Thursday, 15 May 2014

New version of GNU Ionospheric Tomography Receiver Out!

I finally got around to updating the ionospheric tomography receiver code than can be used to measure relative TEC using simple ground stations that listen to satellites.

Improvements are in stability, performance, phase curve fidelity, as well as in data portability. The code now uses only python and c++. The data container is now the widely supported hdf5 format. Other minor improvements include better Doppler residual estimation, as well as a new hybrid coherent and incoherent integration based phase curve estimation method that also produces error estimates for the phase curve. The performance of the new phase curve estimator is better with low signal to noise ratio.

The new algorithm is better at estimating the Doppler residuals (Doppler shift not predicted by the ephemeris), which allows me to coherently integrate longer vectors of data (use a more narrow bandwidth) and get better signal to noise ratio. This also has the effect of smearing out interference spectrally, which weakens the power spectral density overlap with the satellite. Because of this, the new algorithm produces much less jumps in the phase curve when an interfering signal intersects the satellite signal.

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