Important Terms To Understand - Comtech EF Data CMR-5975 Installation And Operation Manual

Digicast Media Router S2 Receiver CMR-5975 (MR-S2)
Setting Up a Digicast Digital Satellite Receiver
D.5

Important Terms to Understand

Backup Whether there is a backup carrier provided.
Carrier
Band The Digicast satellite receiver operates at L-Band (950 to 2,150 MHz). The LNB
located up at the satellite dish, down-converts the incoming satellite signal at
either C-, X-, Ku- or Ka-Band to L-Band, where it is fed into the receiver.
The frequency bands are:
Downlink The RF frequency received from the satellite to the remote site.
Frequency
DVB Digital Video Broadcasting
The type of DVB transmission either DVB-S or DVB-S2.
Earth Station Where the transmission signal originates
FEC Forward Error Correction
Additional coding added to the transmission to enable the receiving site
(Digicast satellite receiver) to detect and correct errors experienced during
transmission over the satellite.
Filter Roll Off The filter roll off is known as the Alpha coefficient (α).
For DVB-S, α is fixed at 35%, but for DVB-S2, α can be configured as 20%,
25% or 35%. The smaller the α, the less bandwidth will be required on the
satellite.
IFL Interfacility Link
The coax connecting the LNB to the Digicast satellite receiver.
LNB Low Noise Block converter.
Local The frequency of the local oscillator in the Low Noise Block converter.
Oscillator
Modulation QPSK
8-PSK
16-APSK
Pilots On or Off
DVB-S2 introduced the use of Pilots for allowing the satellite receiver to remain
locked to the carrier under degraded signal conditions. The use of Pilots will
allow the receiver to maintain carrier recovery, even when the user data payload
cannot be decoded. Enabling Pilots does come at a slight bandwidth cost,
since the Pilot requires 36 symbols out of every 16 payload slots, but the gain in
performance offsets a minimal inefficiency.
L-Band 950 to 2,150 MHz
C-Band 3,700 to 4,200 MHz
X-Band 7,000 to 12,500 MHz
Ku-Band 11,000 to 18,000 MHz
Ka-Band 18,000 to 40,000 MHz
D–7
Revision 3
MN-CMR5975-IOM