www.cooperbussmann.com/wirelessresources
Cooper Bussmann 245U-E Wireless Ethernet Modem & Device Server User Manual
41
Rev Version 2.19
Interference
Mitigation
(Access point only.) Interference Mitigation should only be turn on (default is off) if
using demo whip antennas or if there is a high level of background interference.
By enabling this option, the radio will dynamically adjust the radio parameters to
help mitigate interference based on any background interference. It will reduce the
receiver sensitivity and therefore should only be enabled on paths with a high fade
margin and good signal quality.
Bursting
Selecting this option can increase the data throughput by reducing the overheads
associated with wireless transmissions. If communicating with a device that does not
support bursting, the modem will drop back to non-bursting mode.
Enable Iperf Server
Enable Iperf server function in the modem. Iperf is used for performing radio surveys
or radio path testing. See “4.4 Throughput Test.”
Fixed Noise Floor
Allows the radio receiver noise floor (and therefore sensitivity) to be moved above
any interference. This essentially stops the radio from communicating with devices
that have lower signal strength. For use in areas where there is a greater amount of
interference.
Fixed Noise Floor
Due to the popularity of the 2.4 GHz band, there are many sources of interference. This interference can sometimes
be a problem due to the way 802.11 devices communicate. Standard 802.11 communications uses a system called
“clear channel assessment” which means the radio will listen before transmission and if the channel is busy it will
hold off regardless of the level of signal. If the background interference is high due to other radio systems or noise,
you can raise the fixed noise floor to compensate. The Channel Utilization page can be used to identify excess
noise or interference.
Raising the noise floor will block out any receive signal levels below the value configured under “Fixed Noise Floor”
on the Advanced Radio configuration page. The value must be entered as a negative dBm number and should be
at least 8 dB greater than the weakest RSSI of any connected modems, otherwise communications may be lost.
For example, if the interfering noise levels are around -80 dB, you can raise the noise floor to -70 dB to block out
any signals below, making sure the RSSI levels of any connected modules are not below this noise floor as they will
not communicate. The Connectivity page can be used to determine if other systems are in the area and their RSSI
levels.
After configuring the fixed noise floor, confirm that the channel utilization has dropped to a desirable level and
where possible perform an Iperf throughput test to confirm acceptable performance.
3.11 Serial Port Configuration
The 245U-E has an RS-232 and an RS-485 port for serial communications. These ports may be used for different
purposes. The 245U-E offers three serial functions—PPP server, serial gateway, and Modbus TCP to RTU gateway.
RS-232 PPP Server
The 245U-E can be used as a PPP (Point-to-Point Protocol) server to connect the wireless system to serial devices
via the RS232 or RS485 serial ports. PPP server enables a network connection to the 245U-E over a serial cable.
This is much like dial-up Internet. The maximum serial data rate is 115,200 bps. Hardware or software flow control
may be selected. With minimal configuration on the PC, you may use dial-up networking in Windows XP to connect
to the network via the serial port.
For the 245U-E, users must configure the local IP address for the 245U-E and the remote device IP address. Some
care must be taken in selecting these IP addresses.
• If you want to use routing over this serial network connection, the IP addresses selected must not lie on
wireless or wired Ethernet networks already configured into the device. You must ensure they set routing rules
appropriately for devices either side of the network.
