User's Manual

Elpro Technologies 450U-E Wireless Ethernet Modem & Device Server User Manual
Rev Version 1.4.0 www.cooperbussmann.com/wirelessresources 31
Receive Frequency
The Frequency that you wish to configure for the radio Receiver. Frequency
selection will be in multiples of the frequency step configured in the previous
parameter. E.g. 450.00500, 450.01000, 450.01500, 450.02000, etc. for 5Khz or
450.00625, 450.01250, 450.01875, 450.02500, etc. for 6.25KHz frequency step
size.
The following are advanced settings and care should be taken when making changes to the parameters on this
page.
Figure 34 - Advanced Radio
Beacon Interval (AP only)
This interval is the period between beacon transmissions sent by an Access
Point. The default value is 15 seconds, and it may be adjusted from 1 to 60
seconds. Reducing the Beacon Interval will increase the amount of radio
messages in the system which could compromise normal communications.
Do not change unless advised by an Elpro Systems Engineer.
Fragmentation Threshold
(Client Stations only). The maximum transmission unit (MTU) of data over the
radio. If more than this number of bytes is input into the module, it will be
transmitted in more than one message (or fragmented).
Disable SSID broadcast.
(AP only)
This should be used to reduce bandwidth eavesdroppers from detecting the
radio network System Address (SSID) by passively listening to beacon
transmissions from the Access Point. When disabled, Access Points will not
transmit the System Address openly in Beacon messages. This is particularly
useful in unencrypted radio networks and where all stations know the SSID of
the Access Point.
Data Compression
Enable/Disable Data compression. See below for details
Save Changes
Save changes to non-volatile memory
Save Changes and
Reset
Save changes to non-volatile memory and activate the process
Data Compression
The radios incorporate a data compression algorithm based on RFC1951 specifications. This algorithm is similar to the
one used in file compression utilities such as PKZip, etc. which simply matches duplicate strings within the data frame
with pointers to previous data patterns. It keeps a running image of previous received data frames which it uses to
compare with the current data frame. When it finds a data string that is the same as a previous data string a pointer to
this location is sent instead of the data. Depending on the data this could considerably reduce the amount of data that
needs to be sent.
Performance is dependent on the type of data frames that are being sent. Typical improvements in throughputs that can
be expected when compression is enabled are:
 15-40% improvement if using Modbus, depending on the radio baud rate
 70% improvement for web page download
 40% improvement if using FTP download