[Linrad] Re: [Moon-net] Parameter description MAP65(iQ) needed

[Joe Taylor <Princeton.EDU; joe@xxxxxxxxxxxxxxxx>]

Hi Michael and all,

dg0opk wrote:
> i am looking for a description of parameter settings in MAP IQ which can
> be found in 
> 
> SETUP-> OPTIONS-> MISCELLANEUS ->
>  
> Dphi(deg)
> Fcal(Hz)
> Fadd(MHz)
> Csmin
> Rxt1

Your questions are very reasonable.  This information should 
of course be covered in the "MAP65 User's Guide and 
Reference Manual" ... but unfortunately, this document has 
not yet been written.

Very briefly:

1. Dphi (deg) is relevant only for a dual-polarization 
(MAP65) system.  It is the phase shift required to match the 
Rx systems (H/V, or 45/135 deg) and thus prevent "leakage" 
of linear polarization components into circular.  Dphi is 
not used by MAP65-IQ.

2. Fcal (Hz) is a frequency correction to correct MAP65's 
frequency readouts.  My WSE converters lead produce a 630 Hz 
frequency error at center frequency 144.125 MHz, so I enter 
630 here.  You can experiment with a known signal in order 
to get the right magnitude and sign.

3. Fadd (MHz) is the number to be added to your SDR-IQ 
frequency setting in order to get your on-the-air received 
frequency.  For example, if you use a 144 to 28 MHz 
down-converter, enter 166.0 here.

4. CSmin is the minimum length of a "word" considered to be 
a callsign for entry in the Band Map.  The second "word" in 
a decoded message is normally taken to be the transmitting 
station's callsign.  With CSmin=4 (the default value), the 
message "TNX JOE 73 GL" will not put "JOE" in your Band Map, 
because JOE has only 3 characters.  (Obviously a better 
algorithm could be implemented here; this was a 
quick-and-dirty solution.)

5. Rxt1 is the time (in seconds, since the start of an Rx 
minute) at which the decoder will start to compute FFTs as 
part of the JT65 synchronizing procedure.  Full decoding 
begins at about t=52 or t=53 s.  Decoding speed is improved 
somewhat if Rxt1 is set somewhat earlier, say t=48 s (the 
default value).  The optimum value depends somewhat on the 
details of individual computers (CPU speed, cache size, 
etc.), but you will probably not notice much difference.

Items 4 and 5 were put there mainly for my own use during 
program development.  There is probably no need for you to 
change them.


Let me take this opportunity to call attention to the new 
WSJT Home Page, http://physics.princeton.edu/pulsar/K1JT/ . 
  I have tried to simplify it and make things easier to 
find, while at the same time bringing a number of links up 
to date.  This has also been an excuse for me to spend some 
time learning HTML and a little bit about web design, of 
which previously knew only the barest essentials.

I will appreciate any feedback on the new layout -- of 
course, including suggestions for how it could be further 
improved!

	-- 73, Joe, K1JT

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