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COFDM modulator SFN |
Appearance of COFDM-modulator SFN
* For use in the set of transmitting equipment in the organization multifrequency (MFN) and single frequency (SFN) networks over-the-air
digital television broadcasting standards DVB-T and DVB-H (mobile broadcasting)
* It effects shaping of a high-frequency signal with a QPSK modulation (and reception of these very signals) according to
the EN 300 421 (DVB-S) standard for primary distribution networks
* Shaping of a high-frequency signal with a COFDM modulation according to the EN 300 744 (DVB-T/H) standard for a secondary
network according to the TS101191
* The SFN operates in three modes:
1) Multifrequency network (MFN mode)
2) Master of single frequensy network (SFN-Master mode)
3) Slave of single frequency network( SFN-Slave mode)
* Control: local or via an Ethernet network
* Technical description and manual (1547 kb) 
| Specifications of a primary distribution network (Radio relay link) |
| Modulator QPSK | Output IF signal level | -24 dBm @ 30 MHz |
| IF signal level frequency | 70 MHz | |
| Internal coding | Convolutional coding К=7 (171, 133) | |
| Coding rate | 2/3 | |
| External coding | Reed-Solomon (204, 188, Т=8) | |
| Randomizer/Interleaver | Convolutional/ I=12 | |
| Modulation kind | QPSK | |
| Symbol rate | 27 Msps | |
| Receiver QPSK | Input signal level | -65...-25 dBm |
| Operating frequency range | 950...2150 MHz | |
| Input frequency step | 1 MHz | |
| Modulation kind | QPSK | |
| Input resistance | 75 Ω | |
| Coding rate | 2/3 | |
| Symbol rate range | 3.3...29.9 Msps | |
| Converter | Transfer ratio | -14 dB |
| Operating frequency range | 950...2150 MHz* |
* Due to the fact that the output of the COFDM modulator SFN on IF2 a filter with a bandwidth of 30 MHz, the frequency IF2 installed at the manufacturer's.
| Specification of Secondary distribution network (DVB-T) |
| Modulator (4) | Output IF signal level | -20 dBm @ 8 MHz |
| IF signal level frequency | 36 MHz | |
| RF output signal level | -20 dBm @ 8 MHz | |
| RF signal frequency | 470...862 MHz | |
| Internal coding | Convolutional coding К=7 (171, 133) | |
| Coding rate | 1/2, 2/3, 3/4, 5/6, 7/8 | |
| External coding | Reed-Solomon (204, 188, Т=8) | |
| Randomizer/Interleaver | Convolutional/ I=12 | |
| Guard interval | 1/4, 1/8, 1/16, 1/32 | |
| Modulation kind | QPSK, QAM16, QAM64 | |
| Modulation mode | 2k, 8k, 4k | |
| Long-term transmission frequency stability | 1*10Е-9 |
| GPS receiver specifications |
| Adjustment frequency L1 | 1.57542 GHz |
| Input signal level | -130...-100 dBm |
| Common specifications |
| Time of sync circuit start in operation mode (COFDM transmitter frequencies in points A and B differentiate in 1 Hz, not more) | <=15 min |
| Voltage supply/Consumption current | 220 ± 30V / 0,2A |
| Dimensions | 1U(19")483x260x44 mm |
| Weight | 5 kg |
The term Primary Distribution Network means relay transfer/reception of an integrated transport stream TS in/into different destination points.
The term Secondary Distribution Network means DVB-T/H signal shaping and transmission (COFDM-8k) with a 1 Hz frequency difference in various destination points with time delay compensation occurring in a primary distribution network and coincident symbol shaping and distribution at the same moment in the indicated destination points (because time delay compensation is a necessary but not a sufficient condition of coincident symbol shaping).
An SFN structure scheme is given in fig.1.
|
Shorthand names of units: |
An MFN structure scheme is given in fig.2.
|
Modulator COFDM SFN mode MFN (the key in the middle position) received on the ASI-input formed transport stream and then he goes to the input of the modulator COFDM. High-frequency signal from the output of the modulator COFDM, on the UHF frequency range, is fed directly into the secondary distribution network, ie the digital TV transmitter. |
A single-frequency network arrangement in points A and B (see fig.2).
