[Hackrf-dev] Odd issue on running hackrf_transfer multiple times in a row

[Shannon Holland]

No idea why I didn’t get all of your previous email - from the list archives it clearly was very different than what I got (should have thought to check the archives). This one is fine though :) Stupid Macs!


> On Sep 1, 2015, at 8:32 AM, Dominic Spill <dominicgs at gmail.com> wrote:
> 
> Good point!  Although the greater range of values in the first capture
> is still something that I would like to look at.  Also, the very small
> range of values that you see overall.

I was able to get the test mode (for standard rate bluetooth) going with the uberttooth which gave me a much stronger signal to look at. I also shifted the frequency to be a 1Mhz offset from the BT channel I was looking at to remove the DC offset issues. This got me to a much happier place where I was able to receive something that clearly wasn’t noise.

But, doesn’t resolve the odd issues I was seeing earlier…

In response to your question regarding HACKRF_ERROR_STREAMING_EXIT_CALLED: that seems to be a function of specifying a sample count. If I just leave the transfer running and ctrl-c I’m not seeing this. However, either case produces similar results.

> 
>> I’ve played with different rx gain settings (as well as turning the antenna amp on and off) and really see very little change in the recorded data. Looking at a FFT waterfall (using baudline) I do see an changes but am still not having any luck finding any sort of apparent signal from all the noise. Switching antennas did help a bit.
> 
> What are you using for your antenna?

I was initially using the ubertooth antenna (with adapters). I’ve switched to a higher gain 2.4Ghz antenna (which also helped). No idea what the real specs on this one are however.

> Yes.  There is a transmit test in the firmware, it can be enabled from
> ubertooth-util.  You can also produce test patterns from CSR Bluetooth
> dongles using the bccmd tool, which is how I was able to write the
> first version of gr-bluetooth.

Thank you! I got the ubertooth-util tx test going (which helped a lot). I’ll check out the CSR dongles as well - don’t think I have one laying around but they look cheap :)

> That code is quite old, but I don't think it should be too much effort
> to get it working with libbtbb (the Bluetooth baseband library).  It's
> definitely on my list of projects to revive but it's not going to
> happen very soon.  Any help would be gladly received; pull requests
> are especially welcome.

I’ll take another look and see if I can figure out what’s up - I really didn’t do much more before than just try to run it and see the exception.

> 
>> Any suggestions as to what I can do to improve things on the Rx side would be greatly appreciated!
> 
> Could you try some simple reception tasks with the HackRF, e.g. FM [1]
> or ADS-B [2] ?  I think that will give us a better idea of whether the
> radio is working correctly.  We can then address the out of date
> gr-bluetooth code.

I think I have that issue resolved with the ubertooth transmit test. I can try out the FM Rx test tonight when I get home (I don’t have a suitable antenna here at work).

Thank you!

Shannon

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