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

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

I apologize for several typos in the original version of 
this message.  Here is another try, with several corrections.

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, that 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 to prevent 
"leakage" of linear polarization into apparent elliptical or 
circular polarization.  Dphi is not used by MAP65-IQ.

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

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 116.0 here.

4. CSmin is the minimum length of a "word" that will be 
considered 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 programming 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 for Rxt1 depends somewhat 
on the details of individual computers (CPU speed, cache 
size, etc.).  The value is not critical.

Note: 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 web layout -- of 
course, including suggestions for how it could be further 
improved!

     -- 73, Joe, K1JT

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