APCO P-25 Sound Quality Fine Tuning

With each APCO Project 25 system, particularly at 800MHz, the sound quality (C4FM Demodulation Threshold) may need to be fine tuned specifically for that system. If the scanner is not adjusted correctly, the P-25 voice transmissions will sound robotic or unintelligible.

To adjust the sound quality to match the P-25 system you want to monitor follow these four steps:

1.While monitoring a specific APCO P-25 frequency, press the HOLD/MAN key.

Note: In the Trunking mode, press the TRUNK key instead of the HOLD/MAN key.

2.Press and hold the number 9 key.

3.On Line 1 of the screen you will see SOUND QULTY: 0050 (for example).

SOUND QULTY:0050

867.8375 P25

Low Mid Upp

0533 1985 3342

This shows the Sound Quality. The lower the level the better the Sound Quality. For better Sound Quality rotate the VFO up or down. As the threshold adjusts in increments of 50 at the bottom of the screen watch the Sound Quality level increase or decrease and continue to rotate the VFO until you have achieved the lowest Sound Quality level.

Note: • When APCO P-25 signal is not received, SOUND QULTY: **** appears on the display.

•You must have the BCi25D card installed and have an APCO P-25 signal during this adjustment.

-A chart showing the Threshold Adjustment Range is listed below.

Threshold Adjustment Range

 

 

Lower

 

Mid

 

Upper

 

Band

Min

Default

Max

Default

Min

Default

Max

800MHz

33

533

1883

1985

1992

3342

3842

UHF

33

633

1883

1985

1992

3342

3842

VHF

330

930

2130

2147

2264

3464

4064

Note: • The above Min and Max values are the calculated values that can be

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