Method and apparatus for measuring displacement of molten metal

An apparatus for measuring displacement of molten metal comprising:

• a first pseudo random signal generating means for generating a first pseudo random signal;
• a second pseudo random signal generating means for generating a second pseudo random signal which has the same pattern as said first pseudo random signal but which is slightly different in frequency from said first pseudo random signal;
• a first electrode inserted into molten metal having electrical conductivity and connected to said first pseudo random signal generating means;
• a second electrode inserted into said molten metal;
• a first multiplier for multiplying an output of said first pseudo random signal generating means by an output of said second pseudo random signal generating means to thereby obtain a first product value;
• a second multiplier connected to said second electrode and for multiplying an output of said second electrode by the output of said second pseudo random signal generating means to thereby obtain a second product value;
• a first integrate operation means for integrating the output of said first multiplier;
• a second integrate operation means for integrating the output of said second multiplier;
• and
• an arithmetic operation means for obtaining a time difference between maximum correlation values respectively appearing in time series patterns of said first and second integrated values to thereby calculate displacement of said molten metal.