Hi Markus,
Really? Wonderful! :-) And the stream is still running. I'll watch it
some days now to see if all Raspi problems are gone, then the next
part-project is the RX.
Meanwhilethe sky wave is present and i can see you quite strong in
DFCW-30 with your 3 mW ERP from the loop. I missed watching you on the
remote grabber in daytime. What was the SNR ralative to the city
location? Same or better? I switched back to the T antenna in the
afternoon. It would be interesting so see you on my loop. On 21:19 i
switched to the loop!
Ah and now you can see the drift of my RX which is quite visible, but
still uncritical for QRSS-30 or WSPR.
I thought about changing the 12 MHz xtal of the soundcard. It is the
cheap SMD xtal which has 100 ppm/K but there are other versions with 30
ppm/K. Maybe an idea, they are no expensive and still compact...
73, Stefan
Am 26.06.2015 21:04, schrieb Markus Vester:
Hi Stefan,
good to
see the remote station working nicely now.
>> but don't see you
...yes you do ;-) There is a slight
frequency offset in the remote grabber which had put me out of your
QRSS-30 band. I now switched to my "heritage" QRG 136172.5 ahem
476172.5 Hz, and voila there it is, loud and clear.
Currently still on the low Marconi,
also about 2 mW EMRP. The relatively strong coupling to the LF
grabber E-field antenna produced some aliases and noise there, which
have been mitigated by a 475 kHz Saugkreis (trap) - same as in old AM
radios ;-)
73, Markus
Sent: Friday, June 26, 2015 7:46 PM
Subject: Re: LF: 476.181 kHz from indoor loop
Hi Markus,
Thanks for your DFCW-30 transmission. I can see you clearly in daytime
on my RX in the city! However i can't see you on my RX is the garden!
The remote system seems to run stable now, at least for a longer time
then in the last 3 days :-)
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_remote_Grabber.html
I switched between a T antenna and a loop beaming 300/120 deg but don't
see you. It appears that the hill between us is (my garden is on the
hill side, the city antenna is more distant to the hill) actually
reducing the SNR. So it also reduces QRN from the east and favours the
west. But i would prefer an omnidirectional pattern :-/
73, Stefan
Am 24.06.2015 12:11, schrieb Markus Vester:
I am currently running a DFCW-60 beacon on 476.181 kHz, using
the same 10m^2 indoor transmit loop as previously on LF. With 35 Watts
of RF input, estimated radiated power is around 2 mW, with lobes
pointing west and east.
The daytime groundwave signal is visible in the bottom panel
of the DK7FC MF grabber. Going by the CCIR plots for 3 mS/m
conductivity, the groundwave attenuation for this distance would be
about 23 dB in excess off lossless 1/r propagation, resulting in
approximately 0.2 uV/m in Heidelberg.
Best 73,
Markus (DF6NM)
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