SATELLINE-2ASxE
User Guide, Version 2.0
22
5.6 A repeater chain using dual addressing
If the data terminal equipment is not able to generate a string of addresses to the beginning of the
data packet, dual addressing can still be used to connect two points using several repeaters.
In dual addressing every single link and direction is given a unique address, which prevents
duplicate and circulating messages. Data terminal equipment does not need to add anything to the
data.
The idea of dual addressing is that the primary transmission address (TX1) is normally used, except
when a packet with the secondary reception address (RX2) is received and the repeater mode is
turned on. In this case secondary transmission address (TX2) is used instead.
In the following example two repeaters are used. Notice how unique addresses for each link (arrow)
can be derived from the modem numbers. It’s important that only the two repeating modems are
set in the repeater mode, otherwise messages will circulate in the network. Repeaters can
simultaneously function as normal substations. In this case the base station would have to be in
position 4 so that routing of data from stations 2 and 3 would be correct.
21
12
(21)
(12)
12
23
32
21
34
43
(34)
(43)
23
34
43
32
txd
rxd
rxd
txd
Modem 1
Modem 2
repeater
Modem 3
repeater
Modem 4
RX1
TX1
RX2
TX2
Addresses:
