LF: hunting IK1HGI on LF

[Domenico IZ7SLZ <iz7slz.domenico@gmail.com>]

Hi LF,

in these days, Tony IK1HGI from JN45jj, is transmitting some (not announced) EbNaut test message on LF and he is active in op32. He is using a very stable exciter formed by a GPS Neo-7 which time port TP5 has been reprogrammed to output directly the operating frequency (i.e. 137493,000 Hz).

I invite all interested LF operators to try this solution becouse it's cheap, easy to built and it works !

Riccardo IW4DXW, who had this idea, is writing some

post to the group with his indications on buffering the TP5 signal, obtain a BPSK and ASK modulator, reprogramming the GPS parameters.

Erp transmitted by Tony is low due to very short antenna placed on his balcon, short cap-hat wires,  poor ground system and low power output (around 70 W) with some mismatching.

So catching  his signal is a challenge for me in JN80nu (abt. 920 km).

Last night i saw some traces of his signal on my opds Spectrum Lab waterfall but no opera detections were possibile even by reducing thresholds in opds.ini.

I have also used Paul Nicholson's vlfrx-tools programs to record the audio coming from LF receiver. Then i tried this morning to obtain  4 hour-long  FFT  centered on IK1HGI qrg after filtering and blanking the signal. 

I got an evident peak that i'm almost sure that comes from Tony.

These are the commands that i have used (i'm new on vlfrx-tools so i hope do not make big mistakes):

vtread -v -T2017-06-22_23:40,+16000 /media/iz7slz/Storage/ |
vtfilter -v -h bp,f=1500,w=2000 |
vtblank -v -a2 -d0 -t10 |
vtnspec -v -f 1493 -w0.02 -r6.25e-5 > spectrum.dat

that vtblank settings comes out after many attempts.

73, Domenico IZ7SLZ

IK1HGI op32 activity spectrum 23-06-17 4 h integr .png
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