CIS-11 transmissions are mainly in the Russian M2 (3-SHIFT-CYR) adaptation of the ITA-2 alphabet. It is a full-duplex system with two transmission frequencies.
|
Parameter |
Value |
|
Frequency range |
HF |
|
Operation modes |
Full-duplex |
|
Modulation |
FSK |
|
Symbol rate |
100 Bd, variable 30-650 Baud |
|
Receiver settings |
DATA, CW, LSB or USB |
|
Input format(s) |
AF, IF |
|
Additional Info |
ITA-2 with 4-bit parity |
CIS-11 operates at a Symbol rate of 100 Bd on the radio link.
Synchronization for the CIS-11 mode is started with the selection of a baud rate. An AUTO start causes the automatic determination of the frequency shift and baud rate to be executed first. The signal polarity (USB or LSB sidebands) is automatically detected.
The CIS-11 data format is 11 bits wide. Data bits 1 - 5 contain the M2 character. The data bits are arranged in reverse order if compared to normal M2 systems. Bits 6 and 7 specify the system state as well as the alphabet.
Bits 8 - 11 handle error detection. The four test bits allow the position of a bit in error to be computed and then to be corrected. The value of the parity bits is obtained by calculating the modulo-2 sum of the binary weights of the respective information bits.
To maintain synchronization between the two duplex stations, both transmitters operate continuously and transmit idle characters if no traffic is transferred.