Apco P-25 Sound Quality Fine Tuning - Uniden BC785D Owner's Manual

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 L/HOLD key.
Note: In the Trunking mode, press the TRUNK key instead of the L/HOLD key.
2. Press and hold the number 9 key.
3. On Line 1 of the screen you will see SOUND QULTY: 0050 (for example).
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.
• You can also use the L and M keys to adjust the sound quality.
- A chart showing the Threshold Adjustment Range is listed below.
Threshold Adjustment Range
Band
800MHz
UHF
VHF
Note: • The above Min and Max values are the calculated values that can
• The mid threshold value will not change while adjusting the upper and lower
limits.
Lower
Min Default
33 533
33 633
158 658
be assigned theoretically, and the values are not to guarantee the
operation of the unit.
Mid
Max Default Min
1883 1985 1992
1883 1985 1992
2058 2085 2190
70
Upper
Default Max
3342 3842
3342 3842
3590 4090