TM 11-6625-3041-12/TO 33A1-8-908-1
Asynchronous . . . . . . Independent. Data source (SG-1139) and path under test have
independent timing.
Bit error rate
(BER) . . . . . . . . . . . . . Number of bits in error per total bits.
Balanced . . . . . . . . . . A path in which two wires are used, each of the same amplitude
with respect to ground but of opposite polarity.
Clock . . . . . . . . . . . . . A signal or circuit used to achieve synchronization between
various signals and equipments.
Channel . . . . . . . . . . . A direct path of electrical communication.
Code . . . . . . . . . . . . . . A method of preparing information for electrical transmission
(e.g., diphase, NRZ).
Diphase . . . . . . . . . . . A code in which a change in level occurs at the start of every
bit period and in which a logic O is a second change in level
one-half bit period later. Logic 1 is no transition at the
start of the bit period.
Data . . . . . . . . . . . . . . Information.
Data rate . . . . . . . . . Number of bits per time, usually given in thousands of bits per
second (kb/s).
Duplex . . . . . . . . . . . . A communications path in which information can be both trans-
mitted and received at the same time.
Error . . . . . . . . . . . . . A received bit that is opposite to that transmitted (e.g., O
when it should have been 1, or 1 when it should have been O).
End-to-end . . . . . . . . From one end of a path to the other.
Family . . . . . . . . . . . A class of signal with specific characteristics (e.g., unbal-
anced NRZ, diphase, balanced NRZ).
Fault . . . . . . . . . . . . . Malfunction, failure.
Group . . . . . . . . . . . A path that contains more than one channel.
Inhibit . . . . . . . . . . . Prevent an action from taking place.
Inverted . . . . . . . . . . Reversed polarity.
Line-to-ground . . . . Measured from one wire to ground.
Line-to-line . . . . . . Measured from one wire to the other.
Loopback . . . . . . . . . . From one end of a path to the other, then back again.
GLOSSARY-1