Comtech EF Data VMS v3.12.x Vipersat - Manual (Page 535)

Appendix H - Glossary H-3
MN/22156, rev 12
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.
DES Data Encryption Standard – A federal standard method for encrypting informa-
tion for secure transmission. The Vipersat system offers 3xDES (Triple DES)
for encrypting traffic.
DHCP Dynamic Host Configuration Protocol – An Internet protocol for automating
the configuration of computers that use TCP/IP.
DLL Dynamic Link Library – The implementation of the shared library concept in
the Microsoft Windows system.
DPC Dynamic Power Control
DSCP Differentiated Services Code Point – The 6-bit field in an IP packet header that
is used for packet classification purposes and is the portion of ToS that is
detected by Vipersat modems.
DVB Digital Video Broadcasting – A suite of internationally accepted open standards
for digital television. DVB-S, DVB-S2, and DVB-RCS are the standards
utilized by satellite services.
DVP Digital Voice Processor – Used in packet voice applications.
E
E
b
/N
0
The ratio of E
b
(energy per bit) and N
0
(noise power spectral density per Hz).
This is a normalized signal-to-noise ratio (SNR) measure, also known as the
“SNR per bit”. The bit error rate (BER) for digital data is a decreasing function
of this ratio. E
b
is the energy of an information bit measured in Joules or, equiv-
alently, in Watts per Hertz.