.7 dB
1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023
DRAFT 18
STMR (P.79) = SOLR (IEEE) + 9.5 dB These relationships take into account a nominal 600 ohm impedance for the P.79 calculations and a nominal 900 ohm impedance for the IEEE Std 661 calculations. There are no other known sources of systematic difference between the two methods, other than the effects of the weighting functions on various frequency response shapes, for the receive calculations. For the send and sidetone measurements, the method that has previously been used to calibrate the artificial mouth † would result in actual measured sensitivities and transmit levels that are about 0.5 dB lower than those calculated in Table E.1. Based on the above, the following approximate relationships between P.79 and IEEE Std 661 loudness ratings can be established: †† SLR (P.79) = TOLR (IEEE) + 57 dB
1024
RLR (P.79) = ROLR (IEEE) - 51 dB
1025
STMR (P.79) = SOLR (IEEE) + 9 dB
1026 1027 1028 1029
The conversion factors for real handsets may vary from the above idealized conversion factors due to mechanical shape, transducer sensitivity and transducer frequency response. Therefore, the actual conversion factors for each handset model must be determined by measurement.
†
The 1979 version of IEEE Std 661 used a free field microphone aligned coaxially with the artificial mouth for its calibration. The revised 1992 version of IEEE Std 269 adopts the ITU method of using a pressure microphone aligned perpendicular to the mouth axis. The latter method very nearly approximates a true free field measurement, whereas the former method indicates a sound pressure that is about 0.5 dB too high. This results in lowering the drive level to the artificial mouth by a corresponding amount. †† ITU-T Supplement No. 19 to the P-Series Recommendations lists slightly different values for these relationships. In particular, it uses +56 for the send relationship, -50 for receive, and +8 for sidetone. 48
PN-3-4350.120-RV3
DRAFT 18
TIA-470.120-C
10
0 dB
-10
-20 100
1000
10000
Frequency (Hz)
1030 1031
Figure E.1 – Nominal send frequency response
1032 1033 10
0 dB
-10
-20 100
1000 Frequency (Hz)
1034 1035
Figure E.2 – Nominal receive frequency response
1036
49
10000
PN-3-4350.120-RV3
DRAFT 18
TIA-470.120-C
1037 1038
Table E.1 – Nominal Frequency Response Characteristics and Loudness Ratings Calculations
1039 Nominal Nominal Nominal Frequency Send Hz dBV/Pa
Receive Sidetone dBPa/V dB
ITU-T P.79 Ws
Wr
Wms
LE
SLR
IEEE 661 RLR
STMR TOLR ROLR SOLR
100
-26.54
-3.18
-31.82
110.4
0.0006
125
-23.01
0.35
-24.77
107.7
0.0010
160
-19.59
3.76
-17.94
104.6
0.0017
200
-17.22
6.12
-13.21
76.9
85.0
98.4
8.4
0.0225 0.0296 0.0031
250
-15.68
7.64
-10.15
62.6
74.7
94.0
4.9
0.0426 0.0549 0.0045
300
-14.95
8.35
-8.71
315
-14.81
8.47
-8.45
62.0
79.0
89.8
1.0
0.0452 0.0559 0.0062 0.0097 0.0329 0.0135
400
-14.37
8.86
-7.61
44.7
63.7
84.8 -0.7
0.0924 0.1127 0.0083 0.0484 0.1633 0.0682
500
-14.14
9.02
-7.23
53.1
73.5
75.5 -2.2
0.0664 0.0811 0.0138 0.0460 0.1547 0.0657
630
-13.95
9.08
-6.97
48.5
69.1
66.0 -2.6
0.0806 0.0987 0.0228 0.0481 0.1612 0.0692
800
-13.71
9.11
-6.71
47.6
68.0
57.1 -3.2
0.0844 0.1059 0.0367 0.0503 0.1670 0.0725
1000
-13.38
9.12
-6.37
50.1
68.7
49.1 -2.3
0.0773 0.0993 0.0565 0.0477 0.1562 0.0688
1250
-12.86
9.13
-5.84
59.1
75.1
50.6 -1.2
0.0549 0.0734 0.0537 0.0488 0.1562 0.0704
1600
-11.90
9.13
-4.88
56.7
70.4
51.0 -0.1
0.0629 0.0849 0.0553 0.0561 0.1728 0.0810
2000
-10.47
9.13
-3.45
72.2
81.4
51.9
3.6
0.0357 0.0469 0.0568 0.0540 0.1562 0.0780
2500
-8.51
9.13
-1.49
72.6
76.5
51.3
7.4
0.0380 0.0490 0.0649 0.0591 0.1562 0.0853
3150
-8.81
9.13
-1.79
89.2
93.3
50.6
6.7
0.0192 0.0256 0.0663 0.0638 0.1618 0.0921
3300
-9.64
9.13
-2.62
4000
-34.45
-10.87
-47.43
5000
-60.10
-30.87
-93.08
49.7
0.0006
6300
-65.29
-30.87
-98.27
50.0
0.0005
8000
-70.17
-30.87
-103.15
52.8
0.0003
0.0125 0.0326 0.0180 117.0 113.8
51.0
1040
50
8.8
0.0022 0.0046 0.0061
SLR
RLR
8.0
2.0
STMR TOLR ROLR 15.0
-49.4
52.7
SOLR 5.5
PN-3-4350.120-RV3
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054
DRAFT 18
Annex F (Informative) – Use Of The Free Field As The Telephonometric Reference Point Current performance requirements are based on measurements referred to the ERP. Future requirements may be based on measurements referred to the free field. This annex provides background information on this concept. One goal of a telephonic experience is to simulate a conversation where two people are one meter apart, talking to each other. Now insert a complete telephone system between our two talkers. In a perfect world, the quality of the conversation would be the same with a telephone system and in free space. This is called the orthotelephonic reference. Consider a loudspeaker with a perfectly flat free field frequency response through the audio band (Figure F.1): Speaker
Microphone
Free Field Response (simplified)
100Hz
1055 1056 1057 1058 1059 1060 1061 1062
TIA-470.120-C
1K
Figure F.1 – Flat free field loudspeaker response
Play the same speaker into a HATS ear simulator, and the result is a 17 dB peak at 2.8 kHz. (For more complete data, see ITU-T P.57 and P.58). See Figure F.2. Speaker HATS Eardrum (DRP) to Free Field Transfer function (simplified)
100Hz
1K
1063 1064
10K
Figure F.2 – HATS measurement of same loudspeaker
1065
51
10K
PN-3-4350.120-RV3 1066 1067 1068 1069 1070 1071 1072 1073 1074
DRAFT 18
TIA-470.120-C
The HATS ear simulator replicates the resonances which occur in a typical human pinna and ear canal system, and measures at the (ear) Drum Reference Point or DRP. It is because of the pinna and the resonances in the ear canal that a loudspeaker with a flat free field response will not measure flat into a HATS, at the DRP. Therefore, if a telephone receiver or headset is to sound the same as a hypothetical flat speaker in the free field, the frequency response at the DRP should follow the free field curve(s) referenced in ITU-T P.57 and P.58. (Figure F.3) HATS
Eardrum (DRP) to Free Field Transfer Function (simplified)
100Hz
1K
10K
1075 1076 1077 1078 1079 1080 1081 1082 1083 1084
1085 1086
Figure F.3 – HATS measurement of handset telephone
Most telephone manufacturers are more familiar with the Type 1 ear simulator. This type of simulator uses the Ear Reference Point (ERP) rather than the DRP, which results in a different frequency curve shape. Using the above hypothetical receiver tested into a Type 1 ear simulator yields a frequency response which looks like Figure F.4: Type 1 Ear Simulator
ERP to Free Field Transfer Function (simplified)
100Hz
1K
10K
Figure F.4 – Type 1 ear simulator measurement of handset telephone
52
PN-3-4350.120-RV3 1087 1088 1089 1090 1091 1092 1093 1094 1095
DRAFT 18
TIA-470.120-C
The important thing to remember is that the above curves, using either Type 1 simulators or HATS, all can be referenced to a free field response. Another way of looking at it is that if you want your handset or headset to sound like a flat loudspeaker in the free field, e.g. simulating the orthotelephonic reference, the frequency response should look like either the ERP or DRP to free field transfer function curves above. The complete orthotelephonic response is due to the combination of frequency responses in the send, network, line and receive paths of an overall (end-to-end) connection. The exact distribution of frequency response shaping in these paths is outside the scope of this annex.
Nominal 1/3 Octave Band (Hz)
Lower Band Edge
Upper Band Edge
(Hz)
(Hz)
100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000
89.1 112 141 178 224 282 355 447 562 708 891 1120 1410 1780 2240 2820 3550
112 141 178 224 282 355 447 562 708 891 1120 1410 1780 2240 2820 3550 4470
(Rounded to three significant places.)
53
PN-3-4350.120-RV3
1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126
DRAFT 18
TIA-470.120-C
Annex G (Informative) - Bibliography The following is a list of some generally applicable basic standards that are relevant to the requirements of this Standard. 47 CFR Part 68 – Code of Federal Regulations (CFR), Title 47, FCC Part 68, Connection of Terminal Equipment to the Telephone Network. Hearing aid compatibility: Technical requirements. ANSI/TIA-464-C-2002 – Requirements for PBX Switching Equipment. ANSI/TIA-464-C-1-2004 – Requirements for PBX Switching Equipment, Addendum. ANSI/TIA/EIA-810-A-2000 – Transmission Requirements for Narrowband Voice over IP and Voice over PCM Digital Wireline Telephones. ANSI/TIA-968-A-2002 – Telecommunications Telephone Terminal Equipment Requirements for Connection of Terminal Equipment to the Telephone Network
Technical
ANSI/T1.508-2004 – Loss Plan for Evolving Digital Networks. TIA-912-A-2004 – Voice Gateway Transmission Requirements. TIA-920-2002 – Transmission Requirements for Wideband Digital Wireline Telephones. ITU-T Recommendation G.101 (2003) – The transmission plan. ITU-T Recommendation P.58 (1996) – Head and Torso Simulator for Telephonometry UL 60950-1 Issue 3 (2003) - Information Technology Equipment - Safety - Part 1: General Requirements
54
PN-3-4350.120-RV3
DRAFT 18
TIA-470.120-C
1127 1128 1129 1130 1131 1132
Annex H (Informative) – Items for Future Consideration
1133
H.1
1134 1135 1136 1137 1138 1139 1140 1141 1142 1143
Descriptions of timings and levels refer to IEEE-1329 Figure 12. Requirement The Send Threshold Level shall be
