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[Linrad] Re: [Moon-net] Parameter description MAP65(iQ) needed
- Subject: [Linrad] Re: [Moon-net] Parameter description MAP65(iQ) needed
- From: Joe Taylor <Princeton.EDU; joe@xxxxxxxxxxxxxxxx>
- Date: Mon, 20 Apr 2009 16:21:16 -0400
I apologize for several typos in the original version of
this message. Here is another try, with several corrections.
Hi Michael and all,
> i am looking for a description of parameter settings in
MAP IQ which can
> be found in
> SETUP-> OPTIONS-> MISCELLANEUS ->
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.
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
-- 73, Joe, K1JT
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