User's Manual

AR24027 Operator’s Manual (rev E)
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1 INTRODUCTION
The AR24027 Wireless Ethernet Bridge is a license free radio that can be used to bridge Ethernet
LAN’s (Local Area Networks) across distances ranging from a few hundred feet to 50 miles (80 Km)
and beyond. In a standalone configuration the radio provides an Ethernet interface to the user. It can
also be paired with the Afar NetCrossing™ Gateway (NX2048), to provide a full duplex synchronous
serial stream connection, in addition to the Ethernet interface, between the two end points.
The AR24027 is a Spread Spectrum radio operating in the “Industrial Scientific and Medical” (ISM)
band from 2.400GHz to 2.4835 GHz. It is designed from the ground up to provide a robust link under
very adverse conditions, often encountered in this unlicensed band. This includes the following
features:
1. All the electronics are housed in an environmentally sealed enclosure rated for outdoor
installation. You can mount the unit in close proximity to the antenna, which increases system
performance by avoiding RF cable losses or expensive rigid coax cables.
2. The radio RF bandwidth is much narrower than other unlicensed devices in the 2.4 GHz band.
This has several advantages, namely (i) the radio sensitivity is greatly improved allowing longer
ranges, (ii) there is a much larger number of non-overlapping channels to choose from, and (iii) it is
much easier to find an unused gap in a crowded spectrum.
3. For long range links in a crowded spectrum the most desirable receive frequencies at each end of
the link are often different. In the Afar radio the transmit and receive frequencies can be selected
independently of each other.
4. The radio incorporates spectrum analysis and timing analysis tools, which allow the operator to
quickly perform a survey of the RF environment without the need for expensive or heavy spectrum
analyzers.
5. Unique antenna alignment aid provides audio feedback proportional to the RSSI, freeing the
installer’s hands to adjust and tighten the antenna without having to hold or look at other
instrumentation.
The radio implements a transparent bridge algorithm, where each unit automatically learns the
addresses of all stations in the network and forwards over RF only the traffic that needs to be
delivered to the remote unit. This reduces the RF throughput required by the radio. If the radio is
used standalone, an indoor “power inserter” unit combines the power and Ethernet data into a single
CAT5 cable connected to the radio.
If the application requires a serial synchronous interface, the radios can be paired with the Afar
NetCrossing™ Gateway to provide both an Ethernet and a serial link of up to 1.024 Kbps across the
same wireless connection. In this case the NetCrossing™ Gateway provides both the power and data
to the radio across the single CAT5 cable. Refer to the NetCrossing™ Gateway Operator’s Manual
for complete details.
The radios operate in Time Division Duplex (TDD) mode using a configurable size time slot. One
advantage of TDD operation is that the radios can synchronize their transmissions such that all co-
located radios transmit at the same time, thereby avoiding self-generated interference. This technique
allows deploying a star network with 30 or more radios at the same location.