Operation
RFI-9256 Radio Modem User Manual
Page 26 of 109
This problem can be exaggerated by additional retries occurring for frame 1 or frame 2. In order to
counteract this problem, packetisation timers can be configured. For a description on packetisation timers
see section Time Based Packetisation of Data on page 31.
5.2.2 Radio Parameters
ADDRESSING
Each radio in a RFI-9256 network has a local address. The local address is a decimal number between 1 and
9999.
When allocating addresses on an RFI-9256 network, the convention is to allocate the address 1000-9999 to
the master and slaves, while reserving the addresses 10-99 to be allocated to any back-to-back repeaters. In
general, addresses 1-9 are not used. The reason for this is explained in the section Back-to-back Repeater
Operation on page 29.
NETWORK FAIL TIMER
When power is first applied to a slave, it enters the unlocked state. In the unlocked state the slave has not
heard a master unit, and waits on a single channel listening for a master to hop past. When the master hops
past, the slave will start hopping with the master.
If the master loses power, or becomes unreachable, then the slave will continue to hop over the channels,
searching for the master. If after the network fail timer period expires the slave has failed to hear from its
master and it reverts to the unlocked state.
For more information on configuring the network fail time, see section B.1.1 on page 71.
TRANSMIT POWER
The transmit power of the RFI-9256 can be configured at fixed intervals 0dBm, +10dBm, +20dBm,
+25dBm, and +30dBm.
When operating in the 900MHz ISM band, the maximum allowed output power at the antenna is 1 Watt
effective isotropic radiated power (EIRP). This translates to +30dBm. Noting that cables will introduce loss,
and the antenna may introduce gain, the transmit power of the RFI-9256 should be adjusted so that the
power at the antenna is as close to +30dBm as possible.
RSSI TRIGGER LEVEL
The RFI-9256 supports a configurable RSSI trigger level, or squelch. The RSSI trigger level sets the lowest
RSSI that the RFI-9256 is to attempt to acquire data. When the radio has to operate in a very noisy
environment, where the background noise has risen above its sensitivity (-108 dBm), the RSSI trigger level
will need to be set higher than the default to allow the radios to communicate.
When operating in a normal environment the RSSI trigger level should be set below the radio’s sensitivity
otherwise the radio will be artificially deafened.
Main -> Radio
Main -> Radio -> Link Control
Main -> Radio -> Radio Characteristics
