Motorola MTR3000 Basic Service Manual

13-16 MTR3000 Programming and Tuning: Modulation Limit Alignment
13.6.3 Tuning Procedure (with Tx Data or PL)
1. Connect the radio’s antenna port to the attenuation pad, if necessary, before connecting to
the Communication Analyzer.
2. Turn on the base station/repeater using an AC or DC source.
3. Click the “Read” button on the Tuner application to read the radio’s softpot values.
4. Select “Modulation Limit” under the Tx menu in the tree view.
5. Enter the tuning frequency into the Communication Analyzer (the value displayed by the
Tuner application).
6. Click the “PTT Toggle” button within the Tuner environment to key up the radio.
7. Apply a 1 kHz signal at 1.2Vrms to Pin 22 of the J7 backplane connector.
- Signal ground is Pin 9 of the J7 backplane connector.
- If the manufacturer of the third party controller specifies that the Tx Audio is not to be pre-
emphasized, use Pin 1 instead of Pin 22.
8. Adjust the Modulation Limit softpot to a value that limits the maximum deviation to “X”% RSD,
where “X” is equal to “92% RSD” minus “Tx Data’s % RSD”.
E.g. If Tx Data deviation is equal to 17%,
X = 92% - 17% = 75% as the maximum deviation limit.
Figure 13-12 Example of maximum deviation limit calculation
9. Click the “PTT Toggle” button within the Tuner environment to de-key the radio.
10. Click “Write” to save the newly tuned softpot value into the radio’s codeplug.
11. Alignment is complete.
Note
Refer to Figure 5-2 for details regarding the audio and data flow.
Note
Set the modulation limit to 92% to compensate for any additional deviation incurred by the
transmitter VCOs over temperature.
Note
The Tuner application always aligns the Modulation Limit parameter in a 12.5 kHz channel
spacing regardless of the CPS setting, so calculate the tuning % RSD accordingly. If the
CPS is set for 25 kHz operation, the base station/repeater will automatically scale the
deviation by a factor of two when outside of the Tuner environment.
8%
17%
75%
100%
0%
%RSD
92%
With Tx Data or PL
Buffer
Data or PL
Voice

Motorola MTR3000 Specifications

General

Brand	Motorola
Model	MTR3000
Category	Accessories
Language	English