[Hackrf-dev] Static/warbling non reception issue

Dominic Spill dominicgs at gmail.com
Mon May 2 09:37:29 EDT 2016


David,

Did you try the suggestion below from Karl?  I'm fairly sure this will
solve your problem.

Thanks,
  Dominic

On 1 May 2016 at 21:29, Karl Koscher <supersat at cs.washington.edu> wrote:
> I don't think you sent the screenshot to the mailing list... or at least I
> didn't see it? (Does this mailing list even support attachments?)
>
> You don't need anything special to do offset tuning. The DC spike should not
> move as you drag the spectrum display left or right. Drag the spectrum
> display until the signal you want is free of the DC spike or other noise,
> then click on the middle of the signal you want to tune in. It should then
> demodulate cleanly.
>
> Here is a screenshot of how it should look:
> http://sysnet.ucsd.edu/~supersat/sdrsharpfm.png
>
> Make sure WFM is selected with a bandwidth of 150000.
>
> On Sun, May 1, 2016 at 1:13 PM, davidmarkusgoldstein at gmail.com
> <davidmarkusgoldstein at gmail.com> wrote:
>>
>> I'd even consider buying studio1, if I can get this to work.  I posted the
>> basic settings screens...the signals are strong on the spectrum.
>> Everything's just so inaudible and static'd.
>>
>>
>> Sent via the Samsung Galaxy Note® II, an AT&T 4G LTE smartphone
>>
>>
>> -------- Original message --------
>> From: Cinaed Simson
>> Date:05/01/2016 3:49 PM (GMT-05:00)
>> To: hackrf-dev at greatscottgadgets.com
>> Subject: Re: [Hackrf-dev] Static/warbling non reception issue
>>
>> On 05/01/2016 06:38 AM, David Goldstein wrote:
>> > Maybe someone has an extio that will fix this...?
>>
>> Yes there is an extio - the poster could supply the list with the
>> parameters he's using and his hardware setup.
>>
>> >
>> > On Apr 30, 2016 11:39, "Dominic Spill" <dominicgs at gmail.com
>> > <mailto:dominicgs at gmail.com>> wrote:
>> >
>> >     I can't remember how it works in SDR#, but in GQRX you can just
>> > click
>> >     on the display and it will start demodulating that frequency instead
>> >     of the centre frequency.  It's probably the same in SDR#
>> >
>> >     Dominic
>> >
>> >     On 30 April 2016 at 16:36, davidmarkusgoldstein at gmail.com
>> >     <mailto:davidmarkusgoldstein at gmail.com>
>> >     <davidmarkusgoldstein at gmail.com
>> >     <mailto:davidmarkusgoldstein at gmail.com>> wrote:
>> >     > Hi Dominic,
>> >     >
>> >     > Yeah 101.5 and 103.3 are right in town or nearby.  I will have to
>> >     test the
>> >     > offset features better...I will let you know how this goes.
>> >     >
>> >     > David
>> >     >
>> >     >
>> >     > Sent via the Samsung Galaxy Note® II, an AT&T 4G LTE smartphone
>> >     >
>> >     >
>> >     > -------- Original message --------
>> >     > From: Dominic Spill
>> >     > Date:04/30/2016 11:23 AM (GMT-05:00)
>> >     > To: david.goldstein.93 at alumni.vanderbilt.edu
>> >     <mailto:david.goldstein.93 at alumni.vanderbilt.edu>
>> >     > Cc: hackrf-dev
>> >     > Subject: Re: [Hackrf-dev] Static/warbling non reception issue
>> >     >
>> >     > On 30 April 2016 at 00:32, David Goldstein
>> >     > <davidmarkusgoldstein at gmail.com
>> >     <mailto:davidmarkusgoldstein at gmail.com>> wrote:
>> >     >> Hi, here's a screenshot of the settings that I can change, plus
>> > the
>> >     >> spectrum analysis shot.  The audio I get is heavily distorted on
>> >     the strong
>> >     >> local FM stations.
>> >     >
>> >     > The station at 101.5MHz looks like an excellent signal.
>> >     >
>> >     >> So, I have no idea what's wrong, except that it could be the
>> >     sound driver
>> >     >> or on-board sound.
>> >     >
>> >     > Are you demodulating the signal at the centre frequency?  Or at an
>> >     > offset?  The spike in the middle is the DC offset, so if you're
>> >     > demodulating there you're going to see bad data.  It's explained
>> > in
>> >     > more detail here:
>> >     >
>> >
>> > https://github.com/mossmann/hackrf/wiki/FAQ#what-is-this-big-spike-in-the-center-of-my-received-spectrum
>> >     >
>> >     > Thanks,
>> >     >   Dominic
>> >     >
>> >     >> -----Original Message-----
>> >     >> From: Dominic Spill [mailto:dominicgs at gmail.com
>> >     <mailto:dominicgs at gmail.com>]
>> >     >> Sent: Friday, April 29, 2016 5:40 PM
>> >     >> To: davidmarkusgoldstein at gmail.com
>> >     <mailto:davidmarkusgoldstein at gmail.com>
>> >     >> Cc: hackrf-dev
>> >     >> Subject: Re: [Hackrf-dev] Static/warbling non reception issue
>> >     >>
>> >     >> On 29 April 2016 at 17:31, davidmarkusgoldstein at gmail.com
>> >     <mailto:davidmarkusgoldstein at gmail.com>
>> >     >> <davidmarkusgoldstein at gmail.com
>> >     <mailto:davidmarkusgoldstein at gmail.com>> wrote:
>> >     >>> Hi, how can I test the hackrf to see if it's damaged?  I have
>> > sound
>> >     >>> card issues, it seems, on my i7-2600 win7 64 bit system, so I
>> >     tried it
>> >     >>> on a Vista laptop and experienced the same: static and
>> >     choppiness and
>> >     >>> some distorted voice on local fm.  So perhaps the radio is
>> > damaged.
>> >     >>
>> >     >> This doesn't necessarily mean that the radio is damaged, although
>> >     we can
>> >     >> help to test whether it is, but it may be something not quite
>> >     right in your
>> >     >> settings.  Telling us which settings you are using for sample
>> >     rate, gain,
>> >     >> filter, etc would really help us to diagnose the problem.
>> >     >>
>> >     >> Thanks,
>> >     >>   Dominic
>> >     >>
>> >     >>> -------- Original message --------
>> >     >>> From: Dominic Spill
>> >     >>> Date:04/28/2016 7:31 PM (GMT-05:00)
>> >     >>> To: davidmarkusgoldstein at gmail.com
>> >     <mailto:davidmarkusgoldstein at gmail.com>
>> >     >>> Cc: hackrf-dev
>> >     >>> Subject: Re: [Hackrf-dev] Static/warbling non reception issue
>> >     >>>
>> >     >>> On 28 April 2016 at 20:28, davidmarkusgoldstein at gmail.com
>> >     <mailto:davidmarkusgoldstein at gmail.com>
>> >     >>> <davidmarkusgoldstein at gmail.com
>> >     <mailto:davidmarkusgoldstein at gmail.com>> wrote:
>> >     >>>>
>> >     >>>> Hi, this might not be a tech support list but I don't know what
>> >     to do
>> >     >>>
>> >     >>> Hi David,
>> >     >>>
>> >     >>> We're happy to provide tech support through this mailing list;
>> > I'm
>> >     >>> sure we'll be able to help you.
>> >     >>>
>> >     >>>> ...everything seems set up properly but I get static and broken
>> > up
>> >     >>>> voice broadcast on local fm.  I think it's the alc889 Realtek
>> > sound
>> >     >>>> card doing this...I had this issue with a winradio g 315
>> >     because I'm
>> >     >>>> running win 7 64bit.
>> >     >>>
>> >     >>> Are you using SDR# on your Win7 install?  Could you give us some
>> >     >>> examples of the settings you are using?  If it's easier, you can
>> >     >>> attach a screenshot of the setting panel in SDR# (or whichever
>> > tool
>> >     >>> you're using).  You could also attach a screenshot of the tool
>> >     so that
>> >     >>> we can see how strong the signal is compared to the background
>> >     noise.
>> >     >>>
>> >     >>>>  They tweaked a driver for me and I got the winradio running
>> > but I
>> >     >>>> don't know what to do now with the hackrf I have, if it is the
>> >     sound
>> >     >>>> card at all.  Any tips?
>> >     >>>
>> >     >>> One option would be to try not using realtime processing.
>> >     Capture ~20
>> >     >>> seconds FM station to a file, then demodulate it from the file
>> >     >>> afterwards.  Finally, you should be able to play back the file
>> > as
>> >     >>> audio.  If it's a problem with the quality of the signal being
>> >     >>> received, the output will still be choppy, but if the output is
>> >     smooth
>> >     >>> we can look at where else things may be going wrong.
>> >     >>>
>> >     >>> It certainly looks like you have enough CPU power and RAM to
>> > support
>> >     >>> the task that you're trying to do, so we'll have to narrow down
>> >     where
>> >     >>> the problem could be.
>> >     >>>
>> >     >>> Thanks,
>> >     >>>   Dominic
>> >
>> >
>> >
>> > _______________________________________________
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>> >
>>
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