Hello Alberto,
I just read the Jason documentation. It looks most interesting and
promising, although there is some chance that some will call it 'pocks' ...
as 7FSK was called 'measles' ;-)
For transmitting Jason I was thinking of an alternative path, using a PLL
and let Jason control the divider (via LPT of COM port).
Least complex would be a 27.2xx MHz PLL in 50Hz steps that is divided by
200, what would give a 136kHz signal in 0.250Hz steps. Since Jason uses
0.252Hz steps the error over 32 steps would be 0.064Hz (or 76% of a bin).
As I read from the documentation Jason can handle errors of +/- 1 bin,
would the 0.064Hz error be acceptable ?
An alternative (and a bit more complex) would be to make a 26.9xxMHz PLL in
50Hz steps and divide it by 198, resulting in a 0.2525252Hz step and
reducing the overall error to 0.0168Hz (20% of a bin). Jason would surely
have no problem to handle this error, but it would be a bit more complex to
read out the exact frequency at 136kHz (due to the odd step).
A second alternative would be to use a HF tranceiver (with transverter
output) on 13.6MHz and divide the signal by 100. As most modern HF
tranceivers can be controlled via the serial port and can be tuned in 10Hz
steps (= 0.01Hz on 136kHz) this might be a easy and low cost alternative.
73, Rik ON7YD
At 17:05 14/01/02 +0100, you wrote:
Hello group,
I have devised a novel coding scheme, and have written a new
software to support it.
I have named it Jason, from the name of the coxswain of the mythological
ship Argo, which was headed to Colchis by the Greek hero Jason.
The coding scheme of Jason is based on the ideas about IFK that can be found
on the Web site of Steve Olney, VK2ZTO.
I need your cooperation to test it. I have done some preliminary tests, which
have given very good results, but a true test on the LF hasn't been performed
yet. Instead of cluttering this reflector with the gory technical details
of Jason,
I invite you to visit this page : http://www.weaksignals.com/jason
You can use Jason with a mosfet Class-D Tx, no need for a linear amp.
You can drive the Tx either using a DDS board connected via the parallel
port or
the serial port, or up converting an audio signal generated by Jason.
I tested only the audio interfacing. I need someone who volunteers for
testing
the interfacing via the DDS board (I haven't one), with true on-the-air
tests.
Thanks for any cooperation
73 Alberto I2PHD
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