Hi Mal, LF,
That sounds good! So, you can be sure that you have some dB more RX level or
better said SNR than others. That's why you can do it in CW/QRSS and others
not. But if the others do it e.g. in QRSS10 instead of QRSS3 and have the same
fun and are satisfied and happy, what do we want more?
I am impressed by the happyness of Roger/G3XBM with his 1mW ERP success. That's
what is important. Regardless if we have 1mW or 25W...
Mal, what about your earth losses? If you are in the near of the sea, your
ground conductivity seems to be excellent? Less than 20 Ohm? And if it is a
full size L Ant for 137, you do not have a loading coil? Or is it 1/4 wave for
600m?
Probably i get a temporarily special licence by the german air traffic control
(1 month) for a maximal kite braid length of 150m! Normally, the braid length
is limited to 100m (in most countries even to 60m) So i could build a full size
1/4 wave vertical for 600m. But since i am not qrv there i use it for 137 kHz,
just 27% of 1/4 wave ;-) That will give >3dB more signal but the main interest
is bringing to resonance, watching the change of the overall loss resistance
and so on.
Yes, you heard me (569), and my neighbour (599, if you mean DK7SU and/or
DF6NM). But also OE5ODL (589 with 20W TX power) and Andrey/RN3AGC (559 in
>2000km (without sea water between), with a little more pwr ;-) ) and OH5UFO,
M0BMU......
73s
Stefan/DK7FC
________________________________
Von: [email protected] im Auftrag von mal hamilton
Gesendet: So 24.01.2010 02:38
An: [email protected]
Betreff: Re: LF: JT4A simple guide?
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 are
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 Schäfer" <[email protected]>
To: <[email protected]>
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? What
about your local noise level? Would be interesting for me, since you gave me
569 in our QSO...
Stefan/DK7FC
________________________________
Von: [email protected] im Auftrag von mal hamilton
Gesendet: Sa 23.01.2010 22:07
An: [email protected]
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 always
VISIBLE and therefore if KEYED would convey the transmitted message.
G3KEV
----- Original Message -----
From: Roger Lapthorn <mailto:[email protected]>
To: [email protected]
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 <[email protected]> wrote:
Obviously not reading recent postings about no decodes from others although
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. Dummies
alias Appliance operators
The word is ill-informedtry
g3kev
----- Original Message -----
From: Roger Lapthorn <mailto:[email protected]>
To: [email protected]
Sent: Saturday, January 23, 2010 7:17 PM
Subject: Re: LF: JT4A simple guide?
Mal informed.
On 23 January 2010 18:52, mal hamilton <[email protected]> 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 <mailto:[email protected]>
To: [email protected]
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 <[email protected]> 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 <http://www.g4jnt.com/>
On 23 January 2010 14:43, Roger Lapthorn <[email protected]> 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 <[email protected]> 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
<http://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 <http://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 <[email protected]> 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
--
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http://www.youtube.com/user/G3XBM
G3XBM GQRP 1678 ISWL G11088
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G3XBM GQRP 1678 ISWL G11088
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http://www.youtube.com/user/G3XBM
G3XBM GQRP 1678 ISWL G11088
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G3XBM GQRP 1678 ISWL G11088
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http://www.youtube.com/user/G3XBM
G3XBM GQRP 1678 ISWL G11088
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