[Hackrf-dev] sweep capabilities

[RizThon]

Thanks for the detailed info Michael.

Reading https://github.com/mossmann/hackrf/blob/master/host/hackrf-tools/src/hackrf_sweep.c
I see that the minimum number of samples per frequency is 8192. Would
it be possible to lower it to get, I suppose, shorter capture times?

I'm interested in signals in the ISM 2.4GHz band that may be short.
Even if I reduce the band to 80MHz, 1/100s may still be too slow.
Having a sweep taking 1/300s to 1/200s might be enough.

2017-05-25 23:45 GMT+08:00 Michael Ossmann <mike at ossmann.com>:
> On Thu, May 25, 2017 at 03:58:51PM +0800, RizThon wrote:
>>
>> What can I expect exactly from a performance point of view? I've read
>> "sweep rate of 8 GHz per second" so does that mean that to scan
>> 100MHz, it'll take 100M/8G=1/80s to scan? It should depend on the
>> capture time and tuning time, but maybe it's taken into account in the
>> 8GHz/s?
>
> That is correct.  You'll get 80 sweeps per second across 100 MHz.  (In a test I
> just ran for verification, I had 81.37 sweeps per second.)
>
>> What kind of computer does one need to run something like hackrf_sweep
>> than returns the FFT, with a resolution of 100kHz ie 10 bins per MHz?
>
> With 100 kHz bin width, my test used 20% of one core of this CPU:
>
> model name      : Intel(R) Core(TM) i5-7200U CPU @ 2.50GHz
> bogomips        : 5427.48
>
> Bin width is the main thing that affects CPU utilization.
>
> Michael