User's Manual

Page 38
E Series Data Radio – User Manual
© Copyright 2005 Trio DataCom Pty. Ltd.
Part F - Operational Features
Multistream functionality (SID
codes)
The E Series sends data messages in packets. A feature of the E
Series is that an address can be embedded in each packet. This
address is called the stream identifier code (SID).
By configuring a user serial port for a specific SID code, it is
possible to steer messages to similarly configured ports between
radio modems. In effect, it is possible to use the multiple serial
ports available on the E Series, to enable multiple protocols to
share the same RF channel. The SID codes also facilitate the use
of other features such as TView diagnostics. Unique selective
routing, repeating, and data splitting functions available in the
radio modems configuration allow data steering and bandwidth
management in complex systems.
See Part I - TView+ Management Suite - Programmer and Part J
- TView Remote Diagnostics and Network Controller for details.
Collision Avoidance (digital and
RFCD based)
Where multiple “unsynchronised” protocols coexist on a common
“multiple access” radio channel, there is always a possibility that
both “hosts” may poll different “remote” devices at the same time.
If both devices attempt to answer back to the single master radio
at the same time, it follows that a collision could occur on the radio
channel.
To facilitate the operation of multiple protocol operation on the
radio channel, a transparent collision management system has
been implemented : See Part I - TView+ Management Suite
- Programmer for details.
Digital Collision Avoidance System
If the “multiple access master” has been configured for full duplex
operation, it is possible to use the inbuilt collision avoidance
signalling system.
Once the master radio receives a valid incoming data stream
from a remote, a flag within the “outbound” data stream is used to
alert all other remote devices that the channel has become busy.
Remote devices wishing to send data will buffer the message
until the channel status flag indicates that the channel is clear. A
pseudo-random timing value is added to the retry facility to ensure
that waiting remotes do not retry at the same time.
RF Carrier Detect RSSI based Collision
Avoidance
In half duplex systems, the receiver’s RF carrier detect is used to
inhibit the transmitter whilst a signal is being received.
Digipeater Operation
A feature of the E Series radio modems is the ability to internally
repeat data packets to provide stand alone repeater facilities
without the need for external intelligence.
This is done by programming “SID Codes” to “Repeat” a stream or
range of streams. Wizard templates can be used to simplify setup
of this and other features.
See Part I - TVIEW+ Management Suite for details.
TVIEW+ Diagnostics
The E Series has an inbuilt remote configuration and diagnostics
utility.
This facility allows transparent remote access to the key
configuration and operating parameters of the radio.
See the TView+ Diagnostics User Manual for more information.
Part F – Operational Features
Poor VSWR Sensing
To protect the transmitter, forward and reverse power are
measured on each transmission.
If a VSWR of 3:1 or greater is measured, transmitter output power
is reduced to +31 dBm.