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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 13:26:19 -0400
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, this 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 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
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
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
-- 73, Joe, K1JT
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