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SCTV Digital - Technology
MMDS Hypercable System

Well, what is the system that SCTV intend to use to provide their digital TV system. At first, it seemed as if a digital deflector system would be basically DTT - indeed, we at ICDG reported that (erronously as it turned out) at the time.

In fact the system developed by MDS International (MDSI) - MMDS Hypercable - is, in fact, a variant on the traditional "QAM" Multipoint Microwave Distribution System currently in use here by Chorus and NTL. (Something, that, for obvious reasons to do with marketing and politics, SCTV deny - they call it "terrestrial satellite" instead - but that's a contradiction in terms). MMDS Hypercable uses a different set of wavebands to QAM MMDS. It uses the frequency wavebands from 1.7-60 GHz, in the FM band. It allows up to 130 analogue or 2000 digital channels, although SCTV are for various reasons planning to use rather less than this - fifty digital channels. According to MDSI, a single transmitter can cover a radius of 200 km - easily covering SCTV's coverage area in Counties Cork, Kerry, and Waterford. MDSI also claim that the signal can be reflected by "a mirror, or a piece of metal, or a tree", you don't need to have a line-of-sight to the transmitter - unlike traditional MMDS. Also the head-end equipment is apparently rather cheap - equipment possibly costing thousands rather rather than millions of pounds. For the viewer, the equipment will cost £85 and include an LNB (Low Noise Block) fitted to your rooftop aerial and a Digital Set Top Box. Some people in exceptional circumstances will however need a 35cm digital minidish, simular to analogue MMDS aerials.

Technical documentation for MMDS Hypercable is available at MDSI's website at www.mds.fr

HyperCable® Transmitter Technical Specifications
HyperCable® may transmit any type of frequencies or modulation from 2.5 to 60 Ghz, but the basic system uses frequencies in the satellite band from 10.7 to 12.5 Ghz. This enables any satellite receiving set to process the signal, provided that the L.N.B. gain is adapted to the high power of the transmitter, in order to avoid transmodulation problems. Modulations are FM and QPSK.
Frequency : 3.4 GHz to 4.2 GHz and 10.7 to 13.25 GHz
Energy Dispersion Signal
70 MHz Filter : 24 MHz @ 1 dB
Maximum IF Attenuation < 10 dB (between cable and head)
If Filter to the Head : Included
Transmitter Power : 0.250W(23dBm)- 1W(30dBm)- 4W(36dBm)- maximum 5w
DVB Standard
Modulation type : QPSK
TX pulse shaping : Square-root raised cosine roll-off factor =0.35
Symbol rate : Ds= 2 to 30 Mbauds
Outer code : RS (204, 188, 8)
Interleaving : Convolutional, depth I=12
Inner Code : Convolutional, K=7, R=1/2 to 8/9
Energy Dispersion : IESS 309 following DVB standard
Data Rate (MPEG-2) : D=2xDs x R x (188/204) Mb/s (Up to 60 Mb/s )
Input Interface : MPEG-2 DVB LVDS Parallel (ASI, RS422 optional)
Serial Interf. (optional) : CCITT, G703 (HDB3)
Config. / Monitoring : Front panel, RS 232 and Ethernet
Direct Test Access : I & Q, symbol clock, IF
Input voltage : 48 VDC (85V to 264V AC )
Power Consumption : 85 W
Operating T° Range : +5°C to +45°C
Humidity : 85 %
Modulator Size and Weight : 19", 4U cabinet 20 kg
SHF Head size and Weight : 28 x 25 x 16 cm, 2kg