Abstract: A method for retrieving predetermined locations in sewer and pipeline systems after application or deposition of a layer of material. A carrier vehicle having a microwave sensor emits microwave signals and receives backscattered microwave signals. A first run is conducted inside the sewer or pipeline system before application or deposition of the layer of material. A first temporal signal profile of the backscattered microwave signals is recorded and the sought locations are marked in the first signal profile. After the application or deposition of the layer of material, a second run is conducted. A second temporal signal profile of the backscattered signals is recorded. The current position of the vehicle in the sewer or pipeline system relative to the sought locations is determined by comparison with the first signal profile.

Abstract: The present invention relates to a method for retrieving predetermined locations in sewer and pipeline systems (7) after the application or the deposition of a layer of material, in which a carrier vehicle having a microwave sensor (1) is used which emits microwave signals and receives backscattered microwave signals, having the following steps. In the method a first run is conducted inside the sewer respectively the pipeline system (7) is conducted before the application or the deposition of the layer of material, with in at least one section of said sewer respectively pipeline system a first temporal signal profile of said backscattered microwave signals being recorded and the sought locations being marked in the first signal profile.

Abstract: A system for three-dimensional measurement of inaccessible hollow spaces g. sewage canal pipes) by means of a light source and a camera, which are disposed on an inspection head or carrier. A structured light source is used, and the camera and the structured light source have a common entry and exit aperture and have before the aperture at least partially one common optical axis or parallel axes, the distance between which is substantially smaller than the distance between the source point of the pattern and the object-side principle plane of the camera lens.

Abstract: A process for detecting totally or partially hidden faults, such as cracks, and bubbles and the like in an opaque medium, by using microwave radiation. Microwaves from a transmitting antenna are directed against the surface of the medium which is to be inspected, and microwave radiation reflected or back scattered from the medium is detected and analyzed. In order to maximize the signal to noise ratio, minimizing the detection of radiation reflected by the surfaces of the medium itself, at least one of the transmitting antenna and the receiving antenna is oriented at an oblique angle relative to the surface of the medium.