How to reduce image reception in peaberry / hdsdr

General discussion and support for the Peaberry SDR V1.

How to reduce image reception in peaberry / hdsdr

Postby k8it » Sun Apr 28, 2013 12:52 am

ok unit rx and tx ok. Now time to improve reception.
unit has good sensitivity but lacks image rejection.
what settings in hdsdr are people using?
LO offset?
what I/Q / audio channel selections?
Has anybody had this issue before?

Thanks

73 Neil K8IT
:D :D
k8it
 
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Re: How to reduce image reception in peaberry / hdsdr

Postby hansvi » Sun Apr 28, 2013 1:46 am

During my tests I did install HDSDR on a windows box. I would check SSB stations and see if they follow the LSB/USB conventions for the band you're listening on. If they don't match, your I and Q channels are reversed (swapping I and Q will also swap USB and LSB). Another effect will be that the frequencies don't make real sense.

I had to swap I and Q in about any application I encountered, including HDSDR.

I still need to calibrate my Peaberry, but after swapping I and Q I think it's fairly good now. More testing is needed.

As far as I understand, image rejection can be fine-tuned by adjusting the angle between the I and Q phase in some setting.

Hope that helps,
Hans.
73,
Hans - ON8VQ
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