Table of Contents
Advertisement
♦
Measuring Method
If a Motorola Centro Plus control console is connected to the TRICK, the line attenuation at 1
kHz and 3 kHz will be measured when the Centro Plus initiates line compensation. The tones
are transmitted by the Centro Plus at a known level, allowing the TRICK to calculate the
correct gain and equaliser values to compensate the wire line.
♦
Approximation Method
Line compensation can also take place by measuring the level of the high level guard tone
(HLGT) when it is detected. The attenuation at the HLGT frequency is calculated based on
the nominal level. Using this information and a model of a wireline, the attenuation at 1 kHz
and 3 kHz is approximated and compensated for.
1.2.7
RX Audio Inhibit on PL Detect
If selected via the RSS, received audio is not sent to the wireline if PL is detected.
This feature provides a means of preventing calls from other base stations being heard.
As an example of an application of this feature, consider the situation where several base stations
are used by the same customer on the same frequency. It is necessary to employ a "blocking"
mechanism whereby if one base station is transmitting, all other base stations are prevented from
transmitting and, furthermore, are unable to hear the conversation.
The TRICK provides this "blocking" mechanism by using "reverse PL" - ie. audio is sent to the
wireline if PL is NOT detected. When PL is detected, audio is not sent to the wireline and the TRICK
generates a guard tone to prevent the console from transmitting.
The Carrier Squelch Detect (CSQ) and PL Detect (PL) signals from the RX radio, control this feature
as shown in Table 1-3 below:
* Signalled from pin 4 of the Rx radio accessory connector
** Signalled from pin 8 of the Rx radio accessory connector
1.2.8
Console TX Inhibit on Busy Channel (4-wire systems only)
If selected via the RSS, guard tone is sent to the wireline as long as carrier is detected without PL.
This prevents the control console from transmitting over transmissions from radios which do not
belong to the same PL group.
Functional Description & Applications
Table 1-3 Receive Inhibit Funtionality
PL*
CSQ**
0
0
inhibit wireline audio
0
1
valid audio sent to wireline
1
0
not possible
1
1
inhibit wireline audio - send guard tone
Action
Functional Description
1-11
Advertisement
Table of Contents
