Method for determination of a distance and distance measuring device with improvement of the effective resolution of an A/D converter by phase modulation of the measured signal

A method for determination of a distance using an optical signal, comprising the steps of:

• generating an optical target signal;
• transmitting the target signal by an optical transmitter on a target, wherein said target signal is reflected on the target;
• receiving the target signal by an optical receiver;
• transforming the target signal to an analog evaluation signal, the evaluation signal having a phase information which depends on the distance to be measured;
• digitizing the analog evaluation signal in an analog-to-digital converter, wherein the analog-to-digital converter has a given resolution;
• evaluating the phase information of the digitized evaluation signal in an arithmetic unit, wherein phase resolution quanta of the arithmetic unit depend on the resolution of the analog-to-digital converter;
• modulating the phase of the analog evaluation signal such that the analog evaluation signal reaches said analog-to-digital converter in phase-modulated form, wherein the phase modulation of the analog evaluation signal is matched to the analog-to-digital converter by shifting the phase of the evaluation signal on both sides around a middle phase position.