General Information
CIS 405-3915 is a synchronous teleprinter system in a CIS-8181 variant, but uses the half baud rate. This system is used by the Soviet military and railways authorities for point to point connections. Despite its simplicity this modem is still in operation today. Traffic is always encrypted. Sometimes operator chat or station id in Morse telegraphy can be copied.
Usage:
§ Transfer of textual information over HF.
§ Point-to-point communication between stations in CIS (Commonwealth of Independent States)-region.
Mode Details
|
|
Item |
Value |
|
Standard |
Modulation |
FSK |
|
|
Number of tones |
2 |
|
|
Shift (Hz) |
500 |
|
|
Symbol rate (Baud) |
40.5 |
|
|
Encryption |
|
|
Demodulator Settings |
Demodulator |
FSK 2 matched |
|
|
Symbol rate (Bd) |
40.5 |
|
|
SR tolerance (Bd) |
5 |
|
|
Shift (Hz) |
500 |
|
|
Shift tolerance (Hz) |
10 |
|
|
Modem type |
Synchronous |
|
Features |
Demodulation |
yes |
|
|
Recognition |
yes |
|
|
Decoding |
yes |
|
|
Automatic Polarity Adjustment |
no |
|
|
Combination with other modems (modem list) |
yes |
|
Tuning |
The tuning frequency is the center of the signal | |
Table 73: CIS 405-3915
Figure 26: CIS 405-3915 Spectrogram