New SSTV modes added in MMSSTV

Written by JE3HHT Makoto Mori
Translated into English by JA7UDE Nob Oba


1. VIS code

  All the even-parity codes in the VIS have already been used now.  If I use the remaining odd-parity codes for defining new modes, it is a matter of time to run out of them.  For this reason, I have extended the VIS code to 16 bits as follows: 


	1900	300ms
	1200	10ms
	1900	300ms
	1200	30ms
	d0	30ms
	d1	30ms
	:	:
	d15	30ms
	1200	30ms

	(d0-d15 : 1-1100Hz, 0-1300Hz)

When you assign a code to your new mode, it is a good idea to use an odd parity code, which is not in use now, in the least 8 bits (d0-d7), so as not to get the conventional 8-bit VIS decoder confused.  For this reason, MMSSTV uses VIS code 23H in d0-d7.  If you add a code for your new mode, I would recommend you to assign some code other than 23H in d0-d7, so that you can make full use of upper 8 bits to represent up to 256 modes.


2. MP mode

MP mode is based on the color difference scheme used in PD mode.  I have added this mode for alleviating multi-path/jitter effects on the 20-meter band.  To increase the scan time for each pixel, the color information is compressed along the vertical axis.


Mode	Size	VIS	TW [ms]
MP73	320x256	2523h	140.000
MP115	320x256	2923h	223.000
MP140	320x256	2a23h	270.000
MP175	320x256	2c23h	340.000


	1200Hz	9.000ms
	1500Hz	1.000ms
	Y(odd)	TW
	R-Y	TW
	B-Y	TW
	Y(even)	TW
	(Repeat 128 scans)


3. MR/ML mode

MR/ML mode is based on the color difference scheme used in Robot 24/72 mode.  It is aimed to provide good resolution under good condx.  The color information is compressed along the horizontal axis.

Mode	Size	VIS	TW [ms]
MR73	320x256	4523h	138.000
MR90	320x256	4623h	171.000
MR115	320x256	4923h	220.000
MR140	320x256	4a23h	269.000
MR175	320x256	4c23h	337.000
ML180	640x496	8523h	176.500
ML240	640x496	8623h	236.500
ML280	640x496	8923h	277.500
ML320	640x496	8a23h	317.500

	1200Hz	9.000ms
	1500Hz	1.000ms
	Y	TW
	LP	0.100ms
	R-Y	TW/2
	LP	0.100ms
	B-Y	TW/2
	LP	0.100ms
	(Repeat 256 or 496 scans)

	LP = output the last pixel signal


It is free to use these modes in any kind of software or equipment.  You do not have to inform me.  Feel free to do it.

73 Mako