| 摘要 |
A tank level meter includes an elongated sound conductor of a solid material extending over the entire height of the tank and having a coating partially surrounding it. A sound generator is coupled to one end of the sound conductor to excite thereon surface waves and the opposite end of the conductor is coupled to a sound receiver. Due to different acoustic impedances of the material of the sound conductor of the fluids present in the tank that means of the air and of a liquid whose level is to be measured, the sound waves propagating at the interface of the sound conducting member and fluids arrive to the receiver with a phase shift which is proportional to the liquid level in the tank. By a suitable selection of materials of the sound conductor and coating it is possible to obtain an unambiguous measuring signal at the receiver or a measuring signal having a high resolution. By using at least two sound conductors in the tank it is possible to obtain both a single value volume reading and a high resolution.
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