[Hackrf-dev] not so good experience for my first SDR

[Cinaed Simson]

On 03/18/2017 11:18 AM, mohammed hamoud alkindy wrote:
> Thank you all for the support, it seems I am trying things without any
> improvement, changing sampling rates give me strange error messages no
> matter what rate I put:
> 
>  
> 
> Failed to set RX input rate to 8e+07
> 
> Your device may not be working properly.
> 
> The same with other lower rates

Assuming you didn't as mistake inputting the rate, this may be a bug in
your gqrx.

8e+07 is 80 MHz - which may be the maximum sampling rate for gqrx - but
this is just a wild eye guess - I have no idea where that number is
coming from.

Try blowing away

   $HOME/.config/gqrx/default.conf

You may have to do this each time you change the sampling rate via the
input rate window below 8 MHz using the HackRF.

I can use gqrx at lower sampling rates on the HackRF.

Also, try actually working through the tutorials at greatscottgadgets
and figuring out what your sampling rate is based on using hackrf_transfer.

Then take half of that value for a ball park figure for using gqrx.

If you're using a Beagle Bone or a Raspberry Pi, you're going to have
nothing but trouble at high sampling rates.

> 
> If you have sampling issues you will get an *underrun* not an *overrun*. 

You're ignoring the CPU/USB between the HackRF and the sound card.

If the CPU/USB can't keep up with the HackRF's sampling rate you get
over flows, i.e., the computer is dropping data.

> 
>  
> 
> If you are getting an *overrun* between the HackRF and your audio card
> then you need to put a sample decimeter between them. You can slow the
> 'output' samples from a decimeter block arbirarily down. In other words
> you could sample the HackRF at 20Mhz and decimate it by 200,000 and the
> output would be 1,000 samples per second (very slow). 
> 
>  
> 
> If you are getting OVERRUNs add more decimation
> 
> if you are getting UNDERRUNs then increase the sample rate.
> 
>  
> 
> --Chuck
> 
>  
> 
>  
> 
> On Tue, Mar 14, 2017 at 11:03 AM, mohammed hamoud alkindy
> <mohammed at omantel.net.om <mailto:mohammed at omantel.net.om>> wrote:
> 
>     Actually the lowest rate seating I could set is 8000000 but still
>     getting the over run I will try to check how to change the audio
>     setting to 44.1khz as it show me now it is at 45khz as my card is
>     now set to 44.1khz but I do not know how to change it on my mac yet
> 
>      
> 
>     *From: *HackRF-dev <hackrf-dev-bounces at greatscottgadgets.com
>     <mailto:hackrf-dev-bounces at greatscottgadgets.com>> on behalf of
>     Simon Kennedy <simon at thekennedys.info <mailto:simon at thekennedys.info>>
>     *Date: *Tuesday, March 14, 2017 at 1:35 AM
>     *To: *hackrf-dev <hackrf-dev at greatscottgadgets.com
>     <mailto:hackrf-dev at greatscottgadgets.com>>
>     *Subject: *Re: [Hackrf-dev] not so good experience for my first SDR
> 
>      
> 
>     On gqrx choose menu option 'I/O Devices' then change Input Rate to a
>     low rate like 1000000 to change the sample rate to 1 Msps (bandwidth
>     of 1 MHz). Even my Intel Atom powered netbook will work with this
>     sample rate. My quad core i5-2400 handles 20 Mbps (20 MHz bandwidth)
>     well. Once you find a sample rate that works you can increase it
>     until you reach the limit of you processing power.
> 
>      
> 
>     On 13 March 2017 at 19:11, Dominic Spill <dominicgs at gmail.com
>     <mailto:dominicgs at gmail.com>> wrote:
> 
>         On 13 March 2017 at 13:09, mohammed hamoud alkindy
>         <mohammed at omantel.net.om <mailto:mohammed at omantel.net.om>> wrote:
>         >
>         > Yes I use gqrx and watched the lessons from greatscottgadgets.
>         if gqrx could allow to introduce throttling I would hsve test it
>         but could not see such feature
> 
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>  
> 
> 
> 
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