| A/D |
Analog to digintal conversion |
| ADPCM |
Adaptive differential pulse code modulation |
| AIS |
Alarm indication signal; a signal transmitted in lieu of the normal
signal to maintain transmission continuity, and indicates to the receiving
terminal that there is a transmission fault located upstream or at the
transmitting terminal |
| ALBO |
Automatic line build out |
| AMI |
Alternate mark inversion |
| ANSI |
American National Standards Institute |
| APS |
Automatic protection switch |
| ASPR |
Automatic span powering repeater |
| AWG |
American wire gauge |
| B8ZS |
Bipolar eight zero substitution; a line coding scheme to substitute
000 + - 0 - + for 00000000 if the preceding pulse was +, and 000 - + 0
+ - for 00000000 if the preceding pulse was -. Done to maintain ones density |
| BER |
Bit error rate |
| BERT |
Bit error rate test |
| BOC |
Bell Operating Company |
| bps |
Bits per second |
| BPV |
Bipolar violation; the detection of any isolated error, whether it
deletes a pulse or adds a pulse |
| CCC |
Clear channel capability; allows unrestricted data bearing any number
of consecutive zeros to pass through a transmission facility. This
usually requires B8ZS line coding on all elements |
| CO |
Central office; of a telephone company; the location of the switching
center |
| CODEC |
Coder-decoder; converts analog voice to digital and vice-versa |
| CPE |
Customer premises equipment |
| CRC |
Cyclic Redundancy Check; a method of detecting the existence of errors
in the transmission of a digital signal using polynomial division |
| CSU |
Channel Service Unit; the interface from CPE to the public T-1 line |
| D4 |
Fourth generation digital channel bank |
| DACS |
Digital access and cross-connect system; a digital switching device
for routing T-1 lines and possibly DS-0 portions of lines, among multiple
T-1 ports |
| dB |
Decibel |
| dBdsx |
Decibels with respect to the standard level at the DSX-1 cross-connect |
| DC |
Direct current; battery power |
| DLC |
Digital loop carrier |
| DS-0 |
Digital signal, level 0; 64 kilobits per second, the international
standard rate for digitized voice channels |
| DS-1 |
Digital signal, level 1; 1.544 megabits per second, the North American
standard |
| DS-3 |
Digital signal, level 3; 44.736 megabits per second, the North American
standard |
| DSU |
Digital service unit; converts RS232, RS422, or V.35 terminal interface
data to DSX-1 interface |
| DSX-1 |
Digital service cross connect, level 1; part of the DS-1 specification |
| DTMF |
Dual tone multi-frequency; TOUCHTONE dialing, as opposed to rotary
dialing |
| E&M |
Signaling leads on a voice tie line; known as Ear and Mouth |
| ESF |
Extended Super Frame, a DS-1 framing format of 24 frames. In this format,
2 Kbps are used for framing pattern sequence, 4 Kbps are used for the Facility
Data Link, and the remaining 2 Kbps are used for CRC |
| FB |
Framing bit |
| FCC |
Federal Communcations Commission |
| FDL |
Facility data link; an embedded overhead channel within the ESF format |
| FEC |
Forward error correction |
| Hz |
Hertz, cycles per second |
| ISDN |
Integrated Services Digital Network |
| IXC |
Interexchange carrier; a long distance telephone company (not a LEC) |
| kA |
Kiloamperes |
| kHz |
Kilohertz, thousands of cycles per second |
| LATA |
Local access and transport area |
| LEC |
Local exchange carrier |
| M24 |
Multiplexer that converts one DS-1 line to 24 voice channels for a
C.O. |
| M44 |
Multiplexer that converts one T-1 of 44 ADPCM channels into two T-1s
with PCM encoding |
| mA |
Milliamperes |
| MHz |
Megahertz |
| Mux |
Multiplexer |
| NI |
Network interface; demarcation point between the public network and
CPE |
| NIU |
Network interface unit; the unit installed at the demarcation which
provides loopback test capabilities |
| OOF |
Out of frame |
| OOS |
Out of synchronization or else out of service |
| PAM |
Pulse amplitude modulation |
| PBX |
Private branch exchange; a private telephone switching system |
| PCM |
Pulse code modulation |
| pF |
Picofarads, a measure of capacitance PIC Polyethylene insulated conductor |
| PL |
Private line; a leased line, not switched |
| POP |
Point of presence; termination of long distance line from a long distance
carrier at a central office |
| POTS |
Plain old telephone service |
| PSTN |
Public switched telecommunications network |
| QRSS |
Quasi random signal sequence |
| RBOC |
Regional Bell Operating Company |
| RZ |
Return to zero; DS-1 signals pause at zero voltage between each pulse
when making zero crossings |
| SLC |
Subscriber loop carrier |
| SF |
Superframe Format; a DS-1 framing format of 12 frames |
| T1 |
A 1.544 Mbps transmission standard |
| T-BERD |
A tradename for T1 bit error rate tester made by TTC |
| TDM |
Time division multiplexer |
| TSI |
Time slot interchange; a method of temporarily storing data bytes so
they can be sent in a different order than received; a way to switch |
| VF |
Voice frequency |
| VG |
Voice grade; the common analog telephone line |
| VMR |
Violation monitor removal; a function which removes all violations
which are detected so that they do not propagate along the span line |
| ZBTSI |
Zero Byte Time Slot Interchange; a method of providing Clear Channel
Capability without using B8ZS. This was an interim solution advocated by
Verilink |
[end of tutorial]
