[hfsig] Sidebands on Raspberry Pi WSPR carrier

Orrin Winton orrin.winton at gmail.com
Sun Sep 4 03:17:34 EDT 2016

I may be experiencing that too. I say *may* because i haven't looked at it
with another radio + waterfall like fldigi.

But i *hear* with my ear a lot of grunge on my transmitted signal,
listening with another radio 20 feet away.

If i disconnect the antenna from the 2nd radio, i hear just the pure tone.
Which is what you'd expect if the grunge was quite a few dB down from the
main signal.

I may try some other 5V power source and see if there is any change.

Orrin WN1Z in CN90

On Sep 4, 2016 00:05, "Ron Ott" <ronott at sbcglobal.net> wrote:

> This is my first post to the group, my apology if I'm not following the
> correct protocol.
> I just got a Raspberry Pi 3 working on 20m WSPR using the TAPR kit. I
> quickly discovered that there are sidebands 120Hz above and below the
> carrier frequency and these sidebands are modulated like the carrier and
> are only 15dB or so below it in amplitude.
> In the last few days I read some chatter about others seeing such
> sidebands on received WSPR signals, but there was no mention of a Raspberry
> Pi (normally the listener wouldn't know what the sender is using).
> I'd be surprised if no one else has discovered this issue, which is
> serious since the sidebands are pretty strong.  I suspected modulation by
> the main USB power source, but tried other supplies including a well
> regulated HP with no change.
> What's the solution?
> Thanks, Ron / W6XY
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> hfsig at tapr.org
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