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Technical Topics => SDR - Software Defined Radio => Topic started by: Antennae on January 11, 2015, 0620 UTC

Title: Cut down on EMI into SDR?
Post by: Antennae on January 11, 2015, 0620 UTC

I recall a post about SDRs and computer interference but I couldn't find it.

Problem: humble portable receives better than fancy (expensive) new SDR on the same 43m beverage antenna.

Assumption: the new SDR is getting noise from the computer its connected to.

At 10pm, I've got a -115dBm noise floor on my SDR on the beverage.  

I was just listening to a pirate station in USB on my SDR. Its an ELAD FDM-SW2. It plugs into my tower computer and is powered by USB wire.  I could definitely hear more pirate music when my portable was connected to the beverage. My portable is a RadioShack DX 398.

I don't think it was a difference in the speaker but that could be the case. My computer has a 2" speaker compared to portable's 3".  

I have a late 90's sound card, 16 bit Creative Sound Blaster ES1371 ES1373. specs: http://en.wikipedia.org/wiki/Ensoniq_AudioPCI#ES1371_and_ES1373

Is there anything that I can do to lower noise levels?
How do I know when I've got it all?  
Are there common culprits that cause EMI to SDRs?  

Thanks folks

Title: Re: Cut down on EMI into SDR?
Post by: ChrisSmolinski on January 11, 2015, 1809 UTC

I wrote this up a while back: http://www.radiohobbyist.org/blog/?p=1374

Basically, I needed ferrite toroids on the various cables.