Hey Paul,
You are right, if I reduce the gain the peaks are reduced too. Do yo have an explanation for it?
Playing with SDR# I have seen that setting the LNA noise and the VGA noise to 0dB all the peaks are removed. If then I increase the LNA noise and maintain VGA noise to 0dB the peaks appear again (as it gets higher more peaks appear). And finally by increasing the VGA noise the peaks just go higher with the rest of the spectrum. However, if after setting both gains to 0dB I start increasing the VGA gain a few peaks appear too, but not as many as in the other case. Does it makes sense to you?
Many thanks for your reply,
Marc.
On 19/01/2017 12:19:49, Garver, Paul W <address@hidden> wrote:
If you change the receiver gain, does anything happen to the peaks? Try lowering it.
Paul Garver
On Jan 19, 2017, at 4:32 AM, Marc Pàmies Massip <
address@hidden> wrote:
Oh, really? I was using a HackRF-One and sampling at 10MHz.
Now I've tried with different sample rates (8MHz, 10MHz, 12.5MHz and 16MHz) and the peaks are always there. Maybe it's true that they appear more often for higher sample
rates, but I am not able to make them disappear.
On 19/01/2017 9:38:34, Cinaed Simson <address@hidden> wrote:
On 01/18/2017 01:31 PM, Marc Pàmies Massip wrote:
> Hi,
>
> Maybe this is a stupid question for experts in SDR, but I haven't find a
> clear explanation yet. I know it is normal to have a DC offset in the
> center of the spectrum, but I am surprised by the amount of static peaks
> that I see sometimes in specific bands (you can find attached some
> images to better understand what am I talking about). It is obvious that
> those are not "real" signals, in fact when I re-tune the SDR peripheral
> they don't move according to the frequency displacement. I want to
> understand if it is due to a software problem (the screenshots were
> taken from SDR#) or if it has something to do with the hardware (maybe
> those are just harmonics from some kind of square signal, i.e clock). I
> am worried because they are extremely strong and because of this I could
> have trouble detecting weaker signals nearby.
>
> Summarising, my questions are:
>
> - What causes those peaks?
> - Is it necessary to remove them for a proper signal detection?
>
> Thanks in advance,
>
> Marc.
You haven't indicated what hardware you used or the sampling rate.
Try reducing the sampling rate - the sampling rate used may be unstable.
>
>
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