Patent ID: 8410976

Claim:
A method of determining a distance to an object, the method comprising: generating a primary, frequency-modulated signal having a frequency which changes monotonically over a frequency range ΔF throughout a frequency sweep period T SW ; deriving from the primary signal a reference signal and a transmission signal, the transmission signal comprising a plurality of successive pulses during the frequency sweep period, the plurality of successive pulses having different frequencies and each pulse being transmitted at the beginning of a respective pulse repetition interval, wherein the primary signal has a frequency which varies, during a beginning part of each pulse repetition interval, at a greater rate than the mean rate ΔF/T SW of frequency change for the frequency sweep period T SW ; transmitting the transmission signal; obtaining a received signal comprising a reflection of the transmission signal from an object; and combining the reference signal with the received signal to derive a beat frequency indicative of the distance to the object.