System for monitoring and/or surveying conduits

1. A system for monitoring a conduit, comprising:

an acoustic source, pointed in a direction, wherein the acoustic source emits a forward-traveling swept signal into the conduit in the direction that the acoustic source is pointing to establish an acoustic plane wave within the conduit, the acoustic plane wave being a guided wave to propagate along the conduit,

wherein the emitted signal is a linear frequency sweep; and

a pair of acoustic detectors for receiving one or more signals that are propagating along the conduit, wherein the acoustic source and the acoustic detectors are co-located within a housing.

2. The system according to claim 1 , further comprising:

a memory for storing data relating to detected signals,

a processor for analysing signal data, wherein the analysis of signal data only from the pair of acoustic detectors in the housing provides determination of a condition of the conduit.

3. The system according to claim 1 , wherein the conduit is a polyurethane pipe.

4. The system according to claim 1 , further comprising a mount for locating the acoustic source and/or acoustic detector on an external wall of the conduit.

5. The system according to claim 1 , arranged as a blockage detection system configured to generate an acoustic signal and receive a reflected acoustic signal.

6. The system of claim 1 , wherein the acoustic source and the acoustic detector are vibrationally isolated from each other.

7. A method for monitoring the condition of a conduit comprising:

providing an acoustic source with a first detector and a second detector, wherein the acoustic source and the first and second detectors are co-located within a housing;

deploying, within a conduit, the acoustic source with the first and second detectors, wherein the acoustic source is pointed in a direction;

emitting a forward traveling swept signal from the acoustic source into the conduit in the direction that the acoustic source is pointing to establish an acoustic plane wave within the conduit, the acoustic plane wave being a guided wave,

detecting a reflected signal from the conduit using the first detector and the second detector, wherein the emitted signal is a linear frequency sweep;

determining, based on signal processing data obtained from the first detector and the second detector, a direction in which the sound is traveling; and

determining, based on the signal processing data, a condition of the conduit.

8. The method of claim 7 , wherein the first and second detectors are omnidirectional microphones or omnidirectional hydrophones.

9. The method of claim 7 , wherein the acoustic source and the first and second detectors are vibrationally isolated from each other within the housing.

10. The method of claim 7 , wherein the conduit is selected from a group consisting of: a pipe, a pipeline, a culvert, a sewer, a drain, and a tunnel.

11. The method of claim 10 , further comprising determining a condition of the conduit, wherein the condition is a blockage and the blockage is an improvised explosive device (IED) in the conduit.

12. The method of claim 7 , wherein the conduit is an air-filled conduit.

13. The method of claim 7 , wherein the conduit is filled with fluid.

14. The method of claim 7 , wherein the conduit is part-filled with fluid and part-filled with gas.

15. The method of claim 7 , wherein the acoustic plane wave has a frequency that is dependent upon a diameter of the conduit and the highest frequency has a wavelength that is larger than the diameter of the conduit.

16. A method for detecting a sewer blockage comprising:

identifying a sewer to be checked;

providing an acoustic source with a first detector and a second detector, wherein the acoustic source and the first and second detectors are co-located within a housing;

deploying, within a sewer, the acoustic source with the first and second detectors, wherein the acoustic source is pointed in a direction;

emitting a forward traveling swept signal from the acoustic source into the conduit in the direction that the acoustic source is pointing to establish an acoustic plane wave within the conduit, the acoustic plane wave being a guided wave,

detecting a reflected signal from the conduit using the first detector and the second detector, wherein the emitted signal is a linear frequency sweep; and

determining, based on signal processing data obtained from the first detector and the second detector, a direction in which the sound is traveling; and

determining, based on the signal processing data the location of a sewer blockage.

17. The method of claim 16 , wherein the acoustic plane wave has a frequency that is dependent upon a diameter of the conduit and the highest frequency has a wavelength that is larger than the diameter of the conduit.