Leak detection apparatus and method

• US 20030167847A1
• Filed: 05/01/2003
• Published: 09/11/2003
• Est. Priority Date: 06/26/2000
• Status: Active Grant

• Current Assignee: Palmer Environmental Ltd. (Halma PLC)
• Original Assignee: Palmer Environmental Ltd. (Halma PLC)
• Inventors: Brown, Ian J., Williams, Andrew J., Smith, Brynley D.
• Granted Patent: US 6,820,016 B2
• Time in Patent Office: Days
• US Class Current: 73/592
• CPC Class Codes: G01M 3/243 for pipes

Abstract

An apparatus and method for detecting a leak in a pipe, the apparatus comprising a sensor (11) located at a pipe (7), configured to detect a signal from the pipe, converter means to convert the signal detected by the sensor into a digital signal, and transform means to transform the digital signal into a different orthogonal space. The apparatus also comprises a transmitter (15) for transmitting the transformed digital signal back to a remote processor.

Claims

1. An apparatus for detecting a leak in a pipe, the apparatus comprising:

a sensor located at a pipe configured to detect a signal from a pipe;

converter means to convert the signal detected by the sensor into a digital signal;

transform means for transforming the digital signal into a different orthogonal space; and

a transmitter for transmitting the transformed digital signal back to a remote processor.

2. An apparatus according to claim 1, wherein the transform means uses a transform which forms an unconditional basis for the signal.

3. An apparatus according to either of claims 1 or 2, wherein the transform means is configured to perform a wavelet transform.

4. An apparatus according to claim 3, wherein the transform means is configured to transform the digital signal according to the general formula:

5. An apparatus according to claim 4, wherein the transform means is configured to perform a Fourier transform.

6. An apparatus according to claim 4, wherein the wavelet function has substantially a harmonic form.

7. An apparatus according to any preceding claim, wherein the output from the transform means is directed into a scalar quantiser which is configured to quantise the data.

8. An apparatus according to any preceding claim, further comprising encoder means for compressing the signal from the transform means.

9. An apparatus according to claim 8, wherein the encoder means is configured to perform a loss less compression technique.

10. An apparatus according to claim 9, wherein the loss less compression technique is a hierarchical coding technique.

11. An apparatus according to claim 10, wherein the loss less compression technique is Huffman coding or a technique based on Huffman coding.

12. An apparatus according to claim 11, wherein the encoding technique comprises the steps of:

a) converting digitised data into an array of numbers, each number being assigned an index;

b) determining a first threshold value;

c) locating the last number in the array which is greater than the said threshold value;

d) adding the index of the said last number onto the data stream to be transmitted;

e) adding the numbers of the array up to and including the said last number, wherein numbers below the threshold being added as a 0 and numbers above the threshold being added as a bit number with the sign of the number being encoded in the last bit;

f) setting a second threshold value wherein said second threshold is less than the first threshold; and

g) repeating steps c) to f) until a predetermined final threshold value is reached.

13. An apparatus according to any preceding claim, wherein the sensor and the converter means are provided in a sensor module located at the pipe.

14. An apparatus according to claim 13, the transmitter being connected to the housing via a cable which is capable of carrying digital signals.

15. An apparatus according to any preceding claim, wherein the sensor comprises a compressible member, wherein compression and expansion of the member causes an electric signal to be generated, the member being at least partially compressed when located in a position at the pipe.

16. An apparatus according to claim 15, wherein said sensor is provided in a sensor module, said sensor module having a biasing member which is configured to bias the compressible member against a rigid part of the sensor module.

17. An apparatus according to claim 16, wherein a compressible sealing member is provided for the sensor module, and said sealing member is used to bias said compressible member.

18. A correlator for detecting and determining the position of a leak in a pipe, the correlator comprising:

a plurality of apparatus according to any preceding claim,

a remote processor capable of receiving a signal transmitted from at least two adjacent apparatus and which is capable of comparing the signals received from the two adjacent apparatus.

19. A correlator according to claim 18, wherein the remote processor is capable of receiving signals from the at least two apparatus when the remote processor is moving.

20. A method of detecting a leak in a pipe, the method comprising the steps of:

detecting a signal from a pipe using a sensor located at the said pipe;

converting the signal detected by the sensor into a digital signal;

transforming the digital signal into a different orthogonal space and

transmitting the transformed digital signal.

21. An apparatus as substantially hereinbefore described with reference to any of the accompanying drawings.

22. A correlator as substantially hereinbefore described with reference to any of the accompanying drawings.

23. A method as substantially hereinbefore described with reference to any of the accompanying drawings.