WIT2450
©
2000- 2005 Cirronet
™
Inc
18
M-2450-0000 Rev B
2.2.5. Store and Forward Repeater Operation
The WIT2450 supports operation as a store and forward repeater while also acting as an
end device. A store and forward repeater acts to extend range or avoid obstructions by
receiving data from upstream transmitters and relaying or repeating the data to devices
downstream. The data received from the upstream transmitter will also be output on the
devices serial data ports. This avoids the expense of dedicated repeaters whose only
purpose is to repeat data transmissions it receives. The WIT2450 in S&F mode, listens on
one hop and then relays or repeats the received data on the next hop. Thus the throughput
of data passing through an S&F repeated is cut in half. If the network has more than one
level of repeaters, while the data latency will increase with each level, the data
throughput will not be reduced further.
In S&F mode, there are two types of WIT2450 radios, the Root radio and the Repeater(s).
The Root radio acts as the base radio for the entire network and establishes the timing for
all of the radios in the network (and all other WIT2450 radios). There must be one and
only one Root radio for each network and it is set as the Root using the wb3 command.
All other radios in the network must be informed that an S&F network is being setup.
This is performed using the wb2 command for all radios in the network except for the
Root radio thus making them Store and Forward Repeaters.
Each radio will repeat the data it receives from another radio even if there are no radios
downstream. Thus each radio must be configured with a network number for receiving
data and a network number for repeating the data. The receiving network number is set
using the
wn
command and the repeating network number is set using the
wo
command.
Given the long range capability of certain radios, in most situations it is difficult to know
which radios can hear which other radios. Thus, it is advisable to set unique repeating
network numbers for each radio that has other radios downstream. All radios that have no
other radios downstream can have the same repeating network number.
