Free tools for designing your wireless network
Designing an RF network can be a challenge, even for the most
seasoned engineer.
Thankfully, there are a number of tools available to make the
job a little easier. And some of them are even free.
The
best free tool that we have used is
Radio Mobile.
Radio Mobile is a program that runs under MS Windows and allows
you to map RF networks using terrain and elevation data,
calculating and displaying RF link quality.
The
process of using Radio Mobile begins by identifying the
geographic coordinates of your network. These are polar
coordinates in the form of longitude and latitude. Every node in
your network should be recorded for coordinates using a good
quality GPS device.
Once
identified, you will need to download an elevation "map" for the
area you will be installing. Radio Mobile makes this fully
automatic for you, all you need to do is provide a center point
and scale, and Radio Mobile will download the appropriate
elevation maps from the Shuttle
Radar Topography Mission (SRTM). These are free maps of
elevation data provided by NASA.
The
SRTM maps are really a set of elevation numbers spread out over
your service area. They do not show roads, buildings, etc.
Fortunately, you can also download images that can be
superimposed over the elevation data. Again, Radio Mobile can do
this automatically. It can get images from
Terraserver,
Tiger,
OpenStreet Map and
others. You can also save your Radio Mobile Maps for import to
Google Earth, allowing
you to see buildings, streets, trees, etc.
Once
you have your elevation and map images loaded, then you can
begin planning and simulating your network. You will create a
network, which is a set of members. The network is a way to
group members together based on frequency, topology, weather
conditions or other logical grouping.
Your
members are defined from a systems template. Each system will
have the equipment tx power, rx sensitivity, cable loss, antenna
gain and antenna pattern.
HauteSpot Networks provides all of this information to it's
customers, just ask.
Once
you create your members, then you place them on the elevation
map, based on coordinates. Radio Mobile will then simulate the
RF links between members, showing you full details on link
quality, coverage, shadowing and more.
Once
you have designed your network, testing different antenna types,
transmitter types, gain levels, etc, you can export the data to
Google Earth or print the files out as PDF or JPEG files.
Radio
Mobile is most useful for outdoor, relatively long range (2km or
longer) links. It can be used for shorter networks, but the lack
of a clutter database (mapping of trees, buildings and other
immovable objects not in the elevation maps) makes it less
useful in these applications.
There
is an extremely
helpful tutorial on using Radio Mobile located here. There
is also an active
Yahoo Group which is worth joining.
Be
prepared for a long learning curve. Radio Mobile was designed by
HAM radio operators who know what they are doing. This is not a
tool for beginners. But if you are considering RF simulation
modeling software, this is a great place to start.
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