Acoustic doppler channel flow measurement device

• US 20030076742A1
• Filed: 08/27/2002
• Published: 04/24/2003
• Est. Priority Date: 08/28/2001
• Status: Active Grant

• Current Assignee: Teledyne Instruments Incorporated (Teledyne Technologies Incorporated)
• Original Assignee: ROWE Deines Instruments Incorporated
• Inventors: Rowe, Francis D.
• Granted Patent: US 6,714,482 B2
• Time in Patent Office: Days
• US Class Current: 367/89
• 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: G01P 5/241 by using reflection of acoustical waves, i.e. Doppler-effect
• CPC Class Codes: G01S 15/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S15/46
• CPC Class Codes: G01S 15/60 wherein the transmitter and receiver are mounted on the moving object, e.g. for determining ground speed, drift angle, ground track
• CPC Class Codes: G01S 7/521 Constructional features
• CPC Class Codes: G01S 7/539 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: Y02A 90/30 Assessment of water resources

Abstract

An improved acoustic Doppler flow measurement system which employs multiple acoustic frequencies to acquire multiple independent backscatter data from the flow channel, combining the data to enable survey measurement of channel flow properties beyond what can be achieved with either a single frequency system or multiple independent single frequency systems. The system is installed on small moving channel survey boats, remotely measuring vertical profiles of river currents, achieving accurate surveys of channel flow velocity structure and bottom topography, enabling accurate (approximately 1% resolution) survey measurement of channel flow discharge. Significant synergistic improvements are realized from both physical and functional integrations of the multi-frequency operational capability into a single integrated flow survey system. Use of phased array transducer techniques further reduces flow disturbance and transducer size, enabling use on even smaller survey boats.

Claims

1. A Doppler sonar flow measurement system comprising:

a transducer assembly mounted on a platform wherein the transducer assembly is adapted to transmit two or more different frequency acoustic signals underwater and then receive backscattered echoes of the acoustic signals;

an electronic assembly that drives the transducer assembly to generate the two or more different frequency acoustic signals, and processes the echoes so as to determine relative velocity of underwater characteristics of a river flowing in a defined channel; and

a housing assembly that houses the transducer assembly so as to reduce the disturbance of the flow of the river caused by the sonar system.

2. The system of claim 1, wherein the housing assembly comprises a single housing that houses the transducer assembly.

3. The system of claim 1, wherein the transducer assembly comprises two or more transducers wherein each transducer transmits at a characteristic frequency.

4. The system of claim 1, wherein the transducer assembly comprises a first phased array transducer transmitting at a first frequency and a second phased array transducer transmitting at a second frequency.

5. The system of claim 4, wherein the first frequency is in a range of approximately 300-600 KHz and the second frequency is in a range of approximately 1200-2400 KHz.

6. The system of claim 1, wherein the platform is a fixed structure relative to the defined channel and wherein the transducer assembly mounted thereon measures the flow velocity of the river with respect to the fixed structure.

7. The system of claim 1, wherein the platform is a boat moving relative to the defined channel and wherein the transducer assembly mounted thereon measures the flow velocity of the river with respect to the boat.

8. The system of claim 7, wherein the transducer assembly measures the motion of the boat relative to the bottom of the defined channel.

9. A Doppler sonar flow measurement system comprising:

at least one phased array mounted on a platform wherein each of the at least one phased array comprises a plurality of transducer elements arranged in a selected manner and wherein the at least one phased array is adapted to transmit acoustic signals underwater and receive their backscattered echoes;

an electronic assembly that drives the at least one phased array to generate the acoustic signals, and processes the echoes so as to determine relative velocity of underwater characteristics of a river flowing in a defined channel; and

a housing assembly that houses the at least one phased array so as to reduce the disturbance of the flow of the river caused by the sonar system.

10. The system of claim 9, comprising a first phased array operating at a first frequency and a second phased array operating at a second frequency.

11. The system of claim 10, wherein the first frequency is in a range of approximately 300-600 KHz and the second frequency is in a range of approximately 1200-2400 KHz.

12. The system of claim 9, wherein the platform is a fixed structure relative to the defined channel and wherein the at least one phased array mounted thereon measures the flow velocity of the river with respect to the fixed structure.

13. The system of claim 9, wherein the platform is a boat moving relative to the defined channel and wherein the at least one phased array mounted thereon measures the flow velocity of the river with respect to the boat.

14. The system of claim 13, wherein the at least one phased array measures the motion of the boat relative to the bottom of the defined channel.

15. A Doppler sonar flow measurement system comprising:

at least two phased arrays mounted on a platform wherein each of the at least two phased arrays comprises a plurality of transducer elements arranged in a selected manner and wherein the at least two phased arrays are adapted to operate at different frequencies to transmit acoustic signals underwater and receive their backscattered echoes;

an electronic assembly that drives the at least two phased arrays at the different frequencies, and processes the echoes so as to determine relative velocity of underwater characteristics of a river flowing in a defined channel; and

a housing assembly that houses the at least two phased arrays so as to reduce the disturbance of the flow of the river caused by the sonar system.

16. The system of claim 15, wherein the housing assembly comprises a single housing that houses the at least two phased arrays.

17. The system of claim 16, comprising a first phased array operating at a first frequency and a second phased array operating at a second frequency.

18. The system of claim 17, wherein the first frequency is in a range of approximately 300-600 KHz and the second frequency is in a range of approximately 1200-2400 KHz.

19. The system of claim 15, wherein the platform is a fixed structure relative to the defined channel and wherein the at least two phased arrays mounted thereon measure the flow velocity of the river with respect to the fixed structure.

20. The system of claim 15, wherein the platform is a boat moving relative to the defined channel and wherein the at least two phased arrays mounted thereon measure the flow velocity of the river with respect to the boat.

21. The system of claim 20, wherein one of the at least two phased arrays measures the motion of the boat relative to the bottom of the defined channel.

22. A method of measuring flow velocity of a river, the method comprising:

mounting a Doppler sonar system on a boat wherein the sonar system comprises a first and a second acoustic transducer operating at different frequencies;

streamlining the mounted sonar system so as to reduce its effect on the disturbance of the flow of the river; and

transmitting a first and a second acoustic signal into the river wherein the first signal is transmitted by the first transducer and the second signal is transmitted by the second transducer;

receiving and processing backscattered echoes of the first and second acoustic signals wherein the echo from the first signal is used to measure the flow velocity of the river within a first range and the echo from the second signal is used to measure the flow velocity of the river within a second range.

23. The method of claim 22, further comprising traversing the river on the boat to measure a sectional profile of the river'"'"'s flow velocity.

24. The method of claim 23, wherein one of the acoustic signals is used to measure boat'"'"'s velocity relative to the bottom of the river.

25. The method of claim 22, wherein transmitting the first and second signals comprises transmitting the first signal at a first frequency and transmitting the second signal at a second frequency.

26. The method of claim 25, wherein the first frequency is in a range of approximately 300-600 KHz and the second frequency is in a range of approximately 1200-2400 KHz.

27. The method of claim 26, further comprising offsetting the motion of the boat from the measurement using the first frequency acoustic signal to determine the boat'"'"'s motion relative to the bottom of the river.

28. A method of measuring flow velocity of a river, the method comprising:

mounting a Doppler sonar system on a boat wherein the sonar system comprises a phased array of transducers;

streamlining the mounted sonar system so as to reduce its effect on the disturbance of the flow of the river;

transmitting into the river at least one set of a plurality of acoustic beams formed by the phased array;

receiving a plurality of backscattered echoes from the river; and

processing the echoes to determine the flow velocity of the river wherein the plurality of acoustic beams from the phased array system permit measurement of the flow velocity independent of speed of sound in the water.

29. The method of claim 28, further comprising traversing the river on the boat to measure a sectional profile of the river'"'"'s flow velocity.

30. The method of claim 29, further comprising offsetting the motion of the boat from the measurement using a low frequency acoustic signal to determine the boat'"'"'s motion relative to the bottom of the river.

31. The method of claim 28, wherein transmitting into the river comprises transmitting a first set of acoustic beams at a first frequency and a second set of acoustic beams at a second frequency.

32. The method of claim 31, wherein the first frequency is in a range of approximately 300-600 KHz and the second frequency is in a range of approximately 1200-2400 KHz.

33. A method of measuring flow velocity of a river, the method comprising:

mounting a Doppler sonar system on a boat wherein the sonar system comprises a first and a second acoustic transducer operating at different frequencies;

transmitting a first and a second acoustic signal into the river wherein the first signal is transmitted by the first transducer and the second signal is transmitted by the second transducer; and

receiving and processing backscattered echoes of the first and second acoustic signals wherein the echo from the first signal is used to measure the flow velocity of the river within a first range and the echo from the second signal is used to measure the flow velocity of the river within a second range.

34. The method of claim 33, further comprising traversing the river on the boat to measure a sectional profile of the river'"'"'s flow velocity.

35. The method of claim 34, wherein one of the acoustic signals is used to measure boat'"'"'s velocity relative to the bottom of the river.

36. The method of claim 33, wherein transmitting the first and second signals comprises transmitting the first signal at a first frequency and transmitting the second signal at a second frequency.

37. The method of claim 36, wherein the first frequency is in a range of approximately 300-600 KHz and the second frequency is in a range of approximately 1200-2400 KHz.

38. The method of claim 37, further comprising offsetting the motion of the boat from the measurement using the first frequency acoustic signal to determine the boat'"'"'s motion relative to the bottom of the river.

39. A method of measuring flow velocity of a river, the method comprising:

mounting a Doppler sonar system on a boat wherein the sonar system comprises a phased array of transducers;

transmitting into the river at least one set of a plurality of acoustic beams formed by the phased array;

receiving a plurality of backscattered echoes from the river; and

processing the echoes to determine the flow velocity of the river wherein the plurality of acoustic beams from the phased array system permit measurement of the flow velocity independent of speed of sound in the water.

40. The method of claim 39, further comprising traversing the river on the boat to measure a sectional profile of the river'"'"'s flow velocity.

41. The method of claim 40, further comprising offsetting the motion of the boat from the measurement using a low frequency acoustic signal to determine the boat'"'"'s motion relative to the bottom of the river.

42. The method of claim 39, wherein transmitting into the river comprises transmitting a first set of acoustic beams at a first frequency and a second set of acoustic beams at a second frequency.

43. The method of claim 42, wherein the first frequency is in a range of approximately 300-600 KHz and the second frequency is in a range of approximately 1200-2400 KHz.