Studying VOR Signals with the RTL-SDR
VHF Omni Directional Radio Range (VOR) signals are used in aviation as a short range radio navigational system. Amateur radio hobbyist F4GKR decided to study these VOR signals by recording them using his RTL-SDR, and then analyzing them in MATLAB. On his post he shows his method of analysis and discusses his results.
I was trying to replicate the analysis result using 2.4 Ms per second wav file captured by HDSDR provided by the author. I am unable to get 30 Hz signal as achieved by Author.
% Close all previous figures
[y, Fs, nbits]= wavread(‘HDSDR_20140205_185023Z_115533kHz_RF.wav’,No_Of_Sample);
%[y, Fs, nbits] = wavread(‘HDSDR_20140205_185023Z_115533kHz_RF.wav’);
%Original Sampling is at 2.4 Mhz
%Down Sample to 30Khz
% clear y_d;
Fech = Fs_Downsample ;
L = length(y_d);
freqs = -Fech/2:Fech/L:Fech/2-Fech/L;
fir_coeff = fir1(order, cutoff_norm);
filtered_signal = filter(fir_coeff, 1, y_d);