Return-Path: Received: from mtain-de06.r1000.mx.aol.com (mtain-de06.r1000.mx.aol.com [172.29.64.206]) by air-mb07.mail.aol.com (v126.13) with ESMTP id MAILINMB073-a7a34b5b0b45109; Sat, 23 Jan 2010 09:44:21 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-de06.r1000.mx.aol.com (Internet Inbound) with ESMTP id D863E3800006E; Sat, 23 Jan 2010 09:44:19 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NYhCs-0005je-HM for rs_out_1@blacksheep.org; Sat, 23 Jan 2010 14:43:22 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NYhCr-0005jV-TT for rsgb_lf_group@blacksheep.org; Sat, 23 Jan 2010 14:43:21 +0000 Received: from mail-bw0-f221.google.com ([209.85.218.221]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NYhCo-0003kv-PO for rsgb_lf_group@blacksheep.org; Sat, 23 Jan 2010 14:43:21 +0000 Received: by bwz21 with SMTP id 21so1729753bwz.4 for ; Sat, 23 Jan 2010 06:43:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=/PYsWTCdfp3/fILEqmhhVYCrvQZwbCrBkGQMqsEXHSg=; b=A5uAGnuOlPLmdZWZd370EzDyaJ5ODNZz1HYB7XKqH45cS42vnX+UctIDHEQUi8e9vb 3QGLzARrdtbPjWJ0tiSwEthg+1+hNIep9eOrjZC81uk+X6/Z6vzVpAijVDGpK4KL5CaO KenkUKlX9GfF41g5OhO5u8mMIYJCB+Kmil2oA= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=YaJfC+6dfIh80TeVSi5eLsWxiffM5i7M/b4qNEtOVqJSb1Sh9YR7Rhwq62xPgt9CrD +0YcmJY4S920VOlPQRe+yjwClfkv2v9bG1VqMODOyI0KCwABf/lXGpTl5j+oC2rqFhat Ym+4rg9Q3oj+GOn2x+deSPIp2Z6WcBxQa9MqU= MIME-Version: 1.0 Received: by 10.204.10.13 with SMTP id n13mr2470174bkn.60.1264257789933; Sat, 23 Jan 2010 06:43:09 -0800 (PST) In-Reply-To: References: <9afca2641001230548m3538db64y92b335aa75c1dc00@mail.gmail.com> Date: Sat, 23 Jan 2010 14:43:09 +0000 Message-ID: <9afca2641001230643s4cf01377h70165d22d325dbe1@mail.gmail.com> From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: JT4A simple guide? Content-Type: multipart/alternative; boundary=00032555b2ce793904047dd5f465 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=BIZ_TLD,HTML_FONTCOLOR_UNSAFE, 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 x-aol-global-disposition: G x-aol-sid: 3039ac1d40ce4b5b0b4321c4 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --00032555b2ce793904047dd5f465 Content-Type: text/plain; charset=ISO-8859-1 Thanks for this help Andy. I'd not like to derive others of your valuable 500kHz WSPR beacon, but could you beacon in JT4A at certain pre-arranged times or days perhaps? If JT4A looks like offering the possibility of really weak signal QSOs to people like me running flea-power then I'd like to explore the mode some more and having a reliable signal to test with initially would be useful. I am sure there will be others who would value this too. 73s Roger G3XBM On 23 January 2010 14:26, Andy Talbot wrote: > AFAIK The is no 'simple guide' JT4x was never originally going to be one > of Joe's supported modes, although after our extensive use on uWaves it > certainly is now. JT65x was the more popular and documented code, being > heavily used for EME on 144 / 432 / 1296MHz, with JT4x just one of those > included in the WSJT suite to 'try out' If you download and read the > WSJT users guide and other supporting files, there's all you need to know to > get it going is in there. > > http://www.physics.princeton.edu/pulsar/K1JT/WSJT_User_600.pdf > *http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html* > http://www.physics.princeton.edu/pulsar/K1JT/JT2_JT4.TXT > > Its still debatable as to whether JT4 is better or worse than JT65x, but at > least it does have the options of being available in a range of bandwidths / > tone spacings making it usable from DC to red light. (Although I think > I've only ever come across A, D and G being used respectively on LF, HF and > uWaves) There's probably only a fraction of a dB in it and both are, as > far as I can ascertain, only a dB or two away from the Shannon limit. > [Which knocks spots off CW or any fuzzy mode, as well as straight > PSKnn without error correction]. Wolf has a similar signalling efficiency, > but unfortunately is wider, needs a linear TX to avoid being too wide and > seems less user friendly. > > A year or so ago we (the microwave community) wanted something for use on > 1.3GHz and up to 10GHz or beyond. JT4G, the widest spaced varient of > them looked suitable. After some prompting, Joe was persuaded not to > abandon that mode, and in fact he modified the code to enhance the decoder > routine so the wide spaced version would be decoded with the same S/N as > JT4A. We discovered just how good the mode was, even under severe > rainscatter conditions where each tone was spread out to 200Hz bandwidth > (tone spacing in JT4G is 315Hz for 1kH zwide overall, so this rain scattered > signal still had discrete tone energy). > > There are now two microwave beacons that transmit JT4G waveforms, the 10 > and 2.3GHz ones in Dorset GB3SCX and GB3SCS www.scrbg.org and now > GB3CSB on 1.3GHz from central Scotland > http://www.rayjames.biz/gm4cxm/id14.html Other will follow before long as > it is quite an easy mode to generate from a simple PIC keyer provided > accurate timing information is available to keep it synched. > > My beacon engine - the one that currently drives the 503.7/503.85 signals > - can give JT4A immediately just by reprogramming the PIC. Would there be > any interest, bearing in mind both the WSPR and "5MHz type" waveforms will > be lost for the duration? > > Andy > www.g4jnt.com > > This email has been scanned for damaging side-effects by the health and > safety police, is guaranteed to contain no substances hazardous to health, > but may contribute to dissolving the nether and polar regions > > > On 23 January 2010 13:48, Roger Lapthorn wrote: > >> Having looked on the WSJT website there is little (no?) reference to JT4A >> in the help files. I assume it is similar to modes like JT6M which I have >> managed to receive in the past on 50MHz but never tried TXing. >> >> Can someone point me in the direction of a "*JT4A for Dummies*" guide, or >> something similar that I might understand, please? >> >> 73s >> Roger G3XBM >> >> -- >> >> http://g3xbm-qrp.blogspot.com/ >> http://www.g3xbm.co.uk >> http://www.youtube.com/user/G3XBM >> G3XBM GQRP 1678 ISWL G11088 >> > > -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088 --00032555b2ce793904047dd5f465 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Thanks for this help Andy.

I'd not like to derive others of yo= ur valuable 500kHz WSPR beacon, but could you beacon in JT4A at certain pr= e-arranged times or days perhaps? If JT4A looks like offering the possibil= ity of really weak signal QSOs to people like me running flea-power then= I'd like to explore the mode some more and having a reliable signal= to test with initially would be useful. I am sure there will be others wh= o would value this too.

73s
Roger G3XBM


On 23 January= 2010 14:26, Andy Talbot <andy.g4jnt@googlemail.com> wrote:
AFAIK The is no 'simple guide'=A0=A0 JT4x was never originall= y going to be one of Joe's supported modes, although after our extensi= ve use=A0on uWaves it certainly=A0is now.=A0=A0 JT65x was the more popular= and documented code, being heavily used for EME on 144=A0/ 432 /=A01296MH= z,=A0 =A0with JT4x just one of those included in the WSJT suite to 'tr= y out'=A0=A0 If you download and read the WSJT=A0users guide and other= supporting files, there's=A0all you need to know to get it going is= in there.
=A0
=A0
Its still debatable as to whether JT4 is better or worse than JT65x,= but at least it does have the options of being available in a range of ba= ndwidths / tone spacings making it usable from DC to red light.=A0=A0 (Alt= hough I think I've only ever come across A, D and G being used respect= ively on LF, HF and uWaves)=A0=A0=A0 There's probably only a fraction= of a dB in it and both are, as far as I can ascertain, only a dB or two= away from the Shannon limit.=A0 [Which knocks spots off CW or any fuzzy= mode, as well as straight PSKnn=A0without error correction].=A0=A0 Wolf= has a similar signalling efficiency, but unfortunately is wider, needs a= linear TX to avoid being too wide and seems less user friendly.
=A0
A year or so ago we (the microwave community) wanted something for us= e=A0on 1.3GHz and up to 10GHz or beyond.=A0=A0JT4G, the widest spaced vari= ent of them=A0looked suitable.=A0=A0=A0 After some prompting, Joe was pers= uaded not to abandon that mode,=A0 and in fact=A0he=A0modified the code to= =A0enhance the decoder routine so the wide spaced version would be decode= d with the same S/N as JT4A.=A0=A0=A0 We discovered just how good the mode= was, even under severe rainscatter conditions where each tone was spread= out to 200Hz bandwidth (tone spacing in JT4G is 315Hz for 1kH zwide overa= ll, so this rain scattered signal still had discrete tone energy).
=A0
There are now two microwave beacons that transmit JT4G waveforms,=A0= =A0 the 10 and 2.3GHz ones in Dorset=A0 GB3SCX and GB3SCS www.scrbg.org=A0 =A0 and=A0 now GB= 3CSB on 1.3GHz from central Scotland http://www.rayjames.biz/gm4cxm/id14.html= =A0 Other will follow before long as it is quite an easy mode to gener= ate from a simple PIC keyer provided accurate timing information is availa= ble to keep it synched.=A0=A0
=A0
My beacon engine - the one that currently drives the 503.7/503.85 sig= nals -=A0can give JT4A immediately just by reprogramming the PIC.=A0=A0 Wo= uld there be any interest, bearing in mind=A0both the=A0WSPR and "5MH= z type" waveforms will be lost for the duration?

Andy
www.g4jnt.com

This email has been scanned for damaging= side-effects by the health and safety police, is guaranteed to contain no= substances hazardous to health, but may contribute to dissolving the neth= er and polar regions


On 23 January 2010 13:48, Roger Lapthorn <rogerlapthorn@gmail.com> wrote:
Having looked= on the WSJT website there is little (no?)=A0 reference to JT4A in the hel= p files. I assume it is similar to modes like JT6M which I have managed to= receive in the past on 50MHz but never tried TXing.

Can someone point me in the direction of a "JT4A for Dummies" guide, or something similar that I might understand, please?
<= br>73s
Roger G3XBM

--
=
http://g3xbm-= qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/G3XBM
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088




--

http://g3xbm-qrp.blogspot.com/http://www.g3xbm.co.uk
http://www.youtube.com/user/G3XBM
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--00032555b2ce793904047dd5f465--