Applications
Application for Low Bandwidth, CBS Newspath Digital Satellite News Gathering
CBS Newspath provides ten (10), 5.35 MHz channels on a single 54 MHz trnasponder on AMC-5. Conventional SD applications are configured to operate at 3.9878 Msym/s with a roll-off factor of 1.35. Using DVB-S QPSK modulation with rate ¾ FEC, provides a payload data rate of 5.5948 Mbps for the compressed video and audio with an Eb/N0 ~ 4.9 dB. The spectral efficiency of this modulation is 1.403 bits/symbol. This same architecture can be used to carry high quality HD programs by applying improved compression and improving spectral efficiency.
A 5.35 MHz RF channel can be created using DVB-S2 with 8PSKP modulation with rate 3/4 FEC provides an Eb/N0 ~ 4.6 dB. Including a Pilot signal, this provides a payload data rate of 7.967 Mbps with a spectral efficiency of 2.086 bits/symbol.
New MPEG-4 compression techniques, combined with DVB-S2 modulation offer unprecedented abilities to reduce occupied bandwidth and associated satellite transponder resources costs. ComtechTV’s MPEG-4 encoding technology provides exceptional video quality at video data rates below 5 Mbps.
The ComtechTV AVC4000HD will provides exceptional video quality at video encode rate consistent with a 7.967 Mbps payload data rate. This data rate provides adequate capacity to support a contribution quality HD video feed with associated audio. The low latency of the ComtechTV AVC4000 encoder and associated IRD make this an ideal solution for a Newspath migration to HD support without modifying the existing channelization plan on the satellite transponder.