Return-Path: Received: from rly-me06.mx.aol.com (rly-me06.mail.aol.com [172.20.83.40]) by air-me04.mail.aol.com (v126.13) with ESMTP id MAILINME041-9c14b5b4b8f390; Sat, 23 Jan 2010 14:18:51 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-me06.mx.aol.com (v125.7) with ESMTP id MAILRELAYINME065-9c14b5b4b8f390; Sat, 23 Jan 2010 14:18:40 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NYlU1-0007K5-Ug for rs_out_1@blacksheep.org; Sat, 23 Jan 2010 19:17:21 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NYlU1-0007Jw-1I for rsgb_lf_group@blacksheep.org; Sat, 23 Jan 2010 19:17:21 +0000 Received: from mail-bw0-f221.google.com ([209.85.218.221]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NYlTy-0005CL-2y for rsgb_lf_group@blacksheep.org; Sat, 23 Jan 2010 19:17:21 +0000 Received: by bwz21 with SMTP id 21so1822103bwz.4 for ; Sat, 23 Jan 2010 11:17:12 -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=rzItreI8D0b2KlZGxtSlMhrqcNwoQbfRTq4xZyxoTwk=; b=PS6QPlKBVR7na4l7AQa+eyDOqmPwO5e7rA6w2o06HzZg2Vaem93yzLKiuOy8AUQpG/ 0Es/oxhw61ZezmZuQz3io3gGLVaS3Mmb89RTSK6OhzQw0omwkstVcXZK2X2TvRPL7P/w /XZ2fLji5LbcXt8+BDzlY6cyX2cAS/3gM6oKA= 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=uksbVtc4FHw1EM04M+G8+d2hU2b/WGeCQIr5X/IzY7ST/agjcdzumfJveD1ghz++2i JskY7KvVp/lKDpc38QO1mIA2qhzQnvIo0uszl8wQASML09clYamMK8JgJjzTDx/GF4gv lDtJOWqnDboZGcZX/lh0ZHNlYRTRkr7sJOcKc= MIME-Version: 1.0 Received: by 10.204.5.138 with SMTP id 10mr2534720bkv.110.1264274230228; Sat, 23 Jan 2010 11:17:10 -0800 (PST) In-Reply-To: <007201ca9c5d$3614e0f0$0401a8c0@xphd97xgq27nyf> References: <9afca2641001230548m3538db64y92b335aa75c1dc00@mail.gmail.com> <9afca2641001230643s4cf01377h70165d22d325dbe1@mail.gmail.com> <9afca2641001230852x7c870d8r3837c9b6eb60c67b@mail.gmail.com> <007201ca9c5d$3614e0f0$0401a8c0@xphd97xgq27nyf> Date: Sat, 23 Jan 2010 19:17:10 +0000 Message-ID: <9afca2641001231117y223fea2cgb37f658c04708e2c@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=0015175906b6643976047dd9c824 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.4 required=5.0 tests=BIZ_TLD,HTML_20_30, 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-IP: 193.82.116.20 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d232.1 ; domain : gmail.com DKIM : pass X-Mailer: Unknown (No Version) --0015175906b6643976047dd9c824 Content-Type: text/plain; charset=ISO-8859-1 Mal informed. On 23 January 2010 18:52, mal hamilton wrote: > I still see these data signals as a waste of time since had the carrier > been keyed I could read them 100% without having to wait for the right > circumstance to get a decode, no need for level 2 demodulation. > There are several traces now visible but only an odd decode!!!!!!!!!!!!!!! > Try a QRS or CW QSO if you need an immdediate report. These signals are > audible with me. > > > > g3kev > > > ----- Original Message ----- > *From:* Roger Lapthorn > *To:* rsgb_lf_group@blacksheep.org > *Sent:* Saturday, January 23, 2010 4:52 PM > *Subject:* Re: LF: JT4A simple guide? > > Ok, fully understand Andy. Jim G7NKS is sending JT4A but I'm not getting > any decodes yet. > > Roger G3XBM > > On 23 January 2010 16:38, Andy Talbot wrote: > >> After posting that, I realised the JT4 PIC/DDS beacon code is designed for >> 100% duty cycle operation, viz JT4, CW + carrier, which is a bit antisocial >> (certainly the wide bandwidth CW bit). And more importantly, as my PA is a >> low efficiency clas AB linear one - enough said... >> >> To adapt for low duty cycle would need the PIC code changing, so will put >> the idea on hold unles there is a real demand. For a beacon, WSPR has more >> to offer anyway. >> >> Incidently, WSPR and JT4 are the same mode anyway, albeit with a bandwidth >> change from 1.46 to 4.375Hz with a resulting 4.75dB reduction in S/N. The >> coding and demodulation are all the same, so this bandwidth difference >> should be directly detectable between the two modes. The differing message >> contents wont affect the efficiency, its the added error correction , sync >> and modulation that matters - and they use the same algorithm. >> >> Andy >> www.g4jnt.com >> >> >> On 23 January 2010 14:43, Roger Lapthorn wrote: >> >>> 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 >>> >> >> > > > -- > > 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 --0015175906b6643976047dd9c824 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Mal informed.

On 23 January 2010 18:52,= mal hamilton <g3kevmal@talktalk.net> wrote:
I still see these data signals as a= waste of time=20 since had the carrier been keyed I could read them 100% without having to= wait=20 for the right circumstance to get a decode, no need for level 2=20 demodulation.
There are several traces now visible= but only an=20 odd decode!!!!!!!!!!!!!!! Try a=A0QRS or CW=A0QSO =A0if you need an=20 immdediate report. These signals are audible with me.
=A0
=A0
=A0
g3kev
=A0
----- Original Message -----
Sent:= Saturday, January 23, 2010 4:52=20 PM
Subject: Re: LF: JT4A simple gu= ide?

Ok, fully underst= and Andy.=A0 Jim G7NKS is sending JT4A but=20 I'm not getting any decodes yet.

Roger G3XBM

On 23 January 2010 16:38, Andy Talbot <andy.g4jnt@googlemail.com>=20 wrote:
After posting that, I realised the JT4 PIC/DDS beacon code is des= igned=20 for 100% duty cycle operation, viz JT4, CW + carrier, which is a bit= =20 antisocial (certainly the wide bandwidth CW bit).=A0 And more=20 importantly, as my PA is a low efficiency clas AB linear one - enough= =20 said...
=A0
To adapt for low duty cycle would need the PIC code changing, so= will=20 put the idea on hold unles there is a real demand.=A0=A0 For a beacon,= =20 WSPR has more to offer anyway.
=A0
Incidently, WSPR and JT4 are the same mode anyway, albeit with a= =20 bandwidth change from 1.46 to 4.375Hz=A0 with a resulting 4.75dB=20 reduction in S/N.=A0 The coding and demodulation are all the same, so= =20 this bandwidth difference should be directly=A0detectable=A0between=20 the two modes.=A0 The differing message contents wont affect the=20 efficiency, its the added error correction , sync and modulation=A0tha= t=20 matters - and they use the same algorithm.
On 23 January 2010 14:43, Roger Lapthorn <rogerlapthorn@gmail.com> wrote:
Thanks=20 for this help Andy.

I'd not like to derive others of you= r valuable=20 500kHz WSPR beacon, but could you beacon in JT4A at certain pre-arra= nged=20 times or days perhaps? If JT4A looks like offering the possibility= of=20 really weak signal QSOs to people like me running flea-power then I&= #39;d like=20 to explore the mode some more and having a reliable signal to test= with=20 initially would be useful. I am sure there will be others who would= value=20 this too.

73s
Roger G3XBM=20



On 23 January 2010 14:26, Andy Talbot <andy.g4jnt@googlemail.com> wrote:
AFAIK The is no 'simple guide'=A0=A0 JT4x was never= =20 originally going to be one of Joe's supported modes, although= after our=20 extensive use=A0on uWaves it certainly=A0is now.=A0=A0 JT65x=20 was the more popular and documented code, being heavily used for= EME on=20 144=A0/ 432 /=A01296MHz,=A0 =A0with JT4x just one of those=20 included in the WSJT suite to 'try out'=A0=A0 If you downl= oad and=20 read the WSJT=A0users guide and other supporting files,=20 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= =20 JT65x, but at least it does have the options of being available in= a=20 range of bandwidths / tone spacings making it usable from DC to re= d=20 light.=A0=A0 (Although I think I've only ever come across A,= D and=20 G being used respectively on LF, HF and uWaves)=A0=A0=A0=20 There's probably only a fraction of a dB in it and both are,= as far as I=20 can ascertain, only a dB or two away from the Shannon limit.=A0=20 [Which knocks spots off CW or any fuzzy mode, as well as straight= =20 PSKnn=A0without error correction].=A0=A0 Wolf has a similar=20 signalling efficiency, but unfortunately is wider, needs a linear= TX to=20 avoid being too wide and seems less user friendly.
=A0
A year or so ago we (the microwave community) wanted somethin= g for=20 use=A0on 1.3GHz and up to 10GHz or beyond.=A0=A0JT4G, the=20 widest spaced varient of them=A0looked suitable.=A0=A0=A0=20 After some prompting, Joe was persuaded not to abandon that mode,= =A0=20 and in fact=A0he=A0modified the code to =A0enhance the decoder=20 routine so the wide spaced version would be decoded with the same= S/N as=20 JT4A.=A0=A0=A0 We discovered just how good the mode was, even=20 under severe rainscatter conditions where each tone was spread out= to=20 200Hz bandwidth (tone spacing in JT4G is 315Hz for 1kH zwide overa= ll, so=20 this rain scattered signal still had discrete tone energy).
=A0
There are now two microwave beacons that transmit JT4G=20 waveforms,=A0=A0 the 10 and 2.3GHz ones in Dorset=A0 GB3SCX and=20 GB3SCS www.scr= bg.org=A0 =A0 and=A0 now GB3CSB on=20 1.3GHz from central Scotland http://www.rayjames.biz/gm4cxm/id14.html= =A0 Other=20 will follow before long as it is quite an easy mode to generate fr= om a=20 simple PIC keyer provided accurate timing information is available= to=20 keep it synched.=A0=A0
=A0
My beacon engine - the one that currently drives the 503.7/50= 3.85=20 signals -=A0can give JT4A immediately just by reprogramming the=20 PIC.=A0=A0 Would there be any interest, bearing in mind=A0both=20 the=A0WSPR and "5MHz type" waveforms will be lost for th= e=20 duration?

Andy
www.g4jnt.com

This email has been scanned fo= r=20 damaging side-effects by the health and safety police, is guarante= ed to=20 contain no substances hazardous to health, but may contribute to= =20 dissolving the nether and polar regions


On 23 January 2010 13:48, Roger Lapthor= n <rogerlapthorn@gmail.com> wrote:
Having= =20 looked on the WSJT website there is little (no?)=A0 reference to= =20 JT4A in the help files. I assume it is similar to modes like JT6= M=20 which I have managed to receive in the past on 50MHz but never= tried=20 TXing.

Can someone point me in the direction of a "<= b>JT4A for=20 Dummies" guide, or something similar that I might under= stand,=20 please?

73s
Roger G3XBM

--

http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www= .youtube.com/user/G3XBM
G3XBM =A0=20 =A0GQRP 1678 =A0 =A0 =A0ISWL=20 G11088

<= /div>


--

http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk<= br> http://www= .youtube.com/user/G3XBM
G3XBM =A0=20 =A0GQRP 1678 =A0 =A0 =A0ISWL=20 G11088

=



--

http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk<= br> http://www= .youtube.com/user/G3XBM
G3XBM=20 =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL=20 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
--0015175906b6643976047dd9c824--