SCS PTC-IIex, Manual

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6 Commands
6.57 MAXSum
Default setting: 30
Parameter: X 5... 60, maximum count for memory ARQ.
MAXSum
is the timeout value for the memory ARQ counter. It determines the maximum
number/sum of faulty packets that are summed up. If
MAXSum
is exceeded, the sums are
deleted, since it can be assumed that crude errors have entered the sum, and that further
summation of the packet will not restore it. The optimum value of
MAXSum
depends on
the condition on the HF channel. The worse the condition, the higher should MAXSum be
set in order to be able to pass any information at all.
6.58 MAXTry
Default setting: 2
Parameter: X 1... 9, maximum number of 'speed-up' attempts.
MAXTry
determines how often the PTC repeats a packet with the next speed level during
an attempt to 'speed-up' the transfer rate.
6.59 MAXUp
Default setting: 4
Parameter: X 2... 30, number of error free packets before up-speed.
Selection of up-speed parameter for automatic speed changing.
MAXUp
determines how
soon the system steps up under good channel conditions (2=fast / 30=slow).
Example:
MAXUp
3 i.e. the PTC switches to a higher speed after receiving 3 correct
packets in a row.
6.60 MOde
Default setting: 2
Parameter: 0 ASCII mode with no compression
1 Huffman mode & Auto-ASCII, if necessary (Level I compression).
2 Full Level II compression with Huffman, Pseudo-Markow and run
length coding and Auto ASCII if required.
The 8 bit ASCII mode allows to transmit all characters from 0 to 255 (8 bit), inclusive the
IBM special characters. Defined special characters (e.g. Idle, CANGEOVER characters,
etc.) can be transmitted using the Ctrl-character (refer to chapter
6.26 , page 48 ).
In the Huffman mode only the ASCII characters 0... 127 (7 bit) can be transmitted. To
transfer certain IBM special characters (umlauts), the PTC converts these characters
according to the following table:
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