Transcript
WAEICD
~·~ SERVICE ,MANUAL 5786
CARRIER EQUIPMENT 6.8, 8.2 & 9.6KC '
(TRANSMITTER UN398044-001, 002, & 003, RECEIVER UN398045-001, 002, & 003 ; i REPEATER UN398046-001, 002 & 003
********** DESCRIPTION & MAINTENANCE
1. 1
INTRODUCTION The carrier equipment is a frequency modulated single channel carrier,
designed for use with a single or multiple station solid state code system. The carrier provides communication by superimposing a carrier on existing physical DC equipment, several independent carrier circuits can be added to an existing pair of wires or cable circuits.
1. 2
SPECIFICATIONS
Guard-bandwidth requirements:
600 cps for 150 bits/sec., maximum
Transmitter Input:
-6V for ZERO, +6V for ONE (minimum)
Transmitter Output:
+15 dbm
June, 1975 B-75-100-1095.3
WESTINGHOUSE AIR BRAKE COMPANY UNION SWITCH & SIGNAL OIVISION Swissvale Po;t Office, Pittsburgh, Pa. 15218 An American-Standard Company
WF\BCC
"""'~ Receiver Input:
-25 dbm
Receiver Output:
-8V for ZERO, +8V for ONE, OV for NO information
Carrier Keying Rate
150-600 bits/second maximum
Environmental Range:
-40°C. to +70°C.
Power Requirements:
Transmitter -12V, +12V, Receiver -12V, +12V, Repeater -12V,
1. 2.1
0. 10 0. 01 0. 15 O. 01 0. 08
amp; amp. amp; amp. amp.
RECEIVER INPUT AND TRANSMITTER OUTPUT IMPEDANCE
~·~~~~~~~~~~~~~~~~~~~~~~~~~~
The impedance of both the transmitter putput and the receiver input is 1600 ohms at nominal frequency.
The input and output impedance of the
repeater is 600 ohms at nominal frequency.
The output impedance of the
receiver is 10 K and the input impedance of the transmitter is 4 K.
1. 2. 2
TRANSMITTER LEVEL The outputs of the transmitter and repeater are +15 dbm minimum
into a 600 ohm line.
1. 2. 3
RECEIVER SENSITIVITY Sensitivity of the receiver input is -28 dbm and the squelch sensitivity
is -25 dbm.
1. 2.4
VOLTAGE REQUIREMENTS The receiver and transmitter sections of the carrier require a
negative and a positive 12 volt DC power supply. Power is supplied from the code system supply. The repeater requires -12V.
1. 2. 5
MAXIMUM KEYING The maximum keying speed adaptable to the carrier is 150 bits
U-5786, p. 2
WABCO ~
per second.
I. 2. 6
FREQUENCIES The Master Station transmitter and Remote Station receiver and their
associated repeater frequency is 8. 2 kc and the Master Station receiver and Remote Station transmitter and their associated repeater frequency is 6. 8kc. or 9. 6kc. * Other frequencies can be made available.
1. 3
CIRCUIT DESCRIPTION The carrier is a narrow band frequency modulated single channel :•
~
carrier providing communications over line or cable. There is one plug-in board containing the transmitter (UN398044-002 for the Master Station, and UN398044-001
~~-~~3-~ for the ~el?_?!_E?~tati~~and one pl~g-~oa_r:d~?~!aining the]
receiver (UN398045-001 or 003* for the Master Station-~nd UN398045-002f~~h~- __ ·-·'"-'" --·--- -
- - ::ar - -- --
-
. -
-
I
Remote Station). Plug-in boards containing the repeaters are located at the repeater station (see Figure 1-6).
1. 3.1
TRANSMITTER (SEE FIGURE 1-1) The transmitter circuit consists of oscillator Q3, isolation stage Q4,
power amplifier QS, and transistors Ql and Q2 which act as switches to convert logic into frequency translations. The frequency of oscillation of transistor Q3 is determined by coil L2 and capacitors C7 and C8. Transistor QI and its collector load, capacitor C3, are connected across inductance L2. The nominal frequency of the transmitter with no logical inputs is the frequency marked on the board. A positive input pulse greater than 6V amplitude (MARK) causes transistor QI to conduct and places capacitor C3 in parallel with the circuit. As a result, the transmitter frequency decreases approximately 80 cycles. Capacitor C4 is used as the collector load of transistor Q2. Transistor Q2, due to the bias load, is normally conducting. A negative input greater than -6V causes transistor Q2 to be taken out of conduction, removing capacitor C4 from the tuned circuit. Thus, Note: *Depending on application. U-5786, p. 3
WABCO
~
a SPACE input causes the transmitter frequency to increase by approximately 80 cycles. The output of transistor Q3 is amplified by Q4 and the gain of the amplifying stage is controlled by resistor Rl9. This is accomplished by varying the impedance of the emitter circuit of Q4. The collector circuit of transistor Q5 (for the Remote Station) is normally open, and the collector lead is brought out of transformer Tl to pin 11. When a Remote Station sends information, the Key-On logic transistor in the Remote Station logic conducts causing transistor Q5 to be conducting. Thus, the transmitter sends information to the Master Station. Transformer Tl in parallel with capacitor C5 and coil LI in series with capacitor C2 are a pair of tuned circuits which are both tuned to the center frequency of transmission. They act as a filter, which presents a high impedance to the line at pins 14 and 15 (1600 ohm impedance at frequency).
Resistor RI is
a bridging resistor permitting a 1000 ohm output to be matched to the line impedance. Resistor RI also serves as protection for thyractor DI which provides transient protection.
1. 3. 2
RECEIVER (SEE FIGURE 1-2) The receiver circuit consists of a two stage amplifier (QI and Q2),
a limiter (Q3), an emitter follower (Q6), a squelch amplifier (Q4), a squelch switch (QS), and a bridging resistor (RI) to the line. The input filter coils LI, L2, L3, and T3 and their associated capacitors are used as tuned circuits. Transformer T3 also provides line isolation from the power supply. A feedback amplifier, consisting of QI and Q2, brings the line input voltage to the limiting level. Transistor QI is coupled directly to the base of transistor Q2. This provides DC feedback stability from the emitter of transistor Q2 to the base of transistor QI. Some AC loop feedback is also provided. At signal levels greater than -25 dbm, transistor Q3 is driven into limiting by transistor Q2. Transistor Q3 drives tuned circuits (Tl, C7) and (T2, CS) through line coupling. When an input signal across the collector load of Q3 drops sufficiently from limiting, the feedback path across capacitor Cl5 will cause Q3 U-5786, p. 4
WABCO ~
to be non-conducting (although noise otherwise may be present that might cause Q3 to conduct). Transformer Tl is tuned to a frequency approximately 70 cycles lower in nominal frequency.
Transformer T2 is tuned to approximately 70
cycles higher. Tuned circuits (Tl, C7) and (T2, C8), diodes D2 and 03 and resistors Rll and Rl2 are used as a frequency discriminator. The output of the discriminator becomes +8V if the input is a ONE (MARK), -8V if the input is a ZERO (SPACE), and OV if there is no input (center frequency).
A two stage
low pass filter provides carrier suppression and modulation waveform shaping. Coils L4 and LS and capacitors C9 and ClO are the filter. The logic output is the emitter of Q6. The output at pin 12 is approximately the same as at test point TP2. Q4 is directly coupled to Ql and it amplifies the carrier signal. The amplified signal is fed to a full wave rectifier (04 and 05) which produces a DC voltage proportional to the carrier input. When there is a carrier input, transistor QS conducts and the output at pin 11 is O. 2V. If the carrier level decreases sufficiently (-28dbm), the input signal to Q4 is lowered, causing the DC voltage from the rectifier circuit to be reduced. This causes QS to fall out of conduction and the output at Pin 11 becomes +12V, indicating the absence of a carrier signal.
1. 3. 3
REPEATER (SEE FIGURE 1-3) The repeater circuit is a combination of the carrier transmitter and
receiver circuits. The transistors QI and Q2 form a two stage amplifier. Q4 is used as a squelch amplifier and QS as a squelch switch. These two transistors combine to turn off Q3 when the Master Station or Remote Station is not transmitting. Q3 is used as the output power amplifier. Coils Ll, L2 and L3 and their associated capacitors are used as tuned circuits. Transformer TI provides line isolation from the power supply. The feedback amplifier, consisting of QI and Q2, brings the line input voltage to the limiting level. Transistor QI is directly coupled to the base of transistor Q2. This provides DC feedback U-5786, p. 5
WABCO
'v'.A.'v' stability from the emitter of transistor Q2 to the base of transistor QI. Some AC feedback is also provided. At signal levels greater than -25 dbm, transistor Q2 provides the drive for Q3. Q4 is directly coupled to QI and it amplifies the carrier ·signal. The amplified signal is fed to a full wave rectifier (D4 and DS) which produces a DC voltage proportional to the carrier input.
1. 4
TEST POINTS There are five test points for the transmitter, four test points for the
repeater, and five test points for the receiver. These test points can be used for a fast checkout of the boards. replaced
If major malfunctions arise, the board should be
by a new one and the existing board returned to the shop or manufacturer
for repairs. Table 1-1 describes the test points and gives typical voltage readings. Table 1-2 illustrates typical waveforms which can be measured at designated locations on the boards.
U-5786, p. 6
WABCO ~
TABLE 1-1 TEST POINTS
TEST POINT
FUNCTION
REQUIRED VOLTAGE*
TRANSMITTER (Fig. 1-1) Output voltage
+15 dbm nominal with 600 ohm load at pins 14 & 15 (use AC VTVM or multimeter) ·
3
-12V check
-12V
4
OV check
ov
5
+12V check
+12V
1 2
RECEIVER (Fig. 1-2) 1
+12V check
+12V
2
Discriminator O check
ov
3
-12V check
-12V
4
Input signal level
Varies (Min. -30 dbm.)
5
OV check
ov
REPEATER (Fig. 1-3) 1
Output voltage
+15 dbm nominal with 600 ohm load at pins 15 & 16 (use AC VTVM or multimeter)
2
-12V check
-12V
3
OV check
ov
4
Input signal level
Varies (Min. -22 dbm.)
* A 20k volt multimeter
is satisfactory for all readings. U-5786, p. 7
WABCO ~
TABLE 1-2 WAVEFORMS
FUNCTION
TEST POINT
Transmitter
Figure 1-1
OSCILLOSCOPE SETTING Vertical O. 5 Volt/CM
A
Transmitter
Figure 1-1
Vertical O. 5 Volt/CM
B
Transmitter.
Figure 1-1
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Figure 1-2
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U-5786.- p. 8
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15 POSITION BOARD FILE ( UE451015·3001)
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2
3
046-001 OR 046 • 003* CARRIER REPEATER
046-002 CARRIER REPEATER
A
A
4
5
7
6
052 LINE COUPLING BOARD
046·001 OR 046·003 CARRIER REPEATER
*
s
A NOTE:
8
$_ 046·002 CARRIER REPEATER
·-10
..II 052 LINE COUPLING BOARD
s
ALL PART N.UMBERS PRECEDED BY UN398 EXAMPLE : UN398046·00f A • INDICATES ACTIVE EQUIPMENT S • INDICATES STANDBY EQUIPMENT SEE DRAWING !1062 SHEET CRI FOR WIRING DIAGRAM
*· DEPENDS UPON APPLICATION Yf}~· ·~
Figure 1-6
Repeater Station Front Panel Layout
s
·-
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13 ·-
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15 .. 043 POWER
043 POWER SUP PLY
SUPPLY
A
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