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 w9Q8CgxT027100 for ; Fri, 26 Oct 2018 10:12:44 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gFx3f-0004gh-1X for rs_out_1@blacksheep.org; Fri, 26 Oct 2018 09:01:27 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gFx3e-0004gY-7I for rsgb_lf_group@blacksheep.org; Fri, 26 Oct 2018 09:01:26 +0100 Received: from mout01.posteo.de ([185.67.36.65]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1gFx3b-00010p-QK for rsgb_lf_group@blacksheep.org; Fri, 26 Oct 2018 09:01:25 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout01.posteo.de (Postfix) with ESMTPS id 46318213E8 for ; Fri, 26 Oct 2018 10:01:22 +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=1540540882; bh=VCC39hBis2HqMvuipNsXISz7fR3qzYhSEX4mAMjINJY=; h=Date:From:To:Subject:From; b=h76zuVebNfKBLEoXR6/WcSbeWHmn4HHNuS3kkvSDigYgnR29/FeilVKu78Lz1Z/nD eCVTDlCWCZvNkbfItOoA/Br7TXrPZPM/fw0iAIFTM4I1glO+WxPHDf1ifkMo/zrRas mBPk491jguoBe0zAP9o+eoLOsyGfp/CEWNYofx+qRD3Ooat9vMvi8UbPtC7qs21kuB jF3HIOzihGZX6jxwO6h/aWbCMjZOTyhUklOucJvI+cAcE40/bNPqHd3ff+NOxkirob 5c6mAY7EOoWW/nVKekbC10wRZ5nBLzEeVzkiJV11N0Pa2pHjTSUjP+Rp3Z402ALqnB CDM04OmJjZ3mw== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 42hGf940SFz6tm7 for ; Fri, 26 Oct 2018 10:01:19 +0200 (CEST) Message-ID: <5BD2C9CE.3090606@posteo.de> Date: Fri, 26 Oct 2018 10:01:18 +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: <763951142.3421505.1538570933960.ref@mail.yahoo.com> <763951142.3421505.1538570933960@mail.yahoo.com> <91515688.15648332.1540409392034@mail.yahoo.com> <1868135071.15646177.1540409639111@mail.yahoo.com> <5BD16EE7.6050702@posteo.de> In-Reply-To: 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: Hi Domenico, Thanks for the feedback. Is the auto-notch filter necessary at 17.2 kHz? Hopefully it doesn't trigger on the SAQ signal and removes it ;-) Maybe not a suggestion, just my point of view (you asked about it): The noise blanker may improve the S/N but listening to a CW signal doesn't sound so good when a noise blanker is used. Also i would choose a smooth filter, low pass + high pass, maybe combined with the brick wall filter. There is/was that Russian transmitter arround 18.2 kHz, very strong here. It will lower the performance of the noise blanker. Here i used vtread | vtcat -p | vtmix | vtmult -f16500 | vtmix -c1,j | vtfilter -h hp,f=850,poles=10 -h lp,f=550,poles=10 -g1000 | vtresample -r4000 | vtraw -ow > audio.wav ..., i.e. i convert the SAQ signal to 700 Hz, apply a rough band pass filter, resample to 4 kS/s and then i read the wav file in SpecLab and apply a rough noise blanker (high threshold, just for the few very strong sferics), then a better CW filter and then a slow AGC. [...] 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 [185.67.36.65 listed in list.dnswl.org] -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -0.0 SPF_PASS SPF: sender matches SPF record 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: 91e1efbff209cbddb14bc9e018c2cfe8 Subject: Re: LF: SAQ Content-Type: multipart/alternative; boundary="------------020504060804050208090305" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_MESSAGE,HTML_TITLE_EMPTY 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. --------------020504060804050208090305 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Domenico, Thanks for the feedback. Is the auto-notch filter necessary at 17.2 kHz? Hopefully it doesn't trigger on the SAQ signal and removes it ;-) Maybe not a suggestion, just my point of view (you asked about it): The noise blanker may improve the S/N but listening to a CW signal doesn't sound so good when a noise blanker is used. Also i would choose a smooth filter, low pass + high pass, maybe combined with the brick wall filter. There is/was that Russian transmitter arround 18.2 kHz, very strong here. It will lower the performance of the noise blanker. Here i used vtread | vtcat -p | vtmix | vtmult -f16500 | vtmix -c1,j | vtfilter -h hp,f=850,poles=10 -h lp,f=550,poles=10 -g1000 | vtresample -r4000 | vtraw -ow > audio.wav ..., i.e. i convert the SAQ signal to 700 Hz, apply a rough band pass filter, resample to 4 kS/s and then i read the wav file in SpecLab and apply a rough noise blanker (high threshold, just for the few very strong sferics), then a better CW filter and then a slow AGC. Are you regularly archiving the VLF stream from your soundcard to a database (using vtwrite) ? 73, Stefan Am 26.10.2018 00:20, schrieb Domenico IZ7SLZ: > Hi Stefan, > > Thanks for informations on your temporary setup for SAQ. > > For this last SAQ reception, I have used vlfrx-tools to acquire > (vtcard) and record (vtwrite) the VLF signal coming from E-probe > antenna.Then filters, NB and vtvorbis have been used for stream the > 'RF' to the other pc where Spectrum Lab is running. > > vtfilter -v -h bp,f=17200,w=3000 @input:1 | # Pre-filter > before blanking > vtfilter -v -a th=5 | # > hum filter > vtblank -v -a15 -d0 -t300 | # > sferic blanker settings > vtresample -v -r 48000 | # > Reduce to 48000 sample pairs/sec > vtvorbis -v -ep -t -q1 -kn 1236 #port 1236 > > So, in a similar way as your setup Stefan, Spectrum Lab here uses > this stream, a bp filter with a frequency shift (to obtain a central > frequency of 700 Hz) and an AGC (slow) before the D/A converter (see > attached screenshot). > > Maybe there is a better way to stream the raw audio to a Windows PC > but this i'm using is working ok. > I also use this method to stream LF audio (filtered and timestamped by > vlfrx-tools) into another pc where SL and OPDS are running. > > https://www.qsl.net/iz7slz/OPDS/detected.txt > > Any suggestions and improvements are welcome. > > 73, Domenico IZ7SLZ > > > > On Thu, 25 Oct 2018, 09:30 DK7FC, > wrote: > > Hi Domenico, > > Which filter settings did you choose to obtain the CW filter? > > I also used vlfrx-tools to extract the SAQ message. The SNR was much > stronger on the N-S loop than from the E field. Mixing E and H > (including a small portion of the E-W loop) resulted in an SNR > increase > of > 6 dB. > But in the end i used SpecLab to build the CW filter, a rough noise > blanker for the very loud sferics (12 dB threshold) and finally a > slow > AGC which made it even more comfortable to listen to... > > 73, Stefan > > Am 24.10.2018 23:35, schrieb Domenico IZ7SLZ: > > > > Good reception of SAQ here in JN80nu thanks to very low QRN and to > > Paul's vlfrx-tools used for acquiring, filtering and stream the > audio > > to Windows PC. Then i have used Spectrum Lab to convert to > analog and > > send the audio to the speaker. Path is about 2300 km. > > This is the audio recordered: > > > https://drive.google.com/file/d/1QzJYH8GajL2PzCngnkteNT3p5vBN-tAY/view?usp=sharing > > In perfect 'vintage' marine radio officer style, i have prepared > the > > text sent by SAQ : > > > https://drive.google.com/file/d/1R36BPmf5lyiAlOzDj-bj1dZuNkKleQt3/view?usp=sharing > > > > a nice text about the Peace. Thanks to the SAQ staff for their > activities. > > > > 73, Domenico IZ7SLZ > --------------020504060804050208090305 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Domenico,

Thanks for the feedback.
Is the auto-notch filter necessary at 17.2 kHz? Hopefully it doesn't trigger on the SAQ signal and removes it ;-)
Maybe not a suggestion, just my point of view (you asked about it):
The noise blanker may improve the S/N but listening to a CW signal doesn't sound so good when a noise blanker is used. Also i would choose a smooth filter, low pass + high pass, maybe combined with the brick wall filter. There is/was that Russian transmitter arround 18.2 kHz, very strong here. It will lower the performance of the noise blanker.
Here i used vtread | vtcat -p | vtmix | vtmult -f16500 | vtmix -c1,j | vtfilter -h hp,f=850,poles=10 -h lp,f=550,poles=10 -g1000 | vtresample -r4000 | vtraw -ow > audio.wav
..., i.e. i convert the SAQ signal to 700 Hz, apply a rough band pass filter, resample to 4 kS/s and then i read the wav file in SpecLab and apply a rough noise blanker (high threshold, just for the few very strong sferics), then a better CW filter and then a slow AGC.

Are you regularly archiving the VLF stream from your soundcard to a database (using vtwrite) ?

73, Stefan

Am 26.10.2018 00:20, schrieb Domenico IZ7SLZ:
Hi Stefan,

Thanks for informations on your temporary setup for SAQ.

For this last SAQ reception, I have used vlfrx-tools to acquire (vtcard) and record (vtwrite) the VLF signal coming from E-probe antenna.Then filters, NB and vtvorbis have been used for stream the 'RF' to the other pc where Spectrum Lab is running.

vtfilter -v -h bp,f=17200,w=3000 @input:1  |          # Pre-filter before blanking
vtfilter -v -a th=5 |                                                # hum filter
vtblank -v -a15 -d0 -t300 |                                    # sferic blanker settings
vtresample -v -r 48000 |                                       # Reduce to 48000 sample pairs/sec
vtvorbis -v -ep -t -q1 -kn 1236                               #port 1236

So, in a similar way as your setup Stefan,  Spectrum Lab here uses this stream, a  bp filter with a frequency shift (to obtain a central frequency of  700 Hz) and an AGC (slow) before the D/A converter (see attached screenshot).

Maybe there is a better way to stream the raw audio to a Windows PC but this i'm using is working ok.
I also use this method to stream LF audio (filtered and timestamped by vlfrx-tools) into another pc  where SL and OPDS are running.


Any suggestions and improvements are welcome.

73, Domenico IZ7SLZ



On Thu, 25 Oct 2018, 09:30 DK7FC, <selberdenken@posteo.de> wrote:
Hi Domenico,

Which filter settings did you choose to obtain the CW filter?

I also used vlfrx-tools to extract the SAQ message. The SNR was much
stronger on the N-S loop than from the E field. Mixing E and H
(including a small portion of the E-W loop) resulted in an SNR increase
of > 6 dB.
But in the end i used SpecLab to build the CW filter, a rough noise
blanker for the very loud sferics (12 dB threshold) and finally a slow
AGC which made it even more comfortable to listen to...

73, Stefan

Am 24.10.2018 23:35, schrieb Domenico IZ7SLZ:
>
> Good reception of SAQ here in JN80nu thanks to very low QRN and to
> Paul's vlfrx-tools used for acquiring, filtering and stream the audio
> to Windows PC.  Then i have used Spectrum Lab to convert to analog and
> send the audio to the speaker. Path is about 2300 km.
> This is the audio recordered:
> https://drive.google.com/file/d/1QzJYH8GajL2PzCngnkteNT3p5vBN-tAY/view?usp=sharing
> In perfect 'vintage' marine radio officer style, i have prepared the
> text sent by SAQ :
> https://drive.google.com/file/d/1R36BPmf5lyiAlOzDj-bj1dZuNkKleQt3/view?usp=sharing
>
> a nice text about the Peace. Thanks to the SAQ staff for their activities.
>
> 73, Domenico IZ7SLZ

--------------020504060804050208090305--