Return-Path: Received: from rly-dg02.mx.aol.com (rly-dg02.mail.aol.com [172.19.151.86]) by air-dg07.mail.aol.com (v126.13) with ESMTP id MAILINDG074-5a74b5b45c0205; Sat, 23 Jan 2010 13:54:23 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dg02.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDG022-5a74b5b45c0205; Sat, 23 Jan 2010 13:54:04 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NYl6R-00076z-Kh for rs_out_1@blacksheep.org; Sat, 23 Jan 2010 18:52:59 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NYl6Q-00076q-Qs for rsgb_lf_group@blacksheep.org; Sat, 23 Jan 2010 18:52:58 +0000 Received: from out1.ip08ir2.opaltelecom.net ([62.24.128.244]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NYl6N-00054m-KE for rsgb_lf_group@blacksheep.org; Sat, 23 Jan 2010 18:52:58 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AosFAKHUWktZ8Y3g/2dsb2JhbAAtjUcFyBSEOwQ X-IronPort-AV: E=Sophos;i="4.49,330,1262563200"; d="scan'208,217";a="437540562" Received: from unknown (HELO xphd97xgq27nyf) ([89.241.141.224]) by out1.ip08ir2.opaltelecom.net with SMTP; 23 Jan 2010 18:52:32 +0000 Message-ID: <007201ca9c5d$3614e0f0$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: <9afca2641001230548m3538db64y92b335aa75c1dc00@mail.gmail.com> <9afca2641001230643s4cf01377h70165d22d325dbe1@mail.gmail.com> <9afca2641001230852x7c870d8r3837c9b6eb60c67b@mail.gmail.com> Date: Sat, 23 Jan 2010 18:52:28 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 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="----=_NextPart_000_006F_01CA9C5D.35E2D470" 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 ------=_NextPart_000_006F_01CA9C5D.35E2D470 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I still see these data signals as a waste of time since had the carrie= r been keyed I could read them 100% without having to wait for the rig= ht 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 sign= als are audible with me. g3kev ----- Original Message -----=20 From: Roger Lapthorn=20 To: rsgb_lf_group@blacksheep.org=20 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 ge= tting any decodes yet. Roger G3XBM On 23 January 2010 16:38, Andy Talbot wr= ote: After posting that, I realised the JT4 PIC/DDS beacon code is desi= gned for 100% duty cycle operation, viz JT4, CW + carrier, which is a= bit antisocial (certainly the wide bandwidth CW bit). And more impor= tantly, 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 beaco= n, 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 reduct= ion in S/N. The coding and demodulation are all the same, so this ban= dwidth 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.=20 I'd not like to derive others of your valuable 500kHz WSPR beaco= n, 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 exp= lore the mode some more and having a reliable signal to test with init= ially would be useful. I am sure there will be others who would value= this too. 73s Roger G3XBM=20 On 23 January 2010 14:26, Andy Talbot wrote: AFAIK The is no 'simple guide' JT4x was never originally goi= ng to be one of Joe's supported modes, although after our extensive us= e on uWaves it certainly is now. JT65x was the more popular and docu= mented 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= =20 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 bein= g 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 wi= der, needs a linear TX to avoid being too wide and seems less user fri= endly. 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 per= suaded not to abandon that mode, and in fact he modified the code to= enhance the decoder routine so the wide spaced version would be deco= ded with the same S/N as JT4A. We discovered just how good the mode= was, even under severe rainscatter conditions where each tone was spr= ead out to 200Hz bandwidth (tone spacing in JT4G is 315Hz for 1kH zwid= e overall, so this rain scattered signal still had discrete tone energ= y). There are now two microwave beacons that transmit JT4G wavefor= ms, the 10 and 2.3GHz ones in Dorset GB3SCX and GB3SCS www.scrbg.or= g and now GB3CSB on 1.3GHz from central Scotland http://www.rayjam= es.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 ti= ming information is available to keep it synched. =20 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 "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 haza= rdous 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?) ref= erence 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 --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088 --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088 --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088 ------=_NextPart_000_006F_01CA9C5D.35E2D470 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
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 QRS or CW QSO  if you= need an=20 immdediate report. These signals are audible with me.
 
 
 
g3kev
 
----- Original Message -----
Sent: Saturday, January 23,= 2010 4:52=20 PM
Subject: Re: LF: JT4A simple= guide?

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

Roger G3XBM

On 23 January 2010 16:38, Andy Talbot <an= dy.g4jnt@googlemail.com>=20 wrote:
After posting that, I realised the JT4 PIC/DDS beacon code is= designed=20 for 100% duty cycle operation, viz JT4, CW + carrier, which is a= bit=20 antisocial (certainly the wide bandwidth CW bit).  And more= =20 importantly, as my PA is a low efficiency clas AB linear one - eno= ugh=20 said...
 
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.   For= a beacon,=20 WSPR has more to offer anyway.
 
Incidently, WSPR and JT4 are the same mode anyway, albeit wit= h a=20 bandwidth change from 1.46 to 4.375Hz  with a resulting 4.75d= B=20 reduction in S/N.  The coding and demodulation are all the sa= me, so=20 this bandwidth difference should be directly detectable = between=20 the two modes.  The differing message contents wont affect th= e=20 efficiency, its the added error correction , sync and modulation&n= bsp;that=20 matters - and they use the same algorithm.
On 23 January 2010 14:43, Roger Lapthorn= <rogerlapthorn@gmail.com> wrote:
T= hanks=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-= arranged=20 times or days perhaps? If JT4A looks like offering the possibili= ty of=20 really weak signal QSOs to people like me running flea-power the= n I'd like=20 to explore the mode some more and having a reliable signal to te= st with=20 initially would be useful. I am sure there will be others who wo= uld 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'   JT4x was never= =20 originally going to be one of Joe's supported modes, although= after our=20 extensive use on uWaves it certainly is now. &n= bsp; JT65x=20 was the more popular and documented code, being heavily used= for EME on=20 144 / 432 / 1296MHz,   with JT4x just one= of those=20 included in the WSJT suite to 'try out'   If you dow= nload and=20 read the WSJT users guide and other supporting files,=20 there's all you need to know to get it going is in there.=
 
 
Its still debatable as to whether JT4 is better or worse= than=20 JT65x, but at least it does have the options of being availabl= e in a=20 range of bandwidths / tone spacings making it usable from DC= to red=20 light.   (Although I think I've only ever come acros= s A, D and=20 G being used respectively on LF, HF and uWaves)  &nb= sp;=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.&n= bsp;=20 [Which knocks spots off CW or any fuzzy mode, as well as strai= ght=20 PSKnn without error correction].   Wolf has a= similar=20 signalling efficiency, but unfortunately is wider, needs a lin= ear TX to=20 avoid being too wide and seems less user friendly.
 
A year or so ago we (the microwave community) wanted some= thing for=20 use on 1.3GHz and up to 10GHz or beyond.  JT4G,= the=20 widest spaced varient of them looked suitable.  = ; =20 After some prompting, Joe was persuaded not to abandon that mo= de, =20 and in fact he modified the code to  enhance th= e decoder=20 routine so the wide spaced version would be decoded with the= same S/N as=20 JT4A.    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= overall, so=20 this rain scattered signal still had discrete tone energy).
 
There are now two microwave beacons that transmit JT4G=20 waveforms,   the 10 and 2.3GHz ones in Dorset = GB3SCX and=20 GB3SCS www.scrbg.org    and  now GB3CSB on=20 1.3GHz from central Scotland http://www.ray= james.biz/gm4cxm/id14.html  Other=20 will follow before long as it is quite an easy mode to generat= e from a=20 simple PIC keyer provided accurate timing information is avail= able to=20 keep it synched.  
 
My beacon engine - the one that currently drives the 503.= 7/503.85=20 signals - can give JT4A immediately just by reprogramming= the=20 PIC.   Would there be any interest, bearing in mind&= nbsp;both=20 the WSPR and "5MHz type" waveforms will be lost for the= =20 duration?

Andy
www.g4jnt.com

This email has bee= n scanned for=20 damaging side-effects by the health and safety police, is guar= anteed 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 Lapth= orn <rogerlapthorn@gmail.com> wrote:
Having=20 looked on the WSJT website there is little (no?)  refer= ence to=20 JT4A in the help files. I assume it is similar to modes like= JT6M=20 which I have managed to receive in the past on 50MHz but nev= er tried=20 TXing.

Can someone point me in the direction of a "JT4A for=20 Dummies" guide, or something similar that I might unders= tand,=20 please?

73s
Roger G3XBM

--

http://g3xbm-qrp.blogspot.com= /
http://www.g3xbm.co.uk
http://= www.youtube.com/user/G3XBM
G3XBM  =20  GQRP 1678      ISWL=20 G11088




--

http://g3xbm-qrp.blog= spot.com/
http://www.g3xbm.co.uk
http://www.yout= ube.com/user/G3XBM
G3XBM  =20  GQRP 1678      ISWL=20 G11088




--

http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/= user/G3XBM
G3XBM=20    GQRP 1678      ISWL=20 G11088
------=_NextPart_000_006F_01CA9C5D.35E2D470--