Communication protocol in directional drilling system, apparatus and method utilizing multi-bit data symbol transmission

Patent metadata

Field	Value
Publication number	US-11230921-B2
Application number	US-201715676057-A
Country	US
Kind code	B2
Filing date	Aug 14, 2017
Priority date	Sep 5, 2014
Publication date	Jan 25, 2022
Grant date	Jan 25, 2022

Abstract

A system includes a transmitter for use in conjunction with a horizontal directional drilling system that transmits a multi-bit symbol stream that characterizes sensor symbols for receipt by an aboveground portable device. The portable device receives the symbol stream for aboveground recovery of the sensor signals. The transmitter can precisely place the symbol frequencies at least to avoid a noise environment, as well as to avoid powerline harmonics, and can utilize wave shaping for transmitted symbols at least to provide for transmission power control, spectral content control and wideband antenna matching. The receiver can measure the noise environment to identify the symbol frequencies used by the transmitter. The noise can be scanned at an incremental resolution across a wide frequency bandwidth for display or automatic symbol frequency selection.

First claim

What is claimed is:

1. A transmitter for use in conjunction with a horizontal directional drilling system that includes a drill string that extends from a drill rig to an inground tool that supports the transmitter such that extension and retraction of the drill string moves the inground tool through the ground during an inground operation, said transmitter comprising:
an antenna;
one or more sensors for generating one or more sensor signals;
a processor configured for generating a multi-bit symbol stream based on the sensor signals wherein the multi-bit symbol stream includes at least four different symbols such that each symbol represents at least two bits; and
an antenna driver arrangement for electrically driving the antenna based on the multi-bit symbol stream to emit an electromagnetic symbol stream at least for aboveground recovery of the sensor signals, wherein each multi-bit symbol is transmitted at a symbol frequency that is unmodulated such that the different symbols are transmitted at different symbol frequencies.

2. The transmitter of claim 1 wherein said processor is configured for transmitting each of the symbol frequencies at a specified power level based on a power allocation such that one of the symbol frequencies is transmitted at a first power level that is different than a second power level for at least one other symbol frequency.

3. The transmitter of claim 1 further comprising:
a direct digital synthesizer configured to generate the multi-bit symbol stream.

4. The transmitter of claim 3 wherein the direct digital synthesizer is operable to generate a plurality of symbol frequencies across a wide frequency bandwidth and the direct digital synthesizer is configured to limit the symbol frequencies to a narrow bandwidth that is less than the wide frequency bandwidth and at least approximately matched to said antenna.

5. The transmitter of claim 1 wherein the processor is configured for generating a depth signal and the antenna driver arrangement drives the antenna based on the depth signal to emit a dipole locating signal at least for use in determining a depth of the transmitter.

6. The transmitter of claim 1 wherein the multi-bit symbol stream includes at least sixteen different symbols such that each symbol represents at least four bits.

7. The transmitter of claim 1 wherein the processor is configured to transmit the multi-bit symbol stream subject to an error correction code for above ground reception of the multi-bit symbol stream by a receiver configured to determine a depth of the transmitter based at least in part on decoding the received multi-bit symbol stream subject to the error correction code.

8. A portable device for use in conjunction with a transmitter that is configured to move through the ground in a region during an operational procedure while transmitting a transmitter signal that is receivable by the portable device subject to electromagnetic noise that can vary within said region, said portable device comprising:
a receiver configured to receive the transmitter signal as a multibit symbol stream, wherein each multi-bit symbol is transmitted at a symbol frequency that is unmodulated and each such symbol frequency represents two or more bits such that the different symbols are transmitted at different symbol frequencies, and which at least characterizes a set of sensor information relating to the operation of the transmitter during the inground operation to recover the set of sensor information.

9. The portable device of claim 8 wherein said receiver is configured to determine a depth of the transmitter during the inground operation based on reception of a plurality of multi-bit symbol frequencies.

10. The portable device of claim 9 wherein the depth is determined based on a received amplitude of the multi-bit symbol frequencies.

11. The portable device of claim 9 wherein the depth is determined based on multiplication of each multi-bit symbol frequency by an offset frequency.

12. The portable device of claim 8 wherein the transmitter transmits the multi-bit symbol stream subject to an error correction code and the portable device determines the depth of the transmitter based at least in part on received amplitudes associated with corrected ones of the symbols in the received multi-bit symbol stream.

13. A system for use in horizontal directional drilling that includes a drill string that extends from a drill rig to an inground tool such that extension and retraction of the drill string moves the inground tool through the ground during an inground operation, said system comprising:
a transmitter that is supported by the inground tool including
an antenna,
one or more sensors for generating one or more sensor signals,
a processor configured for generating a multi-bit symbol stream based on the sensor signals, and
an antenna driver for electrically driving the antenna to emit an electromagnetic symbol stream based on the multi-bit symbol stream wherein each multi-bit symbol is transmitted at a symbol frequency that is unmodulated such that the different symbols are transmitted at different symbol frequencies and each such symbol frequency represents two or more bits; and

a portable device including
a receiver configured to receive the multibit symbol stream in a normal mode and decode the symbol frequencies during the inground operation to recover the set of sensor information subject to the electromagnetic noise.

14. A system for use in horizontal directional drilling that includes a drill string that extends from a drill rig to an inground tool such that extension and retraction of the drill string moves the inground tool through the ground during an inground operation, said system comprising:
a transmitter that includes one or more sensors for measuring one or more operational parameters characterizing the status of the inground tool, wherein such transmitter transmits at four or more frequencies with at least one of such frequencies itself representing multiple data bits characterizing said status of the inground tool irrespective of any modulation of such frequencies and wherein each such frequency is unmodulated and represents two or more bits; and
a portable device including
a receiver configured to receive the four or more frequencies, and
a processor configured to recover said status of the inground tool from the four or more frequencies.

15. The system of claim 14 wherein said portable device is operable in a frequency selection mode to measure electromagnetic noise, absent the transmission of said frequencies, and identify frequencies based on the measured electromagnetic noise for subsequent transmission from said transmitter as said four or more frequencies.

16. A transmitter for use in horizontal directional drilling that includes a drill string that extends from a drill rig to an inground tool such that extension and retraction of the drill string moves the inground tool through the ground during an inground operation, said transmitter comprising:
an antenna;
one or more sensors for measuring one or more operational parameters characterizing the status of the inground tool; and
an antenna driver for driving the antenna to transmit at four or more frequencies with at least one of such frequencies itself representing multiple data bits characterizing said status of the inground tool irrespective of any modulation of such frequencies for above ground receipt to recover the status of the inground tool and wherein each such frequency is unmodulated and represents two or more bits.

17. A portable device

Assignees

• Merlin Technology Inc

Inventors

• Zeller Rudolf
• Garrabrant Gary
• Bayliss Timothy
• Mercer John E

Classifications

• E21B47/13 Primary

  by electromagnetic energy, e.g. radio frequency · CPC title

• E21B47/12

  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 title

• E21B7/046 Primary

  horizontal drilling (drilling with mechanical conveying means E21B7/003) · CPC title

• G01S11/06 Primary

  using intensity measurements · CPC title

• E21B7/04

  Directional drilling · CPC title