Application of RSSI Signal Strength in Wireless Transmission

What is the RSSI signal strength？

RSSI is Received signal strength indication, which refers to the signal strength during wireless reception. It is related to the transmit power of the wireless module, the design of the RF front-end and the gain of the antenna. The unit is the unit of power, generally expressed in dBm. The signal-to-noise ratio (SNR) is also calculated by RSSI, SNR = Signal/Noise Ratio, which is the power ratio of signal to noise.

What is the display of RSSI signal strength?

For the display of RSSI signal strength, the modules of different wireless chip solutions present different values, and in general, there are multiple RSSI distinctions for different wireless chip manufacturers. Many wireless chips have two kinds of RSSI, one is the RSSI of the received packet, and the other is the RSSI in the environment.

The received packet RSSI refers to the register value of the signal strength of the currently received data after the wireless module at the receiving end receives the data after the wireless module sends information, that is, the receiving module obtains the signal strength currently sent by the sending module.

The RSSI value in the environment is also the frequency noise. When the wireless module is in the receiving state, it can detect the strength of the radio frequency signal of the same frequency band in the current environment.

For the received packet RSSI, the RSSI value can only be generated when the module receives the data normally; for the RSSI value in the environment, as long as the module is in the receiving state, the signal strength in the current environment can be detected at any time. In terms of detection conditions, the detection range of RSSI values in the environment is wider, which is more suitable for users to use RSSI.

What are the applications of RSSI signal strength in wireless transmission？

1.       The networking application of RSSI signal strength in wireless transmission

Since it is necessary to detect whether a wireless module of the same frequency band is currently transmitting during the wireless radio networking, it is necessary to use the RSSI value to judge. For example, No. 1 needs to send data to the host. At this time, it enters the RSSI mode to detect the frequency noise in the environment, and judges whether the transmission is currently allowed to avoid the interference of simultaneous transmission in the same frequency band.

2.       Application of RSSI Signal Strength in Distance Test

In practical applications, sometimes it is necessary to detect the distance between two devices, and the RSSI signal strength can also be used for detection, and the distance between the devices can be judged by converting the current RSSI value into the distance.

This method can only roughly estimate the distance, the power supply of the module and the gain of the antenna, which has a great impact on RSSI.In this case, it is necessary to measure a relatively close distance value only when the antenna gain is the same, the environment is open, and the power supply is stable.

3.       Application of RSSI Signal Strength in Positioning

There are many positioning applications of RSSI signal strength, through the three-point positioning method. The device to be tested is in a triangle area networked by fixed devices. When the device to be tested sends radio frequency information, the fixed device can calculate the specific location of the device through the current three RSSI values.