Errors
are listed separately for communication from the intercom system to the Trunking
Master Controller and from the Trunking Master Controller to the intercom system. Two
types
of
errors
are listed: the total accumulated errors are listed in the "Err" column; the bit
error rate is listed in the "Ber" column. The bit error rate is the number
of
errors during the
last ten minutes of operation. All counters are reset to zero on reset or power-up
of
the
Trunking Master Controller. All counters may be updated by pressing the ENTER key while
viewing the screen.
In general, error rates of no more than one error per hour are normal. Error rates between one
per hour and one per minute are higher than normal but may not cause significant problems.
Error rates
1 per minute usually require immediate attention.
Systems installed in facilities with good grounding, using high quality telephone type twisted
pair wiring will normally operate with error rates between
0
and
20
per
24
hours. With
shielded wire, the rates are generally higher, because of the additional cable capacitance
(5-30
per
24
hours). Symptoms of higher error rates begin to appear when the rate exceeds 1 per
minute. Symptoms include cross points which remain closed for no apparent reason,
with muted program when no keys are closed, slow response (especially to keypad), and
general inconsistent or "flaky" operation. General causes of high error rates include:
Cables too long
Poor facility grounding practices
Crosstalk, especially when using non-twisted wiring, with long parallel runs
of data
cables
in
close proximity to each other containing differing data streams.
Noise Induction: intercom data cabling running parallel to lighting cables etc.
One side
of
a data line shorted to ground or audio
CStrunk
User
Manual
3-11
