Poor Mobile Coverage at Home? The Telstra Cel-Fi Smart Antenna Solution

Written by Martin Regtien on . Posted in Mobile Devices

Cel-Fi system
I have never considered myself a fringe dweller except when it comes to mobile phone coverage, stuck at the fringes of Telstra's network. There are thousands of people in the same situation who have been relegated to second class citizenship in this 21st century when it comes to mobile connectivity.  For years you've been paying for missed calls, dropped calls not to speak of extremely poor wireless broadband.

You've tried all the solutions: rooftop antennas, blue tick phones, perhaps even looked at the promises made by repeater units....
Is there a real solution, one that is even sanctified by Telstra?

 

If you are reading this article you most likely have been subsidising Telstra for many years by making calls to your message bank because you missed another call. Poor coverage in your area is not just an inconvenience: it can cost you business and sometimes even lives are at stake.
We may have been waiting for Telstra to put another tower in our area, but if you live in a sparsely populated area, the economics are against it.
Rather, Telstra has been researching ways to bring a better signal to the end-users and getting them to pay for it. Yes, that's right: there is a solution, an excellent one, but it will cost ye! Whether or not this is fair is a different topic. I've got some strong feelings about the subject but the task at hand allows me only to describe the solution which will bring great coverage to your home.

There Is Only One Proviso...
... and that one condition is that you must have at least some signal somewhere on your property.


You know you have some sort of signal if the only place where you can send a message is when you have to go to the veranda and hold your phone high! I've done it for years....
So as long as you have one bar or so, that signal can be amplified and broadcast throughout your home. That's the idea of a repeater.


Now repeaters are not new and there have been many illegally imported. That would not be so much of a problem if it solves the coverage issue for you without causing issues for the carriers' mobile networks. When I say "illegally", strictly speaking repeaters are not prohibited in Australia but generally cannot be activated without express permission from the spectrum owner and the device has to be registered by the Australian Communications and Media Authority. That means that they have to be tested to prevent them from interfering with the network and impacting other uses in that cell. So if you get yours through eBay just be aware that you could be fined up to $165,000 and even face some jail time for illegal use. That seems excessive but apparently sometimes an illegal repeater can knock out the coverage in an entire area! Most of the times though a degradation of the network takes place.


So let's look at the officially sanctioned solution.
Telstra has been very quietly introducing what they call the SmartAntenna. Their branding of a repeater as the Telstra Mobile Smart Antenna is a second-generation Nextivity Cel-Fi device which has been extensively tested on their networks. And it also includes some features specifically developed for our national telco.

How Does It Work?
Let's talk in layman's terms.

I've read all the technical papers that give a background to this unit but what it boils down to is this: the system has two units, a Window Unit (WU) and a smaller Coverage Unit (CU). The function of the WU is to amplify whatever signals are coming to the house and send it to the Coverage Unit. Obviously, you need to place the WU close to the window with the best signal. The WU has four internal antennas to cover every direction. You place the CU at the other end of the house where it will rebroadcast the amplified signal from the WU. That's it in a nutshell.


How Did it Go in Practice?
Let me first comment on my first impressions of these black boxes. They are attractively styled with easy to read LED indications. The Windows Unit is the size of a small shoebox and the CU is a lot smaller still. They both have exactly the same power units.


I selected the window next to the veranda where, on a lucky day, I would get one bar on my phone. Having plugged in the unit, which gives the signal strength in five gradations, I straightaway got three bars! That was a good omen. I took the Coverage Unit to my office, plugged it in and received a red Out Of Range indication.

Hmmm. Perhaps a room too far?
So, when I placed the Coverage Unit 18 m from the Windows Unit it did not give any connection.
I was surprised about that because the walls in between are just wood and plasterboard....
However, when I placed the CU 2 m closer on a high cupboard it connected with a 9. This is the highest that it can get and anything between a seven and nine is good.

Cel-Fi 1

 

I've got a screenshot that says it all: here is the exact moment when it went from no coverage to full signal strength!

 Cel-Fi signal

 

Now, I had been using a USB Cell Ranger for a little while before testing the Cel-Fi, trying a real low-cost "solution" but even though I got 4 bars on my Samsung S3 with it if I placed it right onto the unit, the Network Signal Info Pro software doesn't show much of a real improvement in dB gain...
In other words: those 4 bars are just fake, if you ask me!
However, the Cel-Fi system gave real signal strength improvements, resulting in perfect calls.

At this stage of testing the Cel-Fi had already scored 8/10 in my books in that it provides coverage in the room I need it most: my home office. Now let's see what it will do for network coverage throughout the house.

Signal boost within 5 m of the CU is excellent but drops off pretty fast: in the rest of the house it is practically zilch with the current placement of the CU.
Within 3 m of the Windows Unit there is hardly any additional signal strength even though the WU itself is getting three bars.

Yagi yoga
Maybe things will change once I plug in the optional extra: the yagi antenna. A yagi antenna, as opposed to an omnidirectional antenna, needs to be pointed in the direction of the broadcasting tower. If you don't know which tower gives you the best (or only) signal, there is an app for that. You will find the exact location on Google Maps.

I installed the yagi antenna on the rafters just below the gutters, more or less in line of sight with the tower, nearly 50 k's away which is a fair distance of course.

 Cel-Fi 3


I plugged in the antenna cable on the underside of the Windows Unit and immediately it went to 5 bars!

Cel-Fi 2


Have a look at the very tight angle of the plug when connecting the cable to the WU. A slight redesign here would be useful...

 20121223 125228

 

So now I have full signal strength on the Cel-Fi repeater and consequently on my phones and Telstra Bigpond router!
Plugging in a yagi antenna also means you can place the WU anywhere you like and not just against a window...

Observations
1. Whilst the Bigpond router now also shows high antenna signals, Speedtests only max out between 1 and 3Mbps and high ping rates.
So there has been no improvement on that score but it is probably just Telstra related.

2. The CU, being pretty much at the edge of its range, sometimes goes from 8 to 9 down to the red no signal sign.
Strangely enough, it still gives full bars on the mobile phones when that happens.
Haven't come across any satisfying explanation for this phenomenon...
(I could move it closer to the WU but its placement now is the most practical for me and reception through the rest of the house is quite satisfactory).


3. The Cel-Fi is registered and locked to your geographical location within the cell. You can move it around on your property but not outside your cell.

Conclusion
Let's summarise the benefits of the Cel-Fi:


1.Full signal strength on the NextG network if you have some signal to begin with.
2. Simple installation
3. No fixed broadband connection needed.
4. Greater battery life for your mobiles as they are not constantly struggling to connect to a distant tower
5. Cost savings in no more dropped or missed calls.
6. Fully tested and supported by Telstra.


Downside: the high cost of purchase for the Cel-Fi to make up for Telstra's lack of decent coverage in your area.
Some subsidy would be in order seeing that over the years we've been contributing to our telco's coffers for missed calls, dropped calls, lack of speed...


So while the Nextivity Cel-Fi is a great solution to poor coverage in your area, the price at around  AUD800 might be beyond reach for many.


Highly recommended – 8 out of 10 (if you can afford it)!

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