Standard Electric Supply Company

1
Welcome!
Standard Electric Supply Company Automation
Express Getting Ready for Wireless March 13,
2003 Dan Blome, Senior Applications Engineer
2
Todays Agenda Getting Ready for Wireless!

• Path studies
• Propagation models
• Site surveys
• Cabling issues
• Understanding GAIN
• Choosing antennas

3
Path Studies

• Do I need a path study?
• Is your application indoors or outdoors?
• How far apart are the points at which you want to
  place radios?
• Do you have line-of-sight between these points?

4
Path Studies, continued...

• The customer provides
• The latitudinal and longitudinal coordinates of
  their sites, in degrees, minutes and seconds
• The known heights of any man-made objects
• The maximum tower height the customer is willing
  to consider on which to mount antennas

5
Path Studies, continued...

• Locus provides
• 30-meter resolution data
• A written summary of findings
• Site coordinates, their corresponding elevations,
  any tower recommendations and heights, antenna
  recommendations and directional position
• Topographical views, proposed paths, cutaway
  graph views between radios

6
Path Studies, continued...

• Sample Path Study Data

7
Path Studies, continued...

• Sample Topographical Map

8
Path Studies, continued...

• Sample Cross-cut Between Sites

9
Path Studies, continued...

• Path Study Fees Depend on...
• Number of sites
• The amount of data needed to complete the study
• The amount of time it takes Locus to complete the
  study
• Fees generally range between 250 and 1,000,
• fees are credited to a Locus radio order

10
Propagation Models

• What are they, do I need one?
• A propagation model measures signal strength
• Is your application indoors or outdoors?
• How far apart are the points at which you want to
  place radios?
• Are there environmental factors which may affect
  signal strength?

11
Propagation Models, continued...

• The customer provides
• The latitudinal and longitudinal coordinates of
  their sites, in degrees, minutes and seconds
• The known heights of any man-made objects, and
  any environmental factors that exist
• The maximum tower height the customer is willing
  to consider on which to mount antennas

12
Path Studies, continued...

• Locus provides
• 30-meter resolution data
• A written summary of findings
• Estimated received signal strength
• Parameter reports from area coverage models
• Area coverage of the signals

13
Propagation Models, continued...
This chart shows signal strength calculations
14
Propagation Models, continued...
This chart shows single point field calculations
15
Propagation Models, continued...
This chart shows topo data and the propagation
modeling data
16
Propagation Models, continued...
This chart shows signal coverage area
17
Propagation Models, continued...

• Propagation Model Fees Depend on...
• Number of sites
• The amount of data needed to complete the study
  (if a customer has purchased a path study, the
  data is already available to Locus)
• The amount of time it takes Locus to complete the
  study
• Fees generally range between 250 and 1,000,
• fees are credited to a Locus radio order

18
Site Surveys

• Do I need a site survey?
• Is your application indoors in a
  high-interference environment?
• Is your application outdoors in a dense
  metropolitan area?
• Does your application involve 25 or more sites
  over an area spanning 25 miles or more?

Locus provides site surveys on a time and
materials basis, call us and well discuss your
specific site survey needs.
19
Understanding GAIN

• What is it?
• Technically, gain is the relative increase in
  radiation at the maximum point expressed as a
  value in dB above a standard. In the case of dBi,
  this standard is a perfect isotropic radiator in
  which power is radiated equally in a sphere about
  the antenna, like a light bulb.
• Now, what does that mean?!

20
Understanding GAIN continued...

• Think of it this way
• Since antennas do not "create" power, gain is
  achieved by taking some of the wasted energy (for
  example that which is going skywards) and
  focusing it towards a more useful direction,
  similar to a flashlight. You can get increasingly
  more gain by focusing the energy in tighter and
  tighter patterns.

21
Understanding GAIN continued...

• The trade-off is that the higher the gain the
  more tightly focused the beam becomes which means
  that the antenna must be more precisely aimed.
• Directional antennas such as yagis, patches, and
  parabolic grids typically have more gain because
  they focus their energy in a single direction.
  Omni-directional antennas on the other hand
  usually have less gain since the energy must be
  dispersed 360 degrees horizontally.

22
Understanding GAIN continued...

• Gain increases the distance that the radio signal
  can travel and thus increases the range of your
  radio network!
• You can determine the gain of a radio link by
  adding the dBi gain of the antenna at both radios
  and subtracting the dB of loss from the cable, as
  shown in the following slide. This information
  can be used to select the correct antenna and
  cable configurations for specific link distances.

23
Understanding GAIN, continued...
24
Cabling Issues

• You will need cables if you are using an antenna
  which is not mounted directly onto the radio.
• Extension cables
• Conversion cables
• Use the shortest cable possible to minimize loss
• as shown in the previous slide!

25
Choosing Antennas

• Choosing the right antenna for your installation
  means considering several factors
• Path
• Mounting
• Cabling

26
Choosing Antennas, continued...

• Path
• consider any obstructions between antennas and
  try to work around them or eliminate them if
  thats an option (equipment, walls, foliage)
• Although some signal may be lost if several feet
  of cable is required, that loss is much less than
  when the view is obstructed!

27
Choosing Antennas, continued...

• Mounting
• Is there a mast that either antenna will be
  mounted to?
• Or, is it only possible to mount it directly to
  the radio?
• In general, it is best to mount the antenna as
  high as possible!

28
Choosing Antennas, continued...

• Cabling
• Can the radio be mounted close to the antenna and
  have the serial cable run from the radio down to
  the equipment?
• Keeping the RF cable as short as possible limits
  signal loss!

29
Any Questions? Thank you!

• Locus, Inc.
• 5540 Research Park Drive
• Madison, WI 53711-5377
• 608-270-0500
• www.locusinc.com