Patent ID: 11947072
Assignee: HAINAN ACOUSTICS LABORATORY, INSTITUTE OF ACOUSTICS, CHINESE ACADEMY OF SCIENCES
Field: Measurement (Instruments)
Classification: CPC G  Y | IPC G

Claim 7:
8. An automatic trigger and self-calibrated ultrasonic rain measurement system, comprising: a rainfall monitoring module, a self-calibration and rainfall measurement module, a central processing module, a water level monitoring module, and a drainage module; wherein
the rainfall monitoring module is configured to monitor rainfall and send a rainfall signal to the central processing module;
the self-calibration and rainfall measurement module is configured to transmit ultrasonic signals and receive calibration echo signals to perform speed self-calibration under a control of the central processing module, and obtain a calibrated flight time and send the calibrated flight time to the central processing module, and the self-calibration and rainfall measurement module is also configured to transmit the ultrasonic signals to a water surface in a bucket under the control of the central processing module and receive a measurement echo signal reflected by the water surface for rainfall measurement, obtain a measured flight time and send the measured flight time to the central processing module;
the central processing module is configured to receive the rainfall signal to start the water level monitoring module and to control an operation of the self-calibration and rainfall measurement module, to receive a self-calibration flight time and the measured flight time, calculate a rainfall value and output the rainfall value in a fixed format;
the water level monitoring module is configured to monitor a water level in the bucket, and send a drainage signal to the drainage module if the water level exceeds a predetermined height or the water level remains unchanged for a predetermined time;
the drainage module is configured to open a drainage and empty water from the bucket after received a drainage signal,
wherein the central processing module includes a wake-up unit, a self-calibration and rainfall measurement control unit, and a rainfall calculation unit; wherein

the wake-up unit is configured to receive the rainfall signal, and start the water level monitoring module and the self-calibration and rainfall measurement module to work;
the self-calibration and rainfall measurement control unit is configured to control the self-calibration and rainfall measurement module to perform self-calibration and rainfall measurement respectively;
the rainfall calculation unit is configured to receive the self-calibration flight time and the measured flight time for calculating the rainfall value then outputs the rainfall value in the fixed format,
a specific realization process of the rainfall calculation unit comprising:

according to a distance h between a first self-calibrating ultrasonic probe and a second self-calibrating ultrasonic probe, and the calibrated flight time to, calculating a corrected propagation velocity v of the ultrasonic signal in a current environment, in millimeters per microsecond:

v=h/t0,

according to the measured flight time t1 in microseconds, the distance D from the first measuring ultrasonic probe to the water surface as:

D=v×t1/2,

calculating a vertical distance H from the first measuring ultrasonic probe to the water surface by the following formula:

H=√{square root over (D2−(d/2)2)},

where, d is the distance between the first measuring ultrasonic probe and the second measuring ultrasonic probe;
comparing the vertical distance H from the first measuring ultrasonic probe to the water surface at the current moment and a vertical distance H1 from the first measuring ultrasonic probe to the water surface at the previous time,
if H>H1, the rainfall ΔH is:
ΔH=H−H1,
if H<H1, the rainfall ΔH is:
ΔH=0,
assigned H to H1, where H is the vertical distance from the first measured ultrasonic probe to the water surface obtained at the current moment;
expanding the rainfall ΔH by a fixed multiple to an integer and outputting.