AML KDT750 Price Verification System - Manual (Page 38)

KDT750 User’s Guide
5 - 2
Overview
The KDT750 terminal can contain an optional 802.11b/g/n radio and internal antenna. This
radio is specifically designed to communicate with any 802.11b/g or 802.11n (Draft v2.0)
Access Point.
The range of the radio depends greatly on the quality of the Access Point and the RF com-
munications characteristic of the environment where the device is used. The typical range
for an 802.11 radio is 500 feet through free air. Additional Access Points must be added to
improve coverage in a larger area, or in electrically noisy RF environments.
802.11 Fallback
Wireless LAN technology is designed to make maintaining a connection between two
devices as reliable and consistent as possible. Since the speed of the connection between
wireless devices will vary as range and signal quality varies, the wireless devices will inten-
tionally sacrifice throughput (data rate or connection speed as measured in bits per sec-
ond) in exchange for maintaining a reliable connection. In other words, a reliable connec-
tion at a lower speed is preferred over an unreliable connection at a higher speed (i.e., it is
easier to maintain the connection if data rate is deliberately reduced, or put another way,
lower data rates will tolerate a higher range and/or worse signal quality). This characteristic
is known as fallback. As example, an 802.11b system will fallback from 11 Mbps to 5.5 Mbps
as range increases or signal quality decreases. Subsequent fallbacks from 5.5 Mbps to 2
Mbps and 1 Mbps are also supported.