Powering Ubiquiti links from 12v

So it seems that I can power a Ubiquiti Bullet and Rocket directly with DC 12v. In the past I have been chasing POE and wasting precious milli-watts converting 12V to POE standard (Usually 24v or 48v) then powering the devices.  A power saving can be made by connecting direct to 12V. If using a solar setup, the power savings can mean more up-time, and better use of your batteries. Some testing will follow this blog post. However in the interim, it seems pretty stable here in the workshop.


How to make your own cable for 12v power supply.

  • RJ-45
  • RJ-35 Crimp
  • Pliers
  • Box Cutter
  • Straight through Ethernet cable

In a nutshell, the Ubiquiti Bullets and Rockets grab power from 4 pins on a standard RJ-45 connector. In our case here in Australia (Blue/White-Blue) pins 4 & 5 will carry 12v+ and pins 7/8 12v-.


Prepare your cable

If you have the resources to cut up a straight-through cable, then go ahead and cut one end off. (Otherwise you will have to complete two terminations) Strip the cable back a bit to expose the pairs of wires. Identify the solid blue and Blue-White wires. These will be your 12V Positive injection points. Now identify the Solid Brown and Brown-White wires. This will be your 12V Negative injection point. From here identify the remaining cores and insert them into an RJ-45 housing.

  • PIN 1 – White-Orange
  • PIN 2 – Orange
  • PIN 3 – White-Green
  • PIN 6 – Green

Now crimp your RJ-45 and you are all done. The bare wires can be used in anyway to inject 12v. ie Barrel jack. I would use a fuse close to the source to protect your equipment. Also confirm the pinouts prior to plugging in. The last thing you want is to fry your Ubiquiti gear.


Or Don't hack up a cable and buy some injectors

If you want that more professional look, then you can always purchase a few of these injectors. Have a look at the specs though and make sure the power inputs are on pins 4/5 and 7/8. Let me know how your setup goes? I really need to do some testing on the longevity of this type of setup. My only concern is that the fluctuating 12v from batteries could damage the Ubiquiti gear over time. Maybe I need to look at a circuit to provide clean power.



Third-world countries have better internet then me!

We moved into a brand new home about 3 months ago. Most people would have checked out the comms infrastructure in the area prior to buying. Silly me however assumed that being only 20km from the center of Perth city we would be able to achieve decent DSL speeds. Well… I can tell you that no matter how close you are to the city, it is always wise to check out the telephone exchange in your suburb. After moving in and being sold “ADSL2+” we were very disappointed with the speeds and began looking for alternatives. This is my journey…


"ADSL2+"

After moving in I contacted our Telecom company as you do, and requested ADSL2+ be installed. After a few days sure enough we had been setup with ADSL2+ and a 1000Gb Monthly data plan. I was pretty excited that the service had been setup so quickly, however the joy was short lived after I ran a speedtest… 1.6Mbps … consistently.

To keep the story short, I went back and forward with the telecom company tech support to see if it was a fault or just the standard. As it turns out they could not offer any better speeds into my residence. The company ended up refunding everything because it was not even possible to use the data in a month with speeds like that.

We all have “that mate” who boasts about his internet speed, and it just so happens my mate has up to 100Mbps and is only 900m away. (Yes….devastating I know…). So I hit him up to see if we could pipe some traffic over to mine. But first I needed to see if we had “Line of sight” (LOS) between the two houses. This is what we had to work with.

~900m shot, one house elevated above the other, a few parks in the way. Easy you say! well….it seems the trees are the limiting factor here. We have large pockets of trees in the way.

What I will say about the Airgrids though is that they are super simple to assemble. (Tool-Less design) and really fast to get up and running. With the Airgrid having the radio inside the feed-horn, all you require is a piece of cat5 and the POE injector and your in business. I foresee the Airgrids being used in rural environments with direct LOS to the target. I would probably look elsewhere if I was trying to push further then 10-15km though.


5Ghz (Make note to self: 5Ghz does not like trees!)

My first attempt at setting up the link failed miserably. Now 5Ghz obviously gives us the most throughput. But with the gear I had, I was unable to even achieve a link.

I purchased the Airgrids for an economical $99ea. Hopeful I may achieve even half the 80Mbps suggest on the ubiquiti planner. The Airgrids are a single channel radio operating in the 5Ghz unlicensed band. For the price and output they appeared to be a good bet. Me being a bit of a novice though didn’t take into account the “tree” effect on 5Ghz. It seems that there is a substantial difference in punching power between 5Ghz and say 900Mhz. (Which I ended up with!)


2.4Ghz (Success - But only just! Not our final solution)

Since 5Ghz for me was a total failure, I decided to give 2.4Ghz Unlicensed a crack. The first thing I want to say is that I did not use rockets with rocket-dish antennas. Everyone has told me, “you would be surprised how much better the good gear works” and I agree, however with a $1200+ outlay I decided to try single channel radios first. I could get my hands on some Ubiquti bullets and some cheap 28dBi grid antennas to test the link first.

I did have initial success getting the links up and running, however no matter what I did I was unable to improve the signal strength. I tried to get as much elevation as I could on each roof mount, I tried lowering the channel widths etc etc. At times I would get a solid 5Mbps of internet traffic but most of the time I would equal my 1.6Mbps that I had with DSL.

Maybe I could double the throughput with Ubiquti MIMO Rockets and dishes, but I was still weary to spend money on the gear only to experience the same “flutter” that I was on single channel gear.


900Mhz (Winner Winner! For this link anyways.)

A mate of mine suggested I give 900Mhz radios a go to see how that went. I was starting to see that as we stepped down the frequency range the “punching” power through the trees was indeed getting better. However using the 900Mhz band in Australia is a little bit tricky and you have to be careful with your setup so that you do not break the law. From what I can tell, 922Mhz is the only frequency you are allowed to use and can use up to 10Mhz channel width on this frequency. Thus the throughput is lowered significantly. However If I can still achieve 20Mbps of actual throughput then I’m still winning.

The other consideration is the power levels. You really need to drop the power (Most 900Mhz Ubiquti radios that come out of Australia are limited by firmware so you cannot push the limits anyhow.) From what I can tell some of the 3G mobile services sit on the 900Mhz range and the ACMA does not want unlicensed users to interfere. Which makes sense.

With all that in mind, if you have another radio sitting on 900Mhz close by you could be in trouble because you cannot move from 922Mhz.

So our initial testing saw us setup 2 x 900 Rockets with the MIMO 16dBi Yagi. We had it sitting on the roof and it already had a link. Not very good but was in. Once we got it up the mast and semi aligned we could see straight away that a lot of the “flutter” had disappeared and the signal strength was sitting solid. A quick speed test saw us get a solid 10mbps on a 5Mhz channel width. This put a smile on my face.