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 Y. has done. Â 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