Differential phase velocity determining delay measurement apparatus and associated method

• US 5,698,786 A
• Filed: 11/28/1995
• Issued: 12/16/1997
• Est. Priority Date: 11/28/1995
• Status: Expired due to Term

• Current Assignee: Sawtek Incorporated (Qorvo, Inc.)
• Original Assignee: Sawtek Incorporated (Qorvo, Inc.)
• Inventors: Andersen, Jorgen W.
• Primary Examiner(s): Oda, Christine K.
• Application Number:
  US08/563,397
• Time in Patent Office: 749 Days
• Field of Search: 73/24.01, 73/24.06, 73/24.04, 73/19.03, 73/703, 73/609, 73/610, 73/611, 73/617, 364/506, 364/508, 364/576
• US Class Current: 73/609
• CPC Class Codes: A61K 31/5575 having a cyclopentane, e.g. prostaglandin E2, prostaglandin F2-alpha
• CPC Class Codes: A61K 31/5585 having five-membered rings containing oxygen as the only ring hetero atom, e.g. prostacyclin
• CPC Class Codes: A61K 47/6951 using cyclodextrin cyclodextrins used as simple excipients A61K47/40
• CPC Class Codes: B82Y 5/00 Nanobiotechnology or nanomedicine, e.g. protein engineering or drug delivery

Abstract

An apparatus includes an ultrasonic delay sensor or device having a delay related to the sensed quantity; a pulse recirculating circuit for recirculating pulses through the ultrasonic delay sensor for generating a pulse repetition signal having a frequency related to delay of the ultrasonic delay sensor; and an output circuit for generating an output signal related to delay in the ultrasonic delay sensor based upon a difference in phase velocity between the pulse repetition signal and a time base signal. The output circuit preferably includes a first multiplier for multiplying the pulse repetition signal by a first number, and a second multiplier for multiplying the time base signal by a second number to have a frequency substantially the same as the multiplied pulse repetition signal. The effects of undesired reflections in the ultrasonic delay device may also be reduced or suppressed. Method aspects of the invention are also disclosed.

Claims

1. A sensing apparatus for generating an output signal related to at least one sensed quantity, said sensing apparatus comprising:

at least one ultrasonic delay sensor;

pulse recirculating means operatively connected to said at least one ultrasonic delay sensor for recirculating pulses therethrough to generate a pulse repetition signal having a frequency related to delay of said ultrasonic delay sensor;

time base means for generating a time base signal having a fixed frequency; and

differential phase velocity output means for generating an output signal related to delay in said at least one ultrasonic delay sensor based upon a difference in phase velocity between the pulse repetition signal and the time base signal.

2. A sensing apparatus according to claim 1 wherein said pulse recirculating means comprises:

pulse generator means for generating a series of input pulses to said at least one ultrasonic delay sensor; and

pulse detector means for detecting a series of output pulses after propagation through said at least one ultrasonic delay sensor.

3. A sensing apparatus according to claim 2 wherein said differential phase velocity output means further comprises:

first multiplying means for multiplying the pulse repetition signal from said pulse detector means by a first number; and

second multiplying means for multiplying the time base signal from said time base means by a second number to have a frequency substantially the same as the multiplied pulse repetition signal.

4. A sensing apparatus according to claim 1 wherein said differential phase velocity output means further comprises a phase detector, a phase differentiator, and absolute value means for producing an analog voltage output signal.

5. A sensing apparatus according to claim 1 wherein said differential phase velocity output means further comprises a phase detector, a phase differentiator, and a synchronous demodulator for producing an analog voltage output signal while further reducing noise.

6. A sensing apparatus according to claim 1 wherein said differential phase velocity output means further comprises an analog-to-digital converter for generating a digital output signal.

7. A sensing apparatus according to claim 1 wherein said at least one ultrasonic sensor comprises at least one surface acoustic wave (SAW) vapor sensor, and wherein said differential phase velocity output means further comprises signal conditioning means for generating the output signal related to vapor concentration sensed by said at least one SAW vapor sensor.

8. A sensing apparatus according to claim 1 wherein said at least one ultrasonic delay sensors comprises a plurality of ultrasonic delay sensors, and further comprising time division multiplex means for successively connecting said pulse recirculating means to each of the plurality of ultrasonic delay sensors to generate a plurality of respective output signals related to corresponding respective sensed quantities.

9. A sensing apparatus according to claim 1 wherein said at least one ultrasonic delay sensor generates undesired multiple reflections from pulses propagating therethrough;

and further comprising random phase switching means cooperating with said pulse recirculating means for randomly switching phases of a series of input pulses to said at least one ultrasonic delay sensor to thereby reduce effects of the undesired reflections.

10. A sensing apparatus according to claim 1 wherein said at least one ultrasonic delay sensor generates undesired multiple reflections from pulses propagating therethrough;

wherein said pulse recirculation means comprises a pulse generator and a pulse detector; and

wherein said pulse recirculating means comprises a fixed delay operatively connected between said pulse detector and said pulse generator to thereby reduce effects of the undesired reflections.

11. A sensing apparatus according to claim 1 wherein said pulse recirculating means further comprises a pulse generator and time diversity matching means, operatively connected between said pulse generator and said at least one ultrasonic delay sensor, for providing a conjugate match therebetween during a time interval of each pulse and providing a relatively large mismatch at other times.

12. An apparatus for generating an output signal related to delay of at least one ultrasonic delay device, said apparatus comprising:

pulse generator means for generating a series of input pulses to the at least one ultrasonic delay device;

pulse detector means for detecting a series of output pulses after propagation through the at least one ultrasonic delay device;

pulse recirculating means for causing said pulse generator means to generate the series of input pulses based upon respective previously detected pulses from said pulse detector means to generate a pulse repetition signal having a frequency related to delay of the at least one ultrasonic delay device;

time base means for generating a time base signal having a fixed frequency; and

differential phase velocity output means for generating an output signal related to delay in the at least one ultrasonic delay device based upon a difference in phase velocity between the pulse repetition signal and the time base signal.

13. An apparatus according to claim 12 wherein said differential phase velocity output means further comprises:

first multiplying means for multiplying the pulse repetition signal from said pulse detector means by a first number; and

second multiplying means for multiplying the time base signal from said time base means by a second number to have a frequency substantially the same as the multiplied pulse repetition signal.

14. An apparatus according to claim 12 wherein said differential phase velocity output means further comprises a phase detector, a phase differentiator, and absolute value means for producing an analog voltage output signal.

15. An apparatus according to claim 12 wherein said output means further comprises a phase detector, a phase differentiator, and a synchronous demodulator for producing an analog voltage output signal while further reducing noise.

16. An apparatus according to claim 12 wherein said output means further comprises an analog-to-digital converter for generating a digital output signal.

17. A sensing apparatus according to claim 12 wherein the at least one ultrasonic delay device comprises at least one surface acoustic wave (SAW) vapor sensor, and wherein said differential phase velocity output means further comprises signal conditioning means for generating the output signal related to vapor concentration sensed by said at least one SAW vapor sensor.

18. A sensing apparatus according to claim 12 wherein said at least one ultrasonic delay device comprises a plurality of ultrasonic delay devices, and further comprising time division multiplex means for successively connecting said pulse recirculating means to each of the plurality of ultrasonic delay devices to generate a plurality of respective output signals.

19. An apparatus according to claim 12 wherein the at least one ultrasonic delay device generates undesired multiple reflections from pulses propagating therethrough;

and further comprising random phase switching means cooperating with said pulse recirculating means for randomly switching phases of a series of input pulses to the at least one ultrasonic delay device to thereby reduce effects of the undesired reflections.

20. An apparatus according to claim 12 wherein the at least one ultrasonic delay device generates undesired multiple reflections from pulses propagating therethrough;

wherein said pulse recirculation means comprises a pulse generator and a pulse detector; and

wherein said pulse recirculating means comprises a fixed delay operatively connected between said pulse detector and said pulse generator to thereby reduce effects of the undesired reflections.

21. An apparatus according to claim 12 wherein said pulse recirculating means further comprises a pulse generator and time diversity matching means, operatively connected between said pulse generator and the at least one ultrasonic delay device, for providing a conjugate match therebetween during a time interval of each pulse and providing a relatively large mismatch at other times.

22. A method for generating an output signal related to delay of at least one ultrasonic delay device, the method comprising the steps of:

recirculating pulses through the at least one ultrasonic delay device for generating a pulse repetition signal having a frequency related to delay of the ultrasonic delay device;

generating a time base signal having a fixed frequency; and

generating an output signal related to delay in the at least one ultrasonic delay device based upon a difference in phase velocity between the pulse repetition signal and the time base signal.

23. A method according to claim 22 wherein the step of generating an output signal comprises the steps of:

multiplying the pulse repetition signal by a first number; and

multiplying the time base signal by a second number to have a frequency substantially the same as the multiplied pulse repetition signal.

24. A method according to claim 22 wherein the at least one ultrasonic delay device comprises a plurality of ultrasonic delay devices and further comprising the step of successively recirculating pulses through each of the plurality of ultrasonic delay devices to generate a plurality of respective output signals.

25. A method according to claim 22 wherein the at least one ultrasonic delay device generates undesired multiple reflections from pulses propagating therethrough;

and further comprising the step of randomly switching phases of a series of input pulses to the at least one ultrasonic delay device to thereby reduce effects of the undesired reflections.

26. A method according to claim 22 wherein the at least one ultrasonic delay device generates undesired multiple reflections from pulses propagating therethrough;

and further comprising the step of operatively connecting a fixed delay in a feedback path for recirculating pulses through the at least one ultrasonic delay device to thereby reduce effects of the undesired reflections.

27. A method according to claim 22 further comprising the step of providing a conjugate match between a pulse generator and the at least one ultrasonic delay device during a time interval of each pulse and providing a relatively large mismatch at other times.

28. A method according to claim 22 wherein the at least one ultrasonic delay device comprises at least one surface acoustic wave (SAW) vapor sensor;

and wherein the step of generating the output signal further comprises the step of generating the output signal related to vapor concentration sensed by the at least one SAW vapor sensor.