SDS100/SDS200: Noise at end of transmission

[chad_96]

Hello all,

I'm curious and have searched for an answer with no result. Maybe because I'm not sure what to search appropriately...

Lately I've started noticing after a transmission a noise on my sds200.
I usually only hear it on the dispatchers side at the end of their transmission, when they quit talking. It sounds like a slight buzz or digital buzz. Sometimes very short and low, sometimes loud and a little longer. I'm just more so curious what this is, and possibly what causes it.

At first I thought maybe it was just due to my recent change of antennas to a HDTV type antenna. But, I compared my sds100 with the remtronix antenna and hear it on there as well.

Anyways, I'm more so curious what it is and what causes it, if anyone is aware. The only thing I could come close to finding on it was a data burst, but this is at the end of thr transmission when the dispatcher would be letting go of the PTT on their end. And the way I read it, makes it sound as if a data burst would be at the beginning of a transmisson?

Anyhow, just more so really curious what it's all about and what causes this to happen, if it's normal on digital trunking, or what not..

Thanks

 

[doctordialtone]

Beeps and melodies in two-way radio

A look at the diversity of tones in PMR transmissions, and my home listening station. Melody detection, CTCSS, DCS, STE.

www.windytan.com

Listen to some of those to see if the mystery sound is there.

 

[Whiskey3JMC]

Can you post an audio sample?

 

[chad_96]

Can you post an audio sample?

Yes, I will as soon as I start hearing it again. It stops for awhile then starts back up again, kind of odd. But yes, as soon as I can get a sample I will.

 

[nd5y]

At first I thought maybe it was just due to my recent change of antennas to a HDTV type antenna. But, I compared my sds100 with the remtronix antenna and hear it on there as well.

It's impossible that the antenna has anything to do with it.

 

[chad_96]

It's impossible that the antenna has anything to do with it.

Right, I figured that out. But it was the only change recently made that I could assume at first. Again, I then tried my sds100 to see if it was acting the same, which it was, also on a different antenna. This eliminating anything to do with the antenna...

Ultimately, leaving me curious...

 

[chad_96]

Beeps and melodies in two-way radio

A look at the diversity of tones in PMR transmissions, and my home listening station. Melody detection, CTCSS, DCS, STE.

www.windytan.com

Listen to some of those to see if the mystery sound is there.

So none of them sound like it.

But, when you listen to the "Class e" sample, that short little static burst at the end would be the best example, only this sound I'm hearing is more of a digital sound compared to that sample. Sometimes a short little burst, sometimes a little longer and louder.

That's the best example I can give of it until I get an audio sample to share. It comes and goes. But again, I only have noticed it at the end of the state patrol dispatch transmissions, not from the troopers side.

 

[hazrat8990]

It may be something that is carrying over from another type of system that is patched into DTRS. Maybe MDC-1200, or an analog repeater's courtesy tone? In my area, the analog fire repeater is still in use, even though everything migrated to P25 a decade ago. Sometimes you will hear the repeater's squelch tail, static, or a courtesy tone that gets broadcast over P25.

 

[StoliRaz]

So you're only hearing this on a specific channel or on a trunk system? Or on everything you listen to over your scanner? And what is the system? This info can help people troubleshoot. Also ask in your region-specific forum, locals could know better.

I know on my state police system (analog MOT trunk) at the end of every transmission there's a hum that gets slightly louder as the transmission ends once the user lets off the key. It's more noticeable on some scanners than others, and especially with headphones you hear it.

 

[buddrousa]

In the old school days repeaters would always transmit CTCSS tones on the squelch tail then the newer repeaters/controllers give you the option to drop the tone on the squelch tail. This also was more noticeable on the lower CTCSS tones.

 

[Ubbe]

In old Motorola analog voice trunked systems they have that low frequency disconnect tone that are in the subtone CTCSS frequency range. I don't know if the scanner will pass some of that audio but listening with a proper Motorola radio I could hear that tone every time.

Uniden scanners usually have a 250Hz high pass filter in its audio for analog transmissions but not for digital ones. Old Motorola systems have a digital control channel but analog voice channels with a low speed data in the same range as CTCSS tones. Maybe there's some sort of bug in the handling of audio filters.

/Ubbe

 

[Whiskey3JMC]

In old Motorola analog voice trunked systems they have that low frequency disconnect tone that are in the subtone CTCSS frequency range. I don't know if the scanner will pass some of that audio but listening with a proper Motorola radio I could hear that tone every time.

FWIW I've heard this in the past on all of my scanners from my county's now long replaced Type II SmartZone system

 

[scanlist]

Which radio system and talk-group(s) are you hearing this on?

I encounter random data bursts at beginng or end of transmissions on phase 2 talk-groups with Uniden 436 and 996P2 scanners.

.

 

[chad_96]

Which radio system and talk-group(s) are you hearing this on?

I encounter random data bursts at beginng or end of transmissions on phase 2 talk-groups with Uniden 436 and 996P2 scanners.

.

Colorado DTRS statewide system and the talkgroup I've noticed it on, so far, is the Colorado State Patrol Troop 2C dispatch talkgroup.

 

[chad_96]

Thanks everyone. I haven't been able to get an audio sample yet, as I haven't heard it doing it again. It happens like that, however, it's not all the time.

As I said, I'm just more so curious as to what it is, what causes it, and if it's also something I can improve in a setting on my SDS200 or SDS100. But, it's probably more so just more of a radio signal hiccup or similar.

Anyways, I was really hating the sds series up until I hooked up the HDTV antenna and began getting the boost in signal. Now this thing absolutely rocks. Even found a tweak on accident to quit getting the beginning of transmissions clipped or cut off partially when they begin.

Just wish it would scan a little faster. But with the tweak I found it helps.

Anyways, I will attach an audio sample when I can get one. Thanks all!

 

[nd5y]

On some microphones with a solid plastic PTT button when the user unkeys the button can scrape on the mic housing and make a noise that sounds like a squelch tail.

 

[scanlist]

Colorado DTRS statewide system and the talkgroup I've noticed it on, so far, is the Colorado State Patrol Troop 2C dispatch talkgroup.

CSP dispatchers use wireless headsets. You may hear the dispactcher say "stand by for battery change" on occasion.

Might be an anomaly from low battery or weak signal from their headset to their dispatch workstation.

Your scanner is working properly.

.

 

[chad_96]

CSP dispatchers use wireless headsets. You may hear the dispactcher say "stand by for battery change" on occasion.

Might be an anomaly from low battery or weak signal from their headset to their dispatch workstation.

Your scanner is working properly.

.

Yeah, that's a very good possibility I didn't think of.

I do know, now that you mention it, that the dispatchers have battery operated headsets, as I recall not long ago the dispatcher was unaware of the batteries being dead in her headset and the troopers were in a frenzy trying to reach her until one telephoned in apparently and told her to check/change them. That's a good possibility as I only hear that behavior on the dispatcher side of transmissions...

Thanks! You may very well be onto the mystery sound source!

 

[dmfalk]

Just wish it would scan a little faster. But with the tweak I found it helps.

It scans fast enough, at 80 channels per second. It appears slower, because the screen refresh rate is something like 10-15 refreshes a second. And the more channels to scan, the longer it cycles through them.

 

[chad_96]

It scans fast enough, at 80 channels per second. It appears slower, because the screen refresh rate is something like 10-15 refreshes a second. And the more channels to scan, the longer it cycles through them.

Yeah, maybe it does...

I'm certainly an optimist. And with that I think that it could do a little better though.

Like I said, even at the rate it scans now, I found that little tweak that allows it to not have the beginning of transmissions cut off as it was doing. So, although it scans slow to me ( and obviously according to many many other people's threads on this), and could be a little faster in my opinion, that tweak made it work better to eliminate those cut off transmission at the beginning for the most part.

In conclusion, we can just call this a happy medium...