PRF frequency generator for a fill level measuring device

Frequency generator for generating two pulse repetition frequency signals with slightly different frequencies for a radar measuring device that functions according to the pulse correlation principle, wherein the frequency generator has:

• an oscillator (600) that generates an oscillator signal, a first signal path for generating a first pulse repetition frequency signal from the oscillator signal, wherein the first signal path comprises:
• a frequency divider (601) or a first DDS module that is designed, based upon the oscillator signal, to generate a first frequency signal, which, in the case of the frequency divider (601), comprises a number of harmonics or, in the case of the first DDS module, a number of image frequency components,
• a first ceramic bandpass filter (602) that is designed to filter out a specified harmonic or a specified image frequency component of the first frequency signal and to generate a bandpass-filtered first intermediate frequency signal, a second signal path for generating a second pulse repetition frequency signal from the oscillator signal, wherein the second signal path comprises:
• a second DDS module (605) that is designed to generate a second frequency signal based upon the oscillator signal, which second frequency signal differs from the first frequency signal by a specified frequency offset, wherein the second frequency signal comprises a number of image frequency components,
• a second ceramic bandpass filter (606) that is designed to filter out a specified image frequency component of the second frequency signal and to generate a bandpass-filtered second intermediate frequency signal;
• wherein the second frequency divider is arranged in parallel to the first frequency divider or DDS respectively, and
• wherein the second ceramic band pass filter is arranged in parallel to the first ceramic band pass filter.

A method for generating two pulse repetition frequency signals with slightly different frequencies for a radar measuring device that functions according to the pulse correlation principle, wherein the method comprises the following steps:

• generating an oscillator signal;
• generating a first frequency signal based upon the oscillator signal by means of a frequency divider (401) or a first DDS module;
• upmixing the first frequency signal or a signal derived therefrom to an intermediate frequency band and generating a first intermediate frequency signal;
• filtering out a selected frequency component of the first intermediate frequency signal by means of a first ceramic bandpass filter (405) and generating a bandpass-filtered first intermediate frequency signal, wherein the bandpass-filtered first intermediate frequency signal or a signal derived therefrom is usable as a first pulse repetition frequency signal;
• generating a second frequency signal based upon the oscillator signal by means of a second DDS module, wherein the second frequency signal differs from the first frequency signal by a specified frequency offset;
• upmixing the second frequency signal or a signal derived therefrom to an intermediate frequency band and generating a second intermediate frequency signal;
• filtering out a selected frequency component of the second intermediate frequency signal by means of a second ceramic bandpass filter (411) and generating a bandpass-filtered second intermediate frequency signal, wherein the bandpass-filtered second intermediate frequency signal or a signal derived therefrom is usable as a second pulse repetition frequency signal.

A method for generating two pulse repetition frequency signals with slightly different frequencies for a radar measuring device that functions according to the pulse correlation principle, wherein the method comprises the following steps:

• generating an oscillator signal;
• generating a first frequency signal based upon the oscillator signal by means of a frequency divider (601) or a first DDS module, wherein the first frequency signal, in the case of the frequency divider (601), comprises a number of harmonics or, in the case of the first DDS module, a number of image frequency components;
• filtering out a specified harmonic or a specified image frequency component of the first intermediate frequency signal by means of a first ceramic bandpass filter (602) and generating a bandpass-filtered first intermediate frequency signal, wherein the bandpass-filtered first intermediate frequency signal or a signal derived therefrom is usable as a first pulse repetition frequency signal;
• generating a second frequency signal based upon the oscillator signal by means of a second DDS module (605), wherein the second frequency signal differs from the first frequency signal by a specified frequency offset, wherein the second frequency signal comprises a number of image frequency components;
• filtering out a specified image frequency component of the second intermediate frequency signal by means of a second ceramic bandpass filter (606) and generating a bandpass-filtered second intermediate frequency signal, wherein the bandpass-filtered second intermediate frequency signal or a signal derived therefrom is usable as a second pulse repetition frequency signal.