[Hackrf-dev] hackrf with gqrx on low end of HF

[jed martin]

already did that... worked at 22Mhz sample rate. DC Correction box is set... it was working fine without inverting the spectrum when i was using it >5Mhz with an 8Mhz sampling rate


      From: Cinaed Simson <cinaed.simson at gmail.com>
 To: hackrf-dev at greatscottgadgets.com 
 Sent: Tuesday, August 30, 2016 3:20 PM
 Subject: Re: [Hackrf-dev] hackrf with gqrx on low end of HF
   
If you're receiving, don't use the RF gain - use the IF and BB gains.

If you're transmitting, be careful, assuming no loses, 10 mW of
reflected power may fry the RF amplifier.

And note, there most likely a DC offset on the center frequency.

You should use

  hackrf_transfer -r /dev/null

to test your CPU and USB.

See

  https://greatscottgadgets.com/sdr

for tutorials on the HackRF One.

-- Cinaed


On 08/29/2016 08:58 PM, jed martin via HackRF-dev wrote:
> i was going to ask what i was doing wrong, but while waiting for
> subscription to this list to complete, i was playing with settings in
> gqrx, and kind of stumbled on the answer to my question...
> 
> i've been trying to use my hackrf to listen to the 80M ham band (as well
> as 160M and other assorted stuff in that part of the spectrum)  part of
> the problem i was having was that gqrx has a few "presets" for the
> hackrf sample rate, and with the default
> 8Mhz sample rate, if i tuned the center frequency below 8Mhz, i just got
> a lot of hash from interaction of signals within the hackrf. so, i tried
> something not in the list of presets... setting the sample rate at 3Mhz,
> and setting the center frequency at something like 3.57Mhz (i tried a
> few different center frequencies and used the one that generated no
> hash).  then it was working within the 80M band, but something was still
> amiss, it was all backwards, the digital section was up around 4Mhz, and
> the phone section at the lower end, and LSB was USB....  while playing
> with the Input Controls settings, i clicked the Swap I/Q box, and it
> flipped everything back to where it should be...  it's a good thing i
> knew what i was looking for (i.e. what parts of the band are digital vs
> phone, and that 80M phone should be LSB) or i would still be
> befuddled...  i actually like the hackrf better than the sdrplay. it
> seems to have better s/n performance.  i think the sdrplay linux driver
> needs a bit of work, and when i recently upgraded the version of Skywave
> linux i'm using, the new sdrplay driver was really broken (which is the
> reason i tried the hackrf in place of it)
> 
> one question though... the 14db input amp has a limit of -5dbm?  that's
> about 200mV or so... i've been using it, but i need to keep all RF
> sources that can induce that much voltage into the antenna system far
> away from it, even if it's a cell phone and i'm using the radio on HF,
> correct?
> 
> 
> _______________________________________________
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> HackRF-dev at greatscottgadgets.com
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> 

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