The mode was developed by the Australian CODAN PTY. and is very similar to GMDSS/DSC.
|
Parameter |
Value |
|
Frequency range |
HF |
|
Operation modes |
Digital Selcal |
|
Modulation |
FSK |
|
Symbol rate |
100.0 Bd |
|
Receiver settings |
DATA, CW, LSB or USB |
|
Input format(s) |
AF, IF |
|
Additional Info |
ITU R M.493 alphabet |
CODAN SELCAL operates with 100.0 Bd and can be started by selecting the mode.
A preamble of at least 100 dot reversals, which are 50 changes between "0" and "1" (low and high bit), precedes the data block. This lead-in has duration of 2.0 seconds. Digital MARK "1" is represented by a frequency of 1870 Hz and SPACE by 1700 Hz.
The dot pattern is followed by a word synchronization sequence called the "phasing preamble". The characters no. 125 and no. 108 are alternately transmitted for 1.2 seconds.
This sequence is followed by the data block with different control characters and the message. Each data byte consists of 7 data bits and 3 parity bits. Thus the duration of each character is 100 ms.
Selecting Options | Display offers the option of an ASCII or RAW bits display.