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Ham Radio 2000
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Ham Radio 2000.iso
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fax_sstv
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setup.txt
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1996-07-19
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4KB
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144 lines
Setup Menu
----------
This menu is used to display and change various operating
parameters of the system.
VGA Display
-----------
This tells you the current video display mode, resolution, and
number of colors. To change this, you must exit the program,
edit the PKTV.CFG file, change the GMODE command, and restart
the program.
Virtual Memory
--------------
This tells you how much virtual memory is in use and still
available. Expect problems if less than 3 megabytes are
free. Read the file MEMORY.TXT for details.
Thumbnail Images
----------------
This controls the number of images kept in memory and the
number of thumbnail images along the bottom of the screen.
SSTV Mode
---------
Can't remember the duration of an S1 transmission? Want to
know how many scan lines are in an AVT 94 transmission?
This will give you some details of the current mode. Click
on the button marked "Default" to make the current mode the
default when the program starts up.
Interface
---------
This displays some information about the SSTV interface.
I/O Address (PKTV Classic only)
-----------
This allows you to specify a different I/O address for the
Pasokon TV Classic interface. The jumper on the board must
agree with the setting in the program.
Speaker Xmit Audio (EZ SSTV only)
------------------
A check mark next to this activates the internal speaker
during transmission. Transmit audio is available from the
serial port regardless of this setting.
Interrupt
---------
This allows you to specify a different Interrupt (IRQ) for the
SSTV interface.
Pasokon TV Classic:
The jumper on the board must agree with the setting in the
program.
EZ SSTV:
This is the interrupt used by the serial port.
Printer
-------
This displays the current settings for the printer. Additional
menu items are available for changing specifics:
LPT Port - Pick one of 1 parallel printer ports.
Gamma - Controls gray scale mapping.
Printer Types - Pick one closest to your printer type.
More details can be found in the file PRINTER.TXT.
Free Run
--------
All SSTV modes, other than AVT, have sync pulses separating
the scan lines. One reception software strategy is to sit
there in a loop of
* wait for sync pulse.
* gather and display a scan line.
This is OK in theory but results aren't so good in practice.
If a sync pulse is missing, a line won't be displayed at all.
Inconsistent detection of the sync edge results in lines not
being aligned properly. This is called jitter and straight
vertical features become jagged. When the Free Run option
is off, Pasokon TV follows the average sync locations to
minimize the image degradation from missing and corrupted
sync signals. However there is still some pixel jitter.
With the Free Run option on, a precise crystal oscillator
is used instead for timing and the exact sync position is
ignored once locked onto the signal. Pixel jitter is reduced
and image quality improved. There is one disadvantage. If
the transmitting station is not calibrated properly, the
image will be slanted. New users of the low-end systems often
transmit a few slanted images but other helpful hams get them
straightened out.
Unless you need to compensate for signals with improper timing,
leave the Free Run option on for best results.
Sync Squelch
------------
When this option is off, Pasokon TV will make an attempt to
display an image for even very poor signals. This is fine
when you're sitting there watching but not so good when you
turn on "auto save" and go away for a long time. Your disk
would soon be full of images of random noise.
The Sync Squelch option causes images to be displayed only
when there is a fairly high confidence level that a valid signal
is present. We're dealing with noisy HF SSB signals so it's
all based on statistics of the sync pulse spacing. The length
of the line on the left side of the tuning indicator shows the
confidence level that a valid signal is being received. When
the Sync Squelch option is turned on, an image is displayed
only when this line exceeds a certain length.