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F6BXH > VLF 19.06.01 02:20l 124 Lines 5691 Bytes #-8669 (0) @ WW
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Subj: CP F6BXH: Receive VLF without RX, with Soundcard !
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From: DL8AAM @ DB0EAM.#HES.DEU.EU (Tom)
To: VLF @ WW
--- FORWARD from WUN Internet reflector -----
From: "Trond Jacobsen" <trond.jacobsen@halden.net>
Subject: [WUN] How to receive SAQ on 17.2 kHz at the 1st of July, without a VLF
receiver.
Date: Sun, 17 Jun 2001 20:34:18 +0100
Hello EveryWun
SAQ, a historical transmitter using an Alexanderson Alternator, operating from
rimeton, Varberg - south of Gothenburg, at the west coast of Sweden, is on air,
only one day a year.
This years transmission schedule, is as follows:
1st of July 2001 at 0830UTC, 0845UTC, 1230UTC and 1245UTC
The frequency is 17.2 kHz and the mode is A1A morse.
If you don't have a VLF receiver and would like to log this special event, dont
despair. As the frequency of operation of this VLF transmitter, 17.2 kHz, is wi
hin the "audio range" it is easier then you think.
First of all you must have a soundcard installed in your computer. Then you nee
some spectrum analysis software, to record and view the radio signal from SAQ.
For this task you have a selection of several free programs, available for down
oad. One of the
most used is GRAM ( and Spectran ). A quick search on the web will give you se
eral choises of URL's for download of the programs. ( No one mentioned, no one
avoured )
Install the software. Read the instructions. Now you have a very simple yet sen
itive VLF receiver in your computer. Open up and run your soundcard software. C
oose mic input, experiment later with the gain boost select. Open up and run th
analysis tool
you selected to download and install.
If you use one of the GRAM versions ( the newest version of GRAM has time- limi
ed operation before registration, but there are other versions still available
n the WEB, like the much preffered "radio version" GRAM 4 2 6 5 and GRAM 5 ) go
to the file men
u:
select Scan Input or use (F3), at the Scan Input menu,
first you go to the Sample Charactheristics and select: 44 kHz sample rate,
then go to Display Characteristics and select: Display type / Scroll, Scale dB
90, Palette / CB, Scroll Mem / On, Time Scale (msec) / 10
then ytou go to Frequency Analysis and select: Freq Scal / Linear, FFT Size (Po
nts) 1024, keep the Freq Resolution (Hz) at 43.1, Band (Hz) move with left mous
button to read 11020 - 22045 ( wich is Hz ), Spectrum average / 1, PItch Detec
or / Off.
If you would like to save the transmission direct to your HD select: Recording
nable / On
then press OK.
Now you have GRAM up and running, giving you a visual display of a part of the
LF band from 11.020 kHz to 22.045 kHz, but as the input is unconnected, you sho
ld see nothing but some internal noise from the soundcard. No is the time of tr
th, - take the
coax from your ordinary HF antenna, preferably an vertical antenna or any kind
f "longwire" construction, and hook up the antenna via a suitable adaptor to th
mic- input of your soundcard. Wunners in Europa and US east coast will se spec
ral lines from
FSK transmissions at 16 kHz (GBR in UK ) 16.4 ( JXN, NATO COMSUBLANT in Norway
18.1 ( RDL CIS MIL at hh:28-38-48-58 with morse "EAM's" / Strategic Code Messa
es in between) 18.3 ( HWU French Navy ) and 20.9 ( also HWU ) In other places o
the Globe ther
e will be other stations like NWC in Australia at 19.8 kHz and 3SB in China at
0.6 kHz. Also more sporadic ICV NATO at 20.27 kHz from Tavolara in Italia. And
ou will "receive" a lot of sferics, - and if you are in a "manm!
ade radio quiet" location, also other natural radio phenomena. And of course th
15.625 kHz spectral line from TV sets.
If you are suffering from strong electrostatic fields blanking the input, try a
capacitor in series with the antenna lead. If you are suffering interference o
intermodulation from strong or nearby BC stations, try an inductor in series w
th the antenna
lead ( if you like, - up to 10 mH ! )
Remember that antennas might pick up VERY HIGH VOLTAGES, capable of killing bot
you and your electronic equipment, during all stages of a thunderstorm, so tak
precautions to protect yourself, your computer and soundcard interface.
To get to know this method of VLF reception, I suggest you play around with the
settings on both your analysis tool and your soundcard, to get the most out of
his simple, yet effective VLF receiver.
Right now I have one of these "receivers" up and running ( I always have ! ) wi
h a 8 meter vertical, 8 meters above the roof. On the GRAM display is the weak,
but visible spectral lines from NWC at Exmouth in Australia, a distance of impr
ssing 12700 km.
But remember that VLF radio signals are following the earth - ionosphere waveg
ide and are not limited by the "normal" propagation conditions. When we, who mo
itor the basement of the electromagnetic spectrum, are talking of strange and w
ird propagation
effects, they are frankly that, and a bit more too.
Happy hunting for SAQ at July 1st and welcome in the WUNderland of the longwave
. Fell free to mail me off list, with longwave related questions.
best regards
Trond at ALFLAB, Halden in Norway.
--
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Area: 'dl8aam' Current msg# 8 of 26.
----- END of FORWARD -----
73, Tom - DL8AAM
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