Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id w8BIwa0d010401 for ; Tue, 11 Sep 2018 20:58:39 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1fznmh-0006Gv-Cm for rs_out_1@blacksheep.org; Tue, 11 Sep 2018 19:53:11 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1fznmI-0006Gm-Ke for rsgb_lf_group@blacksheep.org; Tue, 11 Sep 2018 19:52:46 +0100 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1fznmF-0005Bk-1v for rsgb_lf_group@blacksheep.org; Tue, 11 Sep 2018 19:52:44 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id D552420E9D for ; Tue, 11 Sep 2018 20:52:40 +0200 (CEST) X-DKIM-Result: Domain=posteo.de Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1536691960; bh=EDPxUnx8KdEjcDWtFuzmc2YVlBUpqJk8jlF9RvYVBI4=; h=Date:From:To:Subject:From; b=gGJ1iKbuUSS/6eX1a6HdGQ/NMh4b7uWM7dkzovWp1Xml4eO35Q0lF9Ym1HMR9EU1D VfALsSsDcyMPoH1VlChk0UZRvH7Q3ylKjUeb4pKe6qoS56dBpmff0JvaoMbbt3XwoG LF4qjE3PgWVBn4jJIoFsQJPjg0rTszCfiYty1/9wab1n1xFFWV1QtXwOu27wgWXl2b Bqj0qUNF1t6bBm/CLqVNsKWZ+qJzkiNTAEcA0pBK40+iOMeGmm9Cjj0JZQEnBWS9Jb 8UYePWdrYcZLSiZkKNgpYMxoasdKR4NwHalz3OUF/iJhm8oR6ej+g7jdNqdLH2mvGX TJk9ad4zUgrhQ== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 428vDR60pHz9rxK for ; Tue, 11 Sep 2018 20:52:39 +0200 (CEST) Message-ID: <5B980EF7.9040507@posteo.de> Date: Tue, 11 Sep 2018 20:52:39 +0200 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <6DB8451D7F3D3947A5918808A59621EA0860A2EE@servigilant.vigilant.local> <165c968175b-1ec0-b7d@webjasstg-vab49.srv.aolmail.net> <6DB8451D7F3D3947A5918808A59621EA0860A3B2@servigilant.vigilant.local> In-Reply-To: <6DB8451D7F3D3947A5918808A59621EA0860A3B2@servigilant.vigilant.local> X-Spam-Score: -2.3 (--) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: Good luck Luis, Later, for a QSO mode, i would suggest rather to use 8K19A than 4K19A. As far as i understand this will have more 'coding gain'. As soon as it all works, it becomes quite easy. In Linux one could even run a script doing all the file preparation and decoding automatically, as demonstrated by Domenico. You just need to watch the screen, like in FT8 ;-) [...] Content analysis details: (-2.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [185.67.36.66 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 T_KAM_HTML_FONT_INVALID BODY: Test for Invalidly Named or Formatted Colors in HTML 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 2d558421a9ab1d9327e3a8c39d23be43 Subject: Re: LF: The return of EbNaut for Dummies Content-Type: multipart/alternative; boundary="------------010501010809060907050903" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.2 required=5.0 tests=HTML_50_60,HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false This is a multi-part message in MIME format. --------------010501010809060907050903 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Good luck Luis, Later, for a QSO mode, i would suggest rather to use 8K19A than 4K19A. As far as i understand this will have more 'coding gain'. As soon as it all works, it becomes quite easy. In Linux one could even run a script doing all the file preparation and decoding automatically, as demonstrated by Domenico. You just need to watch the screen, like in FT8 ;-) 73, Stefan Am 11.09.2018 18:47, schrieb VIGILANT Luis Fernández: > > Hi Markus > > Noted > > Very interesting. So I can reduce the interval between generated files > just changing the “Waterfall scroll interval” at a fixed value as 5 > minutes for example > > I had it configured automatic at 75% overlap, so that was changing > depending on FFT values and then always getting different interval > between files > > Good to see the “light” J > > Let’s see if I’m able to get a decode now > > 73 de Luis > > EA5DOM > > *De:* owner-rsgb_lf_group@blacksheep.org > [mailto:owner-rsgb_lf_group@blacksheep.org] *En nombre de *Markus Vester > *Enviado el:* martes, 11 de septiembre de 2018 18:13 > *Para:* rsgb_lf_group@blacksheep.org > *Asunto:* Re: LF: The return of EbNaut for Dummies > > Yes Luis that scheme should work. > > The 10 minute interval for file generation is not hardwired but > simply the scroll interval, as chosen in the "options - Spectrum > display settings" menu. Each column in the spectrogram produces one > file. You can set faster scrolling (at the cost of more data written > to the disk), possibly allowing you to decode and answer sooner in a > QSO setting. > > Whether an EbNaut transmission is completely contained in a file also > depends on the time when SpecLab was started up, initiating > the sequence of files. If the transmission duration is shorter than > file duration minus scroll interval (e.g. 38-10 = 28 minutes), there > will be at least one file containing the full transmission. But > the EbNaut decoder will also work well with recordings which have been > truncated at either or both ends, albeit with some loss of sensitivity. > > Best 73, > Markus > > > > -----Ursprüngliche Mitteilung----- > Von: VIGILANT Luis Fernández > > An: rsgb_lf_group > > Verschickt: Di, 11. Sept 2018 17:54 > Betreff: RE: LF: The return of EbNaut for Dummies > > Hi Stefan, Markus, EbNaut > > Thank you for the detailed explanations. Now I really understand the > configuration and how is related to bandwith and length of the > > recorded files. There is also a fixed time between files recorded and > it is always 10 minutes. But, files are overlapped, so there you can > > record a file to contain longer than 10 minute transmission > > So, let’s see which would be a good configuration to perform a real > QSO. Lets say in LF with some S/N and not al VLF levels > > At the same time can be a good exercise to check if I finally > understood all this stuff ;-) > > Tx at 4K19A/CRC16/1 sec symbol rate would take 9 min and 4 sec to > transmit 17 characters messages > > Assume 15 minutes periods. Lets say first (even) transmitting at the > hour and 30 min pass the hour > > Second (odd) transmits at minute 15 and 45 > > Rx at 44100 sample rate, using a 65536 FFT length, and 1536 > decimation, file will contain 38 minutes of recorded signal. Looks > more than enough > > as we are using about 9 minutes transmissions. Then bandwidth of the > recorded files will be “Sample rate / decimation” > > 44100 / 1536 = 28.71 and then divided by two as SLab generates the > file, ending with 14.35Hz. Which is enough bandwith for a 1 sec symbol > rate (10/1=10Hz) > > So, assume both stations had Rx running previously and SL already > producing files every 10 minutes. Files will contain 38 minutes of > recorded signal > > A file recorded by windows just after transmission end (lets say) > 22:10 would contain a record of 38minutes, so starting time will be > really 21:32 > > This file will contain the message transmited by the station calling > in first period (CQ). To decode it we will select a timeshift from > 21:32 to 22:00 = 28 minutes > > So there will be time enough to decode the message and then prepare > the transmitter to answer in second period, 15 minutes pass the hour, > 22:15 > > answering the CQ of the station calling first > > The station calling in first period should have to check for files > recorded at about 22:25 to try to decode an answer > > And then prepare the corresponding transmission for next even period > at 22:30 > > Should this timing schem work for QSOs ? Assuming there is enough S/N > to work at this Tx rate of course > > 73 de Luis > > EA5DOM > > *De:* owner-rsgb_lf_group@blacksheep.org > > [mailto:owner-rsgb_lf_group@blacksheep > .org] *En nombre de *DK7FC > *Enviado el:* martes, 11 de septiembre de 2018 15:13 > *Para:* rsgb_lf_group@blacksheep.org > *Asunto:* Re: LF: The return of EbNaut for Dummies > > Hi Luis, > > As Markus mentioned... > And see the attachment. In the example i set the sample rate to 44100 > Hz. If you have a downconverter with an LO of 120 kHz, and expect a > message on 137 kHz exactly, set the internal frequency shift to a > center frequency of 17 kHz, like shown in the image. > > Also remember that the number of exported FFT bins in the FFT export > register card should be set to the half of the FFT input size shown in > the FFT register card. > > Keep us informed about the success :-) > > I'm waiting for your first message to receive here. I'm monitoring > permanently, however only in the range 137.5 kHz +- 50 Hz and only > about 30 minutes message length. Other parameters would work too, but > i need to prepare a special SL instance then... > > 73, Stefan > > > > Am 11.09.2018 13:40, schrieb VIGILANT Luis Fernández: > > Hi Stefan > > Thank you for the detailed explanation. I prefer to understand the > process rather than getting a working .usr > > So, excuse me again for dumming again J > > All understood about the length and relation to FFT windows time > (length) in SL. Width was un unknown parameter for me > > And I’m afraid the problem is about the width: > > >> Choose the FFT width and length to suit your settings. The width > is maybe 10 * 1/(symbol length) or more > > Lets say 1Hz minimum for a 10 sec symbol leght, right ? > > So, in the FFT configuration window the only way to get > >1Hz(1.3Hz) for “Width of one FFT-bin” is to reduce decimation to 1 > > and then set FFT length to 32768 to get some “FFT window time > (length)”. But then, the indows time is just 743ms > > which will not cover the length of the message at all > > I’m stucked here. Can’t get >width with 30 minutes FFT lenghts. > I’m using 44.100Hz sample rate L > > The FFT input type is “Complex ith internal frequency shift”. But > even using “Real FFT starting at 0Hz” doesn’t improve much > > Decimation at 1536 and FFT length 65535 produces “Width of one > FFT” at 438uHz and FFT windows time 38 min. So this time > > good length but small width > > What I’m doing wrong ? > > 73 de Luis > > EA5DOM > > *De:* owner- > rsgb_lf_group@blacksheep.org > > [mailto:owner-rsgb_lf_group@blacksheep.org > ] *En nombre de *DK7FC > *Enviado el:* lunes, 10 de septiembre de 2018 18:57 > *Para:* rsgb_lf_group@blacksheep.org > > *Asunto:* Re: LF: The return of EbNaut for Dummies > > Hi Luis, > > Am 10.09.2018 17:47, schrieb VIGILANT Luis Fernández: > > The fact of getting windows timestamped files which really > start at a > > different time and no aparent indication of when they end ….. > doesn´t help at all > > Well, the FFT settings must be so that you cover enough width (in > Hz) and length (in seconds). The necessary width depends on your > symbol length. The length is mentioned in the FFT settings > register card (FFT window time). Choose a rectangular window for > EbNaut decodes. > Convert the txt files into wav using Markus tools. Load the wav > file in the EbNaut decoder and press RUN. Then you will see the > start time of the file. The end is start time + length. Simple, > isn't it? :-) > > A new txt file is generated in the interval of the scroll time > (Spectrum (1) ) register card. Usually 30 minutes is fine, or even > 1 hour on VLF. Then you get a file each 30 minutes. If the FFT > length is longer than 30 minutes. Your FFT length should be 30 > minutes longer than the transmission length, just to avoid an > incomplete set of data in a txt file. > > Choose the FFT width and length to suit your settings. The width > is maybe 10 * 1/(symbol length) or more. > > > Is there any way of “fast” EbNaut when signals are strong ? > > I think there are no limits, you can run 0.1 second symbol length. > But usually it is used for weak signals and stable paths. > > I really don’t know what to test next. > > Send me your .usr file and the EbNaut settings you want to try. > > 73, Stefan > > > May be to run ebnaut_tx in test mode, which just changes the > phase every symbol length > > And then, analyze the recorded file with a different tool to > determine if this phase changes are there ? Can this be easily > done ? > > 73 de Luis > > EA5DOM > > PS: Congratulations for your amazing test with the guard > rails. And yes, this is much much harder than EME ! J > > *De:* owner- > rsgb_lf_group@blacksheep.org > > [mailto:owner-rsgb_lf_group@blacksheep.org > ] *En nombre de *DK7FC > *Enviado el:* viernes, 07 de septiembre de 2018 22:10 > *Para:* rsgb_lf_group@blacksheep.org > > *Asunto:* Re: LF: EbNaut transmission test in LF > > Hello Luis, > > Another hint: Try to use 4K19A and a shorter message, like EA5 > or so. Use long symbols, like 10 seconds or longer. Then, > timing is less critical and you may get a decode and can tune > to the best Eb/N0 and find out what the timing offset it. It > would guess it is a timing problem. > > 73 Stefan > > Am 07.09.2018 13:36, schrieb VIGILANT Luis Fernández: > > Hi Domenico > > Sorry, I’m not transmitting this weekend. Very stormy > weather here, so the wires are down > > I will notice in the reflector any transmission in > advance. But first want to confirm that all is working ok > > So that was the goal of yesterday test > > Yes, the XOR is AFTER the 1/10 divider, and working at the > final frequency 137485 Hz > > Your auto-decoder is a great tool. EbNaut is quite tricky > for average use and needs a lot of details to care about > > Of course the reward is great when you get decodes with > miserable signal levels. There is never free lunch ! ;-) > > 73 de Luis > > EA5DOM > > *De:* owner- > rsgb_lf_group@blacksheep.org > > [mailto:owner-rsgb_lf_group@blacksheep.org > ] *En nombre > de *Domenico IZ7SLZ > *Enviado el:* viernes, 07 de septiembre de 2018 13:18 > *Para:* rsgb_lf_group@blacksheep.org > > *Asunto:* Re: LF: EbNaut transmission test in LF > > Hello Luis, > > thanks for sharing your experiment. My auto-decoder > https://www.qsl.net/iz7slz/ is already retuned for your > transmissions. > > BTW QRM is large here in the morning time (urban > location). I will try to catch your signal later in the night. > > /At least the decoder is detecting the carrier but may be > there is no proper phase modulation or probably other > failures/ > > /What I’m doing wrong ? Can anybody decode the message > from the file ?/ > > I also suspect some issues on modulator circuit. Of > course the XOR gate is following the /10 divider, is it? > > Good luck. > > 73 all, > > Domenico/IZ7SLZ > > On Fri, 7 Sep 2018 at 11:38, VIGILANT Luis Fernández > > wrote: > > Hi LF EbNauters > > I have been building a disciplined Rx for LF, based in > a GPS LO at 120KHz and a NE602 downconverter to 17KHz > > Then feeding the signal to the soundcard, also > disciplined with 1pps from the same GPS > > At Tx side a GPS LO at 1374850 Hz divided by 10 > provides 0.1Hz steps at LF. Then an XOR gate is used for > > EbNaut modulation from the DTR of a COM port under > Windows. The PA is just a mosfet driver (mic4452 AT 12v) > > Just about 100mW to antenna but good enough to get a > 20dB S/N in my Rx 7Km away > > Stability looks pretty good and also phase modulation > as seen in SL spectrogram. Also monitoring phase changes > > with the SL plot display window. So, yesterday I tried > an EbNaut transmission with the following setup > > Coding: 8K19A > > CRC 16 > > Symbol period: 1s > > Characters: 6 Transmission time: 9.3 minutes > > Transmitting at minute 00 and 30 every hour > > I got the FFT files from SL and converted them to WAV > files. The configuration file (SR) included the > corrected sample rate > > of the soundcard as well as decimation , FFT length > and center frequency > > Attached is a WAV file starting at 16:22 which should > contain the transmission started at 16:30 untill about > 16:40 > > The rawsym graphic shows a clear peak centered in > frequency, but I haven’t been able to get a decode > other than “******” > > At least the decoder is detecting the carrier but may > be there is no proper phase modulation or probably > other failures > > What I’m doing wrong ? Can anybody decode the message > from the file ? > > BTW, I have used a list length of 47274 and also > 141823, but nill L > > 73 de Luis > > EA5DOM > --------------010501010809060907050903 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit Good luck Luis,

Later, for a QSO mode, i would suggest rather to use 8K19A than 4K19A. As far as i understand this will have more 'coding gain'.
As soon as it all works, it becomes quite easy.

In Linux one could even run a script doing all the file preparation and decoding automatically, as demonstrated by Domenico. You just need to watch the screen, like in FT8 ;-)

73, Stefan

Am 11.09.2018 18:47, schrieb VIGILANT Luis Fernández:

Hi Markus

 

Noted

Very interesting. So I can reduce the interval between generated files just changing the “Waterfall scroll interval” at a fixed value as 5 minutes for example

I had it configured automatic at 75% overlap, so that was changing depending on FFT values and then always getting different interval between files

 

Good to see the “light” J

 

Let’s see if I’m able to get a decode now

 

73 de Luis

EA5DOM

 

De: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] En nombre de Markus Vester
Enviado el: martes, 11 de septiembre de 2018 18:13
Para: rsgb_lf_group@blacksheep.org
Asunto: Re: LF: The return of EbNaut for Dummies

 

Yes Luis that scheme should work.

The 10 minute interval for file generation is not hardwired but simply the scroll interval, as chosen in the "options - Spectrum display settings" menu. Each column in the spectrogram produces one file. You can set faster scrolling (at the cost of more data written to the disk), possibly allowing you to decode and answer sooner in a QSO setting. 

Whether an EbNaut transmission is completely contained in a file also depends on the time when SpecLab was started up, initiating the sequence of files. If the transmission duration is shorter than file duration minus scroll interval (e.g. 38-10 = 28 minutes), there will be at least one file containing the full transmission. But the EbNaut decoder will also work well with recordings which have been truncated at either or both ends, albeit with some loss of sensitivity.

Best 73,
Markus  

  

-----Ursprüngliche Mitteilung-----
Von: VIGILANT Luis Fernández <luis@vigilant.es>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Di, 11. Sept 2018 17:54
Betreff: RE: LF: The return of EbNaut for Dummies

Hi Stefan, Markus, EbNaut

 

Thank you for the detailed explanations. Now I really understand the configuration and how is related to bandwith and length of the

recorded files. There is also a fixed time between files recorded and it is always 10 minutes. But, files are overlapped, so there you can

record a file to contain longer than 10 minute transmission

 

So, let’s see which would be a good configuration to perform a real QSO. Lets say in LF with some S/N and not al VLF levels

At the same time can be a good exercise to check if I finally understood all this stuff ;-)

 

Tx at 4K19A/CRC16/1 sec symbol rate would take 9 min and 4 sec to transmit 17 characters messages

Assume 15 minutes periods. Lets say first (even)  transmitting at the hour and 30 min pass the hour

Second (odd) transmits at minute 15 and 45

 

Rx at 44100 sample rate, using a 65536 FFT length, and 1536 decimation, file will contain 38 minutes of recorded signal. Looks more than enough

as we are using about 9 minutes transmissions. Then bandwidth of the recorded files will be “Sample rate / decimation”

44100 / 1536 = 28.71 and then divided by two as SLab generates the file, ending with 14.35Hz. Which is enough bandwith for a 1 sec symbol rate  (10/1=10Hz)

 

So, assume both stations had Rx running previously and SL already producing files every 10 minutes. Files will contain 38 minutes of recorded signal

 

A file recorded by windows just after transmission end (lets say)  22:10 would contain a record of 38minutes, so starting time will be really 21:32

This file will contain the message transmited by the station calling in first period (CQ). To decode it we will select a timeshift from 21:32 to 22:00 = 28 minutes

So there will be time enough to decode the message and then prepare the transmitter to answer in second period, 15 minutes pass the hour, 22:15

answering the CQ of the station calling first

 

The station calling in first period should have to check for files recorded at about 22:25 to try to decode an answer

And then prepare the corresponding transmission for next even period at  22:30

 

Should this timing schem work for QSOs ? Assuming there is enough S/N to work at this Tx rate of course

 

73 de Luis

EA5DOM

 

De: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] En nombre de DK7FC
Enviado el: martes, 11 de septiembre de 2018 15:13
Para: rsgb_lf_group@blacksheep.org
Asunto: Re: LF: The return of EbNaut for Dummies

 

Hi Luis,

As Markus mentioned...
And see the attachment. In the example i set the sample rate to 44100 Hz. If you have a downconverter with an LO of 120 kHz, and expect a message on 137 kHz exactly, set the internal frequency shift to a center frequency of 17 kHz, like shown in the image.

Also remember that the number of exported FFT bins in the FFT export register card should be set to the half of the FFT input size shown in the FFT register card.

Keep us informed about the success :-)

I'm waiting for your first message to receive here. I'm monitoring permanently, however only in the range 137.5 kHz +- 50 Hz and only about 30 minutes message length. Other parameters would work too, but i need to prepare a special SL instance then...

73, Stefan



Am 11.09.2018 13:40, schrieb VIGILANT Luis Fernández:

Hi Stefan

 

Thank you for the detailed explanation. I prefer to understand the process rather than getting a working .usr

So, excuse me again for dumming again  J

 

All understood about the length and relation to FFT windows time (length) in SL. Width was un unknown parameter for me

And I’m afraid the problem is about the width:

 

>> Choose the FFT width and length to suit your settings. The width is maybe 10 * 1/(symbol length) or more

Lets say 1Hz minimum for a 10 sec symbol leght, right ?

 

So, in the FFT configuration window the only way to get >1Hz(1.3Hz) for “Width of one FFT-bin” is to reduce decimation to 1

and then set FFT length to 32768 to get some “FFT window time (length)”. But then, the indows time is just 743ms

which will not cover the length of the message at all

 

I’m stucked here. Can’t get >width with 30 minutes FFT lenghts. I’m using 44.100Hz sample rate L

 

The FFT input type is “Complex ith internal frequency shift”. But even using “Real FFT starting at 0Hz” doesn’t improve much

Decimation at 1536 and FFT length 65535 produces “Width of one FFT” at 438uHz and FFT windows time 38 min. So this time

good length but small width

What I’m doing wrong ?

 

73 de Luis

EA5DOM

 

De: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] En nombre de DK7FC
Enviado el: lunes, 10 de septiembre de 2018 18:57
Para: rsgb_lf_group@blacksheep.org
Asunto: Re: LF: The return of EbNaut for Dummies

 

Hi Luis,

Am 10.09.2018 17:47, schrieb VIGILANT Luis Fernández:

The fact of getting windows timestamped files which really start at a

different time and no aparent indication of when they end ….. doesn´t help at all

Well, the FFT settings must be so that you cover enough width (in Hz) and length (in seconds). The necessary width depends on your symbol length. The length is mentioned in the FFT settings register card (FFT window time). Choose a rectangular window for EbNaut decodes.
Convert the txt files into wav using Markus tools. Load the wav file in the EbNaut decoder and press RUN. Then you will see the start time of the file. The end is start time + length. Simple, isn't it? :-)

A new txt file is generated in the interval of the scroll time (Spectrum (1) ) register card. Usually 30 minutes is fine, or even 1 hour on VLF. Then you get a file each 30 minutes. If the FFT length is longer than 30 minutes. Your FFT length should be 30 minutes longer than the transmission length, just to avoid an incomplete set of data in a txt file.

Choose the FFT width and length to suit your settings. The width is maybe 10 * 1/(symbol length) or more.


Is there any way of “fast” EbNaut when signals are strong ?

I think there are no limits, you can run 0.1 second symbol length. But usually it is used for weak signals and stable paths.

 

I really don’t know what to test next.

Send me your .usr file and the EbNaut settings you want to try.

73, Stefan


May be to run ebnaut_tx in test mode, which just changes the phase every symbol length

And then, analyze the recorded file with a different tool to determine if this phase changes are there ? Can this be easily done ?

 

73 de Luis

EA5DOM

 

PS: Congratulations for your amazing test with the guard rails. And yes, this is much much harder than EME ! J

 

De: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] En nombre de DK7FC
Enviado el: viernes, 07 de septiembre de 2018 22:10
Para: rsgb_lf_group@blacksheep.org
Asunto: Re: LF: EbNaut transmission test in LF

 

Hello Luis,

Another hint: Try to use 4K19A and a shorter message, like EA5 or so. Use long symbols, like 10 seconds or longer. Then, timing is less critical and you may get a decode and can tune to the best Eb/N0 and find out what the timing offset it. It would guess it is a timing problem.

73 Stefan

Am 07.09.2018 13:36, schrieb VIGILANT Luis Fernández:

Hi Domenico

 

Sorry, I’m not transmitting this weekend. Very stormy weather here, so the wires are down

I will notice in the reflector any transmission in advance. But first want to confirm that all is working ok

So that was the goal of yesterday test

 

Yes, the XOR is AFTER the 1/10 divider, and working at the final frequency 137485 Hz

 

Your auto-decoder is a great tool. EbNaut is quite tricky for average use and needs a lot of details to care about

Of course the reward is great when you get decodes with miserable signal levels. There is never free lunch ! ;-)

 

73 de Luis

EA5DOM

 

De: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] En nombre de Domenico IZ7SLZ
Enviado el: viernes, 07 de septiembre de 2018 13:18
Para: rsgb_lf_group@blacksheep.org
Asunto: Re: LF: EbNaut transmission test in LF

 

Hello Luis,

 

thanks for sharing your experiment. My auto-decoder  https://www.qsl.net/iz7slz/  is already retuned for your transmissions.

 

BTW QRM is large here in the morning time (urban location). I will try to catch your signal later in the night.

 

At least the decoder is detecting the carrier but may be there is no proper phase modulation or probably other failures

What I’m doing wrong ? Can anybody decode the message from the file ?

 

 I also suspect some issues on modulator circuit. Of course the XOR gate is following the /10 divider, is it?

 

Good luck.

 

73 all,

Domenico/IZ7SLZ

 

 

 

On Fri, 7 Sep 2018 at 11:38, VIGILANT Luis Fernández <luis@vigilant.es> wrote:

Hi LF EbNauters

 

I have been building a disciplined Rx for LF, based in a GPS LO at 120KHz and a NE602 downconverter to 17KHz

Then feeding the signal to the soundcard, also disciplined with 1pps from the same GPS

 

At Tx side a GPS LO at 1374850 Hz divided by 10 provides 0.1Hz steps at LF. Then an XOR gate is used for

EbNaut modulation from the DTR of  a COM port under Windows. The PA is just a mosfet driver (mic4452 AT 12v)

Just about 100mW to antenna but good enough to get a 20dB S/N in my Rx 7Km away

 

Stability looks pretty good and also phase modulation as seen in SL spectrogram. Also monitoring phase changes

with the SL plot display window. So, yesterday I tried an EbNaut transmission with the following setup

 

Coding: 8K19A

CRC 16

Symbol period: 1s

Characters: 6          Transmission time: 9.3 minutes

Transmitting at minute 00 and 30 every hour

 

I got the FFT files from SL and converted them to WAV files. The configuration file (SR) included the corrected sample rate

of the soundcard as well as decimation , FFT length and center frequency

 

Attached is a WAV file starting at 16:22 which should contain the transmission started at 16:30 untill about 16:40

 

The rawsym graphic shows a clear peak centered in frequency, but I haven’t been able to get a decode other than “******”

At least the decoder is detecting the carrier but may be there is no proper phase modulation or probably other failures

What I’m doing wrong ? Can anybody decode the message from the file ?

BTW, I have used a list length of 47274 and also 141823, but nill L

 

73 de Luis

EA5DOM

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