Things to note when using Link Planners
As point to point projects are a daily occurrence for myself, I use all manner of link planners in my day to day role. I have come to know, love, and dislike the various options out there and have a good understanding of what can and can’t be achieved with them.
I am often contacted by individuals who have done their own link planners for the links they wish to commission who are under the impression the proposed link will work because the link planner says so. But they haven’t always taken everything into consideration that perhaps they should have… a giant tree for example.
What I thought would be useful is a list of Do's and Don'ts for planning a point to point link and thus this blog was born.
First things first, where are your two mounting locations? Do you have the addresses for the two buildings you want to connect, or can you point out the location on Google/Bing maps? If so, that’s a good starting point. If you are using google maps you can double-click on the location you think you might be able to mount a radio, you will be provided with the longitude and latitude which will be useful later (see image below).
Once you have your two locations you will need to work your predicted mounting heights. I find doors are a good point of reference to measure the height of a building if you aren’t able to measure the building with a laser measuring device or a tape measure. A standard door is 2.1 meters tall, so if you stand back and use a pencil to reference how many doors will fit between ground level and your mounting location you’ll have a good idea of the mounting height.
Once you have your longitudes and latitudes and mounting heights you should have enough info to put a basic plan together. The below plan is done using the LigoWave link calculator (others are available). You will need to pick your product depending on which manufacture/link planner you are using.
Once you have imputed the data you should be able to generate a link planner. And you will likely be presented with something resembling the below.
Path Profile - This predicts the fresnel zone in relation to ground level. One key thing to note is that trees and buildings are not taken into consideration. At this stage, this short 120-meter link looks viable and there appears to be a clear line of sight.
The next step is to overlay the link onto a map. Im going to use google maps in the example. Most link planners have an exporting tool to do this.
I would always recommend using satellite view as this will give you a better idea of what trees and building may be along the path of your link and where the line of sight might be an issue.
In the example below, you can see that there are some trees lining Hatch pond road that may be blocking the line of sight. In this instance the desktop survey is inconclusive, and an onsite survey would be required to confirm the validity of the link.
So, those Do's and Donts
- Check you have the correct locations and obtain the longitudes and latitudes from google maps.
- Work out your mounting heights for each side of your link.
- Use satellite view on whichever mapping tool you are using.
- Consider that trees and buildings may be preventing line of sight.
- Follow the path of the link on a satellite view to check for possible obstructions.
- Assume because the link planner looks viable the link will be. Always follow up with an onsite survey to confirm the link is viable.
- Overpower your Radios. Most link planners have an option to see the TX power, you must ensure you are working within legal limits.
- Guess your mounting heights. Always use a device to measure the mounting height where possible.
Obviously, there is nothing better than experience when it comes to these things so why not get in touch with DigitalAir and one of our point to point experts who will be happy to assist you with your wireless link.
If you would like any further information or understanding of using Link Planners, give DigitalAir a call on 0800 310 2050