Technical Manual

M7 GX Technical Manual 26 Raveon Technologies Corp.
7. Using the M6 – Packet Data Mode
This section describes the operation of the M6 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 M6
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. M6 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. M6 uses a 16-bit
address to identify data packets.
4. No Dribble Data Even in the presence of noise, the M6 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 M6 in its Packet Mode.
6. Repeatable and Routable. M6 packets are structured so that they may be
repeated using a store-and-forward repeater, and/or routed using specialized
hardware.