Re: [Discuss-gnuradio] gr-radar and FMCW radar imlementation for measuring range with high resolution

[Martin Braun]

Tilen,

gr-radar is probably still a great starting point. I was playing around
with it just recently, and will be contributing some fixes to gr-radar
in the next few week.

B210 support, I think, is not natively available. I was going to
characterize the TX/TX leakage, I'm not entirely sure how well it'll
fare for radar applications. In you case, leakage could be drown out
your measurements, but maybe it won't.

-- M

On 02/09/2018 12:48 PM, Tilen Matkovič wrote:
> Hi,
> 
> thanks for quick reply!
> 
> I was aware of range resolution equation, apparently I didn't specify
> project enough and wasn't really paying attention while reading some
> articles :/.
> 
> Goal of my project would be to measure breathing/heartbeat rate of a
> human using FMCW radar in GNU radio. I just realized that I do not need
> to measure the distance of some object (human chest in my case), but
> only the phase variation, which would be much more precise for breathing
> monitoring than technique used in gr-radar, with some other limitations.
> 
> I believe that beam antennas would help me, so I will try to use them
> also, once I understand theory and get it working in implementation.
> 
> Article and webpage that helped me to understand such monitoring:
> Smart Homes that Monitor Breathing and Heart Rate
> - http://witrack.csail.mit.edu/vitalradio/content/vitalradio-paper.pdf
> <http://witrack.csail.mit.edu/vitalradio/content/vitalradio-paper.pdf>
> http://hforsten.com/heartbeat-detection-with-radar.html
> <http://hforsten.com/heartbeat-detection-with-radar.html>
> 
> If such implementation for monitoring phase variation already exists in
> GNU radio, please point me in right direction :)
> 
> Regards,
> Tilen
> 
> 2018-02-08 19:02 GMT+01:00 Sebastian Müller <address@hidden
> <mailto:address@hidden>>:
> 
>     Hi Tilen,
> 
>     Am 8. Februar 2018 um 16:31:37, Tilen Matkovič
>     (address@hidden <mailto:address@hidden>) schrieb:
> 
>>     Hello everyone,
>>
>>     I am working on a project where I am using radars to measure
>>     distance/range from one point to another (with relatively high
>>     range resolution - range of centimeters or even millimeters).
> 
>     Generally I’m not sure if you will achieve this with the B210
>     hardware you mention later. Keep in mind the range resolution
>     equation for radar:
> 
>     dr >= c/(2*B)
> 
>     For a range resolution of 1 cm you’ll need a signal bandwidth of 15
>     GHz [1], while the URSP has a maximum frequency coverage of up to 6
>     GHz, which means your center frequency plus half the bandwidth must
>     be less equal 6 GHz. Common radars, for instance in automotive
>     applications, work on a center frequency near 100 GHz, allowing much
>     higher bandwidths!
> 
>>     I found the gr-radar (https://github.com/kit-cel/gr-radar/
>>     <https://github.com/kit-cel/gr-radar/>) module for GNU radio,
>>     which already has some implemented radar techniques, the most
>>     promising for me would be the FMCW radar. But the github
>>     repository was not updated in years, so I am asking you guys if
>>     some of you may know some alternatives for GNU radio (googling
>>     radar gnuradio was not so successful) or maybe anyone has already
>>     worked with gr-radar.
> 
>     I’m not aware of any other projects, but I’ve used gr-radar myself.
>     It definitely works in the real world, which you can see on Stefan’s
>     Youtube channel [2].
> 
>>     Now what exactly is my problem - I managed to get the gr-radar -
>>     FMCW working on one USRP B210 (with TX/RX and RX2 using
>>     omnidirectional antennas). I was playing around with modifying
>>     some of the variables but I am still not getting useful range data
>>     (mostly it is constant, even if moving both of the antennas for a
>>     few meters or putting some obstacles in between). Modifying the
>>     samp_rate or sweep_freq, and others (samp_cw, samp_up, samp_down)
>>     has also not given me useful results.
> 
>     The original setup for gr-radar consisted of two USRP N210,
>     connected with a MIMO cable. It never ran on a B10, though there
>     were some attempts, that seem to never have been further pursued [3].
> 
>     Also, since you’re using omnidirectional antennas with FMCW, you’ll
>     detect a lot of static objects in *all* azimuth angles, while
>     gr-radar was designed for one target only IIRC. So assuming it
>     theoretically could work on a B210 (please let us know!!), I would
>     propose to use beam antennas and try to use the dual CW waveform,
>     which only detects moving objects.
> 
>     Let us know about any progress :)
>>
>>     Perhaps I am doing something wrong and not understanding the
>>     theoretical principles about radars/signal processing or maybe the
>>     FMCW flowgraph is not implemented correctly? I also have to
>>     mention here that author (on github) only tested the FMCW
>>     flowgraph in the simulation (which works ok), but not on the hardware.
>>
>>     Thanks for your help.
>>
>>     Regards,
>>     Tilen
>>     _______________________________________________ 
>>     Discuss-gnuradio mailing list 
>>     address@hidden <mailto:address@hidden> 
>>     https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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> 
> 
>>
> 
>     [1] http://www.radartutorial.eu/01.basics/Range%20Resolution.en.html
>     <http://www.radartutorial.eu/01.basics/Range%20Resolution.en.html>
>     [2] https://www.youtube.com/channel/UCv7cqqFkkiRFJIGkNEyMu3g
>     <https://www.youtube.com/channel/UCv7cqqFkkiRFJIGkNEyMu3g>
>     [3] https://github.com/kit-cel/gr-radar/issues/19
>     <https://github.com/kit-cel/gr-radar/issues/19>
> 
>     Regards,
> 
>     Sebastian Müller
>     address@hidden <mailto:address@hidden>
>     PGP ID DC2AA3EE
>     <http://pgp.mit.edu/pks/lookup?op=vindex&search=0x9FFBD55DDC2AA3EE>
> 
> 
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