What is the Received Signal Strength Indication (RSSI) in detail


RSSI is the abbreviation of Received Signal Strength Indication. The received signal strength characterization is calculated by comparing two values; that is, it can be used to determine how strong or weak the signal strength is compared with another signal.

 

The calculation formula of RSSI is: 10 * log (W1/W2)

The base number of the log is 10 by default, W1 represents power 1 (generally the power to be measured), and W2 represents power 2 (standard power). The results’ significance is an indicator of how much W1 is larger or smaller than W2. The unit is DB, which has no practical significance but represents a relative value. It can be understood as the difference between the ratio of W1 and W2. This is an abstract value without a specific unit. Of course, when comparing W1 and W2 are of the same unit, but no matter what unit is used, the difference between them is the same DB number.

Special case: when W2 is 1, the unit of RSSI can be determined according to the unit of W2. If W2 is 1mw, the unit of RSSI is dBm; if W2 is 1w, the unit of RSSI is dbw. That is when W2 is 1mw or 1w, the unit of W1 can be changed from MW or w to dbm or dbw.

for instance: The value of converting 40000 MW of power to dBm is 10 * log (40000/1mw) 46 dBm.

 

So why introduce DB?
1. First of all, the most obvious function is to reduce the value to facilitate reading and writing, such as the following example:
0.000000000000001 = 10*log(10^-15) =-150 dB

2. It is also convenient to calculate small values: multiplication is used in multi-level magnification, while DB uses addition due to logarithmic log. For example, if you zoom in 100 times and then zoom in 20 times, the total magnification is 100 * 20 = 2000, but the calculation of DB is 10 * log (100) = 20, 10 * log (20) = 13, and the total magnification is 20+13=33db

3. It is more accurate for the actual feeling. When the power base is 1, 10 * log (11/1) ≈ 10.4db increases from 1 to 10. When the base is 100, 10 * log (110/100) ≈ 0.4db increases. When the base changes, the same absolute increment grows in different ways, which matches what people actually see.

RSSI is an indicator of received signal strength. That is to say, the greater the RSSI value, the greater the received signal strength. However, it does not mean that the greater the RSSI value, the better. Because it is often necessary to maintain such an enormous power, more repeaters are needed in the middle, and the cost is high. It is unnecessary. Generally, it is only 0~- 70dbm.

The above is the explanation of Received Signal Strength Indication (RSSI) knowledge brought by Shenzhen HDV Phoelectric Technology Co., Ltd., which is an optical communication manufacture company. Welcome you to inquiry us for high-quality services.

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