Pulsed level gauge system and method

摘要

The present invention relates to a pulsed level gauge system comprising frequency control circuitry. If an acquired signal indicates that the time between the previous filling level determination and the present filling level determination is shorter than a predefined time, the frequency control circuitry controls at least one of a transmit signal generating circuitry and a reference signal generating circuitry comprised in the pulsed level gauge system using previous frequency control settings stored in memory. If the acquired signal indicates that the time between the previous filling level determination and the present filling level determination is longer than the predefined time, the frequency control circuitry iteratively regulates at least one of the transmit signal generating circuitry and the reference signal generating circuitry towards achieving a desired pulse repetition frequency difference between the pulse repetition frequency of the transmit signal and the pulse repetition frequency of the reference signal.

主权项

1. A method of determining a filling level of a product in a tank, using a level gauge system comprising:
transmit signal generating circuitry for generating pulsed electromagnetic transmit signals; a propagation device connected to said transmit signal generating circuitry and arranged to propagate said transmit signals towards a surface of said product, and to return electromagnetic reflection signals resulting from reflection of said transmit signals at said surface; and reference signal generating circuitry for generating pulsed electromagnetic reference signals, said method comprising the steps of: controlling at least one of said transmit signal generating circuitry and said reference signal generating circuitry using first frequency control settings selected to achieve a desired pulse repetition frequency difference between a pulse repetition frequency of said transmit signals and a pulse repetition frequency of said reference signals; transmitting a first transmit signal towards said surface; receiving a first reflection signal resulting from reflection of said first transmit signal at said surface; generating a first reference signal; determining a first filling level measurement value level based on said first reflection signal and said first reference signal; determining an actual pulse repetition frequency difference between the pulse repetition frequency of said first transmit signal and the pulse repetition frequency of said first reference signal; determining second frequency control settings based on said first frequency control settings and a difference between said desired pulse repetition frequency and said actual pulse repetition frequency difference; storing said second frequency control settings; acquiring a signal indicative of a time between consecutive filling level determinations; if the acquired signal indicates that the time between consecutive filling level determinations is shorter than a predefined time then performing steps a1) to f1): a1) retrieving said second frequency control settings; b1) controlling at least one of said transmit signal generating circuitry and said reference signal generating circuitry using said second frequency control settings; c1) transmitting a second transmit signal towards said surface; d1) receiving a second reflection signal resulting from reflection of said second transmit signal at said surface; e1) generating a second reference signal; and f1) determining a second filling level measurement value based on said second reflection signal and said second reference signal; if the acquired signal indicates that the time between consecutive filling level determinations is longer than said predefined time then performing steps a2) to e2): a2) regulating a pulse repetition frequency of at least one of said transmit signal generating circuitry and said reference signal generating circuitry towards achieving said desired pulse repetition frequency difference; b2) transmitting a third transmit signal towards said surface; c2) receiving a third reflection signal resulting from reflection of said third transmit signal at said surface; d2) generating a third reference signal; and e2) determining a third filling level measurement value based on said third reflection signal and said third reference signal.