Here is another look at the HF OTHR signal from Cyprus already mentioned in
this blog post.
This OTHR signal is (at least to 1st order) FMCW modulated (period 0.02 sec, bandwidth 20kHz), as can be seen in the FM demodulated phase which follows a sawtooth pattern with period 0.02 sec.
Although the bandwidth of the KiwiSDR IQ data stream is smaller than the bandwidth of the OTHR signal it turns out that dechirping can be done: using KiwiSDR GPS timestamps
t, dechirping can be implemented by multiplying the IQ samples by
exp(2i*pi*f(t)) with
f=@(x) 0.5*1e6*(mod(x,0.02)0.01).**250; (this is octave notation)
The dechirped signal looks like in the bottom panel below and is flat as expected:

OTHR FM demodulated phase; bottom: dechirped 
The relative range (which includes a contribution from the doppler effect, see, e.g.,
here) is then obtained by performing a FFT transformation on the dechirped signal in each 0.02 sec period (~240 samples):

OTHR dechirped spectrum vs. time 
 There is a main reflection in the ionosphere which has an interesting, timevarying structure to the left of it, i.e., towards smaller ranges
 In the light blue regions there is a kind of digital pattern visible; this might be due to the signal processing and limited bandwidth of the KiwiSDR but it could also be caused by some additional modulation of the radar signal