[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
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