SkyWay Series Multi-Point Operator’s Guide
99
with an RF signal. Any wireless equipment can be a potential source of
interference.
•
Objects in the signal path can cause interference. The bending of signals as
they pass around obstructions or are deflected by them is known as
diffraction. Diffraction can damage signal quality if the diffracted signals
arrive out of phase. A glass window can attenuate the signal to some
extent. Some types of mirrored glass can almost totally block the signal.
Signals passing through the side of a wooden building or a forest are also
attenuated. Wet leaves can affect a signal substantially. The success of an
RF link depends on a clear line of sight.
Connection Types
LAN.
A Local Area Network (LAN) links workstations, processors, and other
equipment within a local area, such as the inside of a building.
WAN.
A Wide Area Network (WAN) is a network with connections spanning
broader distances than a LAN and typically with connections to the Public
Switched Telecommunications Network (PSTW). A WAN might connect
locations in different buildings or different geographic regions.
Internetwork.
An internetwork is formed by linking networks to other networks
or devices. For example, a link between local area networks in different buildings
creates an internetwork.
Point-to-Point.
A point-to-point connection is a direct link between locations.
Multipoint.
A network or internetwork with multiple sites. A large multipoint
connection generally uses a central site to pass messages between the locations,
and the individual locations (substations) have direct connections to the central
site, but not to each other.
Antennas
Antennas come in different configurations to serve different needs. To span large
distances, you must narrow the signal into a focused beam. The more focused is
the signal, the greater is the gain. Since narrowing the signal increases the gain,
you are allowed to exceed six dB only if you reduce the power to less than 1 watt
under FCC rule Part 15.247. On the other hand, a 360
o
omnidirectional antenna
has only a four-fold gain, so it can use the maximum allowable one watt of power.
Antenna Types
Directional.
A directional antenna focuses the signal into a narrow beam. For 2.4
GHz systems, dish antennas achieve the highest gain and span the greatest
distances. Solectek’s dish antenna has 21 dBi of gain, and when using a transmit
power of 15 dBm (a small fraction of one watt) the EIRP is 36 dBm (the FCC
maximum allowable). In the 902-928 MHz range, yagi antennas achieve the
highest gain and span the greatest distances.
In addition to concentrating signal strength, directional antennas also:
Summary of Contents for SkyMate
Page 6: ...About This Manual vi ...
Page 20: ...Chapter 1 Getting to Know Your SkyWay Series 6 ...
Page 100: ...Appendix A RunTime Bios Application Menu Trees 86 ...
Page 102: ...Appendix B SNMP MIB Trap Messages 88 ...
Page 120: ...Appendix C Glossary and Basic Concepts 106 ...
Page 124: ...Index 110 ...