Page 14
J-Series Data Radio – User Manual
Issue 09-10
Part D – Features
Features Useful for Optimizing
Performance.
In addition to the settings made to establish Radio Type, Network
Type and Subnet ID there are a number of parameters configured
in the Access Point radio that can optimize the performance of the
J-Series Ethernet radio network.
Over the Air Data
All Ethernet data sent over the air is packaged into data packets.
These data packets are transported over the network together with
a small amount of overhead (or management data).
The total amount of data sent in one single hop depends on the
hop interval, RF data rate and the amount of data that is waiting to
be sent. The larger the total amount of data, the smaller the ratio
overhead compared to user data.
In almost all situations the default settings of the radio will provide
the adequate performance. However, under some circumstances,
it may be necessary to fine tune specific features so an
understanding of how these features work is important.
Radio Data Rates
The radio data date determines the over the air speed of the
modem. Essentially it defines how much bandwidth is available.
The J-Series 900MHz version offers two selectable data rates.
256kbps with BER of 1E-6 @ -102dBm
512kbps with BER of 1E-6 @ -92dBm
The choice of radio data rates will depend on the level of RF
signal strength, but will also depend on other factors like RF noise.
In general, higher RF signal levels are required when using the
512kbps RF data date, otherwise an unreliable link may result.
It may be preferable to start at the lower speed of 256kbps and
change to 512kbps once the network is configured correctly.
The J-Series also provides the ability to have mixed data rates
in one system as shown in the diagram below. In this mode of
operation, the J-Series Access Point is configured for “Auto Radio
Data Rate”. Remote radios that have weak signal strength are
then configured for 256kbps data rates while those remotes with
stronger signal strength are configured for 512kbps data rates.
The configuration setting for radio Data Rates can be found in the
“Unit Parameters” section of the Radio configuration area of the
web programmer.
