Abstract: The invention relates to a method for acoustic measuring in technical hollow spaces, for example, for measuring reflection points along long pipelines. The method begins with establishing a broadband exciter frequency range. This is followed by establishing interference frequencies which should not be in the exciter signal, and generating a precursor signal over the frequency range with the omission of the interference frequencies. Then, the precursor signal is coupled into the pipeline and a precursor reflection signal reflected out of the pipeline is received. The precursor signal is compared with the precursor reflection signal and damping frequencies are determined at which the precursor signal on the measuring path along the pipeline is damped much more than the average damping of the entire precursor signal. Then, an exciter signal is generated over the exciter frequency range with the omission of the interference frequencies and the damping frequencies.

Abstract: The invention relates to a method for the determination of the impulse response g(t) of a broad band linear system. The method can be used for the application of high frequency technology. For a test signal, a maximum length binary sequence (MLBS) is employed. The measured signal, obtained by the system, is sampled under maintenance of the sample theorem whereby the sampling clock in accordance with the invention is obtained directly from that high frequency clock pulse which is used for the generation of the MLBS. The digitized measured signal is then subjected to a fast Hadamard-transformation for calculation of the impulse response. The invention furthermore, provides a measuring circuit which carries out this method.