Some channels on scanner are understandable, but sound muffled, garbled,and similar to SSB

[Mongoosmike]

{This is on my SDS-100 scanner} San Mateo County, CA Fire channels, are on a P-25 system, and sound very muffled, garbled and similar to SSB tuned to just barely understand what they are saying. The audio is still intelligible and you can hear what they are saying. The SM County Sheriff Dept is also on the P-25 system, but all their channels are clear with no muffled or garbled audio problems. The local police for some individual cities in the county are on the P-25 system and a few are not, but the ones that aren't are simulcast with another city at certain times of the day. All these PD channels are clear like the Sheriff departments with no garbled or muffled sound. I know the SDS-100 doesn't have features to control the volume differences between different channels, but that is not the issue here, since it appears to do with only the P-25 system. On a different question, I don't understand the concept of some city PD's being simulcast with another city, but assume it might have to do with cost or sharing frequencies or equipment possiblty. Thank you for your help

 

[JethrowJohnson]

Might it be that some of them are on an analog frequency that's patched in to the P25 system? Sometimes they sound muffled when they do that (at least in my experience).

 

[ofd8001]

You could try tinkering with the Global Auto Filter (in Settings) to see if any changes are helpful.

I can see possibilities of combined dispatch, a changeover to a regional system, a new system, etc., as being reasons for sometimes they are blended and other times they are not.

The SDS-100 DOES have a feature that can deal with differing audio volume, that being the Volume Offset which is a per channel setting. + numbers increase volume, - numbers decrease volume. So you can make channel A louder than channel B.

 

[RFI-EMI-GUY]

Wow thats just crazy. I have a BCD536HP and the dispatch often sounds just like that. I attribute to the simulcast. Yet here you have an SDS100 and it does same thing, yet supposed to be simulcast compliant. It is weird, the audio quality is all over the place. Dispatch sounds like it is overdriven into nonlinearity. other calls sound clear, sometimes just like analog.

 

[ofd8001]

The SDS series radios are much, much better at dealing with simulcast, but they are not 100%. I still have areas of garbled or cut out transmissions.

A good thing to try to determine whether it is a scanner problem or just bad location luck, is to bring the scanner to within about 1/4-1/2 mile of a known site and see if the "junk" gets better. If it does, short of moving, there isn't much to be done. If it does not, you may have a bad scanner.