This page was contributed by
Stephen, who has a link calculator on the web that you can use for
While we're on the subject of
free link calculators, here's another effort which was pointed out
Microwave links are used to build
private networks where leased lines are either:
a) too expensive
b) take too long to implement or,
c) are not of the required quality.
For these reasons the most used
method of connecting GSM and UMTS mobile networks is microwave.
This is especially true in Europe because of the high speed of the
rollout of competitive networks and in the third world because of
the lack of availability of leased line solutions. The USA has a
lower percentage at the moment but there is a new driver which is
also affecting the USA, this is the capacity/bandwidth that is required
to be transported for new mobile non-voice services. These services
mean that the OPEX costs that the operators pay in leased line rentals
is increasing enormously and the CAPEX costs of a microwave solution
achieves a payback in 1-3 years.
When someone decides to use microwave
he needs a planning tool to check if he has Line of Sight (LOS)
between potential sites and to design the links to a specified availability
as at the higher frequencies microwaves are affected by rainfall.
This planning tool is a simplified version of other planning tools
such as Comsearch IQLink http://www.comsearch.com/software/link.jsp
and Pathloss http://www.pathloss.com/
. Naturally it cannot do all that these tools can do but they both
cost $1000's per user license. This tool is designed for quickly
checking whether a microwave link will work at all between two sites
and if it will what frequency band, antenna sizes etc. would be
required for a given availability. And he can do this online! There
are other advantages such as being able to use addresses to input
sites which none of the big players can do yet.
Now the planning tool is free! (caution, the links below are broken, if anyone knows how to get in touch with Stephen please let us know)
You no longer need to buy an
expensive Microwave Link Planning Tool to plan microwave links,
can now plan microwave radio links from scratch online by using
my Gaggle Maps Microwave Link Planning Tool.
First go to the Line of Sight
where you can enter the Site-A
and Site-B by entering addresses, coordinates or simply by clicking
on the map. You can zoom in and out with the mouse wheel or by using
the controls top left. A new feature is that the site will remember
you (if you enable cookies) and the next time you visit the maps
will be set to the area and zoom level that you were last at. You
can switch between maps, satellite and terrain views with the control
top right. After you have selected the A and B sites the tool will
calculate the coordinates, bearing, distance etc. and also gather
the height data for the link which it displays as a path profile.
You can click on the path profile
to display it in a separate window and print it out. You can raise
the antenna heights until you achieve line of sight. When you are
satisfied with a link you can click on the export button and the
link is exported to the Link Engineering Tool at:
where you can set the antenna
sizes, frequency band, transmit power etc. the tool then calculates
the Rx level, Fade margin, FSL and unavailability of the link in
% and minutes/year. Furthermore if you give a required availability
it will calculate the maximum link length you can achieve using
the given parameters and shows this graphically on the map. You can
then print out a link budget for the link. Both line of sight and
link engineering tools can also be used separately if required.
Please try the tool out I am
sure you will find it both useful and interesting. I am working
on several enhancements at the moment, such as automatic mast height
calculations and several other ideas. Also it would be simple to
make the FSL and availability calculations apply to the actual frequency
channels used rather than simply the frequency band but this was
designed to be a convenient, quick and simple alternative to the
usual Link Engineering Tools.