How is cell signal measured?
Cell phone signal strength is usually measured in decibels (dBm). These are received by the mobile phone from a cellular network. The strength of a signal ranges from about -30 dBm to -110 dBm. Overall, the closer the number is to zero, the stronger the cell signal. Signal bars on mobile phone that are better than -85 dBm are considered great cell phone signals.
In most mobile devices, the signal strength the device is receiving is displayed through a set of bars that highlight the strength the device is receiving. However, the bars on your cell phone are usually unable to accurately measure signal strength. The main reason behind this is the fact that there’s no industry standard for what one bar represents, and whether it’s measuring your 3G voice or 4G data performance.
As such, two bars worth of coverage on one network, say Sprint, is maybe three bars on another network, say Verizon, for example. Besides the carrier differences, the number of bars that you see could vary greatly based on how you’re holding your phone, the previous activity on your device, and your phone’s manufacturer.
Using Field Test Mode
For those that are curious about the signal, your phone gets, determining the dBm on your device is a much more accurate measure of the strength of a cell signal than the bars displayed on a device. Based on the device you’re using, there are a few different ways to do this, including using the field test mode, which is available on both Apple iOS and Android devices.
On iOS, the Field Test Mode gives the user a detailed breakdown of their cellular connection, signal strength, and providers. It ideally displays the cell signal on iPhones as digits instead of dots or bars. In case you’re unable to determine the signal strength reading on your Android device using this method, check your device operations guide.
Moreover, there are apps available from the Android Play Store, including SignalCheck Lite, which lets you read your signal strength. Keep in mind that the closer the dBm is to zero, the stronger the signal. For instance, -100 is a poor signal while a -50 is a stronger signal.
Cell signal is usually strongest when a phone is near a cell tower. As you probably already know, there are relatively very few areas these days without a cell tower close by. Still, some environmental factors could impede cell signals from reaching your phone for reliable connectivity.
What blocks cell signals?
You have probably already experienced dropped calls, or have been in the middle of receiving or sending a document or message only to have the process stopped unexpectedly. This might have happened while driving through a tunnel, riding the subway, stepping into an office building, or entering a parking garage.
Nonetheless, at one time or another, we’ve all entered what’s commonly referred to as the “dead zone”. But you’re not alone. 72% of Americans have complained of dropped calls, and 6% say that they get dropped calls several times a day, based on data from PEW research.
What blocks cell signal in areas where there should be plenty of cell towers and seemingly an abundance of coverage? Well, there are several things. Cell signals can be obstructed by natural barriers like mountains and even common building materials like concrete, steel, and brick. LEED-certified glass windows can also impede a strong signal.
Moreover, as the number of daily cell users increases, networks are increasingly becoming bogged down as devices compete for signals. This is why you will certainly experience some form of lag in service when attending a conference, a concert, or an event with a large number of people using their cell phones.