Comtech EF Data CDM-570/570L Vipersat - Manual (Page 182)

E-4 Vipersat CDM-570/570L User Guide
E
s
/N
0
The ratio of E
s
(energy per symbol) and N
0
(noise power spectral density per
Hz). This is closely approximate to the carrier-to-noise ratio (C/N). E
s
is the
energy of a bit (not an information bit) measured in Joules or, equivalently, in
Watts per Hertz. This measurement is typically used to quantify a DVB-S2
carrier.
ECM Entry Channel Mode – In a Vipersat network, ECM provides a quick and reli-
able method for Remotes requiring SCPC access channels to enter/re-enter the
network initially or after a power or other site outage.
F
FAST Code Fully Accessible System Topology Code – Designation for feature code used
by Comtech EF Data for their satellite modems. The FAST method makes it
easy to quickly upgrade the feature options of a modem while it is running live
in the network, either on site or remotely.
FDMA Frequency Division Multiple Access – A technique where multiple users can
access a common resource (e.g. satellite) by each being allocated a distinct
frequency for operation. See also TDMA and STDMA.
FEC Forward Error Correction – A process whereby data being transmitted over a
communications link can have error correction bits added which may be used at
the receiving end to determine/correct any transmission errors which may occur.
Flash Non-volatile computer memory that can be electrically erased and repro-
grammed.
Forward
Path
Transmission path from the Hub site to a Remote site.
FTP File Transfer Protocol – An application for transferring computer files over the
Internet. See also TFTP.
G
G.703 ITU-T standard for transmitting voice or data over digital carriers such as T1
and E1.
G.729 ITU standard for LD-CELP (Low Delay – Code Excited Linear Prediction)
voice encoding at 8 kb/s.