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 w1DJdGdi016329 for ; Tue, 13 Feb 2018 20:39:17 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1elgGQ-0002Tx-9F for rs_out_1@blacksheep.org; Tue, 13 Feb 2018 19:29:14 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1elgGP-0002Tl-KU for rsgb_lf_group@blacksheep.org; Tue, 13 Feb 2018 19:29:13 +0000 Received: from mout01.posteo.de ([185.67.36.65]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1elgGL-0006JG-Gf for rsgb_lf_group@blacksheep.org; Tue, 13 Feb 2018 19:29:12 +0000 Received: from submission (posteo.de [89.146.220.130]) by mout01.posteo.de (Postfix) with ESMTPS id C6CF120FB2 for ; Tue, 13 Feb 2018 20:29:08 +0100 (CET) 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=1518550148; bh=fl5HHrnjNQYWGJxOdPPV+QRRt9Y2unClzcRwEp2WDcM=; h=Date:From:To:Subject:From; b=LVS2mnexbvzrT82y8i813Rawn8P9HNCXv1hw6T4j20POtAP+gBn9Pq5Bwn4WAHy0P jG54GPDhoZxO3NyqYOQsk64pmDD7REtdBEKtwkO52OHpgRIGvu2T3hxtPg/Pl3KWMq h0Zhi0lMep1L0ao0UVTWz7BFQvIZ+ZKkENhhB1kKQ13H9r8fg7AhDqmMkD2VBqi5kC JYx6od5+MPcBnUGgcAaAtWVOmCcqeLgQ/z2qSWmZyA/5x0xzz7nJXlN/eIneJbyVRe qmA+myv35KjOw4Ze/o0DBNrXOR2E71s5kSaeio8vossV4SSWxTk3nOugWRL99wljzw NH964NzsEvNLw== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3zgszS22s7z9rxn for ; Tue, 13 Feb 2018 20:29:08 +0100 (CET) Message-ID: <5A833C84.9000600@posteo.de> Date: Tue, 13 Feb 2018 20:29:08 +0100 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: <5A82E06D.23523.562F00A9@mike.dennison.ntlworld.com> <8DFB18F5-5CEE-45C3-8AB7-BD478AA62A30@hurontel.on.ca> <18A42D73771E4616AE008148DE17C78B@mal> <302E518F-74A4-4F3C-82AB-B5D547057DC3@hurontel.on.ca> <5A833B06.5050206@posteo.de> In-Reply-To: <5A833B06.5050206@posteo.de> X-Spam-Score: 0.0 (/) 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 the administrator of that system for details. Content preview: PS: I know, it would have been more clever to split the EbNaut messages into daytime and nighttime messages instead of choosing a 24 hour transmission time. And i know, it is more useful to concentrate on the carriers first and then see the day/night phase difference. Later i can correst the day/night phase difference to get better results in EbNaut. All this will be necessary if i want to have a decode of the 5 char message. So all this is a truely excellent tutorial to learn how to use vlfrx-tools :-) A tutorial with a reward in the end... [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 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: f9f85a03ab18710b130c40acc03380f0 Subject: Re: ULF: On the way to results... | vlfrx tools - advice needed... Content-Type: multipart/alternative; boundary="------------010908000901040406030508" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=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. --------------010908000901040406030508 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit PS: I know, it would have been more clever to split the EbNaut messages into daytime and nighttime messages instead of choosing a 24 hour transmission time. And i know, it is more useful to concentrate on the carriers first and then see the day/night phase difference. Later i can correst the day/night phase difference to get better results in EbNaut. All this will be necessary if i want to have a decode of the 5 char message. So all this is a truely excellent tutorial to learn how to use vlfrx-tools :-) A tutorial with a reward in the end... 73 Am 13.02.2018 20:22, schrieb DK7FC: > Hi Paul, > > Well, i'm on the way to produce the results from the data recorded on > the recent *970 Hz experiment*. Meanwhile i managed to actually decode > one of the EbNaut messages but it is quite a struggle. So that's the > first good news, but later more. > > Now, There is a problem with the E field reception: The trees were > higher than expected so the active E field antenna was not high enough > above them, i.e. it has a very low effective height. I knew about that > effect but i didn't think that it is so expressed: When looking on a > 'wideband' (the word developed during the kite experiments time) > spectrogram you can see that the noise floor is almost completely > given by the preamp noise floor, it almost looks like white noise and > some frequency response. One would not expect that the message can be > found in that kind of noise background but it is in there! So it could > have been much better... > > Here is a first image showing the E field in the upper part and the H > field in the lower part: > http://www.iup.uni-heidelberg.de/schaefer_vlf/ULF/E+H_first2days.png > The spectrogram covers about the first 2 days of the recording, > without filters and blankers, just the raw recording. > > I learned how to apply a filter and a noise blanker and i played with > the threshold level. For the E field i found it is best at -a25. The H > field is best at -a10. > > First i concentrated on the 2 character EbNaut message. This message > was transmitted two times, so there was the chance to stack it. From > the E field i found the message at -5.0 dB and -6.5 dB. E field > stacked gives *-3.5 dB!* So far so good. > > Next i tried to decode the message from the H field. But the H field > has a problem too. It looks like is some lack of sensitivity and i can > also hear a Spanish broadcast station at night, i.e. some AM > demodulation. This also happens on the E field but just slightly. > Anyway, i need to improve the ULF reception system and i need to find > a better location for the next experiment. > > The 2char message was found at -5.9 dB and -5.3 dB on the H field. > These two days stacked give *-2.8 dB!* > > Just for fun i stacked E and H now, ignoring the phase. And suddenly i > got a prediction of *-0.1 dB!!!!* This is quite an unconventional way > to combine E and H i guess :-) But i put this stacked file to the > decoder and tried a few variations with the -a option. A screenshot is > in attachment but a summary of the results follows later. So i decoded > the 2 character message with _*Eb/N0 = 0.2 dB*_. > > ----- > > So far so good. But now i'm trying to combine E and H before applying > the noise blanker. This should help because when building a cardioid > with a good F/B, the sferics from the back side are rejected by say 30 > dB, so the noise blanker will not be triggered when the E, H amplitude > weighting is set correctly. I already played a bit arround with vtmix > -c1,1 or vtmix -c1,j or vtmix -c1,-1 (1st channel is E, 2nd channel is > H) and watched how the result changes. But if i want to get the best > results i will first have to remove the mains hum from the H field > channel. Mixing E and H by using vtmix may be easy when both antennas > work well but in this special situation the H field has a high hum > component whereas the E field is almost white noise. When mixing first > and applying a hum filter then, i think the result gets worse. > > I would tend to select E or H and apply a filter and noise blanker and > then save this to a file, i.e. one for E, one for H. Next i would need > to combine/mix these files again. Will the phase and timing still be > as in the original file or will it change, depending on the filter > poles and so on? > How can i mix E and H again from separate files? Is it done with > vtjoin? Do i have to write a script to do that? Starting to read both > files and send the output to a buffer. Then i call both buffers, join > them, and save them into a 2-channel file again? Then i can read that > preapred 2 channel file and use vtmix to build the cardioid antenna, > as well as the resampling to SR=1, converting to base-band etc. to > generate the file which can then be moved to the EbNaut decoder? > Sounds quite complex. > Do you have a better idea? > > 73, Stefan > > PS: Still not watched for the carrier, i guess it will be detectable... --------------010908000901040406030508 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit PS: I know, it would have been more clever to split the EbNaut messages into daytime and nighttime messages instead of choosing a 24 hour transmission time. And i know, it is more useful to concentrate on the carriers first and then see the day/night phase difference. Later i can correst the day/night phase difference to get better results in EbNaut. All this will be necessary if i want to have a decode of the 5 char message. So all this is a truely excellent tutorial to learn how to use vlfrx-tools :-) A tutorial with a reward in the end...

73

Am 13.02.2018 20:22, schrieb DK7FC:
Hi Paul,

Well, i'm on the way to produce the results from the data recorded on the recent 970 Hz experiment. Meanwhile i managed to actually decode one of the EbNaut messages but it is quite a struggle. So that's the first good news, but later more.

Now, There is a problem with the E field reception: The trees were higher than expected so the active E field antenna was not high enough above them, i.e. it has a very low effective height. I knew about that effect but i didn't think that it is so expressed: When looking on a 'wideband' (the word developed during the kite experiments time) spectrogram you can see that the noise floor is almost completely given by the preamp noise floor, it almost looks like white noise and some frequency response. One would not expect that the message can be found in that kind of noise background but it is in there! So it could have been much better...

Here is a first image showing the E field in the upper part and the H field in the lower part: http://www.iup.uni-heidelberg.de/schaefer_vlf/ULF/E+H_first2days.png
The spectrogram covers about the first 2 days of the recording, without filters and blankers, just the raw recording.

I learned how to apply a filter and a noise blanker and i played with the threshold level. For the E field i found it is best at -a25. The H field is best at -a10.

First i concentrated on the 2 character EbNaut message. This message was transmitted two times, so there was the chance to stack it. From the E field i found the message at -5.0 dB and -6.5 dB. E field stacked gives -3.5 dB! So far so good.

Next i tried to decode the message from the H field. But the H field has a problem too. It looks like is some lack of sensitivity and i can also hear a Spanish broadcast station at night, i.e. some AM demodulation. This also happens on the E field but just slightly.
Anyway, i need to improve the ULF reception system and i need to find a better location for the next experiment.

The 2char message was found at -5.9 dB and -5.3 dB on the H field. These two days stacked give -2.8 dB!

Just for fun i stacked E and H now, ignoring the phase. And suddenly i got a prediction of -0.1 dB!!!! This is quite an unconventional way to combine E and H i guess :-) But i put this stacked file to the decoder and tried a few variations with the -a option. A screenshot is in attachment but a summary of the results follows later. So i decoded the 2 character message with Eb/N0 = 0.2 dB.

-----

So far so good. But now i'm trying to combine E and H before applying the noise blanker. This should help because when building a cardioid with a good F/B, the sferics from the back side are rejected by say 30 dB, so the noise blanker will not be triggered when the E, H amplitude weighting is set correctly. I already played a bit arround with vtmix -c1,1 or vtmix -c1,j or vtmix -c1,-1 (1st channel is E, 2nd channel is H) and watched how the result changes. But if i want to get the best results i will first have to remove the mains hum from the H field channel. Mixing E and H by using vtmix may be easy when both antennas work well but in this special situation the H field has a high hum component whereas the E field is almost white noise. When mixing first and applying a hum filter then, i think the result gets worse.

I would tend to select E or H and apply a filter and noise blanker and then save this to a file, i.e. one for E, one for H. Next i would need to combine/mix these files again. Will the phase and timing still be as in the original file or will it change, depending on the filter poles and so on?
How can i mix E and H again from separate files? Is it done with vtjoin? Do i have to write a script to do that? Starting to read both files and send the output to a buffer. Then i call both buffers, join them, and save them into a 2-channel file again? Then i can read that preapred 2 channel file and use vtmix to build the cardioid antenna, as well as the resampling to SR=1, converting to base-band etc. to generate the file which can then be moved to the EbNaut decoder?
Sounds quite complex.
Do you have a better idea?

73, Stefan

PS: Still not watched for the carrier, i guess it will be detectable...
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