Hello Jack,
I'm currently starting to write a short article about using spectrum lab
for vlf for the klubnl.pl site. Could you tell me what you would like to
see there? (example SL configs etc). We can take this off-list if you
want.
This was supposed to be more of an "using Spectrum Lab under linux"
article, but i can include additional non-linux details if you want. I'm
sure this might be helpful for more people.
VY 73
Jacek / SQ5BPF
On Sat, 6 Jan 2018, JACK ASKEW wrote:
Date: Sat, 6 Jan 2018 17:51:17 -0700 (MST)
From: JACK ASKEW <[email protected]>
Reply-To: [email protected]
To: rsgb lf group <[email protected]>
Subject: Re: LF: Re: SL settings for QRSS
Hi Wolf,
SL is ok for just starting out as a beginner using QRSSS, but I can see now why
EbNaut
is far superior, at least you can see text that was sent. Probably a bigger learning
curve
required to fully understand it though.
Sadly I was unable to find any configuration files for QRSS for SL on Stefan's
QRZ.com site.
There is certainly lots of reading material so perhaps I might have missed it.
Cheers,
Jack
_________________________________________________________________________________________________
From: "Wolfgang Büscher" <[email protected]>
To: "rsgb lf group" <[email protected]>
Sent: Saturday, January 6, 2018 1:59:40 PM
Subject: LF: Re: SL settings for QRSS
Hi Jack,
Yes, it takes several hours until the first spectrum (or line of pixels in the
spectrogram)
appears.
To load a complete (FFT-) window for 47 uHz bin width, it takes
1 / 47 uHz = 21276.x seconds = 5.9 hours .
That's dictated by the maths. Not related with CPU speed. "Not a bug but a
feature" .
That's one of the reasons why Paul's Ebnaut has completely replaced these ancient
"visual" modes
;-)
Cheers,
Wolf .
Am 06.01.2018 um 22:07 schrieb JACK ASKEW:
Thanks Wolf, lots to read up on, excellent information on learning
how to use SL for these slower speeds. Also thanks for
pointing me to Stefan's site regarding the configuration
files for QRSSS, I wondered if anyone still had them available.
I recall playing with SL's ability to use VLF stations to lock onto but
they were too weak here in Canada. I do have GPS on my Tx now
but I still see some un-explainable instability over a period of 4-5hrs
but far less than 0.05Hz...so maybe not an issue when I was using
file 8270Hz_QRSSS_4mHz.usr. Not sure what equates to in QRSSS
though. I find that if I try anything like 'VLF_Soundcard_32K_47uHz.USR'
it takes several hours to load up in SL but I guess that stands to reason...I
hope.
Regards
Jack Askew
_________________________________________________________________________________________________
From: "Wolfgang Büscher" <[email protected]>
To: "rsgb lf group" <[email protected]>
Sent: Saturday, January 6, 2018 10:42:14 AM
Subject: SL settings for QRSS (was: Re: LF: RE: Todmorden receiver by Jack)
Hello Jack and all,
you wrote:
>It comes back to using something like SL with its QRSS
capabilities. I wish I had a good file that worked at 8720kHz
for QRSS600 as an example. This would be a good start if nothing else.
<
It's not that difficult to set up. The key point in SL to get into the
microhertz-resolution is the decimation (of the sampling rate), along
with complex frequency to have a complex FFT spanning just a few Hz
around the "frequency of interest". The effect is similar as a
super-long FFT (concerning the frequency bin width, and thus the
"gain"). I think on Stefan (DK7FC's) site you can find some
configuration files for QRSSS.
Back in the "old days" of extremely slow Morse, I wrote this short
how-to (for Spectrum Lab):
http://www.qsl.net/dl4yhf/speclab/qrss_quickstart.htm
(it shows how to pick one of the VLF transmitters to stabilize the
soundcard's sampling rate,
a bit out of fashion since good GPSes with sync output became
available, but anyway..)
To make the FFT window even longer / frequency bins even shorter than
used in the default settings,
use the option 'complex input for the FFT with internal frequency
shift', as shown at
http://www.qsl.net/dl4yhf/speclab/settings.htm#fft_size
And, last not least, there an explanation of FFT length, decimation,
windowing functions, resulting resolution / effective receiver bandwidth
versus dynamic range, etc:
http://www.qsl.net/dl4yhf/speclab/fftinfo.htm
All the best,
Wolf DL4YHF
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