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Re: LF: Auto-EbNaut reception on LF in JN80

To: [email protected]
Subject: Re: LF: Auto-EbNaut reception on LF in JN80
From: DK7FC <[email protected]>
Date: Tue, 04 Jul 2017 19:10:55 +0200
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Hi Domenico,

Thank you, it works very well.

I made a few mistakes here, 13UTC i have been on a false frequency, 15UTC i had an error in the EbNaut txt file and 16 UTC there was a PTT problem :-)

Now at 17 UTC i am testing something new: One SL instance is only setting the PC clock based on 1PPS+NMEA. I can manually add a 0.3 sec offset in SpecLab, so the PC time is manipulated. The second SL instance transmits EbNaut, as usual, just the setting is changed to 1PPS without NMEA (so the PC time is choosen as the reference). I hope this will now compensate my usual 0.3 second offset, which is very relevant at 1 sec symbol length.

It should be easy to extend the script, just let the decoder run on 137.495, write down the results and then let it run on 137.490, so you can monitor 2 frequencies.
We could also consider to use a separate frequency slot which is below 137.450 kHz. These days it should be possible to afford a separate SL instance just for EbNaut. This helps to avoid interference to other modes like WSPR, OP32 etc..

I hope i can see my message soon, it is exciting :-)

73, Stefan

Am 04.07.2017 18:01, schrieb Domenico IZ7SLZ:
Thanks Stefan for the signal !

Yes, your 14.00 UTC transmission has been decoded.

2017-07-04_13:59:30   starting time + 30 s
found rank 0 ber 2.4294e-01 Eb/N0 4.5 M -3.894802856e+02
[73 DK7FC JN49IK] ps [  1  180  180  180  180]

BTW there is also Riccardo IW4DXW attempting to be decoded here and unfortunatly he is trasmitting in the same timeslot.

Yes, this is an issue for the system i.e. no multiple access !

I need to improve the program output. Something like opds printout should be better.

Again tnx for the test Stefan and Riccardo.
73, Domenico

On 4 July 2017 at 15:00, DK7FC <[email protected]> wrote:
Hello Domenico,

many thanks for the great idea. I also made important steps in learning how to deal with EbNaut. As soon as you know how it is done you can build your own scripts and create the functions and services you have done now.

Let's see how it works, i'm sending you a message at 13 UTC!

73, Stefan

Am 04.07.2017 11:24, schrieb Domenico IZ7SLZ:
Just to rectify my previous message:

parameters for the decoder are:

15 Characters, 1 s /symbol, 8K19A, list=20000, CRC=16
The actually chosen RX frequency is 137495.000 Hz

the decoder start time is at hour, every hour.

Domenico IZ7SLZ

On 4 July 2017 at 11:13, Domenico IZ7SLZ <[email protected]> wrote:
Dear LF,

since yesterday i'm testing,  on my ubuntu-PC,  a shell script that pipes some vlfrx-tools and ebnaut linux programs.
This script (see attached) permits to achieve an automatic EbNaut decode from the audio coming from my LF receiver. The decoder is setted with these parameters:
16 Characters, 1 s /symbol, 8k19A, list=20000, CRC=16
The actually chosen RX frequency is 137495.000 Hz

So, i invite all of you (within my LF reception range)  to try lo leave a message on this 'grabber' :

Of course, i'm at disposal to change these settings for any schedule.

These are the programs running on PC:

- vtcard, vttime for manage the audio card and timing;
- gpsd, ntpd for getting utc synchro from GPS (that has nmea + 1pps)
- vtwrite to store the raw audio on HD
- vtread,vtblank,...ebnaut (are launched by the script)
- wput for upload the DETECTED file

This is the occasion to thanks Paul Nicholson for his programs.

OK. Many things need to be improved on this idea. Your suggestions are welcome !

73 and FB summer to all.

Domenico, IZ7SLZ

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