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MFJ-1278B MULTI-MODE BASIC OPERATION
Coding: If, prior to unbiasing, the value of the data byte is an ASCII p, q, or r, then the
received byte is a sync byte. Otherwise, the received byte contains actual display information
as described above. The color level of each pixel contain in the data byte is given below:
000 001 110 111
white lightest grey darkest grey black
NOTE: If the data byte is NOT a sync byte, you must remove the 30H bias BEFORE
extracting the pixel information.
For example, if an ASCII '9' is received, then the following steps should be taken:
1. Remove bias: 39H-30H = 9H
2. Extract pixel information: aaa = 001 bbb = 001
3. Display two pixels of lighest grey level.
If an ASCII 'p', 'q', or 'r' is received, then process the byte as a sync tone.
Saving SSTV Pictures to Disk
When the PRINTGRA command of the MFJ-1278B is ON, SSTV pictures received will be
sent to the graphics printer attached to the printer port. If PRINTGRA is OFF, the MFJ-
1278B will direct the picture graphics, in raw data format, to the user's terminal through the
RS-232C port of the MFJ-1278B. If your terminal program allows you to save a file to disk,
then you can save the picture on disk and re-transmit it later.
Terminating SSTV Printing
Printing of an SSTV picture can be terminated at any time during the printing. User will type
"ESC" then CTRL-C. Printing will stop and the MFJ-1278B will return to command mode.
Transmitting SSTV Pictures
The MFJ-1278B is capable of transmitting color and up to 16 gray level B&W SSTV. To
achieve this you must use a terminal program which support the multi-level SSTV data
format required by the MFJ-1278B.
Each level of gray is represented by a tone produced by the MFJ-1278B modem. The 19
tones which can be produced by the MFJ-1278B FAX/SSTV modem (in Hz) are:
1100, 1200, 1300, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, 2000,
2050, 2100, 2150, 2200, and 2250.
The tone being transmitted determines the shade of gray in the picture. The sync tone of
1500 Hz is automatically generated by the MFJ
-
1278B. The other tones between 1550 Hz