User's Manual
Chapter Four Troubleshooting
Man_455U-D Rev 3.01 Page 61
Take the mobile module to the other end of the radio path. The antenna at this end can be
either held by the tester, or fixed in a temporary fashion. Note that a person’s body will
affect the radiation pattern of an antenna, so if the antenna is hand-held and the test is not
successful, try again with the antenna fixed to a 1 metre length of plastic pipe or timber.
The tester holds the length of pipe or timber with the antenna above head height.
Test the radio path by AT#B command, or the communications test command in the
configuration software
Record these measurements for comparison later during commissioning or if the system
has problems later.
If the radio path test is not successful:
1. Increasing the height of the antenna at either module, or at both modules can significantly
improve the result. Sometimes moving the antenna to the side helps, if there is an obvious
obstruction in the radio path.
2. Change one or both antennas to a higher gain if regulations allow.
3. Use a shorter coaxial cable between the antenna and the 455U.(this may involve moving
the 455U nearer to antenna mounting), or use a different coaxial cable with lower loss.
4. If a reliable radio path is not possible because of distance or path obstructions, you will
need to consider using a repeater module. The ideal repeater is another module in the
system, in a good location to act as a repeater. If this is not the case, you need to consider
installing a module to act specifically as a repeater.
4.6 Changing the Radio Parameters
It is possible to change the radio Transmit and receive frequency and the radio power setting
from the configuration software (Select the “Radio” tab, and enter new values for TX Frequency
and RX Frequency). When changing the frequency of a remote module, over the radio, take care
to change the most distant module (The module that communicates through the most repeaters)
first, then change the closer modules in order.
To change the transmit and receive frequency using AT commands, enter the command
ATFT=xxx.xxxx (transmit) or ATFR=xxx.xxxx (receive) where xxx.xxxx is the new frequency
in MHz. The frequencies must be within the allowed range. Use the AT&V command to display
the current settings and the allowed range of frequency.
To change the power setting using AT commands, enter AT\Px, where x is a number from 0 to 3,
with 0 corresponding to the lowest power setting (500 mW on E455U-D-5W) and 3
corresponding to the highest power setting (5W on E455U-D-5W).
Other radio parameters are available after pressing the “Advanced / Configuration” button, and
entering the correct access password. These items are protected to ensure that the radio is not
inadvertently mis-configured in contravention of radio licensing requirements.