Transcript
ITIS Products
V-XCAST DVB-T Exciter Version 1.20
DVB-T modulation is a difficult process that requires complete understanding of the technology, customer requirements, and industry standards. Since 1996, Harris Broadcast Europe has set the pace in COFDM modulation solutions for DVB-T. V-XCAST, its second-generation DVB-T modulator/exciter, is designed to meet all of your requirements. V-XCAST is a compact and versatile DVB-T modulator/exciter that is ideal for a wide range of applications. Three different types of agile outputs are available: IF, UHF and VHF. All models meet ETS 300 744 specifications and integrate advanced features such as bit rate adaptation, PCR restamping, NIT update, SFN operation, and control through the MIP channel. The unit's modular design allows additional boards to be inserted, including an RF auxiliary input, a second ASI input, an internal GPS receiver, and a low-power amplifier. Integrated digital precorrection ensures top performance. The V-XCAST can be controlled via Ethernet, RS-232 or RS-485. Ready to cover applications worldwide (6, 7 and 8 MHz channel bandwidth, user selectable), V-XCAST is used in leading DVB-T transmitters and also by R&D laboratories, set top boxes manufacturers and ENG operators.
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OVERVIEW V-XCAST belongs to the range of DVB-T device developed by HARRIS Rennes. The declaration of conformity with DVB specifications/standard is identified under the following reference: „ Date: 22.10.99 „ Number: 1920 The COFDM exciter V-XCAST from Harris Rennes is a fully compliant DVB-T exciter and up-converter supporting both 2K and 8K operation, specifically designed for commercial networks. This device performs channel coding and OFDM modulation of a MPEG2 transport stream. One single unit allows to feed a TV transmitter with a fully modulated RF or IF DVB-T channel. Using the high level output version, the RF output can directly drive a power amplifier. The excellent quality and stability of analogue UHF or VHF signal output maximize the TV transmitter efficiency, decreasing global cost. Thanks to its ASI standardized interface, the V-XCAST exciter can be used with any DVB compliant source equipment. A flexible Bit Rate Adaptation mechanism (with PCR restamping) is provided, giving an independence between the multiplexer rate and the DVB-T rate. Test generators are included, which allow to perform BER measurement easier with the V-TER, professional test receiver from HARRIS Rennes. The V-XCAST COFDM exciter accepts a SFN option which allows to set up single frequency networks with use of an SFN adapter at the DVB multiplexer site. In SFN mode, the COFDM modulation and RF up-converter are locked on a stable 10 MHz external reference coming from GPS. With the optional internal GPS receiver, the V-XCAST offers a compact and reliable SFN modulation solution. The full device remote control can be performed via the MIP channel (remote control from network headend), or via a RS232 & RJ45 ports and the PC software (local control or remote control via modem) or via a standard SNMP manager, allowing a very fast integration with most of Control Systems. The same PC software can be used for easy logging and maintenance, thanks to an accessible front panel RS232 connector. It will be used to adjust digital precorrection curves. Alarms are monitored on front panel leds and on a rear side connector as relay contacts. Alarms are optionally controlled and monitored by standard SNMP managers. V-XCAST is a compact system packaged in a 2U 19" rack. It includes only two high density electronic boards which perform all the processing required by the COFDM coding and RF analogue processing. Three different models are available: (6, 7, 8 MHz bandwidth channel are selected by PC software) „ A Modulator with IF output „ An Exciter with UHF outputsim „ An Exciter with VHF outputsim The available common functions or options are: „ PC control software „ SFN synchronization „ Internal GPS receiver „ Digital Pre-correction „ Open Control Interface (OCI) to control via a SNMP manager „ UHF input module (demodulator for 8 MHz bandwidth only) „ High Level Output (for UHF and VHF models only) The PC control software includes its own installation manual and on-line help, the OCI includes its own instruction manual, all other are fully documented in this instruction manual. Page 2/10
V-XCAST Specifications sheet – Version 1.20 – July 2002
V-XCAST INPUT/OUTPUT INTERFACE SPECIFICATIONS MPEG2-TS IN (Main) • ASI Interface: - MPEG2-TS serial input interface - Comply with DVB-PI standard (DVB document A010 rev1, May 1997) - BNC 75Ω female connector
Synchronization • Clock reference input marked "10 MHz IN": -
10 MHz reference input Analogue sinus signal Minimum level:………………………………………………………………………………………..…-10 dBm Maximum level:…………………………………………………………………………………………+13 dBm Required frequency accuracy:………………………………………………….…better than 0,5ppm (MFN) BNC 50Ω coaxial female connector
• Time reference input marked "1 PPS IN": -
1 pps positive or negative pulse Period 1 second (minimum pulse width 1 µs) BNC 10kΩ coaxial female connector Period Accuracy:……………………………………………………………………………………………+- 1µs
• Clock reference output marked "10 MHz OUT": -
10 MHz reference input Analogue sinus signal Level:……………………………….…………………………………………………..…………………> 0 dBm BNC 50Ω coaxial female connector
Control/Alarms • Ethernet: - RJ45 10baseT - TCP/IP protocol (SNMP V1/V2C + FTP) - Trap (cf. OCI) • RS232 - DTE: -
RS232 port (V24 / V28) DTE type for external modem connection DB9 female connector TCP/IP protocol (SNMP V1/V2C + FTP) or ASCII protocol (user switchable)
V-XCAST Specifications sheet – Version 1.20 – July 2002
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• RS232 - DCE: -
RS232 port (V24 / V28) DCE type for terminal connection DB9 female connector TCP/IP protocol (SNMP V1/V2C + FTP)
• RS485 (according to model): - ASCII protocol - Rx/Tx only - DB9 female connector • Digital inputs (according to model): - 4 Relay contacts (galvanic protection) - DB9 female connector • Alarms: -
Each contact is connected to a dry relay Maximum voltage: 30V DC Maximum current: 0.2A DC Maximum voltage between open contacts: 400VAC (50Hz) DB25 female connector
Normal, errorless operation gives all contacts closed. Alarms are signaled by open contacts. When the equipment is not under power, all relay contacts are open (alarm state). The alarm contacts can be dedicated to any kind of error combination using the PC control software. - Contact 1, 2, 3, 4, 5, 6, 7: programmable alarm conditions - Contact 8: power supply alarm The power supply alarm is active when at least one power supply voltage is out of operation. • Monitoring output: - DVB-T signal for monitoring purpose only - BNC 50Ω coaxial female connector
GPS Receiver (optional) • GPS antenna input marked "RF GPS IN": - GPS TNC connector (50 Ohms) • Time reference output marked "1 PPS OUT": -
1 pps pulse BNC 50Ω coaxial female connector Accuracy (GPS locked):……………..…………………………………………………………..+- 100ns Holdover mode:……………………………………………………………………………………<+- 5µs*
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V-XCAST Specifications sheet – Version 1.20 – July 2002
• Clock reference output marked "10 MHz OUT": -
10 MHz reference clock Analogue sinus signal Level:………………………………………………………………………………………………> 0 dBm BNC 50Ω coaxial female connector Accuracy (Average over 24 hours): GPS locked:….….<+/- 3.10-12 , Holdover mode: <+/- 2.10-10 *
* 4 hours after last GPS synchronization, at constant temperature, following 48 hours of GPS lock
Auxiliary RF input (optional) • Antenna input marked "RF IN": -
N connector (50 Ohms) Channel bandwidth: 8 MHz All 120 non-hierarchical modulations are automatically detected Input level:…………………………………………………….………………………-20 dBm..-75 dBm Coarse offset:………………………………………….…………..166.667 KHz step (up to ±14 step)
Auxiliary ASI input (optional) • Input marked "ASI IN“: -
BNC connector 75 Ohms MPEG2-TS serial input interface Comply with DVB-PI standard (DVB document A010 rev1, May 1997)
Automatic Power Control (according to model) • Input marked "APC IN": - N connector - 50 Ohms - Input level:……………………………………………………………………………….- 10 dBm ± 3 dB
DVB-T output Generalities Specifications are guaranteed for operation in an ambient temperature between the following limits: +5°C and +45°C. Correct operation is guaranteed for operation in an ambient temperature between the following limits: 0°C and +50°C.
V-XCAST Specifications sheet – Version 1.20 – July 2002
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Phase noise Offset
Validate AC106 Recomendation
V-XCAST L(f) dBc/Hz
10 Hz
< -55
< -75
100Hz
< -85
< -85
1KHz
< -85
< -85
10KHz
< -95
< -95
100KHz
< -115
< -115
1MHz
< -130
< -130
Spectrum mask without digital precorrection Relative frequency (MHz)
ETS 300 744 Specification
V-XCAST relative level (with no channel filter) (dB)
± 3.8
0
± 0.5
± 4.2
-50
-50
±6
-62
-55
± 12
-87
-55
Frequency accuracy The maximum error between the real output frequency and the desired output frequency is: • With the use of the Internal frequency reference (internal OCXO): -
Factory set: error < 10-9 (20°C) Temperature drift 0°C – 50°C: < 2 10-8 Short term drift: < 5 10-10 / day Long term drift: < 10-7 / year
• With use of an external 10 MHz reference: - Perfect ideal reference: error < 0.1 Hz
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V-XCAST Specifications sheet – Version 1.20 – July 2002
UHF output (with no precorrection)
• RF analogue output: - Analogue DVB-T signal - UHF model Center Frequency range:……………………………..between 470 MHz and 862 MHz - VHF model Center Frequency range:……………………………..between 174 MHz and 230 MHz Range Channels values Depend on Version VHF band III UHF band IV + V
6 MHz
7 MHz
8 MHz
4 –12
5 – 12
6 - 12
14 – 78
28 – 69
21 - 69
- Bandwidth:………………………………………………………………….. 7,61 MHz (8 MHz channel) …………………………………………………………………………..………6.66 MHz (7 MHz channel) …………………………………………………………………………..………5.71 MHz (6 MHz channel) - Output level Low Level model:…………………………………... between -10 and 0 dBm / 50Ω load - Output level High Level model:…………………………..between +6 dBm and +16 dBm / 50Ω load - Output level stability (without Low Power Ampli Option):…………………………………... +/- 0,5 dB - Coarse offset resolution (8 MHz channel):……………………..………………………… 166,666 kHz - Coarse offset resolution (6 & 7 MHz channels):………………………..…………………….. 125 kHz - Fine offset resolution:………………………………………………………………………………… 1 Hz - In band ripple:………………………………………………………………………………… < +/- 0,5 dB - Shoulders attenuation (without Digital precorrection) Output level = -5dBm:………….…… > 50 dB - Out of band (+/- 100 MHz from central frequency) spurious level:…………………………. < -60 dB - Harmonics level:…………………………………………………………………………….…… < -40 dB - Output connector:……………………………………………………………….…… N type 50Ω female
• RF Monitoring output: - Signal for monitoring purpose only:…………………………………………………….……..BNC 50Ω - Power level (Low Level Version –10 to 0 dBm):………………-20 dB ± 3dB below main RF output - Power level (High Level Version +6 to 16 dBm):……………...-36 dB ± 3dB below main RF output Warning: A valid RF monitoring output is available only if the main RF output is loaded. V-XCAST Specifications sheet – Version 1.20 – July 2002
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IF output model
• IF analogue output: - Analogue DVB-T signal: - Center Frequency:……………………... user selectable from 35 MHz to 37 MHz (1Hz resolution) - Bandwidth:…………………………………………………………..…….. 7,61 MHz (8 MHz channel) ………………………………………………………………………..…….. 6.66 MHz (7 MHz channel) ……………………………………………………………………..……….. 5.71 MHz (6 MHz channel) - Output level:…………………………………………………………… between -10 and 0 dBm / 50Ω - Output level stability:…………………………………………………………………………. +/- 0,5 dB - In band ripple:………………………………………………………………………………….< +/- 0,5 dB - Shoulders level (Output level = -5dBm):………………………………………………………..< -50 dB - Out of band spurious level:……………………………………………………………………….< -60 dB - Out of band harmonics level:………………………………………………….…………………< -40 dB - Output connector:……………………………………………………………………..N type 50Ω female
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V-XCAST Specifications sheet – Version 1.20 – July 2002
Digital precorrections Two independently digital precorrections. Amplifier Digital precorrection used to improve MER and shoulders characteristics obtained after power amplifier stages due to non linearities of amplifier technology and Filter Digital compensation used to correct frequency and group delay distorsions of the output channel filter and output combiner used after power amplifier stages of the transmitter. Amplifier Digital Precorrection • AM/AM Curve: - Number of adjusting points:……………………………………………………………………………………………………… 11 - Dynamic range around 0 dB Average power reference (X-Axis):…………..… -10 dB to +10 dB - Dynamic range around 0 dB Gain amplifier reference (Y-Axis):……………….…..-3 dB to +3 dB - Step resolution:……………………………………………………………………………………0.1 dB • AM/PM Curve: -
Number of adjusting points:…………………………………………………………………………..11 Dynamic range around 0 dB Average power reference (X-Axis):…………….. -10 dB to +10 dB Dynamic range around 0° Phase amplifier reference response (Y-Axis):……….. ….-30° to +30° Step resolution:……………………………………………………………………………………. 0.5°
The curves describe directly non linearities responses of the amplifier stages. Efficiency of amplifier non linearities precorrection example: Test on a sample Class AB amplifier LDMOS technology: Reduce shoulders level at 4.2 MHz center frequency offset from –28 dB to 38 dB
V-XCAST Specifications sheet – Version 1.20 – July 2002
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Filter Digital compensation Bw is the value of the DVBT channel and the limits of X-Axis change automatically with the switchable channel bandwidth (6, 7 or 8 MHz). • Frequency response Curve: -
Number of adjusting points:……………………………………………………………………………11 Dynamic range around Center frequency value (X-Axis):………………….………. -Bw/2 to +Bw/2 Dynamic range attenuation response (Y-Axis):…………………………………………-3 dB to 0 dB Step resolution:……………………………………………………………………………………. 0.1 dB
• Group delay response Curve: -
Number of adjusting points:……………………………………………………………………………11 Dynamic range around Center frequency value (X-Axis):………….………………. -Bw/2 to +Bw/2 Dynamic range group delay response (Y-Axis):………………………………………….. 0 to 500 ns Step resolution:………………………………………………………………………………..……... 5 ns
The curves describes directly frequency and group delay responses of the output linear stages (channel filter, combiner).
Harris Broadcast Europe I Harris Rennes I ITIS Products Centre Espace Performance I Bâtiment S I F-35769 Saint-Grégoire Cedex I France Rennes phone: 33 (0)2 99 23 72 20 I e-mail:
[email protected] I www.harris.com
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