In this case the OTHR signal was found between 13965 and 13985 kHz. The slope of the FMCW signal is μ=1MHz/s, and there are 50 sweeps per second. This results in a bandwidth of about 20kHz.

As is well known, the frequencies Δf of the spectrum of the de-chirped signal correspond to time delays τ=-Δf/μ in the case of a stationary target.

- for this one has to multiply the received signal with the original waveform
- tuning offsets w.r.t. center frequency of the OTHR signal correspond to a time delay of the original waveform
- when Δf is positive the delay corresponds to the frequency Δf-f
_{s}(f_{s}is the sampling frequency), i.e. the ranges wrap around the x-axis.

_{d}vs. Δf where f

_{d}= v•λ/2 (for velocity v and wavelength λ). Here one has to be careful to adjust the phases in each bin to correct for the fact that the sampling times are not exactly aligned to multiples of 0.02 seconds.

Plots for 5 KiwiSDR are shown below. The splitting of the ionospheric reflection is most likely due to O- and X-mode propagation in the F layer.

13975 kHz 20180105T1114Z @CS5SEL; the band at f_{d}=0 is caused by an interference |

13975 kHz 20180105T1114Z @DF0KL |

13975 kHz 20180105T1114Z @G8JNJ |

13975 kHz 20180105T1114Z @Izhvesk |

13975 kHz 20180105T1114Z @Julisdalen |

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