Filling level determination using transmit signals with different frequency steps

摘要

A method of determining a filling level comprising transmitting a first transmit signal exhibiting a first ratio between bandwidth number of frequencies; receiving a first reflection signal; mixing the first transmit signal and the first reflection signal to form a first intermediate frequency signal; and determining a first data set indicative of a first set of surface echo candidates based on the first intermediate frequency signal. The method further comprises transmitting a second transmit signal exhibiting a second ratio between bandwidth and number of frequencies being different from the first ratio; receiving a second reflection signal; mixing the second transmit signal and the second reflection signal to form a second intermediate frequency signal; and determining a second data set indicative of a second set of surface echo candidates based on the second intermediate frequency signal. The filling level determined based on subsets of the first and second sets.

主权项

1. A method of determining a filling level of a product in a tank using a radar level gauge system, comprising the steps of:
transmitting towards a surface of said product a first transmit signal comprising a time sequence of a first number of discrete and mutually different frequencies defining a first bandwidth of said first transmit signal, said first transmit signal exhibiting a first ratio between said first bandwidth and said first number of discrete and mutually different frequencies; receiving a first reflection signal resulting from reflection of said first transmit signal at impedance discontinuities encountered by said first transmit signal; mixing said first transmit signal and said first reflection signal to form a first intermediate frequency signal; determining a first data set indicative of a first set of surface echo candidates based on said first intermediate frequency signal; transmitting towards a surface of said product a second transmit signal comprising a time sequence of a second number of discrete and mutually different frequencies defining a second bandwidth of said second transmit signal, said second transmit signal exhibiting a second ratio between said second bandwidth and said second number of discrete and mutually different frequencies being different from said first ratio; receiving a second reflection signal resulting from reflection of said second transmit signal at impedance discontinuities encountered by said second transmit signal; mixing said second transmit signal and said second reflection signal to form a second intermediate frequency signal; determining a second data set indicative of a second set of surface echo candidates based on said second intermediate frequency signal; identifying, based on a comparison between said first data set and said second data set, subsets of surface echo candidates from said first set of surface echo candidates and said second set of surface echo candidates indicating reflection of said transmit signal at impedance discontinuities at the same level in said tank; and determining the filling level based on said subsets of surface echo candidates from said first set of surface echo candidates and said second set of surface echo candidates.