[Lowfer] Wideband lowfer reception with SDR-IQ

[Garry]

Andy's, KU4XR, recent receptions of spaced lowfer signals finally 
spurred me to try the same with an SDR-IQ receiver. The signals of 
interest run from 181.818 kHz for JH to 188.830 kHz for EAR,  a spread 
just over 7 kHz. I usually run the receiver at 50 kHz, the minimum for 
demodulation, so bandwidth is not a problem if the wideband USB mode is 
selected. I like to run ARGO centered around 400 Hz audio so set the 
SDR-IQ tuning to 181.4 kHz. That takes care of lowfer JH. To tune 
lowfers at the watering hole (185.3 kHz) I launch Spectrum Laboratory 
(v2.76b8) using the QRSS30 setting and center the FFT at 3900 Hz audio. 
To get fine frequency resolution an FFT of size 32768 and decimation of 
16 are used. Presumably a second instance of Spectrum Laboratory can be 
launched from the same shortcut but that doesn't work for my Windows 7 
64bit PC. So instead I launch a slightly newer version (v2.79b08) to 
copy lowfer EAR. There the audio sampling rate is increased from 11025 
to 44100 Hz to satisfy Nyquist, the FFT is centered at 7430 Hz, and an 
FFT decimation of 64 is used. Lastly, lowfer TAG is monitored with the 
Wolf GUI centered on 4400 Hz.

That's one way to do it. There must be many other combinations of 
software that will work too. And most SDR receivers have far more 
bandwidth than the SDR-IQ so they will certainly allow viewing 7 kHz of 
audio spectrum as well.

73, Garry, K3SIW, EN52ta, Elgin, IL