| 摘要 |
Method for determining product surface distance in a tank comprising:
i) generating a transmission signal as a first pulse train;
ii) generating a reference signal having a second pulse train by time delaying said first pulse train;
wherein each pulse in said first and second pulse trains have essentially identical waveforms and pulse repetition frequency;
iii) guiding said transmission signal towards the product surface;
iv) receiving a reflected signal;
v) forming a correlation value based on a time correlation between the reference signal and the reflected signal;
vi) carrying out steps i) to v) in sequence for at least three different pulse repetition frequencies, until at least three pairs of correlation values and associated pulse repetition frequencies have been stored;
vii) determining said distance based on said at least three pairs of correlation values and associated pulse repetition frequencies, and said fixed time delay. |
