Hi Alex, LF,
thanks for the wav recording from Uganda! A
5.5 Hz FFT from Spectrogram shows the well-known European sources
DCF39, SXV, and HGA22 (from the image sideband 135500-70
Hz). The small spectrum plot was taken
between static bursts and shows DCF at about 33 dB SNR in a 0.7 Hz FFT (ie. 1 Hz
noise bandwidth).
Extrapolating from 40 kW EMRP to 1 W ERP (-49
dB) and from 0.7 Hz to your 14 mHz FFT resolution (+17 dB), we
find that an amateur signal would have been just marginally above the noise, at
33-49+17 = 1 dB SNR (assuming all statics are suppressed by noise blanking).
Of course this number is just a rough indication,
and we would expect considerable variability with propagation and
QRN.
Wishing you all the best,
Markus (DF6NM)
Sent: Tuesday, November 22, 2011 7:09 PM
Subject: LF: Re[2]: LF: 5X grabber is ON
Hello Stefan,
Mal, Laurence, LF!
Thank you for your activity.
On screenshots which are
on mine grabber, it is possible to see only very weak trace on 136171,2 Hz
(23-00 z) and 136172 Hz (nearby 00z). Calibration of my equipment has an error
of 0,2 Hz. These traces, unfortunately, are not readable, it is possible to
ascertain only that the signal, probably, is.. Having heard to record of a night
air, I have made for myself discovery that I hear signals DCF39 and HGA22! A
small fragment of record at 23:50 z
http://rn3aus.narod2.ru/uganda/lf-uganda-21nov_2350z.wav.
Frequency of the receiver is 135500 Hz. The carrier of HGA22 does not get trough
IFpass-band filter. DCF39 is on the top border of a
pass-band.
Unfortunately, meanwhile I cannot estimate the signal-noise ratio
of DCF39.
The air here is very similar to a summer air during a near
thunder-storm.
I hope that I will to make one more attempt to start grabber,
having established the aerial on more tall mast, within the next few days to
departure from Uganda. Certainly, as soon as it will be possible, I will inform
about it here.
Unfortunately, the Internet is accessible to me only
periodically and I have a lot of work here. Excuse me if I don't answer some
e-mail or I answer with the big delay.
vy 73 de Alex
22 ноября 2011,
00:47 от Stefan Schäfer <
[email protected]>:
>
Hello Alex,
>
> I started my TX now and will run it over
night.
>
> Am 21.11.2011 16:54, schrieb Alex K:
> > Hello
LF! This night my 5X grabber is on-line
http://rn3aus-lf-grabber.narod.ru>
>
>
> Will that be the last night you're running the grabber or
will there be
> even more nights/chances?
>
> Have you tried
to check for the DCF39 S/N and if, which S/N did you get
> (in 1 Hz
NBW)?
>
> Is the region arround 136.17 clear or would it be more
promising to try
> in the 137.777 region?
>
> 73 and many
thanks for that nice portable receiver in
>
Africa!!!!!!!!!!!!!!!!!!!!!
>
> Stefan/DK7FC
>
>
