Comtech EF Data MIDAS Version 4.X Basic Configuration - Manual (Page 62)

MIDAS 4.2 Basic Configuration, Rev. 1
2–28 Setup and Operation
The inbound control channel characteristics are summarized as follows:
• Pre-assigned digital SCPC channel using TDMA.
• Transmission is burst mode at 19.2 kbit/s, QPSK, FEC1/2.
• Only one inbound control channel is supported.
• Messages on the inbound control channel are contained in an HDLC
frame.
• The nodes trigger the transmit off the trailing edge of the controller server
outbound transmissions.
• As the inbound control channel operates in a contention mode, the node
waits for an HDLC level acknowledgment from the controller server on
the outbound control channel. A lack of acknowledgment leads to message
re-transmission after a random back-off..