Return-Path: Received: from mtain-ma05.r1000.mx.aol.com (mtain-ma05.r1000.mx.aol.com [172.29.96.13]) by air-df05.mail.aol.com (v126.13) with ESMTP id MAILINDF053-5ef44b5ba4de2a2; Sat, 23 Jan 2010 20:39:42 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-ma05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 19ECC380000B3; Sat, 23 Jan 2010 20:39:41 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NYrQe-0001UP-TY for rs_out_1@blacksheep.org; Sun, 24 Jan 2010 01:38:16 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NYrQe-0001UG-9o for rsgb_lf_group@blacksheep.org; Sun, 24 Jan 2010 01:38:16 +0000 Received: from out1.ip08ir2.opaltelecom.net ([62.24.128.244]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NYrQb-000788-FI for rsgb_lf_group@blacksheep.org; Sun, 24 Jan 2010 01:38:16 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AjkHAL8zW0tZ8cDw/2dsb2JhbAAth3zMXYQ7BA X-IronPort-AV: E=Sophos;i="4.49,332,1262563200"; d="scan'208";a="437559374" Received: from unknown (HELO your91hoehfy9g) ([89.241.192.240]) by out1.ip08ir2.opaltelecom.net with SMTP; 24 Jan 2010 01:38:06 +0000 Message-ID: <002701ca9c95$e209e580$0301a8c0@your91hoehfy9g> From: "mal hamilton" To: References: <9afca2641001230548m3538db64y92b335aa75c1dc00@mail.gmail.com> <9afca2641001230643s4cf01377h70165d22d325dbe1@mail.gmail.com> <9afca2641001230852x7c870d8r3837c9b6eb60c67b@mail.gmail.com> <007201ca9c5d$3614e0f0$0401a8c0@xphd97xgq27nyf> <9afca2641001231117y223fea2cgb37f658c04708e2c@mail.gmail.com> <008e01ca9c62$d9c0a6d0$0401a8c0@xphd97xgq27nyf> <9afca2641001231215hf5edc24ve8f75cf4968600d6@mail.gmail.com> <00c501ca9c70$0d6dcb90$0401a8c0@xphd97xgq27nyf> <38A51B74B884D74083D7950AD0DD85E82A1AA5@File-Server-HST.hst.e-technik.tu-darmstadt.de> Date: Sun, 24 Jan 2010 01:38:08 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: JT4A simple guide? Content-Type: text/plain; charset="iso-8859-1" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=BIZ_TLD 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: 3039ac1d600d4b5ba4dd1997 X-AOL-IP: 193.82.116.20 Content-Transfer-Encoding: quoted-printable Stefan I have a selection of antennas here. In use at present for TX 1/4wave= inv L up over 100 feet high and the rest horizontal, can also be used for RX= . RX antenna is a 40metre vertical loop resonated for 500 or 137 kcs E/W= . QTH is vy quiet out in the countryside. All utility supplies to QTH ar= e underground ie electric, telephones cables etc. I often hear the USA stations peaking S7 at times, also VE stns. On 160m antenna is 3/8 wave inv L 100 ft high. Receivers various and designed for LF/MF. I gave you 569 and no one else heard you except your neighbour. de mal/g3kev ----- Original Message ----- From: "Stefan Sch=E4fer" To: Sent: Saturday, January 23, 2010 9:29 PM Subject: AW: LF: JT4A simple guide? Mal, Can you explain your RX equipment, pse. Perhaps you can even see/hear= what others just can decode? Is your TX antenna your RX antenna as well? Wh= at about your local noise level? Would be interesting for me, since you= gave me 569 in our QSO... Stefan/DK7FC ________________________________ Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von mal hamilton Gesendet: Sa 23.01.2010 22:07 An: rsgb_lf_group@blacksheep.org Betreff: Re: LF: JT4A simple guide? There cannot be a time when JT4 or WSPR will be received and not QRS= because the trace is always visible long before a data decode. There has never= been a case of an INVISIBLE trace and a data decode. The signal trace is al= ways VISIBLE and therefore if KEYED would convey the transmitted message. G3KEV ----- Original Message ----- From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org Sent: Saturday, January 23, 2010 8:15 PM Subject: Re: LF: JT4A simple guide? Mal, There will be times when this may be true, but modes like WSPR and, I expect, JT4A will get through when signals are extremely weak when CW= simply would not. Here's an idea: why not turning your ERP down to 1mW for a few weeks= and see how you get on? 73s Roger G3XBM On 23 January 2010 19:32, mal hamilton wrote: Obviously not reading recent postings about no decodes from others alt= hough the signals are visible, like I said these signals are not onljy visib= le 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-informedtry g3kev ----- Original Message ----- From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org 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 carrie= r 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 gett= ing any decodes yet. Roger G3XBM On 23 January 2010 16:38, Andy Talbot wrot= e: 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 antis= ocial (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 ha= s more to offer anyway. Incidently, WSPR and JT4 are the same mode anyway, albeit with a bandw= idth 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 me= ssage 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 wro= te: 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 peop= le 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 wrot= e: 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, be= ing 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 bandwi= dths / tone spacings making it usable from DC to red light. (Although I thi= nk 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 PSKn= n 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 aba= ndon 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 spa= cing 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, th= e 10 and 2.3GHz ones in Dorset GB3SCX and GB3SCS www.scrbg.org and now GB3CSB on 1.3GHz from central Sco= tland http://www.rayjames.biz/gm4cxm/id14.html Other will follow before lon= g 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 sign= als - 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 an= d safety police, is guaranteed to contain no substances hazardous to hea= lth, but may contribute to dissolving the nether and polar regions On 23 January 2010 13:48, Roger Lapthorn wro= te: 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 -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088