[Lowfer] TACAMO

[Garry Hess]

VLF has been busy with TACAMO signals today. Perhaps it always is and I 
just happened to notice with the sdr-iq set for Bob's 29.499 kHz 
transmission. Earlier today a signal was on 22.7 kHz. Now I see a signal 
on 27.2 kHz. Usually they aren't on for long.

And since it's no longer April 1 I'll put my two cents in that the idea 
computer "hear" better at higher audio frequencies is simply wrong. SNR 
is what allows one to copy/decode/hear and narrowing the pre-detection 
bandwidth boosts SNR. But actually it's easier to implement bandpass 
filters in computers as the frequency drops, since then the fractional 
bandwidth is less, meaning the filter order required for any particular 
bandwidth is less, meaning less computational power is needed. As for 
human hearing, I suspect a lot of us have turned into low-pass filters 
with age. My preferred tone is now 400 Hz.

Sure enough, in the time taken to type this the TACAMO signal on 27.2 
kHz has gone QRT.
-- 
73, Garry, K3SIW, EN52ta, Elgin, IL