Instrument and method for processing a doppler measurement signal

• US 8,874,390 B2
• Filed: 03/23/2011
• Issued: 10/28/2014
• Est. Priority Date: 03/23/2011
• Status: Active Grant

• Current Assignee: Hach Company (Veralto Corp.)
• Original Assignee: Hach Company (Veralto Corp.)
• Inventors: Rick, David Langley
• Primary Examiner(s): Lau, Tung S
• Assistant Examiner(s): Chang, Stephanie
• Application Number:
  US13/069,729
• Publication Number:
  US 20120245863A1
• Time in Patent Office: 1,315 Days
• Field of Search: 702/50
• US Class Current: 702/50
• CPC Class Codes: G01F 1/002 wherein the flow is in an open channel
• CPC Class Codes: G01F 1/663 by measuring Doppler frequency shift
• CPC Class Codes: G01F 15/06 Indicating or recording devices
• CPC Class Codes: G01F 15/068 with electrical means G01F15/063 takes precedence
• CPC Class Codes: G01P 5/241 by using reflection of acoustical waves, i.e. Doppler-effect
• CPC Class Codes: G01S 15/58 Velocity or trajectory determination systems; Sense-of-movement determination systems velocity measurement in imaging systems G01S15/8979

Abstract

An instrument (100) is provided according to an embodiment of the invention. The instrument (100) includes an interface (101) configured to receive a Doppler measurement signal and a processing system (112) coupled to the interface (101) and receiving the Doppler measurement signal. The processing system (112) is configured to generate a two-sided velocity spectrum including a plurality of discrete frequency bins from the Doppler measurement signal, with the two-sided velocity spectrum distinguishing spectral elements, and process one or more velocity spectrum bin pairs against a plurality of local gate thresholds, with the one or more velocity spectrum bin pairs being substantially symmetrically located about one or more carrier wave bins and wherein each velocity spectrum bin pair is processed against a corresponding local gate threshold of the plurality of local gate thresholds.

Claims

1. An instrument, comprising:

an interface configured to receive a Doppler measurement signal; and

a processing system coupled to the interface and receiving the Doppler measurement signal, with the processing system being configured to generate a two-sided velocity spectrum including a plurality of discrete frequency bins from the Doppler measurement signal, with the two-sided velocity spectrum distinguishing spectral elements, and process one or more velocity spectrum bin pairs against a plurality of local gate thresholds, with at least one pair of the one or more velocity spectrum bin pairs being symmetrically located about one or more carrier wave bins such that bins of a symmetric pair have an equal distance from the carrier position and wherein each velocity spectrum bin pair is processed against a corresponding local gate threshold of the plurality of local gate thresholds.

2. The instrument of claim 1, with the processing system being further configured to process the one or more velocity spectrum bin pairs against a global squelch threshold, wherein if both bin amplitudes of a bin pair are less than the global squelch threshold, then both bin amplitudes of the bin pair are zeroed out and wherein if at least one bin amplitude of a bin pair exceeds the global squelch threshold, then both bin amplitudes of the bin pair are unchanged.

3. The instrument of claim 1, with the processing system being further configured to process the one or more velocity spectrum bin pairs against a global squelch threshold and with the global squelch threshold being substituted for a local gate threshold of the plurality of local gate thresholds if the global squelch threshold is greater than the local gate threshold.

4. The instrument of claim 1, with a local gate threshold of the plurality of local gate thresholds being a smaller value of left and right bin amplitudes of a bin pair.

5. The instrument of claim 1, with a local gate threshold of the plurality of local gate thresholds being derived from a smaller bin amplitude of left and right bin amplitudes of a bin pair, wherein the smaller bin amplitude is multiplied by a predetermined multiplier factor k to form the local gate threshold.

6. The instrument of claim 1, with a local gate threshold of the plurality of local gate thresholds being derived from a smaller bin amplitude selected from left and right bin amplitudes of a bin pair, wherein the local gate threshold is further averaged with weighted values of one or more predetermined local gate thresholds.

7. The instrument of claim 1, wherein a smaller bin amplitude of a bin pair is zeroed out and wherein if a larger bin amplitude exceeds the local gate threshold, then the larger bin amplitude is unchanged.

8. The instrument of claim 1, wherein a smaller bin amplitude of a bin pair is zeroed out and wherein if a larger bin amplitude exceeds the local gate threshold, then the larger bin amplitude is reduced by the smaller bin amplitude.

9. The instrument of claim 1, wherein if both bin amplitudes of a bin pair are less than the local gate threshold, then both bin amplitudes of the bin pair are reduced or zeroed out.

10. The instrument of claim 1, with the processing system (112) being further configured to zero out an isolated bin according to an isolated bin removal rule.

11. A method for processing a Doppler measurement signal, comprising:

generating a two-sided velocity spectrum including a plurality of frequency bins from the Doppler measurement signal and with the two-sided velocity spectrum distinguishing spectral elements; and

processing one or more velocity spectrum bin pairs against a plurality of local gate thresholds, with at least one pair of the one or more velocity spectrum bin pairs being symmetrically located about one or more carrier wave bins such that bins of a symmetric pair have an equal distance from the carrier position and wherein each velocity spectrum bin pair is processed against a corresponding local gate threshold of the plurality of local gate thresholds.

12. The method of claim 11, further comprising processing the one or more velocity spectrum bin pairs against a global squelch threshold, wherein if both bin amplitudes of a bin pair are less than the global squelch threshold, then both bin amplitudes of the bin pair are zeroed out and wherein if at least one bin amplitude of a bin pair exceeds the global squelch threshold, then both bin amplitudes of the bin pair are unchanged.

13. The method of claim 11, further comprising processing the one or more velocity spectrum bin pairs against a global squelch threshold and with the global squelch threshold being substituted for a local gate threshold of the plurality of local gate thresholds if the global squelch threshold is greater than the local gate threshold.

14. The method of claim 11, with a local gate threshold of the plurality of local gate thresholds being a smaller value of left and right bin amplitudes of a bin pair.

15. The method of claim 11, with a local gate threshold of the plurality of local gate thresholds being derived from a smaller bin amplitude of left and right bin amplitudes of a bin pair, wherein the smaller bin amplitude is multiplied by a predetermined multiplier factor k to form the local gate threshold.

16. The method of claim 11, with a local gate threshold of the plurality of local gate thresholds being derived from a smaller bin amplitude selected from left and right bin amplitudes of a bin pair, wherein the local gate threshold is further averaged with weighted values of one or more predetermined local gate thresholds.

17. The method of claim 11, wherein a smaller bin amplitude of a bin pair is zeroed out and wherein if a larger bin amplitude exceeds the local gate threshold, then the larger bin amplitude is unchanged.

18. The method of claim 11, wherein a smaller bin amplitude of a bin pair is zeroed out and wherein if a larger bin amplitude exceeds the local gate threshold, then the larger bin amplitude is reduced by the smaller bin amplitude.

19. The method of claim 11, wherein if both bin amplitudes of a bin pair are less than the local gate threshold, then both bin amplitudes of the bin pair are reduced or zeroed out.

20. The method of claim 11, further comprising zeroing out an isolated bin according to an isolated bin removal rule.

21. A method for processing a Doppler measurement signal, comprising:

generating a two-sided velocity spectrum including a plurality of frequency bins from the Doppler measurement signal and with the two-sided velocity spectrum distinguishing spectral elements;

processing one or more velocity spectrum bin pairs against a global squelch threshold, with at least one pair of the one or more velocity spectrum bin pairs being symmetrically located about one or more carrier wave bins such that bins of a symmetric pair have an equal distance from the carrier position; and

processing the one or more velocity spectrum bin pairs against a plurality of local gate thresholds, wherein each velocity spectrum bin pair is processed against a corresponding local gate threshold of the plurality of local gate thresholds.

22. The method of claim 21, further comprising substituting the global squelch threshold for a local gate threshold of the plurality of local gate thresholds if the global squelch threshold is greater than the local gate threshold.

23. The method of claim 21, further comprising zeroing out an isolated bin according to an isolated bin removal rule.