Mobile phone signal analysis

The concepts of dB and dBm are extracted from the data: dB and dBm are the units of power gain. The differences are as follows: 1. dB is a value that represents the relative value. The pure ratio only indicates the relative size relationship between two quantities, with no unit, when considering the number of dB whose power is larger or smaller than that of B, the following formula is used: 10 log (a power/B power). If the ratio of A to B is used, use 20log (a voltage/B voltage ). [Example] If the power of a is twice the power of B, then 10lg (the power of a/B) = 10lg2 = dB. That is to say, the power of a is 3 dB higher than that of B. If the power of a is half the power of B, the power of a is 3 dB lower than that of B. 2. dBm is a value indicating the absolute value of power (it can also be considered as a ratio based on 1 mw power). The formula is 10 log (power value/1 mw ). [Example] if the power P is 1 mw, it is converted to dBm and then 0 dBm. [Example] For 40 W power, the converted value in dBm unit should be: 10log (40 W/1 mw) = 10log (40000) = 10log4 + 10log10000 = 46dBm. In short, dB is the ratio between two quantities, indicating the relative size between two quantities, while dBm indicates the absolute power size value. In dB and dBm computing, pay attention to the basic concept. When one dBm is used to subtract another dBm, the result is dB, for example, 30dBm-0dBm = 30dB. Well, the unit of the number displayed on the mobile phone is dBm (you can use ALT + NMLL to display the current received signal value on the mobile phone and transfer it from the BlackBerry forum, so this function is available ). when you look at it carefully, you will find that the value is negative. That is to say, the phone will display-67 (dBm), which indicates that the signal is very strong. here we also talk about a small knowledge: China Mobile's specifications stipulate that when the mobile phone reception level is greater than = (city-90dBm; Country-94dBm), the coverage requirements are met, that is to say, the wireless signal strength meets the coverage requirements. -67dBm is more than 20 DBS better than-90dBm signal, so it will have a better voice quality in the call success rate and call process (of course, EDGE/GPRS internet access speed) therefore, the larger the value, the better the signal, because it is a negative value, and it will always be a negative value in your hands. If you are interested in the antenna with a wireless base station nearby, you can also keep your cell phone as close as possible to the antenna panel, so the value is getting bigger and bigger. If the cell phone and the antenna panel get together, then it may be very close to 0 (0 cannot be reached, here 0 does not mean that the phone has no signal.