Tomas Chlebek Since at least the antennagate days of the iPhone 4, the accuracy of the signal quality indicator in smartphones has been a fairly frequent topic of discussion. Those who do not trust the empty and filled circles in the corner of the display can easily replace them with a number that should, at least in theory, provide a more reliable value.
Signal strength is normally measured in decibel-milliwatts (dBm). This means that this unit expresses the ratio between the measured value and one milliwatt (1 mW), which indicates the power of the received signal. If this power is higher than 1 mW, the value in dBm is positive, if the power is lower, then the value in dBm is negative.
In the case of a mobile network signal with smartphones, the power is always lower and the number in the dBm unit is therefore preceded by a negative sign.
On an iPhone, the easiest way to view this value is as follows:
- Type *3001#12345#* in the dial field (Phone -> Dialer) and click the green button to start the call. This step will put the device into Field Test mode (used by default during service).
- Once the Field Test screen appears, press and hold the sleep button until the shutdown screen appears. Do not turn off the phone (if you do, nothing bad will happen, but you will have to repeat the process).
- Press and hold the desktop button until the desktop appears. Then, in the upper left corner of the display, instead of the classic circles, the numerical value of the signal strength in dBm can be seen. By clicking on this place, it is possible to switch between the classic display and the display of the numerical value.
If you want to switch back to the classic display of signal strength again, repeat step 1 and after the Field Test screen is displayed, just briefly press the desktop button.
Values in dBm are, as explained above, practically always negative for mobile devices, and the closer the number is to zero (that is, it has a higher value, taking into account the negative sign), the stronger the signal. Although the numbers displayed by the smartphone cannot be completely relied on, they provide a much more accurate indication than a simple graphical representation of the signal. This is because there is no guarantee how exactly it works and, for example, even with three full rings, calls may drop out, and on the contrary, even one may mean a sufficiently strong signal in practice.
In the case of dBm values, numbers higher than -50 (-49 and above) are very rare and should generally indicate extreme proximity to the transmitter. Numbers from -50 to -70 are still very high and are adequate for a very high quality signal. The average and most common signal strength corresponds to -80 to -85 dBm. If the value is around -90 to -95, it means a lower quality signal, up to -98 unreliable, up to -100 very unreliable.
A signal strength of less than -100 dBm (-101 and below) means that it is practically unusable. It is quite normal for the signal strength to vary in the range of at least five dBm, and factors such as the number of devices connected to the tower, the number of calls in progress, the use of mobile data, etc., have an effect on this.
while this is influenced by factors such as the number of devices connected to the tower, the number of calls in progress, the use of mobile data, etc.
… device grab… :-D
otherwise, when a person is on the home screen, by tapping a finger on the signal, it changes between dots and dBm...
That's right, one is forced to such strong codes and procedures with buttons, when all you have to do is tap your finger on the signal and it switches back and forth. ? Well, at least one wonders at the hidden menu, which is still useful. ?
I tried, but somehow it didn't work without the i7 device code and the latest software
I have an iP5, the latest iOS, and it works even on the locked screen, when entering a code, and on desktops with icons. I don't know how the latest versions of the phone are, I'll ask a colleague. ?
And if I want to return it to its original state? Thank you
We write it in the text: If you want to go back to the classic display of signal strength again, repeat step 1 and after the Field Test screen is displayed, just briefly press the desktop button.
Great, thanks a lot!
It shows me -110 and around -89, so I don't know where the error is. The call works.
I have there - 102 and when switching 3 bubbles. Still, the signal seems to be sufficient, everything works great. And according to you, it really shouldn't. Well, I do not know……………..