Frequency Drift

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allclear

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May 6, 2014
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Hi everyone,

I am using the R820T with SDRSharp and Unitrunker to monitor control channels. The issue I have is when I tune 418.1250 (Motorola P25 1) Unitrunker will decode the control channel info. About 10 minutes later the frequency will drift and I will lose the signal on Unitrunker. I then have to adjust the ppm usually by +1 to get the signal back This will happen about 3-4 times before it eventually stays on the frequency. My question is, how can I prevent this from happening? I understand that dongles need about 20 minutes to warm up but this issue only happens around the 418mhz range.

Hope this makes sense,

Larry
 
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screamin72

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Its a known issue in the nano version. The mini doesn't do that.
 

rbm

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Jan 25, 2005
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Upstate New York
You can try increasing your bandwidth slightly so any drift may still stay within the passband.

After 20-40 minutes, mine all settle down enough to decode digital modes without a problem.
But, in each case, I have the bandwidth set slightly wider than require.

Rich

This is what one of my dongles looks like when it's first powered on.

 
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screamin72

Guest
Both my mini's take 3-5 minutes then they are fine. My nano drifts for 5 or more minutes. Kind of like dancing doing those ppm corrections with the nano.
 
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