User's Manual

Company Confidential 20 Raveon Technologies Corp.
7. Using the M8S – Packet Data Mode
This section describes the operation of the M8S when it is in the Packet Mode of
operation. It is the easiest and most reliable mode of operation for a data
modem.
In Packet Mode, all transmissions are sent in bursts or packets, and contain
address, error detection, and error correction information. Date enters the M8S
modem’s serial I/O port, and is stored in a buffer within the modem until it is
ready to be transmitted. Packetized operation has these advantages over non-
packet modems:
Packet Mode Advantages
1. Error Detection The modem uses a 16-bit CRC at the end of every packet
of data. The CRC is used to check the data for errors, and if there are any
errors, the data will not be passed onto the user.
2. Error Correction Automatic error correction may be used. M8S modems
incorporate an optional ARQ method to re-transmit packets with error, to
ensure the user’s data is delivered error-free.
3. Addressing Packetized operation allows for a more versatile network
architecture, with source, destination, and network addresses. M8S uses a
16-bit address to identify data packets.
4. No Dribble Data Even in the presence of noise, the M8S modem will not
output extra data or have random bit errors. Modems without packet
operation generally do not work well with weak noisy signals.
5. Transparent Operation Because of the high-reliability and error-free
operation the Packet Mode offers the user, most user applications will
seamlessly work using the M8S in its Packet Mode.
6. Repeatable and Routable. M8S packets are structured so that they may be
repeated using a store-and-forward repeater, and/or routed using specialized
hardware.