RTTY
[Top] [All Lists]

[RTTY] MMTTY calibration with screenshots

To: <rtty@contesting.com>
Subject: [RTTY] MMTTY calibration with screenshots
From: wa9als@starband.net (WA9ALS - John)
Date: Sat, 16 Feb 2002 08:31:30 -0500
This didn't fix my problem, but it's interesting nevertheless.  These will
be posted sometime this weekend on the web for future reference.

First I calibrated my Soundblaster Live! Value card.  In MMTTY, click
Options|Setup MMTTY|MISC and then the clock ADJUST button.  Your default
should be 11025.  The instructions for calibration appear on the waterfall,
but eventually scroll off, so print them.  I found them confusing at first,
but eventually figured it out.  The radio is set to 10.00000 MHz in USB
mode.

http://wa9als.mystarband.net/cal1.gif - This shows the Sounblaster set at
11025.  You can tell from the "slant" that the clock speed is off a little.
The green line really serves no purpose other than to remind you what
vertical looks like!  First you click on a tick mark near the bottom of the
screen (and let go).  This will then produce a yellow line dragging from the
mouse pointer, which you can move around.  You should position it on one of
the tick marks near the top of the page and then left-click again.  This
will then enter the new clock speed - you will get a msg that you need to
restart MMTTY to be using the new clock speed.  It shouldn't matter whether
you use the middle, left, or right part of the ticks for the calibration -
it's the slope that's important.  (There's a reason this might remind you of
correcting the "slant" on SSTV!)  Although I always thought my MMTTY was
working great, it's obvious from this screenshot that the clock speed wasn't
calibrated as well as it could be!  *Also note that there are 2 columns of
tick marks, just as it should be as explained in the calibration
instructions.

http://wa9als.mystarband.net/cal3.gif - This shows the Sounddblaster
calibration window -after- I calibrated and restarted MMTTY.  The tick marks
are obviously much more vertical now!  Note that the clock speed is only 2
different - 11027 instead of 11025!

Now let's move on to calibrating the Integrated Sound on my Dell PW330:

http://wa9als.mystarband.net/cal10.gif - HOLY COW!  This is obviously "way
off", right?  Besides the obviously slanted lines, look at how many traces
there are!  Anyone know what that means?  Anyway, I went through the same
steps as above.  http://wa9als.mystarband.net/cal20.gif - This shows the
intermediate step of using the yellow line to line up the slanted tick
marks, and also shows that the new speed is going to be about 11010.9.
http://wa9als.mystarband.net/cal30.gif - This shows the new calibration
screen after MMTTY was restarted with the new clock speed of 11011.  The
tick marks are now vertical as they should be, but I still don't know why
there are so many columns represented when the instructions say there should
only be 2.

So, now we wonder if calibrating the Integrated Sound will bring my signal
into the desired MMTTY range.  Of course not!  I played with this yesterday
before actually doing the calibrations.  Using wildly different clock
speedds has no effect on where the signal appears in the MMTTY spectrum.
http://wa9als.mystarband.net/filt250.gif shows the signal with the filter at
250 Hz and http://wa9als.mystarband.net/filt1k.gif shows the filter at 1000
Hz.

Any elucidating comments and commiserations are welcome!  Before offering
suggestions though, please remember that this doesn't have anything to do
with how the radios are set.  Either of my radios, when played through the
Soundblaster, work fine with the signal in the passband where it should be.
However, EITHER of the radios, using any filter, have the signal outside the
MMTTY range when played through the Integrated sound.  73 - John (WA9ALS)



<Prev in Thread] Current Thread [Next in Thread>