[Aavso-sid-list] VLF/SID monitoring

[Siddhartha Jain]

Hi Jean-Pierre,

I am in San Francisco and yes, you can look up more details about my
location here:
http://www.qrz.com/detail/WV6U

Thanks for the all the detailed configuration information about
SpecLab. What kind of hardware do you have connected to SpecLab?

For antenna, I wound 50 turns of #26 magnet wire on a 2' x 2' pvc
cross. The loop inductance is about 5.6 mH.

At the feedpoint, I have three capacitors in parallel with the loop,
two are 3300pf each and the third is a variable of 115-500pf. I am
hoping to tune into the VLF transmitter in Cutler, ME at 24khz.

What else should I add to this to remove, for example, unwanted noise
and match impedance between the antenna feedpoint and the sound card
input?

Thanks,

- Siddhartha WV6U


On Tue, Aug 5, 2008 at 8:13 AM, Jean-Pierre Godet <godetj at wanadoo.fr> wrote:
> On Mon, 4 Aug 2008, Siddhartha Jain wrote:
>
>> ...
>> Questions:
>> 1. Is there a way to benchmark/test my setup specifically wrt SpecLab
>> including talking to a local mentor?
>> ...
>
>  Hello friend !
>
>  If you are WV6U, I gess that a local mentoring will be difficult. I am
> using SpecLab, but with a fairly different hardware. Anyway, I give you the
> config used here more than three years for SID minitoring after one year of
> adjustments and tests (only important parameters, you will have maybe to
> adjust them a little bit to agree with your harware sensitivity) :
>
> 1) SpecLab Configuration and Display Control :
>  a) FFT properties, frequ. resolution :
>    - Decimate input by (divisor) : 1 ;
>    - FFT input size (length) : 8192 ;
>    - FFT window function : Hanning ;
>    - FFT type : real FFT ;
>    - FFT Output Type : Normal ;
>    - FFT Output Unit : dB ;
>    - FFT Output Internal Average : 1.
>  b) I/O :
>    - Sample Rate : 48000 ;
>    - Input Sample Rate Divisor : 1 ;
>    - Bits/sample : 16
>  c) Spectrum all is as default, but :
>    - One Pixel per FFT bins : Yes ;
>    - Waterfall Time Grid : Enabled ; Every 15 min ; Small ticks ;
>    - Waterfall Scroll Interval : 2000 (ms) ;
>    - Displayed Amplitude Range : -100 ==> -50 dB full scale.
>
>  You have to modify the System Setting too (adjust Timezone)...
>
> 2) Watch List and plot Window :
>  a) Watch List :
>    - for each transmitter monitored, I open a 50 Hz window around the mid
> frequency. Ex : HWU mid freq. is 22.6 kHz, Expression will be :
> (peak_a(22575,22625))+100
> Why "+100" ? To play only with positive numbers. It may be 80 for you, or
> another figure, you choose it to have the background noise at 0 dB or a
> little higher.
>    - Scale Min : 10 (dB) ;
>    - Scale Max : 50 (dB) (to be adjusted to see all the graph in your
> window) ;
>  b) Layout : as you want ;
>  c) Horizontal :
>    - Scroll Rate : 60.0 Sec/Step ;
>    - Small markers interv. : 15*60
>    - Large makers interv. : 60*60
>  d) Channels :
>    - style : mixed ;
>    - Curve : Average Value.
>  e) Memory :
>    - Samples : 2500 (the volume of data in memory ==> here 2500 minutes);
>    -Channels : 4 (for me, for you the number of stations monitored) ;
>  f) Export : as you want. For me : "TAB character as column separator,
> decimal point".
>
>  All the rest is more or less cosmetic. I write my own Waterfall Color
> Palette, something like black ==> blue ==> green  ==> white because I like
> cold colours.
>  With this config, you have one acquisition each second, the mean value of
> the last twenty acquisitions is used to built each step of the waterfall
> (scroll interval 20 sec.), the mean value of the last three mean values is
> the figure used to build each step of the plot (plot scroll interval is one
> mn) and to build the data file.
>
>  The Linux utility gnuplot is used to build a graph from the raw data file.
> If you want to have a look to the result of all the stuff, the last gnuplot
> graph (the plot of each previous day) is displayed at :
> http://jpmere.online.fr/VLF.htm
>  For an exemple of the data structure, the data files of each day of the
> last three years are available at :
> http://jpmere.online.fr/incoming/f5yg/
>  Looks absolutly like the GOES data files, no ?
>
>  Hope that helps. If you want, I can send a post here with the whole config
> file (you will have to copy it in the root directory of SpecLab, then to
> call it with "Quick Setting") as it is harmless genuine ASCII; to make
> matters easier and to work with the beautiful (?) non-aggressive green
> waterfall of my own ; but only if you, my SID colleagues, are not tired of
> too much chattering about SpecLab.
>
>  Best regards (and more active sun !!!)
>
>  Jean-Pierre
>
> --
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>
>



-- 
- Siddhartha
 WV6U