[hpsdr] Listening to VLF / ultrasonic signals using OpenHPSDR

[Henry Vredegoor]

Listening back the Teamspeak recording of 25-FEB-2017, there was a 
discussion on listening to/measuring ultrasonic transducers with 
OpenHPSDR hardware. (K7SR)

For what it's worth, I can report that I was able to listen to the time 
transmitters MSF (60 kHz, Anthorn England, formerly Rugby) and DCF77 
(77.5 kHz, Mainflingen  Germany) using Mercury with quite good results 
using a very improvised antenna (a 10/11 mtr. GP with abt. 15 mtr. of 
coax cable)

Moreover so, I also could "listen to" and "see", /_bat's_/,  flying 
around in my backyard with PowerSDR, using an ultrasonic microphone 
(like those used in earlier TV remote control systems) connected 
directly via an 50 Ohm coax cable to Mercury , with astonishing results 
for this "quick and dirty" setup!
The bat's were around 30 to 50 kHz if I remember correctly.

So maybe the newer HPSDR hardware isn't capable of listening on VLF, but 
my good old Mercury apparently is! ;-)

73's,

Henry - PA0HJA



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