[hpsdr] Janus noise problem?

[Mike Naruta]

Hi David,


I played with my Janus (I just got it
running last Sunday) and I can hear the
noise also.  It is most apparent to me with
the AF set to 50 and the RF set to 25.

It sounds like a hiss/static with higher-
frequency components, like 5KHz - 10 KHz.

If I narrow the filter to 25 Hz, I don't
seem to hear it.  Listening to 250 Hz and
wider has it.

I thought at first I was just hearing the
noise in the filter passband, but if I
bring up the RF on a vacant spot, the
louder noise sounds different; with more
lower frequency components.  I'm using a
Marantz stereo amplifier with a pair of
huge Nikko NS-600T speakers.  I'm doing
48 KHz sampling and run about 15% CPU
with the panadapter on.  I think it
reduced when I switched to a dummy load.

You have a good ear.  I didn't notice it
until I listened for it.


Mike - AA8K



David Woodhead wrote:
> ***** High Performance Software Defined Radio Discussion List *****
> 
> I previously thought this was a problem with my setup but last night I
> ran Janus with no inputs and got the same results:
> 
> In power SDR, if I set the audio and RF gain settings to 50% I hear a
> strange crackling sound in the speakers. With the RF gain at full this
> noise is swamped out by the receiver noise but gradually turning down
> the RF gain does not result in the same gradual noise level reduction
> I'm used to. With Janus, the noise level drops and becomes a little
> distoted. As the RF gain is reduced the noise level fades away and I
> hear a residual scratching noise with the RF gain at about 50%. Anyone
> else seeing the same behaviour?
> 
> David
> KM5TZ

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