User manual

Chapter Three Operation
Page 33 March 2010
In some countries, the radio band is limited to a sub-set of the 902-928 MHz band to suit local
regulations.
In countries which allow the full 902-928MHz band (such as USA and Canada), there are eight
hopping sequences, or “hop-sets” (numbered 0 to 7, user-configurable). Each sequence uses only
half of the frequencies available in the band. Sequences 0-3 use the same frequencies, but in a
different sequence. Sequences 4-7 use the other frequencies.
For example, consider two systems close together. If the systems have hopping sequences in the
same group (0-3 or 4-7), then there is some degree of isolation because of the different hopping
sequence, however they will occasionally hop onto the same frequency and cause momentary
interference. However if one system uses a sequence in the first group (0-3) and the second
system uses the second group(4-7), each system is isolated from each other. Note that this is
only true if the antennas are at least 30 meters (100 feet) apart to prevent “blocking” - that is,
saturation of the other receiver when one unit transmits.
The hop-set is automatically determined from the System Generator String. If you wish to
change the hop-set to move to a different group, the best way is to change the System Generator
String and check what the new hop-set is.
In countries which only allow a sub-set of the 902-928 MHz band, there is only one group of
frequencies and it is not possible to separate systems in this way because the band is smaller and
all hopping sequences use all frequencies available.
3.9 Radio Configuration Menu
The WI-MOD-9-E can be configured to different radio transmission rates. A reduction in rate
increases the reliable range (transmission distance). An “automatic rate” function is provided
which automatically selects the highest data rate for reliable operation. This feature will select
the highest rate possible, and reduces rate in the event of interference or poor signal.
The factory-default settings for the radio port will be correct for the majority of applications.
Only make changes if you experience operating problems.
Select the “Radio” Menu to change the following configuration parameters. If a change is made,
you need to select “Apply Changes and Save” to retain the changes.
Power Level The transmitter power level desired in mW.
By default this is set to maximum power of 1 Watt (1000mW). The
lowest setting is 100mW.
Data Rate The radio baud rate in bits per second (bps). Available rates are
19200, 38400, 100000, 200000bps and Auto.
The default value is Auto. In Auto mode, the WI-MOD-9-E will
automatically adjust the data rate to the fastest rate for reliable
operation in each radio path.