Re: [Discuss-gnuradio] static peaks spectrum

[Cinaed Simson]

On 01/19/2017 01:28 AM, Marc Pàmies Massip wrote:
> Oh, really? I was using a HackRF-One and sampling at 10MHz.

I was betting on a RTL dongle.

And I'm guessing SDR# is running on Windows.

You should also try a WBFM channel - between 88-108 MHz.

There could be Windows USB driver issues - or the version of the HackRF
One libraries and utilities doesn't match the firmware.

Try

  hackrf_transfer -r NUL -s 8000000

The two columns should be equal in magnitude - otherwise the
USB/computer are to slow for 8 MHz sampling - which is minimum requirement.

Don't use a USB hub.

And post

  hackrf_info

on the above information on the mailing list

  address@hidden

- someone on the list may have seen the problem before.

I know next to nothing about Windows.


> 
> 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.
> 
> Marc.
>>
>> 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.
>>
>> >
>> >
>> > _______________________________________________
>> > Discuss-gnuradio mailing list
>> > address@hidden
>> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>> >
>>
>>
>> _______________________________________________
>> Discuss-gnuradio mailing list
>> address@hidden
>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio