SDS100/SDS200: Peculiar behavior - RX cutting out only while mobile

[IcomIcR20]

Hello all,

I have been using my SDS100 while mobile for the past few weeks without issue, but today I noticed that I was getting an unusually high amount of "packet loss" when listening to a P25 system while mobile. So I switched over to a NOAA channel and observed the behavior shown in the following video:

- YouTube

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Some notes:
* It was not a speaker issue as when I tuned to an unused channel with the squelch wide open, there were no drop-outs
* It is not an antenna issue as the behavior continued whether I used the stock antenna, or my mobile whip
* The drop-outs stopped as soon as I brought my vehicle to a stop, but as soon as I started to drive again, the drop-outs would begin again
* I rebooted the scanner, but the issue persisted.
* I reset all settings on the scanner and began to drive again while monitoring NOAA and the issue completely disappeared

Does anyone know what might have caused this odd behavior? I am at a loss here. I just wanted to make sure that nothing is wrong with my new scanner.

Thanks!

 

[KevinC]

NWR needs to be FM, not NFM. Change it and try it mobile again.

 

[ofd8001]

This might be in left field, but does this happen "every where", a specific location or a random location?

Next thing I'd try is when at a location this happens, pull into a parking log or off the road and then turn everything off in your vehicle, taking your foot off the brake, etc., and seeing what happens. There could be some "gremlins" in your vehicle's electrical system causing interference.

 

[trentbob]

Hello all,

I have been using my SDS100 while mobile for the past few weeks without issue, but today I noticed that I was getting an unusually high amount of "packet loss" when listening to a P25 system while mobile. So I switched over to a NOAA channel and observed the behavior shown in the following video:

- YouTube

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

youtube.com

Some notes:
* It was not a speaker issue as when I tuned to an unused channel with the squelch wide open, there were no drop-outs
* It is not an antenna issue as the behavior continued whether I used the stock antenna, or my mobile whip
* The drop-outs stopped as soon as I brought my vehicle to a stop, but as soon as I started to drive again, the drop-outs would begin again
* I rebooted the scanner, but the issue persisted.
* I reset all settings on the scanner and began to drive again while monitoring NOAA and the issue completely disappeared

Does anyone know what might have caused this odd behavior? I am at a loss here. I just wanted to make sure that nothing is wrong with my new scanner.

Thanks!

As far as the weather is concerned I noticed you have the squelch on 8, 2 is the best setting. Sounds like the squelch was blocking some signal.

What is your mobile whip exactly, is the p25 7-800 MHz? Does your RSSI, noise level and error rate fluctuate when you're driving as opposed to stopped, what power source are you using, battery in the radio, one of the USB connections and what's your power source, directly to the battery, cigarette plug, USB port?

 

[IcomIcR20]

NWR needs to be FM, not NFM. Change it and try it mobile again.

Thank you for the suggestion, but I am doubtful that that was the problem. After I reset the scanner, it worked perfectly fine while mobile, still on NFM. I was also noticing drop-outs on non-NOAA systems.

 

[IcomIcR20]

As far as the weather is concerned I noticed you have the squelch on 8, 2 is the best setting. Sounds like the squelch was blocking some signal.

Oh my gosh I think that might be it. Not sure how I failed to notice that. I bet I accidentally turned the squelch up instead of turning the volume up and didn’t realize it since I was driving and hence not looking at the display.

When I reset, that brought the squelch value back to 2 which would explain why it started working again. Thank you for pointing that out… like I said, I should have noticed that

 

[Ubbe]

Another scanner type would not have shown any problem with those signal strengths at -75dBm and stronger using a squelch setting of 8 but SDS scanners have more modulation noise. The more the signal modulates the more noise it will generate that makes the squelch close. You sometimes need to switch to FM instead of NFM to compensate for SDS scanners more agressive modulation noise to keep that modulation more within the bandwidth limit set in the DSP demodulators filter to keep the noise level down. It's more noticed at full modulation from a data signal as it will stop to demodulate any signal as soon as the squelch closes.

/Ubbe

 

[garys]

I do that all the time on my SDS100 and once i a while on my 325P2.

Oh my gosh I think that might be it. Not sure how I failed to notice that. I bet I accidentally turned the squelch up instead of turning the volume up and didn’t realize it since I was driving and hence not looking at the display.

When I reset, that brought the squelch value back to 2 which would explain why it started working again. Thank you for pointing that out… like I said, I should have noticed that