Device for distance measurement comprising at least one signal generator for generating an electromagnetic measurement signal, at least one transmitting antenna for transmitting the measurement signal and at least one receiving antenna for receiving a received signal, wherein the signal generator is connected at least to the transmitting antenna at least a first mixer, wherein a first input of the first mixer is connected to the signal generator and wherein a second input of the first mixer is connected at least to the receiving antenna, so that, during operation, the first mixer mixes at least the measurement signal generated by the signal generator and the received signal received by the receiving antenna and further comprising an evaluation unit, wherein an integrated diagnostic unit is provided, wherein the diagnostic unit has at least one diagnostic line, wherein the signal generator is connected to the diagnostic line in such a way that, during operation, the measurement signal generated by the signal generator is at least partially coupled into the diagnostic line, wherein the diagnostic line has at least one delay element, wherein the measurement signal is formed as a diagnostic signal after at least one pass through the delay element during operation, and wherein the diagnostic line is connected to the first mixer or to a second mixer, so that, during operation, the diagnostic signal is mixed with the measurement signal in the first mixer or in the second mixer to form a diagnostic mixed signal, wherein the output of the first mixer, and if present the output of the second mixer, is or are connected to the evaluation unit, and wherein the evaluation unit is designed in such a way that it uses the diagnostic mixed signal to check the functionality of the signal generator and/or of an evaluation algorithm. at least one signal generator for generating an electromagnetic measurement signal, at least one transmitting antenna for transmitting the measurement signal and at least one receiving antenna for receiving a received signal, wherein the signal generator is connected at least to the transmitting antenna at least a first mixer, wherein a first input of the first mixer is connected to the signal generator and wherein a second input of the first mixer is connected at least to the receiving antenna, so that, during operation, the first mixer mixes at least the measurement signal generated by the signal generator and the received signal received by the receiving antenna and further comprising an evaluation unit, wherein an integrated diagnostic unit is provided, wherein the diagnostic unit has at least one diagnostic line, wherein the signal generator is connected to the diagnostic line in such a way that, during operation, the measurement signal generated by the signal generator is at least partially coupled into the diagnostic line, wherein the diagnostic line has at least one delay element, wherein the measurement signal is formed as a diagnostic signal after at least one pass through the delay element during operation, and wherein the diagnostic line is connected to the first mixer or to a second mixer, so that, during operation, the diagnostic signal is mixed with the measurement signal in the first mixer or in the second mixer to form a diagnostic mixed signal, wherein the output of the first mixer, and if present the output of the second mixer, is or are connected to the evaluation unit, and wherein the evaluation unit is designed in such a way that it uses the diagnostic mixed signal to check the functionality of the signal generator and/or of an evaluation algorithm.