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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).
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
Note: • The above Min and Max values are
the calculated values that can be
78
SOUND QULTY:0050
867.8375 P25
Low Mid Upp
0533 1985 3342
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
BC250D 11/6/2 11:37 AM Page 78