Re: [Discuss-gnuradio] spectrum monitoring / very wide band scanning

[U L]

At my former employer we were using the HackRF in sweep mode to do I think 100 MHz to 6 GHz sweeps at 1 Hz (i.e. almost 6 GHz scanned each second).  For contiguous sweeps I think it used a non-configurable 7.5 MHz (RF tuned) step or something like that, but gave you much better frequency resolution as the waterfall was the output of a some FFT which was somewhat configurable (so you could sort of set the resolution BW).  We did make use of QSpectrumAnalyzer mentioned in a previous post and in combination with the hackrf sweep-mode worked quite well.  I think the HackRF uses the same driver as rtl-sdrs but a typical rtl does not support the sweep-mode of operation.

On Wed, Mar 28, 2018 at 8:00 PM, Balthasar Indermuehle <address@hidden> wrote:

Thanks Marcus, indeed I'm using B200's for this project. X300's are slightly over my budget unfortunately... but I'm also interested in doing the same with RTL dongles.

You mention 450ms for tuning a B200 - that seems rather longish?

Cheers

- Balt

On 29 March 2018 at 06:04, Müller, Marcus (CEL) <address@hidden> wrote:

so, 60 steps in 3 Minutes… sounds absolutely doable with the Ettus B200
(you asked about UHD drivers, so I presume you mean USRPs – the RTL
dongle has nothing to do with UHD) and the usrp_spectrum_sense.py
script that comes with GNU Radio. Even if I do not endorse the
architecture of that script, and would recommend you reserve up to
450ms for tuning, as the B200 can take a bit of time to tune over some
larger steps.
With the other USRPs, you'd be faster. With a X300+TwinRX, you'd be
able to do 80 MHz on each channel at once, and can tune the channels
independently, so that you can actually even interleave tuning and
receiving operation; realistically, that'd imply an effective
observable bandwidth of always at least 120 MHz; 3000 / 120, meaning
you only need 24 steps to cover all that bandwidth. With tuning delays
in single milliseconds (too lazy to look this up right now, so let's
say 1ms), that'd be 25ms tuning, roughly 2.999583 minutes of spectrum
observation for 3 minutes of operation.

Stitching that together to a full spectrum is more of a challenge here,
but assuming you control the frequency hopping with commands to the
USRP Source block, and hence are in control of when which band appears
on the sample streams:
You could do something like have a fixed 13-frequency sequence that
each of the two receive channels hop along in fixed time intervals.
Convert to vectors of interval length, FFT+magnitude-square these, and
reassemble to a full spectrum vector (if your frequency sequence is
strictly ascending, and non-overlapping, then just leave them in the
order they are – all frequency bins should now be equidistantly
spaced).

Best regards,
Marcus

On Wed, 2018-03-28 at 12:19 +1100, Balthasar Indermuehle wrote:
> At my work we're using R&S EB500s for continuous spectrum monitoring at our sites of interest. These machines step through the frequencies 70 - 3000 MHz in about 3 minutes in chunks of 50 MHz (from memory), and then assemble the fragments into a contiguous waterfall display.
>
> Is anyone aware of a wide band scanner software (that may or may not be GNUradio based) that works with RTL-SDR dongles and with UHD drivers and would allow to create a wide band spectrum sweep?
>
> I've built a raw IQ recorder that does just that, but it needs to be wrapped into a decent GUI, showing some nice waterfall displays and needs to be made pretty. Before I'm investing the time to build this I thought I'd check if that's not effort already done and shared by someone else. Google thinks no... anyone know differently?
>
> - Balt

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