User guide

I-2 VMS User Guide
BUC Block Up Converter – An upconverter so called because it converts a whole
band or “block” of frequencies to a higher band. IF is converted to final transmit
frequency for satellite communications.
BPS Bits Per Second – A measure of transmission speed. See also Kb/s & Mb/s.
BPSK Binary Phase Shift Keying – A modulation technique in which the carrier is
phase shifted +/-180 degrees. See also QPSK.
C
C-Band A frequency band commonly used for satellite communications (and sometimes
terrestrial microwave). For terrestrial earth stations, the receive frequency band
is 3.7–4.2 GHz and the transmit band is 5.925–6.425 GHz. See also Ku-band.
CDD Comtech Data Demodulator
CDM Comtech Data Modem
CIR Committed Information Rate – The guaranteed minimum bandwidth assigned
to a remote terminal.
CRC Cyclic Redundancy Check – A method of applying a checksum to a block of
data to determine if any errors occurred during transmission over communica-
tions links.
CXR Carrier – A radio frequency transmission linking points and over which infor-
mation may be carried.
D
DAMA Demand Assigned Multiple Access – A process whereby communications links
are only activated when there is an actual demand.
dBm Decibel referenced to 1 milliwatt.
DHCP Dynamic Host Configuration Protocol – An Internet protocol for automating
the configuration of computers that use TCP/IP.
DNA Dynamic Node Announcement – A process in Vipersat satellite networks
whereby remote sites periodically announce their presence to facilitate network
setup and monitoring.
DPC Dynamic Power Control