Sutron Satlink 3 - Pseudobinary over SMS; SHEF and SHEFFIX Data Format

Sutron Corporation Satlink Operations & Maintenance Manual, Rev 8.04.2 11/3/2016 pg. 144
15.4.3. Example 3. Encoding the Number -12345 in 3 Bytes
 First we have to convert -12345 into two's complement 18-bit binary: -12345 (base 10) =
111100 111111 000111 (base 2)
 Now we can convert each piece back to base 10: 111100 111111 000111 (base 2) = 60,
63, 7
 Finally, we add 64 to each piece and convert to ASCII (since the second piece is 63 we
leave it alone):
 124, 63, 71 = ASCII |?G
15.4.3.1. Example 4. Decoding the 3 byte string @SW:
This is just like encoding except we follow the steps backward.
 First we convert all the characters to ASCII decimal codes:
 ASCII @SW = 64, 83, 87
 Now we subtract 64 from each piece and convert to 6-bit binary:
 0, 19, 23 = 000000 010011 010111
 Finally, we combine all the bits to form one 18-bit two’s complement number and
convert to base 10:
 000000010011010111 = 1239
15.5. Pseudobinary over SMS
Some bytes that are normally used as a part of Pseudobinary transmissions are not allowed in
SMS. When Satlink sends Pseudobinary data over SMS, those bytes are replaced according to
the following table:
[
5B
1
\
5C
2
]
5D
3
^
5E
4
`
60
5
{
7B
6
|
7C
7
}
7D
8
~
7E
9
[
5B
1
15.6. SHEF and SHEFFIX Data Format
SHEF is a format that is commonly used by Sutron's Satlink satellite transmitter. It is an ASCII
format that is easy to read and contains some self-descriptive information.
The format of the transmission data is:
: <LABEL1> <OFFSET> #<INTERVAL> <DATA1> <DATA1> ... <DATA1)>
: <LABEL2> <OFFSET> #<INTERVAL> <DATA2> <DATA2> ... <DATA2> ...
: <LABEL(N)> <OFFSET> #<INTERVAL> <DATA(N)> <DATA(N)> ... <DATA(N)>