What is RSSI? What is Q-Factor?

To achieve peak flow measurement performance, the optimal installation position significantly enhances the signal strength of the ultrasonic waves, enabling the most efficient ultrasonic transmission for measuring the flow rate within a pipe.

• RSSI (Received Signal Strength Indicator) : a measure of signal strength in wireless communications. It is usually expressed as a negative value, with numbers closer to 0 indicating a stronger signal. For example, -30 dBm indicates a very strong signal, while -90 dBm indicates a very weak signal.

• Quality factor（Q-Factor）:a measure of signal quality. It takes into account factors such as signal strength, interference, and error rates. A higher Q value indicates better signal quality and more stable communication.

Using the analogy of spoken communication, the best understanding comes when the speaker is loud enough, articulates well, and the meaning is clear, facilitating unimpeded communication. The best quality is achieved with high volume and clarity; followed by low volume but clear speech; then high volume but unclear speech, with the worst being both low volume and unclear speech. This analogy likens volume to RSSI (signal strength) and articulation and clarity to Quality factor (signal effectiveness). In ranking the second and third levels, clarity (Quality factor) is more important than volume (RSSI).

As illustrated by the spoken word example and quality levels, users need to consider the current state of the facility and equipment, spatial arrangement, installation convenience, and other personal requirements. These are assessed alongside the best standards achievable by RSSI and Quality factor. By marking the feasible installation positions on the quadrant chart as described, the optimal installation location for each user can be identified. Furthermore, determining the "optimal installation position for an ultrasonic flow meter" also involves referring to ToM/ToS values, which will be elaborated in a separate article.