TM 11-6625-3041-12/TO 33A1-8-908-1
2-5. OVERVIEW OF TESTING (cont)
Errors fall into three general categories:
Errors
Intermittent: Errors
that occur infrequent-
ly and at random
intervals.
Intermittent errors usually are caused by events external to the
equipment such as powerline transients, shock, or vibration.
In some cases they may be due to poor connections in or to the
equipment.
Burst: Errors that
occur in groups.
Burst errors usually are caused by events external to the
equipment such as sunspots or overflying aircraft.
Continuous: Errors
that occur contin-
uously.
Continuous errors usually are caused by equipment malfunctions
including bad or missing connections or improper antenna
alinement.
Two types of error indicators are provided:
Error
Indications
ERRORS display: The
ERRORS display is
used primarily for
adjustment or aline-
ment procedures be-
cause the count advances immediately after an error is detected.
The effects of any adjustment can be determined by watching
the speed at which the count on the display changes.
The ERRORS display is a good way to detect burst errors and is
the only way to detect intermittent errors because these errors
never occur frequently enough to light the NO GO or MARGINAL BER
indicators.
BER indicators: The
BER indicators are
used primarily to
monitor a transmis-
sion path because they provide automatic and nearly continuous
indications of the quality of the path.
Continuous errors are determined by a continuously lit NO GO or
MARGINAL indicator. Burst errors are determined by indicators
that may be NO GO one time, MARGINAL the next, or GO, etc.