Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dk05.r1000.mx.aol.com (Internet Inbound) with ESMTP id AE6EA380000A2; Sun, 6 Jan 2013 07:52:06 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Trpgd-0005a8-Rz for rs_out_1@blacksheep.org; Sun, 06 Jan 2013 12:50:47 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Trpgd-0005Zz-5q for rsgb_lf_group@blacksheep.org; Sun, 06 Jan 2013 12:50:47 +0000 Received: from imr-db03.mx.aol.com ([205.188.91.97]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1TrpgZ-0000iO-Jq for rsgb_lf_group@blacksheep.org; Sun, 06 Jan 2013 12:50:46 +0000 Received: from mtaout-db06.r1000.mx.aol.com (mtaout-db06.r1000.mx.aol.com [172.29.51.198]) by imr-db03.mx.aol.com (Outbound Mail Relay) with ESMTP id 8ADBC380000B1 for ; Sun, 6 Jan 2013 07:50:21 -0500 (EST) Received: from Black (188-194-147-142-dynip.superkabel.de [188.194.147.142]) by mtaout-db06.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id B4FC2E00009A for ; Sun, 6 Jan 2013 07:50:20 -0500 (EST) Message-ID: <4D45055C381D4BECA4B1BEF1254E1059@Black> From: "Markus Vester" To: References: <871180718.807959.1357202851097.JavaMail.open-xchange@email.1und1.de> <8CFB7BD49F0E58C-6E8-60E@webmail-d164.sysops.aol.com> In-Reply-To: <8CFB7BD49F0E58C-6E8-60E@webmail-d164.sysops.aol.com> Date: Sun, 6 Jan 2013 13:50:16 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6000.16480 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6000.16669 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1357476621; bh=XQ1lFL5nBCuMX9HEt4pJlKuknxGX4X+gws+WEqi1dx0=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=I69YyescjKYa/z/X9LYlfpRgOrz6mjSOPDpu7oD7bwz8b/2v0nq8o4fSpyWtFEaST 79eFnR3qT8/1XfK94v90FVzr8cDFiqLPnScmTx/44qBFmBsMk5lRon24RIxPK33R5s ea9hDby1C4LE4aXlPlnvVVYlntruttRV7CWxkG0w= X-AOL-SCOLL-SCORE: 0:2:450572000:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Dear LF, around midday I have been conducting some test transmissions using 136.0 kHz USB voice. To comply with German regulations, the audio spectrum has been cut off sharply below 300 Hz and above 1100 kHz, occupying 136.3 to 137.1 kHz RF. Despite this rather mediocre speech quality, it is still possible to hear the voice and copy a simple message. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [205.188.91.97 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) -0.0 SPF_PASS SPF: sender matches SPF record 0.0 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: 059065dc6500ac08f691f2dd07d4538f Subject: LF: Bandlimited SSB test on 136 kHz Content-Type: multipart/alternative; boundary="----=_NextPart_000_002F_01CDEC14.C2083030" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.7 required=5.0 tests=HTML_20_30, HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE,MISSING_OUTLOOK_NAME 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 x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mtain-dk05.r1000.mx.aol.com ; domain : mx.aol.com DKIM : fail X-AOL-OVERRIDE-PIK-REASON: Y x-aol-sid: 3039ac1db40950e973762715 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_002F_01CDEC14.C2083030 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Dear LF, around midday I have been conducting some test transmissions using 136.0 = kHz USB voice. To comply with German regulations, the audio spectrum has = been cut off sharply below 300 Hz and above 1100 kHz, occupying 136.3 to = 137.1 kHz RF. Despite this rather mediocre speech quality, it is still = possible to hear the voice and copy a simple message.=20 To my surprise, the speech was quite audible on the Twente WebSDR (434 = km), squeezed between the bursts of DCF and HGA. There's a recording and = screenshot at http://www.df6nm.bplaced.net/LF/ssb/ Of course it does get boring speaking only to myself ;-). If you'd like = to listen yourself, I intend to do another test transmission starting = 13:30 this afternoon. As the audio is realtime and standard SSB (apart = from the filtering), no software postprocessing is needed.. Slow voice transmission (ie the audio deceleration/acceleration method = originally used by DK8KW and myself) would be nicer as it can fit a full = SSB channel into 800 Hz. I have been working on a semi-automatic = control, with a fixed one minute raster similar to JT9-1. This will = hopefully allow us to comfortably exchange one 20 second voice message = per time slot (speak during seconds 0 to 20, concurrent transmit and = receive at 1/3 speed from 0 to 60, replay starting 40 to 60). Anyone = interested? Best 73, Markus (DF6NM) =20 ----- Original Message -----=20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, January 03, 2013 12:33 PM Subject: Re: LF: SSB - why not go digital?=20 Hi Geri, all, I like the idea of trying voice on MF or even LF, and I was fascinated = by actually hearing Gus talking on 507 kHz, and Geri on LF slow voice. I = admit that I even tried (low-power daytime) SSB above 135.7 kHz once, = and Stefan was actually able to hear and record my voice, albeit at = marginal SNR at 180 km. As my LF TX antenna is fairly narrowband (Q ~ = 200), I had inserted a phase shifter to transform the low output = impedance of the PA into a current source at the feedpoint. The good thing about slow voice is that we also get the SNR gain = associated with the narrower bandwidth. But the non-realtime operating = procedure is sort of difficult. We did use "roger beeps" to mark the end = of message, but there is always an inconvenient delay for recording and = replaying the messages. So some sort of realtime narrowband voice = transmission would indeed be desirable. However I would NOT fancy digital voice modes at all. For one, like = all digital modes it's all-or-nothing. Either the message decodes well, = or you get garbage, and you don't know what has been going on in the = channel. In linear analog SSB, you hear if someone else is calling on = frequency, or what type of interference came up, or whether there is = selective fading. The other thing I don't like about digital modes is = that they tend to occupy the whole channel permanently with high average = power - just look at the spectra of DRM vs AM modulated BC = transmissions. It may well turn out that a 2 kHz linear SSB transmission = is much more friendly than a 1 kHz digital channel.=20 I have been making some attempts on analog quasi-realtime narrowband = voice transmissions. The principle was is much the same that has long = been used for changing audio speed without changing pitch, ie cut the = audio into ~ 20 ms grains. To accellerate or reduce bandwidth, you = either leave out or average several grains, using a sliding window. On = replay, each grain is repeated to extend it in time. This is not = difficult to implement. In my own trials, I could maintain speech = readability with a factor four bandwidth reduction, but it did sound = very "robotic" because the fixed timing for the grains impressed itself = onto the voice pitch. I think that there are better ways of adapting the = timing by tracking the fundamental frequency to preserve the pitch = modulation. Using Windows media player for accelerating and decelerating = seemed to provide quite natural speech quality at a reduction factor of = four. Regarding the frequency allocations, like Graham I would think that on = MF the narrowband beacons should best be placed in narrow slots near the = band edges. To avoid blocking, we would preferably again use split band = for west-east vs east-west intercontinental work, as we do on LF. Parts = of these slots should also be utilized for the slow versions of Opera or = WSPR. The wider modes would better be placed in the in the middle, = perhaps with 2 kHz each for CW, middle-range digital modes, and one = full-width SSB channel. Best 73, Markus (DF6NM) ... ------=_NextPart_000_002F_01CDEC14.C2083030 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
Dear LF,
 
around midday I have=20 been conducting some test transmissions using 136.0 kHz = USB=20 voice. To comply with German regulations, the audio = spectrum has=20 been cut off sharply below 300 Hz and above 1100 kHz, = occupying 136.3=20 to 137.1 kHz RF. Despite this rather mediocre speech quality,=20 it is still possible to hear the voice and copy a simple=20 message. 
 
To my surprise, the speech was = quite=20 audible on the Twente WebSDR (434 km), squeezed between the = bursts of=20 DCF and HGA. There's a recording and screenshot at
http://www.df6nm.bplaced.ne= t/LF/ssb/
Of course it does get boring speaking = only to=20 myself ;-). If you'd like to listen yourself, I intend to do another = test=20 transmission starting 13:30 this afternoon. As the audio is = realtime and=20 standard SSB (apart from the filtering), no software postprocessing is=20 needed..
 
Slow voice transmission (ie = the audio=20 deceleration/acceleration method originally used by DK8KW and myself) = would=20 be nicer as it can fit a full SSB channel into 800=20 Hz. I have been working on a semi-automatic control, = with a=20 fixed one minute raster similar to JT9-1. This will hopefully allow us = to=20 comfortably exchange one 20 second voice message per time slot=20 (speak during seconds 0 to 20, concurrent = transmit and receive at=20 1/3 speed from 0 to 60, replay starting 40 to 60). Anyone=20 interested?
 
Best 73,
Markus (DF6NM)
   
----- Original Message -----
From:=20 Markus=20 Vester
Sent: Thursday, January 03, = 2013 12:33=20 PM
Subject: Re: LF: SSB - why not = go=20 digital?

Hi Geri, all,
 
I = like the idea=20 of trying voice on MF or even LF, and I was fascinated by = actually=20 hearing Gus talking on 507 kHz, and Geri on LF slow=20 voice. I admit that I even tried (low-power daytime) = SSB above=20 135.7 kHz once, and Stefan was actually able to hear and record my = voice,=20 albeit at marginal SNR at 180 km. As my LF TX antenna is fairly = narrowband=20 (Q ~ 200), I had inserted a phase shifter to transform the low = output=20 impedance of the PA into a current source at the feedpoint.
 
The = good thing=20 about slow voice is that we also get the SNR gain associated with the = narrower=20 bandwidth. But the non-realtime operating procedure is sort=20 of difficult. We did use "roger beeps" to mark the = end of=20 message, but there is always an inconvenient delay for = recording and=20 replaying the messages. So some sort of realtime narrowband voice = transmission would indeed be desirable.
 
However I would=20 NOT fancy digital voice modes at all. For one, like all digital=20 modes it's all-or-nothing. Either the message decodes=20 well, or you get garbage, and you don't know what has been going = on in=20 the channel. In linear analog SSB, you hear if someone else is = calling on=20 frequency, or what type of interference came up, or whether = there is=20 selective fading. The other thing I don't like about digital = modes is=20 that they tend to occupy the whole channel permanently with high = average power=20 - just look at the spectra of DRM vs AM modulated BC = transmissions. It=20 may well turn out that a 2 kHz linear SSB transmission is = much more=20 friendly than a 1 kHz digital channel. 
 
I = have been=20 making some attempts on analog quasi-realtime narrowband voice = transmissions.=20 The principle was is much the same that has long been used=20 for changing audio speed without changing pitch, ie cut the = audio=20 into ~ 20 ms grains. To accellerate or reduce bandwidth, you = either leave out or average several grains, using a sliding = window.=20 On replay, each grain is repeated to extend it in time. This = is not=20 difficult to implement. In my own trials, I could maintain speech = readability=20 with a factor four bandwidth reduction, but it did sound very = "robotic"=20 because the fixed timing for the grains impressed itself = onto the=20 voice pitch. I think that there are better ways of adapting=20 the timing by tracking the fundamental frequency to = preserve=20 the pitch modulation. Using Windows media player for=20 accelerating and decelerating seemed to = provide quite natural=20 speech quality at a reduction factor of four.
 
Regarding the=20 frequency allocations, like Graham I would think that on MF the = narrowband=20 beacons should best be placed in narrow slots near the band edges. To = avoid=20 blocking, we would preferably again use split band for west-east = vs=20 east-west intercontinental work, as we do on LF. Parts of these slots = should=20 also be utilized for the slow versions of Opera or WSPR. The = wider modes=20 would better be placed in the in the middle, perhaps with 2 kHz=20 each for CW, middle-range digital = modes, and one=20 full-width SSB channel.
 
Best = 73,
Markus=20 (DF6NM)
 ...
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