SDS100 Audio Distortion, (Not Speaker Problem)

cozway

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Nov 1, 2010
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Location
Springfield, MO
I bought a Uniden SDS100 used about 2 weeks ago. The scanner works beautifully, great sensitivity, etc. except for one thing. The audio seems to clip on peaks on some receptions causing substantial distortion. I've seen posts that mention poor speaker connections, however this is not the case on mine. I've tried external speakers with the same result. Also, recordings have the same clipping and distortion. This only happens with approximately 30% of receptions. I would have liked to attach an audio file recorded on the unit for an example of how it sounds but I wasn't able to. I don't know if it is a defective unit or if I just need to set some option or filter differently. Any help or advice would be appreciated.
 

mheller310

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Jun 13, 2012
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I experienced that problem when I first got my SDS 100. I found that going to the Modulation setting and changing from Auto to FM cured that problem. You my need to go into the Filter settings and change setting there too depending on the system type you are scanning.
 

cozway

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Nov 1, 2010
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Springfield, MO
Thanks. I'll give that a try. I also know it's not Simulcast distortion because I don't think there is any Simulcast in my area.
 

shirsch101

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On a BCD536HP is the modulation a global setting or just site channel or conventional channel that you are on
 

cozway

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Nov 1, 2010
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Springfield, MO
Changing the modulation to FM on the channels that have the problem does seem to cure it. However, it does seem to lessen the sensitivity somewhat. This makes sense to me because it did sound like over deviation. I might try going back to NFM or Auto, then set some attenuation and see what that does also.
 

Ubbe

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Sep 8, 2006
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Stockholm, Sweden
The SDS100 has much more narrow filters than other scanners so that a NFM setting that works ok in a 536 doesn't work in a SDS100 if the transmitter use wider FM modulation. It also has distorsion that sounds like overmodulation if it is interfered from other frequencies so I would suggest to first try different filter settings. The SDR and DSP used in SDS scanners make them sound and behave differently to other scanners and the experiance and knowledge you have from conventional scanners can often not be applied.

/Ubbe
 

cozway

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Nov 1, 2010
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Location
Springfield, MO
Well, after using the scanner for some time after changing the services that I was having the problem with to wide FM, I can say that the problem is cured. Thanks to mheller310 for the suggestion and others for their helpful comments.
 

tvengr

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Feb 10, 2019
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Baltimore County, MD
Correction: In my previous post, I stated that I changed from NFM to wide FM. I meant to say just FM, not WFM.
If the frequencies sound excessively loud, try changing the Volume Offset to -1, -2, or -3. If the frequency is 30-50 MHz (VHF low band), the modulation should be FM. If VHF high or UHF use Auto or NFM. Certain frequencies such as VHF marine band and NOAA weather are exempted from the narrowbanding requirement and should be FM.
 
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