Field Test Mode: An Overview & Enabling it on Your Phone

Posted by on April 20, 2015

Field test mode signal strength chart

How do we determine the signal strength in our phones? Yes, we use the “bars” that indicate signal strength, but it isn’t an accurate way to determine signal strength. Not all phones have identical number of bars; some have five, some even have eight. Even when two phones have four bars, they don’t have same standardization, which means, four bars on one phone can be different from four bars on another. Besides, it is vague – what would you understand by saying three bars of signal?

The field test mode signal strength chart above, shows how to grade signal strength in decibels. Experts talk about signal strength in decibels, which means they measure it in decibels. It is a logarithmic unit to measure signal strength and is accurate, making communicating about signal strength easy. However, not many phones show the strength of cell phone signal in decibels. However, most phones come with something we call, "Field Test Mode", which helps determine more information about the phone, including signal strength. And yes, signal strength in decibels. If you are a professional installer, it would help to purchase the cell phone signal detector to find the spot that has the best signal quickly.

Field Test Mode in iPhone

If you want to try out Field Test Mode on your iPhone, it is quite easy – open the Phone application and dial this code on your keypad: *3001#12345#*. Now, hit call. When dialled right, your iPhone enters Field Test Mode and you can see numerical value of signal strength. It is displayed in the same place where the signal strength was once displayed in bars. If you want to exit or resume to previous status, just hit Home button. If your phone has iOS 4.1 or later OS editions, you can do this.

When you want to know the signal strength in decibels and not bars in your iPhone, you can do this: Enter Field-test mode (you can do this by following the instructions given above), keep the power button firmly pressed till you see “Slide to Power Off”. Then, release and hold Home button till you return to main screen. Now, there would be decibels or numerical representing I signal strength. You can tap the numbers and it would move back to bars, or vice versa. You can exit field-test mode setting by restarting your phone, or by entering Field Test Mode and exiting it using Home button.

Field Test Mode in Android

In Android, you can access Field test mode like this: “Settings” > “About Phone”, and voila, the signal strength will display in numbers under Status or Network, which depends on the phone model and make. It is easier in Android.

Field Test Mode for Other Phones

Most phones do support Field Test Mode. To find out how to put an old phone model into test mode, go to this website for instructions.

Why Use it?

Field Test Mode is commonly used for a specific field test, which is also called as site survey. When you are working or staying in an area where signal strength is weak on your phone and you want to improve your signal strength, site survey is the way to go. It helps determine if a signal booster is apt for you. In a site survey, you take precise signal strength readings around and inside your building, to determine if a cellular signal booster can help and what type of equipment is ideal or needed.

Field Test mode is very useful in such scenarios – you can switch between signal bars that are not precise to numbers that are precise, to determine your signal strength quantitatively, wherever you want.

Of course, site survey involves multiple steps, though it isn’t very complicated and you can do the test with little instructions or following the steps, in your home, office or anywhere using field test mode.

The Numbers Explained

Known as RSSI, it is an acronym for Received Signal Strength Indication. It could be triple or double digits and negative. Though a few phones don’t display the negative sign and just display a number say 79, the real signal strength is -79. The closer the strength is to 90, the better the reception. This means, -80 is better than -90. Measurement unit for RSSI is decibel (dB), which is a measurement for signal power. Just like how volume is for stereo, RSSI tells how “loud” your provider’s network is.

Decibel scale isn’t linear – a small increase as 3 dB shows that the signal is two times stronger, while moving up by 10 dB increases signal intensity by ten times. This means, -60 as RSSI is about 10 times powerful than RSSI -70!

Getting a precise reading of Received Signal Strength is important when you want to install a signal booster. Also, you will be able to know the signal power exactly, both within and outside your building, so you can determine the right signal booster for better reception.

Questions? Call us for a FREE product recommendation. Need a cell phone booster installer? We offer installation services by a certified installing team that installs boosters nationwide across USA and Canada. Submit your details for a quote to have your amplifier kit installed by professionals.

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