In order to quickly and accurately detect liquid level in sealed container in industrial production

design an ultrasonic liquid level meter based on ultrasonic ranging technology

to accurately detect liquid level in airtight conditions. The system adopts digital signal processing（ DSP） control circuit

build low-noise

detecting circuit of wide dynamic range

and complete ultrasonic liquid level sensor selection for sealed container.Experiment uses ultrasonic probe frequency is 3. 0 MHz

and wall thickness of sealed container is 4 mm. Changes in level are measured once every 10 cm

test data at 100 cm range and standard level change values for comparison.Experimental results show that relative error of detecting d

ata obtained by averaging the value of multiple tests on the same liquid level with standard value is less than 0. 5 %

so

the system meets design requirements of liquid level measurement precision is higher than 1mm at range of 0. 2

1 m in sealed container.