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Fred Harding: Use an RF Signal Detector Before Spec’ing a Cellphone Repeater

Don't bother with a cellphone repeater if it won't work on the premises. The Wilson RF Signal Detector helps installers determine if a repeater is necessary.


Fred Harding · September 3, 2013

Installers are responding to market demand for improved cell phone performance in both the residential and commercial spaces by offering cell phone repeaters. A number of manufacturers are offering equipment that essentially picks up the cell phone signal outside the structure, sends it via coax to an amplifier located inside, and than rebroadcasts it through an antenna or antennae.

It’s a nifty idea, because it allows homeowners to continue talking as they move from outside to inside without interruption.

The issue for many installers is whether the systems actually will do any good for their customers. The answer is maybe.

Let me clarify. If a facility does not have any signal to be rebroadcast, no rebroadcasting system will work. If a facility has excellent coverage inside and out, adding a rebroadcasting system won’t do much good other than adding a line item to a sale. The building owner won’t benefit.

The question then becomes whether there is an adequate signal outside to be captured and repeated inside. You can take a look at a signal strength bar graph on your telephone while standing outside and get some idea. You can access one of the utilities bundled into many phones to get a more accurate reading. Or, you can do the right thing and get a meter. Wilson Electronics makes a meter (model 867501) that I’ve been testing out here on the West Coast (of Wisconsin), and it works.

Here’s why you need a meter: Cell phone signals for voice purposes are carried on two separate bands; the 800 Mhz, which has signals ranging from 824 to 894 Mhz, and the 1900 Mhz, with signals between 1850 and 1990 Mhz. Different cell phone service providers use different frequencies. If you are installing a repeater for Mr. Smith, and your phone shows you have signal strength, there’s no guarantee that his phone will show anything at all. He might be on the other band, which may not have a tower nearby.  The Wilson Detector allows the installer to select the band you want to test for all of the bands with multiple button pushes, toggling through each as you go.

There are two types of outdoor antennae for cell repeaters: omnidirectional and yagi. A yagi style requires that you point it at the broadcast tower. Having a signal strength meter clearly lets you know that it is properly aimed.

RELATED: Review: Wilson Electronics 841262 Cell Phone Repeater

Knowing that you can provide service for either type has value in retail and commercial environments, where the type of service can and will vary with the user. In a residential space, it’s nice to know that your customer can change from one carrier to another without discovering that they can’t use their new phone because it’s on the wrong band.

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Back to testing. I use Sprint based service for cell phone coverage, and it works where I live. When my wife and I relocated to the area, however, we were using T-Mobile, and the service was spotty at best. It wasn’t unusual to see me standing on a radiator, rubbing a cat, and hollering into the phone in hopes of making a call. Voicemail was disgraceful; I’d pick up messages days and days later while driving toward a more urban area. 

Using the Wilson device inside my house, I was able to quickly see that the Sprint signal, operating in the 800 Mhz range, was delivering -79 dB worth of signal. Switching the meter to the 1900 Mhz band had me hitting -111.

Here’s what the numbers actually mean. Cell signal strength is measured in decibels, or dB. If you have a signal rating of -50 dB, you live on top of a cell phone tower. If your signal strength meter shows -105, you aren’t talking on the cell phone. 

Knowing that information, you can now take the supplied battery case and fill it with batteries and walk around outside. Typically, you’ll get better results outside, as there is less shielding for the signal to penetrate. Homes made with stucco on top of metal lath tend to have real bad performance indoors, as that metal lath acts as a shield for RF signals. If you show rotten signal inside, but better signal outside, you can comfortably put a cell phone repeating system in and have it work, provided you pay attention to details like rebroadcast antenna placement, square footage and the like.

You would use the Wilson the meter at the site inspection, of course, to determine whether it does any good at all to recommend a repeater. You’ll also use it when you do the installation to check your work. It’s important to make sure that locations inside the house where a cell phone is likely to be used actually has decent signal strength.

All in all, I was very pleased with the performance of the Wilson. It’s robust enough to stand up to some knocking around, and flexible enough to easily check throughout the building without tripping over cords. If installing cell phone repeaters is in your business plan, having this meter will improve your efficiency and your bottom line.



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  About the Author

Fred Harding is in sales and technical support at Capitol Sales, a full service distributor of electronic installation hardware. He is a frequent contributor to CE Pro, writing hands-on product reviews and technical tips. Have a suggestion or a topic you want to read more about? Email Fred at fharding@capitolsales.com

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