System, method, and circuit for distance measurement between two nodes of a radio network

A system for distance measurement between two nodes of a radio network, the system comprising:

• a first node configured to transmit a first unmodulated carrier signal and configured to receive a second unmodulated carrier signal;
• a second node configured to transmit the second unmodulated carrier signal and configured to receive the first unmodulated carrier signal,
• wherein the first node has a first phase measurement unit configured to measure a first value and a second value of a first phase of the received second carrier signal, the first value of the first phase being assigned to a first frequency of the received second carrier signal and the second value of the first phase being assigned to a second frequency of the received second carrier signal, the first frequency and the second frequency having a frequency difference,
• wherein the second node has a second phase measurement unit configured to measure a third value and a fourth value of a second phase of the received first carrier signal, the third value of the second phase being assigned to a third frequency of the received first carrier signal and the fourth value of the second phase being assigned to a fourth frequency of the received first carrier signal, the third frequency and the fourth frequency having the frequency difference, and
• wherein the first node and/or the second node and/or another node are configured to determine the distance from the frequency difference from the first value and the second value of the first phase and from the third value and the fourth value of the second phase.

A circuit for distance measurement for a node of a radio network, the circuit comprising:

• a transmitter/receiver circuit configured to transmit a first unmodulated carrier signal with different frequencies and configured to receive a second unmodulated carrier signal;
• a reference clock generator for a phase-locked loop configured to generate a local oscillator signal for downmixing a received second carrier signal to an intermediate frequency signal by the transmitter/receiver circuit;
• a frequency divider connectable to the reference clock generator to generate a comparison signal;
• a phase measurement circuit configured to evaluate a phase between the intermediate frequency signal and the comparison signal, the phase measurement circuit being connectable to the transmitter/receiver circuit and the frequency divider;
• and
• a control circuit connectable to the phase measurement unit, wherein to control measurement times synchronized in time, the control circuit is configured to measure a first value and a second value of the phase, the first value being assigned to a first frequency of the received second carrier signal and the second value being assigned to a second frequency of the received second carrier signal, the first frequency and the second frequency having a frequency difference.