BCD396XT's "Static Blast"

[Kumba]

Odd issue I've noticed with my BCD396XT lately. If I set the squelch below 2 (say to 1), on various systems, I'll get spots where it just randomly opens squelch and blasts me with static. Usually, this happens when I have a weak signal (as is the case of where I live, something nearby is interfering with the local public safety system). It's almost like the motorboating you'd hear on the older 396T sometimes, except this is just pure static.

There's even cases where it grabs the wrong TGID. Say for example, I have police and fire/ems in distinct groups, but I have the police group locked out. With squelch at 1, sometimes it picks up a police transmission and displays it as a fire/ems transmission.

Outside of pinning down the local interference issue, anyone got tips on tweaking things like the AGC or even P25 decode level to get the static blast to stop at squelch 1? Good to keep the P25 lowpass filter enabled? Squelch 2 just causes the unit to blip the channels too much due to the weak signal issue. Even tried setting the P25 wait time to various values, but no go on it helping any.

I'll eventually get a roof antenna to try and get a better signal, but that's a project that's a ways off for now.

For reference, the main system I'm trying to listen to is a SmartZone II that uses P25 audio for police/fire/ems, and analog for misc county services (which I have locked out). All of my channels are programmed in as digital only, even the Unit ID channels (even though that has no effect).

 

[Kumba]

Now I'm not trying to jinx it, but I may have figured it out. I had the End Code set to "Analog Only". Changed it to "Analog+Digital", and it hasn't done the little confusion dance it was doing earlier at Squelch 1. I'll have to keep an eyeball on it...

 

[JnglMassiv]

Motorola Securenet encryption sounds very much like static and would cause your scanner to behave as decribed.

Listen to this link: Click me..I MAKE NOISE
From KB9UKD's great archive of digital modes:
Digital*Modes*Samples

 

[slicerwizard]

There's even cases where it grabs the wrong TGID. Say for example, I have police and fire/ems in distinct groups, but I have the police group locked out. With squelch at 1, sometimes it picks up a police transmission and displays it as a fire/ems transmission.

The OSW decoding logic in all of the Uniden DMA scanners is broken. The over the air protocol that Motorola uses includes check codes that are used to verify that received data is correct. However, the Uniden DMA scanners do not make proper use of this check code and will attempt to act on bogus decodes. If a bogus decode happens to point to an active system frequency, you'll get to hear one talkgroup while a totally different ID is displayed onscreen.

You don't see (or hear) the majority of these errors, because they point at random frequencies that have nothing on them, so the scanner just hops back to the control channel before you're even aware that it farked up again...