Carrier Access Network Device Axxius 800, User Manual

Page: 538 / 568

Glossary - 6 Axxius 800 - Release 2.2
Glossary
Constant Bit Rate (CBR)
Constant Bit
Rate (CBR)
Refers to the transmission properties that data, video and voice uphold
when traversing a transport medium. Information traveling at a constant
bit rate means there is no fluctuation in signal integrity.
CSU
Channel Service Unit, the interface to the T1 line that terminates the local
loop.
Customer
Premise
Equipment
(CPE)
On digital circuits provided by the telephone company, any terminating
hardware owned by the user and not by the Telco (telephone company)
is generically referred to as CPE.
Cyclic
Redundancy
Check (CRC)
A check sum indicator based on the remainder of a polynomial
calculation performed on the transmitted data that is used to verify, with
some fixed probability of correctness, whether that data was transmitted.
D4 Superframe
(SF)
D4 Superframe (SF) Framing Format. The most popular framing format
in the T1 environment. Its name stems from the way framing is
performed in the D-series of channel banks from AT&T. There are 12
separate 193-bit frames in a superframe. The D4 framing bit is used to
identify both the channel and the signaling frame. In D4 framing,
signaling for voice channels is carried in-band by every channel along
with the encoded voice. “Robbed bit signaling” is a technique used in D4
channel banks to convey signaling information. With this technique, the
eighth bit (least significant bit) of each of the 24 8-bit timeslots is
“robbed” every sixth frame to convey voice related signaling information
(on-hook, off-hook, etc.) for each voice channel.
Data Terminal
Equipment
(DTE)
Data Terminal Equipment refers to communications hardware such as
computers, terminals, and similar equipment, as opposed to DCE such as
modems.
DDS
Digital Data System. DDS is a private line digital service, typically with
data rates at 2400, 4800, 9600 and 56000 bits per second.