Bridging The Gap

When Wi-Fi Goes Horribly Wrong

In general, I hate wi-fi.

I'm just not keen on the vagaries of wireless communication. At least with wires, you can trace the problem. It works or it doesn't work, but only the wires or the connectors are at fault and you can just replace one or the other to find out which. And, of course, you can test wires and connectors with simple testing equipment.

Actually, you can do a lot of testing for wi-fi as well, but the equipment is dramatically more expensive and you are always subject to the issues of environment. Having said that, if someone asks me to set up a wi-fi bridge as part of any installation, I'll have a go.

The Project

Keeping livestock is a full-time 24/7 kind of job. Sure, it's nice to go home at the end of the day and forget about work, but sometimes you just can't do that and need to be available or even on-site around the clock.

One partial solution to this problem is to have a CCTV system that can be viewed remotely, allowing you to monitor your livestock from the comfort of your armchair. Well, I do CCTV so this shouldn't be a problem, even if the farmhouse is half a mile or so from the cattle sheds.

According to Google Earth, that's 0.49 miles (795 metres) from antenna to antenna. At least there's a valley in between, so we do have a good line of site and no major trees in the way or anything. I've bridged a couple of hundred metres in the past, so all we need are bigger antennas and we'll be good to go.

The Set-up

OK, the sheds are big and each of the two sheds will require two cameras with Pan, Tilt and Zoom (PTZ) under remote control. This is a lot of Cat5 cabling (about 250m in total). But it is cable, so we can run the lengths, put the plugs on and test everything. Each shed needs a network switch and the two sheds are joined by another long length of Cat5. A couple of minor problems and it's soon working fine at this end. The laptop shows the pictures from all four cameras and everything is working as it should.

Now we add a wi-fi access point / repeater into the mix and, using a long antenna cable, connect it to a big dish antenna on the end of the roof. The internet is making big claims for these things and is full of tales about how easy they are to set up and how far people are getting a signal from so it all sounds good. Head down to the farmhouse and put up an identical dish and access point connected to the existing ADSL router.

The bridge was set up and tested in the shed so we'll now have it working across the half-mile gap.


Several hours of experimentation and testing follows. Walking around the field carrying the dish, AP, laptop and mobile phone eventually leads to the conclusion that the signal is simply not strong enough. I might have an A-level in physics, but all this dBi and dBm stuff is just a bit more than I need to try and get my head around. I just want something that you plug in and it works. I can do the configuration, but I don't want to have to do calculations and stuff.

This was supposed to be a quick and easy job, but now it's turning into a bit of a nightmare.

Plan B - Well You Should Always Have One

It's time to head off back to the internet and do some more research. I'd seen a couple of reviews for Ubiquity Networking products, but mostly big APs for offices and hotels. Maybe they had something that would act as a bridge. Sure enough, they have a range of base station antennas with built-in high power transmitters. I order a couple of these and wait anxiously for a few days for them to arrive.

Set them up at home, configure them as a bridged pair and see what happens. I can't get more than about 15 metres apart, but at least the interface for these has a meter to tell you how good the signal is. Next step is off to the site and swap antennas for these. They don't look very impressive, but the wiring is just a Cat5 with Power-Over-Ethernet (POE) to drive the transmitter. We set up the one on the shed first, then go straight round to the house and put the other one up. We need a powerline network bridge to access the router, but this isn't a problem as I have a spare pair.

Switch on, log in and ...


Just like that, better than 80Mbit/s between the two networks and no problems with lag or drop-outs. A bridge across about half a mile for only £100. Signal strength is reported as good and I have no doubt it could reach a lot further than is does at the moment if it needed to.

I still have some work to do on site to get the router configured for external access, but finally there's a working network of cameras that can be controlled from half a mile away. Once the router is sorted, they'll be controllable from the other side of the world.

If you want to know more about Network Bridging or CCTV installation, drop me an email or give me a call.