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 w87C5goH023495 for ; Fri, 7 Sep 2018 14:05:43 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1fyFRy-0004Ht-5y for rs_out_1@blacksheep.org; Fri, 07 Sep 2018 13:01:22 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1fyFRw-0004Hk-UE for rsgb_lf_group@blacksheep.org; Fri, 07 Sep 2018 13:01:20 +0100 Received: from mail-ed1-x534.google.com ([2a00:1450:4864:20::534]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1fyFRu-0000jC-1r for rsgb_lf_group@blacksheep.org; Fri, 07 Sep 2018 13:01:19 +0100 Received: by mail-ed1-x534.google.com with SMTP id u1-v6so11366087eds.1 for ; Fri, 07 Sep 2018 05:01:17 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=5y3nm+TSBpEK+74qdwlBXKE+0WuUAVR/2dXHfgNUu3Q=; b=U2yQcP6wjWtzR11Uglre+WPQepb8fur4a8S+jyPrPYl6yy0DhENTpHbqIq+THlq0ta rmXc5NO1X3iXPeDS28cJTPKr7VFdxkEbgQdhvpj6YkomBqNNY/r1pGAaYgAKBKmClwk4 gv1nkz4n+NafVsa/ME5/a4W5nUGdGiIXTvNRvh6hgKN6Qbm2WdVEsknMNWPp5Ihnhm09 6yrw0dyTHSr8hf+aUTFYgzbCVH5OTkGyac6Vu/0GKHgdv34vc9ft74GOPXcR3Cq79wsI gtfnj+hLtS99+atjGh9gdE8LzwvBl+U8UGjdSBFuNtvtAJAcG/XALUJGsH7bBLObT4F+ 66Ig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=5y3nm+TSBpEK+74qdwlBXKE+0WuUAVR/2dXHfgNUu3Q=; b=iIS1d8OMJY2++Z1viLFApgCGrRqGO4dRZ4Vb+RDZCkDdRyUw/Q3eTF0Ln9R8g5SR9m KS0ZvEgS0yeLYN0ja4BPHvsg1QMigl4ng9Rz68cgk2PJnASsxD+pP5l0ZDcQZiXhnpPc /fPa/lXPJWrAFEJ4AUSZ+2N9arr/T2MpBTWhNPEXNL1vpyd3mgLP/schtgSeKgN+Z5Nz YrpS4pLlPxDaoIHcMaTim6Ot85N4xoO3HzFUWYXVLTGycGEI7GBwr8gKbZBuIjJFQL4d nD6NQpcNdFEOesSDgznfXSbuPlEbcRZD2jL0Whygj1B52iNY6MUQnK9uuacPo5lKlDLm bOkA== X-Gm-Message-State: APzg51APdS1qDXmUHWPeoRUrFn0Zcbe8KHdITEy4nfYvEje7IJQAGFg/ kL0dQJaa4zttGrx+gMpLVIyx2xGsoFmfaaYEQ3SZhg== X-Google-Smtp-Source: ANB0VdYMtjTz6hcNMflhx4WbUKlY81BV7+f3WW7Vd55sOsJJyDSLROnUdxD96JgONwUKRxN3Pzk6xlQqnA63gP3Zvjc= X-Received: by 2002:a50:b941:: with SMTP id m59-v6mr8393159ede.20.1536321677081; Fri, 07 Sep 2018 05:01:17 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:aa7:da95:0:0:0:0:0 with HTTP; Fri, 7 Sep 2018 05:01:16 -0700 (PDT) In-Reply-To: <33e4331a-6c57-3040-0c49-74840cbf4a1f@n1bug.com> References: <5B911389.9080807@posteo.de> <165aeea613a-1ec0-427@webjasstg-vab55.srv.aolmail.net> <33e4331a-6c57-3040-0c49-74840cbf4a1f@n1bug.com> From: Andy Talbot Date: Fri, 7 Sep 2018 13:01:16 +0100 Message-ID: To: LineOne 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 @@CONTACT_ADDRESS@@ for details. Content preview: The only reason PSK is said to require linear amplification is that in most practical implementations to control the spectrum the amplitude has an envelope applied, so it goes to zero when the phase flips. PSK doesn't 'have' to use amplitude tailoring to control it's spectrum. It is possible to ramp the phase instead and that will also proviude spectrum shaping - although its shape will be very different from envelope shaping. [...] 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 [2a00:1450:4864:20:0:0:0:534 listed in] [list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (andy.g4jnt[at]gmail.com) -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: d2a449809c9c1ff1983612d049372878 Subject: Re: LF: Slow JT9 modes... Content-Type: multipart/alternative; boundary="000000000000d2c249057546c384" 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 --000000000000d2c249057546c384 Content-Type: text/plain; charset="UTF-8" The only reason PSK is said to require linear amplification is that in most practical implementations to control the spectrum the amplitude has an envelope applied, so it goes to zero when the phase flips. PSK doesn't 'have' to use amplitude tailoring to control it's spectrum. It is possible to ramp the phase instead and that will also proviude spectrum shaping - although its shape will be very different from envelope shaping. With the slow PSK we're talking about for LF do the sidebands matter anyway? Back in the early days of 73kHz several OPs used a mode called 'coherent' that was based around 10 symbols/s (10Hz) hard switched BPSK with strong FEC. And most people did use very hard switched - an XOR gate was typical. When many amateurs hear the term "PSK" they tend to think of PSK31 specifically, which has the most extreme amplitude tailoring possible for the mose - and hence the narrowest bandwidth. Communications efficiency of PSK31 is therefore quite badly degraded over what could be obtained with sharp edged switching with high sideband levels. Andy www.g4jnt.com On 7 September 2018 at 11:28, N1BUG wrote: > Sounds interesting, Andy. Please correct me if I am wrong, but > doesn't PSK require linear amplification? If so, it would eliminate > many potential QSO partners. > > Regarding EbNaut, my understanding was that OCXOs aren't good enough > and that a GPSDO or rubidium standard is needed. If that's not true, > someone please correct me on this also. > > As for someone who is interested in LF either joining the JT > development team or writing code independently, if I had the > relevant skills and development tools I would leap at the > opportunity to bring back the slower JT9 submodes. Unfortunately I > have enough trouble getting my head around simple things these days, > as you've seen with my construction projects... > > 73, > Paul N1BUG > > > > On 09/06/2018 09:21 AM, Andy Talbot wrote: > > As good as JT9 is, in whatever speed-flavour, at LF it throws away one > > aspect of LF propagation that isn't not really availalble for HF, phase > > stability over longer periods, at least suited to a few characters. JT9 > > is a purely power-based system with heavy FEC. > > > > So while slower versions of JT9 would be good for LF in the short term, > > they will not make the most of what propagation can offer. NO one on the > > WSJT-X development team is interested in LF, so it's no good looking > > there. However, I'm sure they'd be amenable to someone else joining > the > > team and adding an LF users perspective and writing / developing the > > relevant submodes. Or do it independently using the open-source code. > > > > EBnaut carries phase signalling to the extreme, carrying no sync / timing > > info in the on-air symbols and being completely reliant on high stability > > frequency sources and people accurately starting and stopping. This > > complex manual setting is, in my opinion its downfall; high stability > > sources are less of a problem these days as OCXOs are now so cheap and > > readily availalble. > > > > What we need is an intermediate slow PSK or QPSK based scheme that > carries > > its own timing and sync. FEC is something that could come later, we > first > > of all want a simple PSK decoder scheme that search over a modest span in > > frequency - say 0.2Hz and with unknown timing . I suggest differential > > BPSK as a stat, where the data depends on teh phase change from one > symbol > > to the next. That removes the need for absolute clock recovery, and > also, > > provided tuning error is appreciably lesss than symbol rate, even for > > carrier recovery. Just compare one block of digitised data (of a > symbol's > > length) witjh the previous one and look for a peak every so often to get > > the boundary . Some framing will be needed in order to guarantee a few > > phase changes for alignment. > > > > A block / timed scheme like WSJT would probably work best as it reduces > the > > searching for sync. It also makes the soundcard driving software easier > as > > a fixed length block can be recorded to a .WAV file more easily than > > continuous real time data reading from the s-card. > > > > Once the signalling and signal recovery is proven, then is the time to > > think about adding FEC but even a none error-corrected scheme ought to > have > > a fair bit to offer in testing. > > > > The only real downside to PSK is its spectrum is you switch rapidly. > But > > its no worse than on-off keying, and if the signal is being generated by > > upconverting from a soundcard phase ramping could perhaps be used to > reduce > > sidebands > > > > > > > > > > > > Andy > > www.g4jnt.com > > --000000000000d2c249057546c384 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
The only reason PSK is said to require linear amplificatio= n is that in most practical implementations to control the spectrum the amp= litude has an envelope applied, so it goes to zero when the phase flips.=C2= =A0 =C2=A0PSK doesn't 'have' to use amplitude tailoring to cont= rol it's spectrum.=C2=A0 It is possible to ramp the phase instead and t= hat will also proviude spectrum shaping - although its shape will be very d= ifferent from envelope shaping.=C2=A0 =C2=A0=C2=A0

With = the slow PSK we're talking about for LF do the sidebands matter anyway?=

Back in the early days of 73kHz several OPs used a mode= called 'coherent' that was based around 10 symbols/s (10Hz)=C2=A0 = hard switched BPSK with strong FEC.=C2=A0 And most people did use very hard= switched - an XOR gate was typical.=C2=A0 =C2=A0=C2=A0

When=C2=A0 =C2=A0 many amateurs hear the term "PSK"=C2=A0 t= hey tend to think of PSK31 specifically, which has the most extreme amplitu= de tailoring possible for the mose - and hence the narrowest bandwidth.=C2= =A0 =C2=A0 Communications efficiency of PSK31=C2=A0 is therefore quite badl= y degraded over what could be obtained with sharp edged switching with high= sideband levels.


<= /div>

On 7 September 2018 at 11:28, N1BUG <paul@n1bu= g.com> wrote:
Sounds intere= sting, Andy. Please correct me if I am wrong, but
doesn't PSK require linear amplification? If so, it would eliminate
many potential QSO partners.

Regarding EbNaut, my understanding was that OCXOs aren't good enough and that a GPSDO or rubidium standard is needed. If that's not true, someone please correct me on this also.

As for someone who is interested in LF either joining the JT
development team or writing code independently, if I had the
relevant skills and development tools I would leap at the
opportunity to bring back the slower JT9 submodes. Unfortunately I
have enough trouble getting my head around simple things these days,
as you've seen with my construction projects...

73,
Paul N1BUG



On 09/06/2018 09:21 AM, Andy Talbot wrote:
> As good as JT9 is, in whatever speed-flavour, at LF it throws away one=
> aspect of LF propagation that isn't not really availalble for HF, = phase
> stability over longer periods, at least suited to a few characters.=C2= =A0 =C2=A0JT9
> is a purely power-based system with heavy FEC.
>
> So while slower versions of JT9 would be good for LF in=C2=A0 the shor= t term,
> they will not make the most of what propagation can offer.=C2=A0 NO on= e on the
> WSJT-X development team is interested in LF, so it's no good looki= ng
> there.=C2=A0 =C2=A0 However, I'm sure they'd be amenable to so= meone else joining the
> team and adding an LF users perspective and writing / developing the > relevant submodes.=C2=A0 =C2=A0Or do it independently using the open-s= ource code.
>
> EBnaut carries phase signalling to the extreme, carrying no sync / tim= ing
> info in the on-air symbols and being completely reliant on high stabil= ity
> frequency sources and people accurately starting and stopping.=C2=A0 = =C2=A0This
> complex manual setting is, in my opinion its downfall;=C2=A0 high stab= ility
> sources are less of a problem these days as OCXOs are now so cheap and=
> readily availalble.
>
> What we need is an intermediate slow PSK or QPSK based scheme that car= ries
> its own timing and sync.=C2=A0 =C2=A0FEC is something that could come = later, we first
> of all want a simple PSK decoder scheme that search over a modest span= in
> frequency - say 0.2Hz and with unknown timing .=C2=A0 =C2=A0I suggest = differential
> BPSK as a stat, where the data depends on teh phase change from one sy= mbol
> to the next.=C2=A0 =C2=A0That removes the need for absolute clock reco= very, and also,
> provided tuning error is appreciably lesss than symbol rate, even for<= br> > carrier recovery.=C2=A0 =C2=A0Just compare one block of digitised data= (of a symbol's
> length) witjh the previous one and look for a peak every so often to g= et
> the boundary .=C2=A0 Some framing will be needed in order to guarantee= a few
> phase changes for alignment.
>
> A block / timed scheme like WSJT would probably work best as it reduce= s the
> searching for sync.=C2=A0 It also makes the soundcard driving software= easier as
> a fixed length block can be recorded to a .WAV file more easily than > continuous real time data reading from the s-card.
>
> Once the signalling and signal recovery is proven, then is the time to=
> think about adding FEC but even a none error-corrected scheme ought to= have
> a fair bit to offer in testing.
>
> The only real downside to PSK is its spectrum is you switch rapidly.= =C2=A0 =C2=A0But
> its no worse than on-off keying, and if the signal is being generated = by
> upconverting from a soundcard phase ramping could perhaps be used to r= educe
> sidebands
>
>
>
>
>
> Andy
> = www.g4jnt.com


--000000000000d2c249057546c384--