Return-Path: Received: from rly-da01.mx.aol.com (rly-da01.mail.aol.com [172.19.129.75]) by air-da10.mail.aol.com (v126.13) with ESMTP id MAILINDA101-a494b5b4f4224d; Sat, 23 Jan 2010 14:34:53 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-da01.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDA011-a494b5b4f4224d; Sat, 23 Jan 2010 14:34:28 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NYljH-0007QZ-Au for rs_out_1@blacksheep.org; Sat, 23 Jan 2010 19:33:07 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NYljG-0007QP-Ct for rsgb_lf_group@blacksheep.org; Sat, 23 Jan 2010 19:33:06 +0000 Received: from out1.ip06ir2.opaltelecom.net ([62.24.128.242]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NYljD-0005GQ-QI for rsgb_lf_group@blacksheep.org; Sat, 23 Jan 2010 19:33:06 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AosFAADeWktOlvwl/2dsb2JhbAAtjUcFyBKEOwQ X-IronPort-AV: E=Sophos;i="4.49,330,1262563200"; d="scan'208,217";a="448233020" Received: from unknown (HELO xphd97xgq27nyf) ([78.150.252.37]) by out1.ip06ir2.opaltelecom.net with SMTP; 23 Jan 2010 19:32:54 +0000 Message-ID: <008e01ca9c62$d9c0a6d0$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: <9afca2641001230548m3538db64y92b335aa75c1dc00@mail.gmail.com> <9afca2641001230643s4cf01377h70165d22d325dbe1@mail.gmail.com> <9afca2641001230852x7c870d8r3837c9b6eb60c67b@mail.gmail.com> <007201ca9c5d$3614e0f0$0401a8c0@xphd97xgq27nyf> <9afca2641001231117y223fea2cgb37f658c04708e2c@mail.gmail.com> Date: Sat, 23 Jan 2010 19:32:50 -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_008B_01CA9C62.D95C8DD0" 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_008B_01CA9C62.D95C8DD0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Obviously not reading recent postings about no decodes from others alt= hough the signals are visible, like I said these signals are not onljy= visible with me but audible so why complicate matters, just send qrs= or cw in the first place. Some one even mentioned DUMMIES, there are a lot of these about. Dummi= es alias Appliance operators The word is ill-informed g3kev ----- Original Message -----=20 From: Roger Lapthorn=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Saturday, January 23, 2010 7:17 PM Subject: Re: LF: JT4A simple guide? 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 ca= rrier 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 -----=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 no= t 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 be= acon, 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 redu= ction in S/N. The coding and demodulation are all the same, so this= bandwidth difference should be directly detectable between the two mo= des. 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= 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 wi= th initially 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= going to be one of Joe's supported modes, although after our extensiv= e 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 =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= being used respectively on LF, HF and uWaves) There's probably onl= y a fraction of a dB in it and both are, as far as I can ascertain, on= ly 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 correct= ion]. 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 somet= hing for use on 1.3GHz and up to 10GHz or beyond. JT4G, the widest sp= aced 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 wa= s 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 wav= eforms, the 10 and 2.3GHz ones in Dorset GB3SCX and GB3SCS www.scrb= g.org and now GB3CSB on 1.3GHz from central Scotland http://www.ra= yjames.biz/gm4cxm/id14.html Other will follow before long as it is qu= ite an easy mode to generate from a simple PIC keyer provided accurate= timing 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= "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 ne= ver tried TXing. Can someone point me in the direction of a "JT4A for Dum= mies" 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 --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088 ------=_NextPart_000_008B_01CA9C62.D95C8DD0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Obviously not reading recent postings= about no=20 decodes from others although the signals are visible, like= I said=20 these signals are not onljy visible with me but audible so why complic= ate=20 matters, just send qrs or cw in the first place.
Some one even mentioned DUMMIES, ther= e are a lot of=20 these about. Dummies alias Appliance operators
The word is ill-informed
g3kev
 
----- Original Message -----
Sent: Saturday, January 23,= 2010 7:17=20 PM
Subject: Re: LF: JT4A simple= guide?

Mal informed.

On 23 January 2010 18:52, mal hamilton <g3kev= mal@talktalk.net>=20 wrote:
I still see these data signals as= a waste of=20 time since had the carrier been keyed I could read them 100% witho= ut having=20 to wait for the right circumstance to get a decode, no need for le= vel 2=20 demodulation.
There are several traces now visi= ble but only=20 an odd decode!!!!!!!!!!!!!!! Try a QRS or CW QSO  i= f you need=20 an immdediate report. These signals are audible with me.
 
 
 
g3kev
 
-----=20 Original Message -----
From:=20 Roger Lapthorn
Sent:=20 Saturday, January 23, 2010 4:52 PM
Subject:=20 Re: LF: JT4A simple guide?

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

Roger G3XBM

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

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

73sRoger=20 G3XBM=20



On 23 January 2010 14:26, Andy Talb= ot <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, altho= ugh after=20 our extensive use on uWaves it certainly is=20 now.   JT65x was the more popular and documented= code,=20 being heavily used for EME on 144 / 432 / 1296MH= z, =20  with JT4x just one of those included in the WSJT sui= te to 'try=20 out'   If you download and read the WSJT us= ers guide=20 and other supporting files, there's all you need to= know to get=20 it going is in there.
 
 
Its still debatable as to whether JT4 is better or wo= rse than=20 JT65x, but at least it does have the options of being avai= lable 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= across A, D=20 and G being used respectively on LF, HF and=20 uWaves)    There's probably only a fraction= of a dB=20 in it and both are, as far as I can ascertain, only a dB= or two away=20 from the Shannon limit.  [Which knocks spots off CW= or any=20 fuzzy mode, as well as straight PSKnn without error= =20 correction].   Wolf has a similar signalling eff= iciency,=20 but unfortunately is wider, needs a linear TX to avoid bei= ng too=20 wide and seems less user friendly.
 
A year or so ago we (the microwave community) wanted= something=20 for use on 1.3GHz and up to 10GHz or beyond. &nb= sp;JT4G,=20 the widest spaced varient of them looked=20 suitable.    After some prompting, Joe was= persuaded=20 not to abandon that mode,  and in fact he m= odified=20 the code to  enhance the decoder routine so the wide= spaced=20 version would be decoded with the same S/N as=20 JT4A.    We discovered just how good the mo= de was,=20 even under severe rainscatter conditions where each tone= was spread=20 out to 200Hz bandwidth (tone spacing in JT4G is 315Hz for= 1kH zwide=20 overall, so this rain scattered signal still had discrete= tone=20 energy).
 
There are now two microwave beacons that transmit JT4= G=20 waveforms,   the 10 and 2.3GHz ones in Dorset&nb= sp; GB3SCX=20 and GB3SCS www.scrbg.org    and  now GB3CSB= on=20 1.3GHz from central Scotland ht= tp://www.rayjames.biz/gm4cxm/id14.html =20 Other will follow before long as it is quite an easy mode= to=20 generate from a simple PIC keyer provided accurate timing= =20 information is available to keep it synched.  =
 
My beacon engine - the one that currently drives the= =20 503.7/503.85 signals - can give JT4A immediately just= by=20 reprogramming the PIC.   Would there be any inte= rest,=20 bearing in mind both the WSPR and "5MHz type" wa= veforms=20 will be lost for the duration?

Andy
www.g4jnt.com

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


On 23 January 2010 13:48, Roger= Lapthorn=20 <rogerlapthorn@gmail.com> wrote:
Having=20 looked on the WSJT website there is little (no?) = reference=20 to JT4A in the help files. I assume it is similar to mod= es like=20 JT6M which I have managed to receive in the past on 50MH= z but=20 never tried TXing.

Can someone point me in the di= rection of=20 a "JT4A for Dummies" guide, or something similar= that I=20 might understand, 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://g3= xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.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


--

http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/G3XBM
G3= XBM=20    GQRP 1678      ISWL=20 G11088
------=_NextPart_000_008B_01CA9C62.D95C8DD0--