초록 ▼

A self-diagnosing FMCW radar level gauge and a method for providing self-diagnosing with a radar level gauge is provided in a radar level gauge comprising a transceiver, a mixer, a signal propagating device and a signal propagation path connecting the transceiver and the signal propagating device, a

A self-diagnosing FMCW radar level gauge and a method for providing self-diagnosing with a radar level gauge is provided in a radar level gauge comprising a transceiver, a mixer, a signal propagating device and a signal propagation path connecting the transceiver and the signal propagating device, a filter arrangement and processing circuitry. The filter arrangement provides a filtered intermediate frequency signal. The transceiver outputs either a diagnostic sweep configured such that a reference echo from the signal propagation path is detectable in said filtered intermediate frequency signal, or a measurement sweep configured such that the reference echo is suppressed in the filtered intermediate frequency signal and that a surface echo is detectable. The processing circuitry is configured to self-diagnose the radar level gauge based on the reference echo, and to determine the distance to the surface based on the surface echo.

대표청구항 ▼

1. A self-diagnosing FMCW radar level gauge for measuring a distance to a surface of a product contained in a tank, said radar level gauge comprising: a transceiver arranged to generate and transmit an electromagnetic transmit signal in the form of a frequency sweep;a signal propagating device;a sig

1. A self-diagnosing FMCW radar level gauge for measuring a distance to a surface of a product contained in a tank, said radar level gauge comprising: a transceiver arranged to generate and transmit an electromagnetic transmit signal in the form of a frequency sweep;a signal propagating device;a signal propagation path connecting said signal propagating device to said transceiver;wherein said signal propagation path and said signal propagating device are configured to guide said electromagnetic transmit signal towards said surface, and return an echo signal including reflections from said surface and an impedance transition in the signal propagation path;a mixer connected to said transceiver and configured to mix said echo signal with a portion of said electromagnetic transmit signal to provide an intermediate frequency signal;a filter arrangement connected to said mixer and configured to filter said intermediate frequency signal in order to provide a filtered intermediate frequency signal; andprocessing circuitry connected to said filter arrangement and configured to process said filtered intermediate frequency signal; wherein said frequency sweep is one of a diagnostic sweep and a measurement sweep, said diagnostic sweep is configured such that a reference echo is detectable in said filtered intermediate frequency signal, said reference echo being indicative of a distance to said impedance transition,said measurement sweep is configured such that said reference echo is suppressed in said filtered intermediate frequency signal, and that a surface echo is detectable in said filtered intermediate frequency signal, said surface echo being indicative of a distance to said surface;wherein said processing circuitry is configured to self-diagnose said radar level gauge based on the reference echo, and to determine the distance to said surface based on said surface echo. 2. The radar level gauge according to claim 1, wherein said processing circuitry further comprises a self-diagnosis block configured to compare said reference echo against a stored reference echo profile, said stored reference echo profile comprises an expected distance to said reference echo and/or an expected amplitude of said reference echo. 3. The radar level gauge according to claim 1, wherein said diagnostic sweep has a shorter sweep time than the measurement sweep. 4. The radar level gauge according to claim 3, wherein the diagnostic sweep time is at least two times shorter than the measurement sweep time. 5. The radar level gauge according to claim 3, wherein the diagnostic sweep time is at least four times shorter than the measurement sweep time. 6. The radar level gauge according to claim 1, wherein said diagnostic sweep has a larger sweep bandwidth than the measurement sweep. 7. The radar level gauge according to claim 6, wherein the diagnostic sweep bandwidth is at least two times greater than the measurement sweep bandwidth. 8. The radar level gauge according to claim 6, wherein the diagnostic sweep bandwidth is at least four times greater than the measurement sweep bandwidth. 9. The radar level gauge according to claim 1, wherein said frequency sweep only comprises frequencies in the range 24 to 27 GHz. 10. The radar level gauge according to claim 1, wherein said frequency sweep only comprises frequencies in the range 1 to 3 GHz. 11. The radar level gauge according to claim 1, wherein said frequency sweep only comprises frequencies in the range 9 to 11 GHz. 12. The radar level gauge according to claim 1, wherein said signal propagating device is one of a parabolic antenna, a horn antenna, or a patch antenna. 13. The radar level gauge according to claim 1, wherein said signal propagating device is one of a sommerfeld probe, a goubau probe, a coaxial probe, a twin-line probe or a still pipe. 14. The radar level gauge according to claim 1, wherein said diagnostic sweep is performed at least once per hour. 15. The radar level gauge according to claim 1, wherein said diagnostic sweep is performed at least once per minute. 16. The radar level gauge according to claim 1, wherein said filter arrangement comprises at least two high pass filters, and at least one low pass filter. 17. The radar level gauge according to claim 16, wherein one of said at least two high pass filters is set at 3 kHz and another of said at least two high pass filters is set at 60 kHz and one of said at least one low pass filter is set at 100 kHz. 18. A method for providing self-diagnosis of a FMCW radar level gauge for measuring a distance to a surface of a product contained in a tank, said method comprising: generating an electromagnetic transmit signal in the form of a frequency sweep;guiding said electromagnetic transmit signal via a signal propagation path and a signal propagating device towards said surface;returning an echo signal including reflections from said surface and an impedance transition in the signal propagation path;mixing said echo signal and said transmit signal to provide an intermediate frequency signal;filtering said intermediate frequency signal to provide a filtered intermediate frequency signal,wherein said generated frequency sweep is one of a diagnostic sweep and a measurement sweep, said diagnostic sweep is configured such that a reference echo is detectable in said filtered intermediate frequency signal, said reference echo being indicative of a distance to said impedance transition,said measurement sweep is configured such that said reference echo is suppressed in said filtered intermediate frequency signal, and that a surface echo is detectable in said filtered intermediate frequency signal, said surface echo being indicative of a distance to said surface;processing said filtered intermediate frequency signal to self-diagnose said radar level gauge based on the reference echo, and to determine the distance to said surface based on said surface echo. 19. The method according to claim 18, wherein said step of processing said filtered intermediate frequency signal to self-diagnose said radar level gauge comprises comparing said reference echo against a stored reference echo profile, said stored reference echo profile including an expected distance to said reference echo and/or an expected amplitude of said reference echo. 20. The method according to claim 18, wherein said diagnostic sweep has a shorter sweep time than the measurement sweep. 21. The method according to claim 20, wherein the diagnostic sweep time is at least two times shorter than the measurement sweep time. 22. The method according to claim 20, wherein the diagnostic sweep time is at least four times shorter than the measurement sweep time. 23. The method according to claim 18, wherein said diagnostic sweep has a larger sweep bandwidth than the measurement sweep. 24. The method according to claim 23, wherein the diagnostic sweep bandwidth is at least two times greater than the measurement sweep bandwidth. 25. The method according to claim 23, wherein the diagnostic sweep bandwidth is at least four times greater than the measurement sweep bandwidth. 26. The method according to claim 18, wherein said frequency sweep only comprises frequencies in the range 24 to 27 GHz. 27. The method according to claim 18, wherein said frequency sweep only comprises frequencies in the range 1 to 3 GHz. 28. The method according to claim 18, wherein said frequency sweep only comprises frequencies in the range 9 to 11 GHz.