Probably you have an Internet connection in your home, that you wish to share amongst other places. For example, in my hometown (Ontinyent) is quite usual to have a home in the town and a house in the countryside (also known like “casetes”).

Nowadays, this is possible thanks to the long range WIFI networks.

In this blog post series, we are going to learn the prerequisites for such project, how to check its viability on the paper and on the field, the required hardware and how to deploy and configure it.

Let’s go!

Introduction

This first blog post will be focused in what are the prerequisites you need to meet before thinking about purchase anything, how to make al the calculations on the paper, and some basic checks on the field.

Prerequisites

What do I need to make this deployment?

  1. There should direct vision between the two locations (from where there Internet connection (Source Point) is and where we want to use it (Target Point). If you are not completely sure, I recommend you to keep reading to learn how to know it.
  2. Obviously, you need an Internet connection in the Source Point 🙂

Planification

In this early stage we are going to use a software that you might be familiar with, Google Earth, and some functionalities that you might not. If you don’t have Google Earth installed on your computer, now is a good moment to do it: https://www.google.es/intl/es/earth/

Connect the points on the map

Open Google Earth. In the toolbar, located at the top, you can find the tool “Add path”. Click on it:

Add path

A new window should opened. Put a name for your path, and then find and click in the maps the two points you want to connect. The Source (where de Internet connection is) and the Target (where you want to bring this connection). This will trace a rect on the map:

Trace path in Google Earth

This path will give us two important things:

  1. What is the distance between the two points?
  2. Is there direct visibility in topographic terms?

All this information can be extracted from the “Elevation Profile” tool. To open it, you only need to right click your path (located in the “Places” menu on the left), right click over the Path, and then choose “Show elevation profile”

Open elevation profile

This will open, just below the map, the elevation profile between the two points. If you move your mouse over the elevation profile, you can also see the exact point in the terrain:

Elevation profile on map

Unless is not reliable at 100%, take a picture of the elevation profile and draw a line (green in this case)  over it. If the green line (direct vision) to not touch with the red one (terrain) you probably have direct vision:

Elevation profile

From the elevation profile we also pick up this information, for latter calculations:

Distance: 5,67 km
Elevation Gain/Loss : 224 m (Elev Gain/Loss)

Finally, we are going to pick the “Ruler” tool, to calcule the orientation of both antes repeat the magnetic north. Choose the Ruler, and click from Source to Target points. Google Earth shows us, in the “Heading” field, how much degrees are there from the magnetic north to point in this exact direction. 232º. Repeat the process in the inverse (Target to Source) and you will get the second heading you need (52º)

OrientationWrite down this information also

Source antenna orientation (from magnetic north): 232º
Target antenna orientation (from magnetic north): 52º

Final calculations before jumping to the field

The last information we are going to need is the antennas tilt. Make a resume of all we know at this point:

Distance: 5,68 km
Elevation Gain: 224 m
Source antenna orientation (from magnetic north): 232º
Target antenna orientation (from magnetic north): 52º
Source antenna tilt:
Target antena tilt:
Link distance:

Taking the elevation profile screenshot we made before, we can draw a triangle. Now you see that we are facing a really trigonometry problem, with a rectangle triangle, where you know both legs:

Trigonometry

Now you can go for you school books, or use one of the thousands of on-line calculators you can found on the Internet:

analyzemath

angles

Now, you have all the information:

earth_trigonom_resolved

Distance: 5,68 km
Elevation Gain: 224 m
Source antenna orientation (from magnetic north): 232º
Target antenna orientation (from magnetic north): 52º
Source antenna tilt: 2,26º
Target antena tilt (hypotenuse): 87,73º

Since things my be good in the paper, let’s go to the field now.

A first look on the field

Hands-on camera, lets go to the source and target locations:

Ok… behind the clouds is our objetive. At least, from the roof, there not seem to be any visual obstacle.

Emitter

However, in the reception side… we have some troubles:

Receiver

Using all the terrain we dispone, we should try to find a location with direct vision with the Source (always inside our property):

Receiver

Better! But some zoom would be great:

zoom

You can find in forums a lot of ways to make the zoom (and even the alignment), from googles to snipers. In this case, we have used a telescope. For the alignment, we have developed a more scientific approach 🙂

All ready to deploy

So, from a theoretical point of view, this project seems feasible, so its time to buy and deploy the hardware.

The last problem we probably should face are those trees in the Target point. But we can only check it with the hardware already in place…

I see you in the next post!