An annular gasket for affecting a watertight seal between two sections of corrugated pipe. In the method, calibration signals, which can include a band-limited white noise, are used with a periodically repeated signal course. The valve housing has a first port, a second port, and a fluid path running between the first and second ports. The cross pin is employed to limit end play of the axle shafts in a direction toward one another. The reflector bodies comprise a coating having a reflection film, by which the reflector body segments of the reflector body are uniformly spanned, performed by suitably selecting the geometric shape of the reflector body segment to be spanned, by injecting molding behind the reflection film in an injection molding process andor by producing the reflector body segments in a forming process.