ADTRAN TSU IQ+ User Manual page 179

Glossary
Appendix D
AIS
alarm indication signal. A signal transmitted instead of the normal signal to
maintain continuity of transmission. The AIS indicates to the far end the exist-
ence and direction of the transmission fault on the line.
ANSI
American National Standards Institute. Devices and proposes recommenda-
tions for international communications standards.
ASCII
American National Standard Code for Information Interchange. The standard
and predominant 7-bit (8-bit with parity) character code used for data communi-
cations and data processing.
asynchronous
A method of data transmission which allows characters to be sent at irregular
intervals by preceding each character with a start bit, followed by a stop bit.
attenuation
The loss of signal amplitude during transmission. The received signal is lower
in signal amplitude than the transmitted signal due to losses in the transmission
medium (resistance in the cable). Attenuation is measured in decibels.
B8ZS
A method of ensuring the ones density requirements in the data flow (12.5%
must be ones) are met by replacing eight zero bits with a code containing inten-
tional bipolar violations (BPVs).
61200275L1-1 TSU IQ+ User Manual D-1