Principle of Operation

Radar uses high frequency electromagnetic waves in the GHz range that are beamed downward from the sensor located on top of the vessel. The sensor receives back a portion of the energy that is reflected off the surface of the measured medium. Travel time of the signal (called the time of flight) is used to determine level. Pulse radar or pulsed time of flight operates on a principle very similar to that of the ultrasonic pulsed method. Where ultrasonic sensors transmit pulses and calculate the level based on the speed of sound, pulsed radar transmits pulses toward a target based on the speed of light.

Consequently conditions that affect the speed of sound used in ultrasonic level measurement such as variations in pressure, vacuum, temperature do not affect the speed of light used in radar level measurement.

The SmartWave transmitter can be programmed to simply send a 4-20 mA analog output signal directly to an existing control system or send data to a PC running a SmartWave’s calibration/data logging program using RS-485 communications.

The major components of pulse radar are:

• The transmitter, consisting of an oscillator and a pulse modulator.
• The antenna system, which passes electromagnetic energy from the transmitter to the transmission medium, and receives reflections from the target.
• The receiver, which amplifies the signal received by the pulse radar and detects returns from targets.
• Interfaces, including displays and interfaces to other electronic systems.