Re: [Discuss-gnuradio] Fwd: Some geophysical applications of USRP2 and USRP

[Marcus D. Leech]

On 07/28/2010 05:39 PM, Juha Vierinen wrote:

Hi,

I recently wrote some preliminary code to see if a USRP2 could be used
as a wide band ionosonde receiver (FM CW ionospheric chirp sounder).
Sure enough, after a morning of programming I managed to create a
simple ionosonde receiver using the following set of hardware: USRP2,
GPSDO, LFRX and a wide band magnetic loop antenna. I'm listening to
ionospheric echos to a transmitter located about 1 km away from the
receiver, which is transmitting a 0.5 MHz/s sweep from 0.5 MHz to 16
MHz every minute. I simply request the USRP2 to start sampling with a
20 MHz bandwidth at the correct time (we have written a sampler that
allows you to specify in unix time when to start sampling). These
files are then analyzed using a simple R script that produces the
following type of an ionogram (see attached file).

The next step would be to program the analysis part in C so that it
would be possible to track multiple ionospheric chirp sounders
simultaneously. I can release the code if somebody is interested
building their own wide band ionosonde receiver.

I also recently finished work on a beacon satellite receiver similar
to the GNU digital beacon receiver that Mamoru Yamamoto has done.  The
program allows you to measure relative total electron content (line
integrals of electron density) between a satellite and a receiving
station. We are planning to build a ionosopheric tomography receiver
chain using USRP hardware and the software is written wit h this in
mind. The program is C++ and allows tracking of multiple simultaneous
beacon satellites. If there is interest, I can also release this code
too. The software should work with a generic USRP and two WBX
daughterboards.

BR,
juha
  

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Juha:

That's very interesting work.

Several months ago, I used Gnu Radio to build a Sudden Ionospheric Disturbance receiver, based
  on a magnetic loop, a commercial audio amplifier for microphones, and a 96KHz sampled sound
  subsystem.

The SID receiver can tune up to 6 different VLF stations, and measure the received power throughout
  the day.  The receiver software is easily able to see the standard diurnal variation in
  ionospheric reflectivity, as well as see sudden enhancements due to solar X-ray flares.  My software
  has captured several solar X-ray events in the last few months.

The code is available for anyone who wants it.

-- 
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org