Paired ZF sampling for pulse running time filling level sensor

摘要

A pulse running time filling level sensor includes a sampling device for sampling an IF signal at discrete instants and for converting the sampling values into digital sampling values, and a digital signal processing device for subsequent processing of the digital sampling values by calculating at least one new value characterizing the IF curve from respectively exactly two digital sampling values.

主权项

1. A pulse running time filling level sensor for digitizing and subsequent processing of an intermediate frequency signal for determining a filling level in a tank, comprising:
a sampling device pair sampling the intermediate frequency (IF) signal at pairs of discrete points in time, the sampling device converting sampling values into sampling pairs of digital sampling values, wherein the intermediate frequency signal comprises an amplitude modulated carrier wave having an intermediate frequency; and a digital signal processing device subsequently processing of the digital sampling values through calculation of at least one characterizing value characterizing the IF signal from respectively exactly one of the digital sampling pairs, and wherein the at least one characterizing value is an envelope value, wherein the calculation of the envelope value for the respective sampling pairs is performed according toHKi=IF⁢⁢1i2+(IF⁢⁢2i-IF⁢⁢1i*cos⁡(ω*(ta⁢⁢1i)))2sin⁡(ω*(ta⁢⁢1i))2 wherein: i: a non-negative integer, with i indicating respective ones of the sampling pairs; HKi is an i-th envelope value for a respective, i-th, one of the sampling pairs; IF1i: a respective first digital sampling value of a respective, i-th, one of the sampling pairs; IF2i: a respective second digital sampling value of a respective, i-th, one of the sampling pairs; ta1i: time interval between sampling of IF1i and IF2i; and ω: angular frequency of the carrier wave.