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Details
General view
The included accessories
The Terra TTX-311 R81714 trans-modulator allows for distribution of digital TV channels in situations when the signal received by the antenna cannot be directly amplified or converted to a different frequency due to high BER and low MER levels. These problems occur in areas with poor terrestrial signal levels.
The regeneration process consists of receiving the DVB-T signal, demodulating it to the transport stream, and then re-modulating RF signals as a new COFDM multiplex (frequency converter function). MER modulation error rate at the output of the device is not lower than 35 dB, which allows for the distribution of the digital multiplex even in very large MATV systems.
The regeneration process consists of receiving the DVB-T signal, demodulating it to the transport stream, and then re-modulating RF signals as a new COFDM multiplex (frequency converter function). MER modulation error rate at the output of the device is not lower than 35 dB, which allows for the distribution of the digital multiplex even in very large MATV systems.
The device can operate in two modes:
- transparent mode - the decoded transport stream is not modified and is directly applied to the COFDM modulator;
- multiplexing mode - the device examines the decoded transport stream (measures the bit rate, updates the SI array) and optionally filters programs and services such as teletext or EPG (it should be noted that in this mode the modulator can only work in 2k mode).
Main functions of TTX-311 R81714 trans-modulator:
- transparent regeneration of DVB-T stream;
- changing the frequency of DVB-T multiplex;
- service filtering: programs, audio streams, teletext;
- EPG multiplexing;
- NIT generation;
- generating new stream descriptors;
- PMT version monitoring.
The received multiplex can be supplied (as the original MPEG-2 TS) to other modules of the Terra MMH-3000 headend.
The trans-modulator can power an antenna preamplifier (12 V).
The trans-modulator can power an antenna preamplifier (12 V).
The idea of using the ttx311 regenerator
An additional advantage of the device is the possibility of modifying transport stream, very useful in hotels, hospitals, correctional facilities etc. The service filtering option allows for cutting out some channels from the DVB-T multiplex.
Specifications
| Name | COFDM-COFDM (DVB-T) trans-modulator ttx311 | |
| Code | R81714 | |
| Standard | EN50083-5 class 2 | |
| RF output | ||
| Modulation | DVB-T QPSK, QAM16, QAM64 | |
| Channel bandwidth | 7 MHz, 8 MHz | |
| Guard interval | 1/4, 1/8, 1/16, 1/32 | |
| FEC | 1/2, 2/3, 3/4, 5/6, 7/8 | |
| Transmission mode | transparent | 2k, 8k |
| multiplexing | 2k | |
| Frequency range | 110...860 MHz (step 0.5 MHz) | |
| Channel bandwidth adj. (7 MHz) | -125 kHz, 0 ,+125 kHz | |
| Channel bandwidth adj. (8 MHz) | -166 kHz, 0 ,+166 kHz | |
| Attenuator | 0...15.5 dB (step 0.5 dB) | |
| Output level | 90 dBμV | |
| Carrier stability | +/-500 Hz | |
| MER | ≥ 35.0 dB | |
| Impedance | 75 Ω | |
| RF input | ||
| Modulation | DVB-T QPSK, QAM16, QAM64 | |
| Frequency range | 104...862 MHz | |
| Input level | 40...100 dBμV | |
| Impedance | 75 Ω | |
| Loop gain | 0 ... 3.5 dB | |
| S/N | ≥ 23 dB | |
| Multiplexing | ||
| Max input bitrate | 31.5 Mb/s | |
| Max output bitrate (modulator) | 31.5 Mb/s | |
| Number of input services | ≤ 256 | |
| PID filtration | ≤ 256 | |
| Monitoring of | PMT | Yes |
| PAT | No | |
| SDT | No | |
| PCR restamping | Yes | |
| EPG (EIT) multiplexing | Yes | |
| Other parameters | ||
| Power | 5.5 VDC, 1.3 A | |
| RF preamp. powering | 12 VDC , max. 0.1 A | |
| Operating temperature | 0...50°C | |
| Dimensions | 47.5 x 117 x 220.5 mm | |
| Weight | 0.7 kg | |