TDoA measurements using GPS time-stamped IQ samples from KiwiSDRs (1)

Some relevant links are:

• http://kiwisdr.com/
• https://github.com/jks-prv/Beagle_SDR_GPS/issues/130
• http://valentfx.com/vanilla/discussion/940/direction-finding-and-linking-existing-kiwisdrs

Big thanks to John Seamons for creating this excellent receiver and for support with the GPS time stamps, as well as to all KiwiSDR owners who have enabled GPS.

All plots below were generated by a combination of 

• kiwirecorder.py (https://github.com/jks-prv/kiwiclient/tree/jks-v0.1) forked from Dmitry’s https://github.com/dev-zzo/kiwiclient
• http://octave.org/ (+signal +mapping)
• http://www.gnuplot.info/

using the code here https://github.com/hcab14/TDoA which for now is the only documentation.

Note that this is preliminary work at a very early stage.

In particular many systematic errors are for now being neglected, such as

• different delays (antenna + frond-end) per KiwiSDR
• delays due to propagation
• not using consistently WGS84 coordinates
• having only approximate locations for the KiwiSDRs

More information will be added later on.

77.5 kHz 20171127T104156Z DCF77

http://www.mwlist.org/vlf.php?kHz=77.5

DCF77 TDoA

225 kHz 20171128T104940Z Polskie Radio 1

http://www.mwlist.org/mwlist_quick_and_easy.php?area=1&kHz=225

TDoA 225 kHz PR2

10611 kHz 20171128T171256Z OTHR

https://en.wikipedia.org/wiki/RAF_Akrotiri

TDoA 10611 kHz

65.8 kHz 20171127T160437Z FUE

http://www.mwlist.org/vlf.php?kHz=65.80

TDoA 68.5 kHz