MULTI-FREQUENCY BORING TOOL LOCATING SYSTEM AND METHOD

• US 20140266212A1
• Filed: 05/27/2014
• Published: 09/18/2014
• Est. Priority Date: 06/01/1999
• Status: Active Grant

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Brune, Guenter W., Mercer, John E.
• Granted Patent: US 9,513,397 B2
• Time in Patent Office: Days
• US Class Current: 324/326
• CPC Class Codes: E21B 47/02 Determining slope or direction
• CPC Class Codes: E21B 47/0232 at least one of the energy sources or one of the detectors being located on or above the ground surface
• CPC Class Codes: E21B 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• CPC Class Codes: E21B 47/092 by detecting magnetic anomalies
• CPC Class Codes: E21B 47/12 Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00

Abstract

Arrangements, apparatus and associated methods are described for use in a multi-frequency boring tool locating system. The boring tool includes a transmitter for transmitting a locating signal at two or more selectable frequencies. One set of above ground procedures may be applied to the transmitter in order to change the frequency of the boring tool transmitter. Another set of procedures is applicable for changing the frequency during below ground drilling operations, for example, by subjecting the boring tool to a predetermined roll orientation sequence. An enhanced portable locator operates in a manual or automatic mode to receive locating frequency information transmitted from the boring tool transmitter including frequency updates. Boring tool transmitter, as well as above ground locator shutdown/restart procedures are described relating to multi-frequency operation. A tone detector is described which implements one or more digital match filters.

Claims

1. A tone detection arrangement for decoding an incoming data stream that is received in sequential bit times and which contains at least one tone that is selectively present for the duration of each bit time, said tone detection arrangement comprising:

a) a plurality of digital filters each of which is tuned for detecting said tone over a filter interval that is at least approximately equal in duration to the bit time from a filter start time to a filter stop time;

b) a first arrangement for starting a first one of said digital filters at a first start time in timed relation to a particular bit time and for starting an additional one of said digital filters at an additional start time which occurs following a predetermined interval after said start time of the first digital filter such that a number of the predetermined intervals at least approximately equals the bit time in duration; and

c) a second arrangement for determining an average magnitude of said tone over the filter interval of the first digital filter at the filter stop time of said first digital filter and, thereafter, for determining the average magnitude of the tone over the additional filter interval of the additional digital filter at the filter stop time of the additional digital filter.

2. The tone detection arrangement of claim 1 wherein said predetermined interval is approximately equal to one-quarter of said bit time.

3. The tone detection arrangement of claim 1 wherein the predetermined interval is approximately equal to the bit time divided by a total number of digital filters which make up the plurality of digital filters.

4. The tone detection arrangement of claim 1 wherein the first arrangement is configured for starting a further additional one of said digital filters at a further additional start time which occurs following said predetermined interval after the start time of a last one of the additional digital filters to be started and the second arrangement is configured for determining the average magnitude of the tone over the further additional filter interval of the further additional digital filter at the filter stop time of the further additional digital filter.

5. The tone detection arrangement of claim 4 wherein said first arrangement is further configured for sequentially starting each remaining one of the plurality of digital filters at consecutive ones of said predetermined interval and the second arrangement is further configured for sequentially determining the average magnitude of the tone over the filter interval of each of the remaining ones of the digital filters upon reaching the filter stop time of each filter.

6. The tone detection arrangement of claim 1 wherein said first and second arrangements are configured for cooperatively determining the approximate magnitude of said tone by sequentially using each one of the plurality of filters.

7. The tone detection arrangement of claim 6 wherein said second arrangement includes an output arrangement for outputting the approximate magnitude determined using each digital filter upon conclusion of the filter interval of each digital filter.

8. The tone detection arrangement of claim 1 wherein said data stream is initially received in analog form and said tone detection arrangement includes a comparator for initially converting the incoming analog data stream to a binary data stream based on one switching threshold and providing the binary data stream to said filters.

9. The tone detection arrangement of claim 8 wherein each digital filter is configured for sampling the binary data stream during the filter interval of that digital filter to establish a plurality of samples, each of which samples is characterized as a binary value, at a rate based on said tone and the second arrangement is configured for using said samples in a way which establishes at least an approximate magnitude of the selected tone for the filter interval of each digital filter.

10. The tone detection arrangement of claim 9 wherein said tone is characterized by a cycle time and each digital filter samples at one-quarter wave intervals of the cycle time.

11. The tone detection arrangement of claim 10 wherein the second arrangement uses alternating ones of said samples in contributing to a first value and a second value such that the first value and the second value are cooperatively indicative of at least the approximate magnitude of the tone.

12. The tone detection arrangement of claim 7 wherein said second arrangement is configured for comparing the first and second values in a predetermined way against one or more thresholds and outputting a magnitude indicative signal based on said one or more thresholds.

13. The tone detection arrangement of claim 12 including an output monitoring arrangement for monitoring the magnitude indicative signal in relation to each digital filter to determine the presence of said tone over said bit time.

14. The tone detection arrangement of claim 12 wherein said magnitude indicative signal is a binary representation of the magnitude of the tone in relation to one or more magnitude ranges.

15. In a system in which a boring tool is moved underground in a region, said boring tool being configured for transmitting a locating signal therefrom at least during the underground movement of the boring tool and for transmitting a data stream that is received in sequential bit times and which contains at least one tone that is selectively present for the duration of each bit time, a locator comprising:

a locating arrangement for receiving the locating signal for use in tracking the boring tool;

a plurality of digital filters each of which is tuned for detecting said tone over a filter interval that is at least approximately equal in duration to the bit time from a filter start time to a filter stop time;

a first arrangement for starting a first one of said digital filters at a first start time and for starting an additional one of said digital filters at an additional start time which occurs following a predetermined interval after said start time of the first digital filter such that a number of the predetermined intervals at least approximately equals the bit time in duration; and

a second arrangement for determining an average magnitude of said tone over the filter interval of the first digital filter at the filter stop time of said first digital filter and, thereafter, for determining the average magnitude of the tone over the additional filter interval of the additional digital filter at the filter stop time of the additional digital filter.

16. The locator of claim 15 wherein the first arrangement is configured for starting a further additional one of said digital filters at a further additional start time which occurs following said predetermined interval after the start time of a last one of the additional digital filters to be started and the second arrangement is configured for determining the average magnitude of the tone over the further additional filter interval of the further additional digital filter at the filter stop time of the further additional digital filter.

17. A tone detection arrangement for decoding an incoming data stream which contains at least one tone that is selectively present, said tone detection arrangement comprising:

a plurality of digital filters each of which is tuned for detecting said tone over a filter interval from a filter start time to a filter stop time;

a first arrangement for starting said digital filters in a staggered time relation with respect to one another so as to operate over a plurality of intervals that are in said staggered time relation with respect to one another including a plurality of said filter stop times which conclude the filter intervals in the staggered time relationship; and

a second arrangement for determining an average magnitude of said tone responsive to the filter stop time of each filter.

18. A tone detection arrangement for decoding an incoming data stream that is received in a series of bit times and which contains at least one tone that is selectively present for the duration of each bit time, said tone detection arrangement comprising:

a plurality of digital filters each of which is tuned for detecting said tone over a filter interval that is at least approximately equal in duration to the bit time from a filter start time to a filter stop time;

a first arrangement for starting said digital filters in a staggered time relation with respect to one another so as to operate over a plurality of intervals that are in said staggered time relation with respect to one another including a plurality of said filter stop times which conclude in the staggered time relationship; and

a second arrangement for determining an average magnitude of said tone responsive to the filter stop time of each filter.

19. In a tone detection arrangement for decoding an incoming data stream that is received in sequential bit times and which contains at least one tone that is selectively present for the duration of each bit time, a method comprising:

a) providing a plurality of digital filters each of which is tuned for detecting said tone over a filter interval that is at least approximately equal in duration to the bit time from a filter start time to a filter stop time;

b) starting a first one of said digital filters at a first start time in relation to a particular bit time;

c) starting an additional one of said digital filters at an additional start time which occurs following a predetermined interval after said start time of the first digital filter such that a number of the predetermined intervals at least approximately equals the bit time in duration;

d) at the filter stop time of said first digital filter, determining at least an approximate magnitude of said tone over the filter interval of the first digital filter;

e) at the filter stop time of the additional digital filter, determining at least an approximate magnitude of the tone over the additional filter interval of the additional digital filter.

20. The method of claim 19 wherein the predetermined interval is approximately equal to the bit time divided by a total number of digital filters which make up the plurality of digital filters.

21. The method of claim 19 further comprising:

f) starting a further additional one of said digital filters at a further additional start time which occurs following said predetermined interval after the start time of a last one of the additional digital filters to be started; and

g) at the filter stop time of the further additional digital filter, determining at least an approximate magnitude of the tone over the further additional filter interval of the further additional digital filter.

22. The method of claim 21 further comprising the step of:

h) repeating steps f and g for each remaining one of the plurality of digital filters.

23. The method of claim 22 further comprising the step of:

i) repeating steps (b) through (h) after starting all of the plurality of digital filters.

24. The method of claim 19 including the step of outputting at least the approximate magnitude of the tone determined using the first and additional digital filters.

25. The method of claim 19 wherein said data stream is initially received in analog form and including the step of initially converting the incoming analog data stream to a binary data stream based on one switching threshold.

26. The method of claim 25 including the step of sampling the binary data stream using each digital filter during the filter interval for that digital filter to establish a plurality of samples, each of which samples is characterized as a binary value, at a rate based on said tone and using said samples in a way which establishes at least an approximate average magnitude of the selected tone for that filter interval.

27. The method of claim 26 wherein said tone is characterized by a cycle time and said sampling step is performed at one-quarter wave intervals of the cycle time.

28. The method of claim 27 wherein the step of using the samples includes the steps of:

using alternating ones of said samples in contributing to a first value and a second value such that the first value and the second value are cooperatively indicative of at least the approximate magnitude of the tone.

29. The method of claim 28 wherein the step of determining the approximate magnitude of the tone includes the step of comparing the first and second values in a predetermined way against one or one more thresholds and outputting a magnitude indicative signal based on said one or more thresholds.

30. The method of claim 29 including the step of monitoring the magnitude indicative signal in relation to each digital filter to establish the presence of said tone over said bit time.

31. The method of claim 29 wherein said magnitude indicative signal is a binary representation of the magnitude of the tone in relation to one or more magnitude ranges.

32. In a tone detection arrangement for decoding an incoming data stream which contains at least one tone that is selectively present, a method comprising the steps of:

providing a plurality of digital filters each of which is tuned for detecting said tone over a filter interval from a filter start time to a filter stop time;

starting said digital filters in a staggered time relation with respect to one another so as to operate over a plurality of intervals that are in said staggered time relation with respect to one another including a plurality of said filter stop times which conclude the filter intervals in the staggered time relationship; and

determining an average magnitude of said tone responsive to the filter stop time of each filter.

33. The method of claim 32 further comprising:

restarting each of said digital filters after the filter stop time of each filter in said staggered time relation, and

determining the average magnitude of said tone responsive to the filter stop time of each restarted digital filter.

34. In a tone detection arrangement for decoding an incoming data stream that is received in a series of bit times and which contains at least one tone that is selectively present for the duration of each bit time, a method comprising:

providing a plurality of digital filters each of which is tuned for detecting said tone over a filter interval that is at least approximately equal in duration to the bit time from a filter start time to a filter stop time;

starting said digital filters in a staggered time relation with respect to one another so as to operate over a plurality of intervals that are in said staggered time relation with respect to one another including a plurality of said filter stop times which conclude in the staggered time relationship; and

determining an average magnitude of said tone responsive to the filter stop time of each filter.

35. The method of claim 34 further comprising:

restarting each of said digital filters after the filter stop time of each filter in said staggered time relation, and

determining the average magnitude of said tone responsive to the filter stop time of each restarted digital filter.