[Hackrf-dev] Static/warbling non reception issue

Cinaed Simson cinaed.simson at gmail.com
Sun May 1 16:47:46 EDT 2016


On 05/01/2016 01:13 PM, 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.
> 

What is your sampling rate? Did you try turning it down?

A sampling rate of 4-5 times the bandwidth is sufficient. WBFM is
roughly 200 kHz - a sampling rate of 1.75 MHz is sufficient.

It might not be the sound card - it might be the USB dropping data.


> 
> 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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