Page 6 National Communications
HANG UP TONE DETECTION
PA2 incorporates a HANG UP TONE DETECTOR which is designed to
detect ‘Australian’ specification hang up tones, that will normally be present
at the completion of a Paging call. This process is fully automatic.
When PA2 is installed on a PABX system, the Hang Up tone generated
may be outside of the cadence and frequency normally used inAustralia for
Hang Up tones.
In this situation, PA2 may not hang up until the Maximum Paging Call Time
has elapsed (see section 4, page 7), or after a period of silence (see section
3, page 7). Our Hang Up detector, looks for :
1. AToneFrequencybetween300Hzand600Hz.
2. A ToneDurationbetween300mSand600mS.
3. A 50% Duty Cycle +/- 20%
(ie ON and OFF periods should be the same +/- 20%)
You should adjust your PABX system to generate Hang Up tones as per
the above specification, or to output normalAustralian Hang Up tones.
OR
You should use one or more of the other Call Termination methods described
on page 7.
ELECTRO MAGNETIC INTERFERENCE
Electromagnetic Interference (EMI) from some Switch Mode Power Supplies
and some low end UPS units (Uninterruptable Power Supplies) can prevent
hang up tones being detected by PA2.
Switch Mode Power Supplies are easily identified because they do not use
a transformer and are very light.
TURN OFF any SWITCH MODE POWER SUPPLIES located near PA2
(and its power adaptor) and test if the problem is resolved. If the problem is
resolved you should move the offending Switch Mode Power Supply away
from PA2 (and its power adaptor) to a distance that overcomes the problem.
If the PA2 power adaptor is connected to an Uninterruptable Power Supply,
remove it and test if the problem is resolved.
