Radar sensor and method of controlling the same
A radar sensor is disclosed. The radar sensor includes a signal generator configured to emit a chirp signal to a target through a transmitting antenna, a waiting loop configured to delay the chirp signal by a predetermined delay time, thereby generating a reference signal, and a frequency mixer configured to receive, as a received chirp signal, the chirp signal reflected from the target through a receiving antenna and to mix the reference signal and the received chirp signal with each other, thereby calculating a beat frequency.
1 . A radar sensor comprising:
a signal generator configured to emit a chirp signal to a target through a transmitting antenna;
a waiting loop configured to delay the chirp signal by a predetermined delay time, thereby generating a reference signal, wherein the predetermined delay time is varied according to an interest detection range for the target and is set longer for a long range mode than for a short range mode;
a frequency mixer configured to receive, as a received chirp signal, the chirp signal reflected from the target through a receiving antenna and to mix the reference signal and the received chirp signal with each other, thereby calculating a beat frequency;
a low-pass filter connected to an output of the frequency mixer and configured to filter out a high frequency beat signal generated due to partial overlap of the reference signal and the received chirp signal in the short range mode; and
a controller configured to adjust the predetermined delay time and a pulse repetition interval of the chirp signal before mixing the reference signal and the received chirp signal based on the interest detection range for the target and control a speed estimation range for the target.
2 . The radar sensor according to claim 1 , wherein:
the interest detection range is set to a first range when the interest detection range corresponds to the long range mode;
the interest detection range is set to a second range shorter than the first range when the interest detection range corresponds to a middle range mode; and
the interest detection range is set to a third range shorter than the second range when the interest detection range corresponds to the short range mode.
3 . The radar sensor according to claim 1 , wherein the predetermined delay time corresponds to a time obtained by dividing a distance corresponding to two times the interest detection range by a speed of light.
4 . The radar sensor according to claim 1 , wherein the signal generator outputs the chirp signal at the pulse repetition interval.
5 . A method of controlling a radar sensor, comprising:
emitting a chirp signal to a target through a transmitting antenna;
delaying the chirp signal by a predetermined delay time, thereby generating a reference signal, wherein the predetermined delay time is varied according to an interest detection range for the target and is set longer for a long range mode than for a short range mode;
receiving, as a received chirp signal, the chirp signal reflected from the target through a receiving antenna; and
mixing the reference signal and the received chirp signal with each other, thereby calculating a beat frequency; and
filtering out a high frequency beat signal generated due to partial overlap of the reference signal and the received chirp signal in the short range mode, the method further comprising:
adjusting the predetermined delay time and a pulse repetition interval for the chirp signal before mixing the reference signal and the received chirp signal based on the interest detection range for the target and controlling a speed estimation range for the target.
6 . The method according to claim 5 , wherein the emitting a chirp signal comprises outputting the chirp signal at the pulse repetition interval.
7 . The method according to claim 5 , wherein:
the interest detection range is set to a first range when the interest detection range corresponds to the long range mode;
the interest detection range is set to a second range shorter than the first range when the interest detection range corresponds to a middle range mode; and
the interest detection range is set to a third range shorter than the second range when the interest detection range corresponds to the short range mode.
8 . The radar sensor according to claim 5 , wherein the predetermined delay time corresponds to a time obtained by dividing a distance corresponding to two times the interest detection range by a speed of light.