XStream
‐
PKG
‐
T™
Telephone
RF
Modem
–
Product
Manual
v5.x00
[2006.02.24]
4.2.2.
Repeater Mode
Characteristics
: Self-organizing - No route configuration is necessary
Self-healing / Fault-tolerant
Low power consumption and Minimized interference
Network throughput is determined by number of hops, not by number of
repeaters. Multiple repeaters within range of source node count as one hop.
Supports “transparent” multi-drop mode or addressed data filtering mode.
Duplicate RF packets are automatically filtered out.
All packets propagate to every node in the network (filtering rules apply).
Broadcast communications - each packet comes out every node exactly once.
Addressed communications - all radios see every packet. Only the modem
with a matching address will forward it to the DO buffer (UART IN).
Data entering the network on any modem is transmitted and forwarded
through every repeater modem until it reaches the ends of the network.
Each repeater will repeat a packet only once.
Constraints:
Requires that each modem have a unique MY (Source Address) parameter.
System must introduce just one packet at a time to the network for
transmission (256 bytes max).
Each hop (H) decreases network throughput by a factor of 1/(H+1).
Additional repeaters add network redundancy without decreasing throughput.
Required Parameter Values (TX Modem)
: MD = 3 or 4, MY = unique value (can be
accomplished by issuing the AM (Auto-set MY) and WR (Write) commands to all modems in the
network)
Related Commands
: Networking (MD, DT, MY, AM), Serial Interfacing (RN, PK, RO, RB)
Recommended Use
: Use in networks where intermediary nodes are needed to relay data to
modems that are beyond the transmission range of the base modem.
Theory of Operation
OEMs and integrators can extend the effective range and reliability of a data radio system by
forwarding traffic through one or more repeaters.
Instead of using routing tables and path discovery to establish dynamic paths through a network,
the repeater system uses a sophisticated algorithm to propagate each RF packet through the
entire network.
The network supports RF packets up to 256 bytes. The repeater network can operate using
broadcast or addressed communications for multi-drop networks and works well in many systems
with no special configuration.
When in Repeater Mode, the network repeats each message among all available nodes exactly
one time. This mechanism eliminates the need for configuring specific routes. The network is self-
organizing and self-healing so that the system is able to receive transmissions in the event of a
modem going down.
Figure
4
‐
05.
Sample
Repeater
Network
Topology
©
2006
MaxStream,
Inc.,
Confidential
and
Proprietary
29
