Creating an internet connection across San Diego with no Line of Sight (LoS).

 

This project utilized two Ubiquity 900Mhz radios to accomplish a Point to Point link between a building in North La Jolla, and a building in Clairemont. This was about a 5km distance that needed to be bridged. The idea was to use my parents quick internet at my own house that could only use DSL. The project really wasn’t able to deliver on that front, as the throughput ended up being too low. Between the two properties lay trees, hills, other buildings and more. Making a normal 2.4 or 5ghz not viable as they don’t penetrate through obstructions well.

These radios establish a standard WI-FI network using normal protocols complete with an SSID and WPA2 encryption. The main difference being that it all runs over 900Mhz instead of 2400Mhz or 5000Mhz.

 

First Connection

It took a while to get first connection. At one point I became concerned the radios were defective as they would not operate in the same room. However, it turns out that the high gain was just too much if they are too close together. After climbing a tree and pointing the antenna where I [thought] its counterpart was I received a beep and a small red light lit up, indicating a connection with the other point. It was faint, wouldn’t stay connected and was too slow to load

the other antennas web interface. Through a mix of remote desktop, a hacked together network and messed up

subnet, I was able to have the antenna on the same network as the internet during troubleshooting.

 

Optimization of the link

After much trial and error and driving between the two points, I was able to establish a stable, albiet weak connection. Over the course of about a week, I did corrections to the antenna alignment and height/position. Moving it in both locations until I reached a level were I was satisfied it would not go any higher.

I then messed around with the channel width, and found that the larger channels actually limited bandwidth likely due to the obstructions weakening the signal if it is less concentrated over a larger area.

 

 

 

 

 

 

 

 

 

 

 

 

End Result

Finally, after a lot of tweaking I was able to reliably attain 10-15MBPS depending on the weather. This was usual

ly a pretty even split between up link and down link when tested. It really wasn’t fast enough to replace my DSL connection, and weather (specifically the marine layer at the La Jolla house) limited its reliability. I never ended up using it much, and it will probably go back to my previous employer when they have a use for it.