4RF Aprisa SR+, Product Description

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10 | Introduction
Aprisa SR+ Product Description
Product Overview
Network Coverage and Capacity
In a simple point-to-multipoint network, an Aprisa SR+ base station can communicate with up to a
practical limit of 150 remote stations.
The Aprisa SR+ has a typical link range of up to 60 km, however, geographic features, such as hills,
mountains, trees and foliage, or other path obstructions, such as buildings, tend to limit radio coverage.
Additionally, geography may reduce network capacity at the edge of the network where errors may occur
and require retransmission. However, the Aprisa SR+ uses Forward Error Correction (FEC) which greatly
improves the sensitivity performance of the radio resulting in less retries and minimal reduction in
capacity.
Ultimately, the overall performance of any specific network will be defined by a range of factors including
the geographic location, the number of remote stations in the base station coverage area and the traffic
profile across the network. Effective network design will distribute the total number of remote stations
across the available base stations to ensure optimal geographic coverage and network capacity.
Automatic Registration
On start-up, the remote station transmits a registration message to the base stations which responds with
a registration response. This allows the base station to record the details of all the remote stations active
in the network.
If a remote station cannot register with the base station after multiple attempts (RF LED flashing red)
within 10 minutes, it will automatically reboot. If a remote station has registered with the base station
but then loses communication, it will automatically reboot within 2 minutes.
Remote Messaging
There are two message types in the Aprisa SR+ network, broadcast messages and unicast messages.
Broadcast messages are transmitted by the base station to the remote stations and unicast messages are
transmitted by the remote station to the base station. These messages are commonly referred to as uplink
(unicast remote to base) and downlink (broadcast base to remote).
All remotes within the coverage area will receive broadcast messages and pass them on to either the
Ethernet or serial interface. The RTU determines if the message is intended for it and will accept it or
discard it.