Signal strength is expressed as a negative number, so the closer it is to zero means a better signal. Thus, -60 dB is a stronger signal than -70dB. Your phone may show this as a positive number, in such cases, simply convert it to negative. For example, 70 dB is actually -70 dB. Any reading above -80 is good and indicates full bars. However, anything under -110 indicates a very poor signal.
There are several methods that can be used to measure signal strength to find the strongest signal from cellular towers. The first method is to use the LCD display on a signal amplifier that shows the downlink power output of the amplifier in each band. The second method is to use a mobile phone or mobile phone app to test signal strength. The third way to see how cellular signal strength is measuring up in a given area is to use a commercially available signal strength meter.
LCD Display Method
Connect the outdoor antenna to the booster’s outdoor port. Fix the outdoor antenna on the roof of the building and point it to the nearest cell tower. Then have a look at the gain and output power value displayed on the amplifier’s LCD.
The outdoor antenna receives the strongest signal when the booster’s downlink output power reaches its highest level in each band. If the LCD shows maximum gain and power, and there are not any alarms (no ISO, ALC, OFF legend flashing and no quick flashing green or red in LEDs), means the present location is the best for ensuring that the booster has maximized performance.
Note: These showed values may vary dynamically at times between 1-3 dB which is normal due to outdoor signal conditions.
In situations where the desired carrier’s signal is much weaker than the other local signals, using the LCD display is not recommended because usually, the LCD will show the strongest carrier’s signal. In such cases, using a mobile phone, app, or signal level meter can be a much more accurate method of homing in on the best signal for installation.
Mobile Phone Method
You can use a telephone to test signal strength on the top of the building. The number of bars on the network indicator will define the approximate strength of the received signal.
Viewing your phone’s actual signal strength reading is much more accurate than reading the bars. The issue with the bars representation is that there are no standards across different carriers for displaying the bars. Different cell phone manufacturers may define different signal strength indications. That means one phone’s 3 bars may well represent a stronger signal than another phone’s 4 bars or even 5 bars.
One phone may look like this:
Signal strength?-85, level is SIGNAL_STRENGTH_GREAT, define 4 bars
Signal strength?-95, level is SIGNAL_STRENGTH_GOOD, define 3 bars
Signal strength?-105, level is SIGNAL_STRENGTH_MODERATE, define 2 bars
Signal strength?-115, level is SIGNAL_STRENGTH_POOR, define 1 bar
Signal strength?-140, level isvSIGNAL_STRENGTH_NONE_OR_UNKNOWN define 0 bar
Another phone may look more like this:
Signal strength?-97, level is SIGNAL_STRENGTH_GREAT, define 4 bars
Signal strength?-105, level is SIGNAL_STRENGTH_GOOD, define 3 bars
Signal strength?-110, level is SIGNAL_STRENGTH_MODERATE, define 2 bars
Signal strength?-120, level is SIGNAL_STRENGTH_POOR, define 1 bar
Signal strength?-140, level is SIGNAL_STRENGTH_NONE_OR_UNKNOWN define 0 bar
So the best way to view the signal strength dBm reading is by your phone’s Field Test Mode.
Apple iPhone Field Test Mode*
*This method will only work on iPhones without the iOS 11 update. The iOS 11 update removed the ability to use field test mode on iPhones with iOS 11 and newer versions. We at HiBoost strongly feel Field Test Mode is an important tool for consumers. We feel buyers have power in this decision. If you agree, contact Apple and tell them you’d like to have Field Test Mode restored in future iOS updates.
- Dial *3001#12345#* and press the Call button. This will launch the Field Test Mode.
- Hold down the power button until the “Slide to Power Off” appears, then release the power button.
- Then hold the Home button until the Field Test mode quits.
So now you’ll see your numerical signal strength on the top line of your phone; you can tap the signal numbers to switch to signal bars and vice versa. The negative number is the decibel signal strength reading and should be based on the carrier name and the network type.
To exit this permanent field-test mode, reboot the phone or go back to Field Test and exit it via the Home button.
For those that have iO11 you can check out this article from our vendor RepeaterStore and it will walk you through the process of getting to field test mode.
Android Field Test Mode
- Press MENU
- Choose “Settings”
- Choose “About Phone”
- Choose “Status” or “Network” depending on your manufacturer
- Check “Signal Strength.”
It may be necessary for you to have to contact your phone manufacturer’s customer support contact for help. Alternatively, there are mobile apps you can download, such as SignalCheck Lite, Network Cell Info, which may allow you to read your signal strength as well.