This page will serve as a gathering place for information relating to the MDC1200 Signalling Protocol.
General specifications of MDC1200 are as follows:
| Modulation | 1200 baud, 1200 and 1800 Hz carriers, MSK 1% MER on frequency, no fading; 12 dB SINAD |
| Noise Fading | less than one per ten years |
| Cross Code Falsing | one false in one million transmissions |
| Data Operated Squelch Falsing | one false per fifteen minutes of received audio |
AKA Stat-Alert, it is a 1200 bit per second digital signalling method which has been specifically designed for high reliability in the land-mobile radio environment.
A Stat-Alert message packet contains 32 information bits. Of these bits, 16 are addresses used to identify particular individuals. Current products support over 13,000 possible different addresses in a fleet. Of the 16 remaining bits, 8 are used to define the particular function of the packet, ie. PTT ID, CallAlert, etc. The remaining 8 bits are used to transfer optional information. To the basic 32 bit information message, additional bits are appended for error detection. These error detection bits are mathematically derived from the information bits, and if received incorrectly, will cause the entire message to be rejected. This provides a very high degree of message falsing protection. Further capability is added to provide burst error correction.
Several message packets may be combined to provide higher tier features. Simple PTT ID or Radio Check requires only one packet. Selective Calling requires two, since the ID of the destination as well as the source are both transferred over the air.
The entire amount of time required to transmit a PTT ID message is 173mS.
Signalling Features:
Message length:
Decode:
Encode: