SONIC JOKER is a high resolution ultrasonic measurement device designed for the precision distance measurement in quality control for continuous production. Almost any solid or liquid object can be detected with high accuracy, independent of its color and surface structure. Due to the high intensity of the ultrasonic pulses and the software controlled gain settings even highly sound absorbing materials like foams, textiles and insulation mats can be measured. Standard applications are thickness measurements of products made of foam, plastic, rubber, canvas, glass and stones during the production process. Fill levels of liquids, pastes and granulates can also be recorded with high accuracy. The Windows based PC software SONIC TOOLS controls the measurement parameters of SONIC JOKER and has special functions for relative measurement. Process control is assisted by special I/O functions of SONIC JOKER: One serial output and two analogue outputs are available for data transfer. The digital input can initiate a zero setting for relative measurement or any other programmed operation. Two sensor heads can be connected to one controller unit thus giving comprehensive survey and redundancy (Fig. 2).

The Measurement Principle

The ultrasonic distance measurement is effected according to the pulse/echo method. The distance between the sensor head and the reflecting object is calculated from the traveling time of the sound pulses from the sensor to the object and their echoes. The knowledge of the sound propagation conditions, i.e. the velocity of sound, is essential for a high accuracy measurement. This is achieved by the patented sensor head FS 1 of SONIC JOKER: A built-in reference bar gives continuous calibration signals and compensates for temperature changes and different air composition.

The measurement data is displayed on the built in LED display and transmitted continuously to a PC or CNC via the serial interface RS 232C. All control parameters of SONIC JOKER are selected from the parameter list of the software SONIC TOOLS (Fig. 3). They are stored permanently in the controller unit and are available after power on.