[Lowfer] 29.499 tonight with OP2H

Garry Hess k3siw at sbcglobal.net
Fri Apr 4 10:37:30 EDT 2014


Bob,

I was listening last night but the noise was too much to even identify 
your signal if it was on.

I've been confused by my speclab/opds2h frequency readouts when I do 
copy your signal. Markus always decodes you as 29499.000 Hz but I get 
offsets on the order of 0.02 Hz and have been adjusting for that in the 
software. Since I have the sdr-iq externally clocked by a GPS-locked 
reference and I calibrate the speclab sample rate by a GPS-referenced 
100 kHz signal I don't expect any error. Yesterday I revisited the 
sdr-iq software and set the clock exactly to the required 66.666667 MHz, 
after measuring it on my GPS-referenced counter to really be that 
frequency. Then I adjusted the speclab audio sample rate to produce a 
tone of 400.000 Hz when the sdr-iq was tuned to a signal on 100 kHz with 
a dial setting of 99.6 kHz. I also used the Wolf frequency measuring 
mode to confirm the tone was just where it was supposed to be.

In the afternoon I summed in a signal from my HP generator at 29.500 
kHz. Unfortunately that generator no longer works with an external 
clock. With my GPS-reference counter, I estimated the true frequency as 
29500.127 Hz and ran that way over night. I did see speclab measure 
29500.125 to .127 (the HP OCXO does drift a bit with time) and that 
seems good, but unfortunately I couldn't copy your signal to see if it 
measured as 29400.000 Hz. Oh well, maybe next time. Thanks for putting 
your VLF signal on the air so often.

73, Garry
-- 
73, Garry, K3SIW, EN52ta, Elgin, IL


More information about the Lowfer mailing list