LF: WOLF QSO / data modes

To:	[email protected]
Subject:	LF: WOLF QSO / data modes
From:	[email protected]
Date:	Tue, 13 Jan 2004 05:20:41 EST
Reply-to:	[email protected]
Sender:	<[email protected]>

In a message dated 1/12/04 2:11:38 PM GMT Standard Time, [email protected] writes:

I think a lot of us were waiting and maybe
hoping for a "instant", real-time version. Then Alberto came along with
Jason as a keyboard decoded mode, and WOLF did not seem to progress.
(Stewart provided some adaptive code to improve the decoder in Alberto's
system) I also believe that WOLF is transmit as BPSK which generally
requires a linear PA. (Jason is an FSK mode so can use non-linear PAs)

On the subject of data modes. I notice there is a new version of the digital (multi tone) mode JT65. This is a weak signal coherent mode in which each station transmits for alternating 30 second periods under computer control. It's mainly used for EME communication and the signals are 'summed' with each successive TX period. After several 30 second periods a signal many dB into the noise slowly appears on the screen.
Although a tone based system, only one tone is transmitted at a time. This sugests that a class C D or E based amplifier could be used. Because the system is coherent both computers must run within 1 second of UTC. ( Use the free 'dimension 4' software to dialup and set your PC time to WWV etc) Frequency for the 'A' version must be set to better than 4Hz.
There are 3 versions of JT65 each with a different overall tone spacing hence different bandwidth. One version is 177Hz wide.

JT65 is part of a suite of programmes called WSJT. (Weak Signals by W1JT)

The download site at Princeton is given in the mail from Joe Taylor W1JT that I've copied below.

73

David G0MRF

=========             =============           =============

To: Users of WSJT
Subject: Beta Release 4.3.3
Date: December 31, 2003
From: Joe Taylor, K1JT

Dear Friends,

Beta Release 4.3.3 of WSJT is now available for free download at
the WSJT home page, http://pulsar.princeton.edu/~joe/K1JT. The
principal change from version 4.2.1 is to offer three JT65
submodes. The submodes differ in tone spacing and total
bandwidth as follows:

Mode   Spacing Total BW
   -------------------------
   JT65A 2.7 Hz 177.6 Hz
   JT65B 5.4    355.3
   JT65C   10.8    710.6

Note that JT65A is identical to the original JT65. If you want
to work people who have not yet upgraded to v4.3.3, be sure to
select mode JT65A. Otherwise, be sure to use the same mode that
your QSO partner is using. Cross-mode contacts will not work.

JT65B should be nearly as sensitive as JT65A, and it will be
twice as forgiving of frequency instabilities. On balance, with
existing "stock" radios, JT65B will probably be better than
JT65A. JT65C is less sensitive by a small amount, perhaps 1 dB,
but will be even more lenient on stability issues. By all means
experiment with the different submodes, and be sure to let me
know your conclusions about them!

I am presently inclined to recommend that JT65B should become the
"standard" JT65 mode. If this tentative conclusion holds up,
future versions of the program may no longer support the A and C
modes.

Other changes from version 4.2.1 include the following:

1. Further improvements have been made to the JT65 decoding
algorithm. These improvements apply to all three submodes. Some
wave files that would not decode with v4.2.1 now decode properly,
especially in averages over several minutes.

2. The frequency width W of the sync tone (the "red spike") is
now measured and displayed in Hz after DF in the main text box.
In any of the three JT65 modes, W should be no more than 2-4 Hz
under good conditions. Uncorrected frequency drifts, excessive
oscillator phase noise, and certain propagation effects can make
the width larger. Anything over about about 4 Hz will impair copy
in JT65A. Similarly, widths greater than about 7 and 15 Hz will
begin to impair copy in JT65B and C, respectively.

3. The utility program CWID.EXE now accepts lower case letters on
the command line. It also permits you to specify the audio
frequency of the tone in the wave file. You may wish to place
the tone at 600 Hz or lower so that it lies well below the tones
generated by any of the WSJT operating modes.

4. The "Clip" function has been improved in several ways. The
yellow and magenta curves in the Big Spectrum display no longer
disappear when Clip > 0. Setting Clip = 3 does hard clipping, as
before, but it also blanks out any data regions with average
power well above the "baseline" of the green curve.
Experimenting with different values of Clip may help you to
recover good copy from noisy data.

5. I believe that the text window displays in Monitor mode, and
when you are using the Include/Exclude buttons, nor function
correctly.

6. Minor bug fixes: the program no longer crashes in EME Echo
mode if you select "EME Calc | Load | Cancel". The correct "S"
value is listed on the status bar in JT6M mode.

7. The program's "Fit and finish" is improved in several not very
important ways.

As usual, I will appreciate receiving email with comments,
suggestions, etc., about this new release of WSJT.

-- 73, Joe, K1JT

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