Garbled Audio, Help!

[KC1ART]

Ok, I've got two scanners set up right next to eachother. Both are Relm HS200 scanners (used to use them at the NASCAR races) anyway....

One of the scanners is conneted to my computer, and broadcasting though the scannercast app. The other scanner is just playing audio into the room.

Here's the feed:
Yarmouth Police / Fire, Cumberland and Freeport Fire

I'm scanning the same 7 frequencies on both.

Whenever the police frequency talks (154.965 - Yarmouth Police) I can hear the audio from the scanner playing into the room. It sounds fine. It is not encrypted, scrambled, trunked, or otherwise modified.

The other scanner plays it's audio into my computer, and about 20 seconds later when the audio makes it though to the 5-0 Radio App, or the Broadcastify Feed, the audio is completely garbled. Almost as if it had been encrypted with inversion or something.

I don't understand what's causing this.

I've switched the scanners, and still the same. Listening to audio (from the police frequency only, all other frequencies broadcast fine) locally, it sounds fine, but through the scanner feed, 90% of the time it's garbled, and only about 10% of the time it can be heard clear like it should be.

Any idea what's going on here?

 

[K9DAK]

I'm in the process of setting up a new feed, so I've been tweaking this the last couple of days.

Wauconda Police and Quad 3 Fire

My thought is the one frequency you're having problems with has hotter audio than the others and is either over-driving your sound card or even if not, the input gain is set too high and clipping the audio. The difference in loudness may not be apparent to the human ear, but might be just too hot for digital audio processing.

Try lowering either the scanner volume or input gain (Recording Control in Windows) or both and monitoring your input signal with one of the methods suggested in the feed setup instructions.

Also, what I've been doing this evening is downloading the mp3 of my archive and pulling that into Audacity and looking at the waveform. You can immediately tell if it's clipping, and if so, lower the volume and/or gain.

Better to have some frequencies lower in volume than to have the loudest one unintelligible.

Good luck!

 

[KC1ART]

I have messed with the volume. It's not clipping. It was actually set so low at one point I had to hold my cell phone external speaker up to my ear to hear what was coming out.

I'm working on a video clip to show what's happening, but it's late here and no one's talking.

 

[KC1ART]

Ok, I've figured out what's going on, but I'm not much closer to a solution:

Yarmouth PD is on 154.965
Falmouth FD is on 154.980

When the audio comes through clear, it's because the scanner is receiving on 154.965. Awesome. It should be. But when it comes through garbled, it's because the scanner is receiving on 154.980. Well no kidding it's going to be garbled!

So what do I do to fix this? My scanner is capable of plugging in PL tones. Would adding those prevent the .... bleed-over? .... Is that what's going on?

Both departments are dispatched through Falmouth Dispatch, but their repeaters are in their respective towns. Could the bleed over be happening at the dispatch console?

 

[K9DAK]

Good investigative work!

Yes, the PL should solve the problem. Program the correct tones and you should be good to go.

According to the manual, your scanner will not even stop on a programmed channel unless it hears the correct tone:

"In SCAN mode, the Unit will not stop on the frequency (or channel) unless the proper tone is on the signal."

 

[KC1ART]

Excellent!

I was pretty desperate, I had an iPad on a tripod video taping the two scanners and my iPhone running the Broadcastify feed. Luckily I caught them stopping on different frequencies. So "garbled or not garbled" was just the luck of which frequency was the next one to stop on.

I plugged in the PLs and hopefully this is behind me.

 

[ecps92]

Yes, if they use two different PL's, otherwise you will still have bleed-over

Ok, I've figured out what's going on, but I'm not much closer to a solution:

Yarmouth PD is on 154.965
Falmouth FD is on 154.980

When the audio comes through clear, it's because the scanner is receiving on 154.965. Awesome. It should be. But when it comes through garbled, it's because the scanner is receiving on 154.980. Well no kidding it's going to be garbled!

So what do I do to fix this? My scanner is capable of plugging in PL tones. Would adding those prevent the .... bleed-over? .... Is that what's going on?

Both departments are dispatched through Falmouth Dispatch, but their repeaters are in their respective towns. Could the bleed over be happening at the dispatch console?

 

[K9DAK]

You should still be OK:

Yarmouth PD is on 154.965 with no PL
Falmouth FD is on 154.980 with 107.2 PL

So if 154.965 is bleeding into 154.980, and hopefully not the other way 'round too, then setting the PL on 154.980 will work. Although if the scanner stops on a valid transmission on 980 and 965 then starts to transmit, you might get some receiver desense. You might also want to consider an inline attenuator.

 

[ecps92]

Last trip to Maine, Yarmouth was using 192.8

You should still be OK:

Yarmouth PD is on 154.965 with no PL
Falmouth FD is on 154.980 with 107.2 PL

So if 154.965 is bleeding into 154.980, and hopefully not the other way 'round too, then setting the PL on 154.980 will work. Although if the scanner stops on a valid transmission on 980 and 965 then starts to transmit, you might get some receiver desense. You might also want to consider an inline attenuator.

 

[jim202]

Any update on this problem?

Others here on the site would be interested on what you might have found. There is a possibility that the radios are talking to each other and causing the problem.

In going over the thread here, I have not seen any indication of what your antenna system being used was. If your using a T coax connector on your antenna, I would suggest that you use a splitter and separate the receivers further apart. It is a know fact that some scanners will talk to each other via IF bleed over between the receivers.

Another thing you can try is to shut off one radio at a time and see if the audio is clear. Then shut off the radio you just used and turn on the the one you had shut off. See if the audio from that one is clear and non distorted. If they both play well independently, then you may have found the link.