Ultrasonic Level Meter & Radar Level Meter. The sensor of the meter pulses in the direction of the product surface. There, they are reflected back and received by the sensor.The meter measures the time between pulse transmission and reception. 

Ultrasonic Level Meter Series ULM-84

Ultrasonic Level Transmitter

Continuous non-contact level measurement with compact version.
Radar Level Meter Series FRL-8XX

The ultra short microwave pulse with very low emitted energy is sent and received by antenna
system. Radar wave travels at the speed of light

Guided Wave Radar Level Meter

Guided wave radar level meter are a kind of measuring instrument based on the time travel , radar wave are travelling as light speed , the travel time can be transformed into level signal by the electronic parts .