User's Manual
Table Of Contents
- Part A – Preface
- Safety Information
- Revision History
- Important Information
- Compliance Information
- Part B – Feature Overview
- Introduction
- Features and Benefits
- Q Data Radio Range
- Part C – System Topologies & Operating Modes
- System Topologies
- Operating Modes
- Part D – Feature Detail
- Hardware
- Efficiency and Bandwidth
- Connectivity
- Ease of Use
- Security
- Part E – Radio Planning and Design
- Radio Path analysis
- BER & Fade Margin
- Radio Accessories
- RF Feeders and Protection
- Part F – Quick Reference Guide
- Introduction
- Half Duplex Radio - QR450
- Full Duplex Radio - QB450
- Hot Standby Half Duplex Radio - QP450
- Hot Standby Full Duplex Radio - QH450
- LED indicators
- Connecting Antennas
- Communication Ports
- Activating Transmitter
- Factory Default
- Digital I/O
- Connecting to Web User Interface (WUI)
- Resolving Ethernet Connection Issues
- Part G– Quick Start Guide
- Step-by-Step Point to Point Setup
- Step-by-Step eDiags Setup
- System Topology Configuration
- Serial and MODBUS
- Single Frequency (Simplex) Mode
- E-Series Emulation Mode
- Part H – Advanced
- Connectivity
- Ease of Use
- Security
- Part I – Installation & Commissioning
- Optimising the Antenna for Rx Signal
- Commissioning
- Part J – Firmware Updating and Maintenance
- Firmware Updating
- Global Firmware Updating
- Fuse Replacement - QR450
- Part K – Open Source License Acknowledgements
- Part L – Support Options
21
Document Number: 0100SM1401 Issue: 05-15
Dynamic Speed Selection
Traditional narrow band SCADA data radios achieved wireless communication over long distances by transmitting at low
RF data rates (typically 9600bps or less). Modern SCADA systems require faster RF data rates, due to the need to support
additional traffic for Ethernet and IP. However, reliable transmission over long distances at faster RF data rates, can be difficult
to achieve.
To assist in reliable data transmission over long distances at faster RF data rates, the Trio Q data radios utilise dynamic speed
selection. Dynamic speed selection provides the following enhancements:
• Operation at the fastest possible RF speeds
• Measurement of Quality of Service - QoS (success of data delivery to other end) and
• Automatically adjusting to a slower RF speed to improve quality, if QoS is inadequate
Dynamic speed selection is individual for each remote in a point to multipoint (PTMP) system. Should one remote need to
operate at a slower RF speed due to limited received RF signal, others will continue to operate at the fastest possible RF
speed as dictated by their own received RF signal strength for that specific site.
RF Data Rate vs RF Sensitivity
As stated earlier in this section, Trio Q Data Radios have four different RF speeds for each channel bandwidth selection
(12.5kHz or 25kHz). Each RF speed has a corresponding receiver 1 x 10-6 BER (Bit Error Rate) sensitivity. The slower the RF
speed, the better RF sensitivity, and therefore the longer the range for a given level of reliability.
Very High Speed
High Speed
Medium Speed
Low Speed
Dynamic Speed Selection Example
The further away from the master station, the weaker the received signal.
Slower RF speeds are required for an acceptable level of reliability
Tx
The further away from the master station, the weaker the received signal. Slower RF speeds are required for an acceptable
level of reliability.
Consider the example shown in the diagram above. An entry point / base station is located in a fixed position. When
communicating with a remote radio, RF energy between the two radios diminishes in strength as the signal propagates over
distance.
Part D – Feature Detail
In a system with out dynamic RF speed selection, the user would need to configure a suitable fixed RF speed, dependent on
the signal strength at the remote site. In most applications, a minimum of 20dB fade margin is recommended for reliable
operation (due to rain fades, cable degradation, multipath fading, etc). If the remote radio is fixed at a specific RF speed,
then in order to maintain a received signal 20dB above the 1E-6 BER sensitivity (20dB fade margin), the user would need to
decrease the RF speed when the receiving radio is further away from the transmitter. This is depicted in the diagram above
by the concentric rings showing what RF speed can needs to be selected in order to maintain a 20dB fade margin.