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Simplify System Design with Automatic Message Delineation

TDMA systems are often used to send consistently timed, periodic data. In these situations, system designers face the challenge of adjusting the rate data is sent to the modem to match the TDMA parameters. With Automatic Message Delineation, this constraint is removed. Instead, the modem is allowed to detect message boundaries and send only the most recent data message when TDMA airtime is available.

Under standard operation, TDMA modems buffer all data received and transmit as much as possible when time slots are available. With Automatic Message Delineation, only a single message will be buffered at a time and the most recent message will be sent over-the-air when a time slot is available.

Messages are detected using inter-character timeout. Characters that are received in rapid succession are grouped into a single message, while longer spaces between characters create an automatic message boundary. Upon reception of a new message, previously received data is cleared and the new message is queued for transmission. Message data is also cleared upon transmission.

Automatic Message Delineation automatically creates new messages and only sends the most recent data.

Automatic Message Delineation automatically creates new messages and only sends the most recent data.

To enable Automatic Message Delineation, issue the command MSGDEL 1 to the modem. To control inter-character timing, the ATR3 setting may be used. The default inter-character timeout of 20 milliseconds is usually sufficient for most systems. Automatic Message Delineation is only in effect when TDMA is enabled.

For more advanced system designs, the WMX protocol should be considered.

Filed under: General, Hardware Information | Posted on July 8th, 2013 by Adam Hickerson

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