Measuring changes in distance using radar

A computer-implemented method of measuring a change in distance over time using FMCW radar signals, the method comprising:

• transmitting a series of chirp signals;
• receiving a series of reflected chirp signals from a target;
• and
• processing the series of reflected chirp signals to determine a change in distance to the target over time from phase differences between the transmitted and received chirp signals,
• wherein phase differences between successive frames derived from the received chirp signals are fitted to a function to correct for any phase differences greater than 2π between the successive frames.

An FMCW radar system comprising:

• a transmitter configured to generate and transmit a series of chirp signals;
• a receiver configured to receive a series of reflected chirp signals from a target;
• and
• a signal processor configured to process the series of reflected chirp signals to determine a change in distance to the target over time from phase differences between the transmitted and received chirp signals,
• wherein the signal processor is configured to fit phase differences between successive frames containing the received chirp signals to a function to correct for any phase differences greater than 2π between the successive frames.

A computer program comprising instructions for causing a signal processor of an FMCW radar system to measure a change in distance over time using FMCW radar signals, the instructions causing the signal processor to:

• transmit a series of chirp signals;
• receive a series of reflected chirp signals from a target;
• and
• process the series of reflected chirp signals to determine a change in distance to the target over time from phase differences between the transmitted and received chirp signals,
• wherein phase differences between successive frames derived from the received chirp signals are fitted to a function to correct for any phase differences greater than 2π between the successive frames.