Radar
A radar for detecting a target wherein a standard deviation of the amplitude of a beat signal from a transmission signal and a reception signal is determined for a predetermined period. A threshold is determined by adding a predetermined value to the standard deviation or by multiplying the standard deviation by a predetermined coefficient. The presence or absence of interference on the beat signal is detected according to the presence or the absence of an amplitude greater than the threshold. For example, an amplitude exceeding the standard deviation×2 is considered a spike noise (SPN), i.e., as “presence of interference”. The threshold used for detecting peaks appearing on a frequency spectrum is then increased. This allows detection of the presence or the absence of a spike noise superposed on the beat signal to be performed more certainly, thereby enabling processing according to the presence or the absence of interference.
1. A radar comprising:
a transmitter that transmits a transmission signal whose frequency gradually changes over time within a predetermined frequency range;
a receiver that receives a reception signal reflected from a target;
a frequency spectrum unit that determines a frequency spectrum of a beat signal of the transmission signal and the reception signal;
a standard deviation computing unit that determines a standard deviation of an amplitude of the beat signal for a predetermined period;
a threshold processing unit that determines a threshold by adding a predetermined value to the standard deviation or by multiplying the standard deviation by a predetermined coefficient;
an interference detecting unit that detects a presence or an absence of interference on the beat signal according to a presence or an absence of an amplitude greater than the threshold;
a signal processing unit that performs processing on the beat signal according to the presence or the absence of the interference; and
a detecting unit that detects information of the target based on the amplitude greater than the threshold.
2. A radar comprising:
a transmitter that transmits a transmission signal whose frequency gradually changes over time within a predetermined frequency range;
a receiver that receives a reception signal reflected from a target;
a frequency spectrum unit that determines a frequency spectrum of a beat signal of the transmission signal and the reception signal;
a high pass filter that allows high frequency components of the beat signal to pass through;
an interference detecting unit that detects a presence or an absence of interference on the beat signal according to whether or not an amplitude of the high pass filtered signal exceeds a predetermined threshold;
a signal processing unit that performs processing on the beat signal according to the presence or the absence of the interference; and
a detecting unit that detects information of the target based on the amplitude greater than the threshold.
3. A radar comprising:
a transmitter that transmits a transmission signal whose frequency gradually changes over time within a predetermined frequency range;
a receiver that receives a reception signal reflected from a target;
a frequency spectrum unit that determines a frequency spectrum of a beat signal of the transmission signal and the reception signal;
a first interference detecting unit that determines a standard deviation of an amplitude of the beat signal for a predetermined period;
a threshold processing unit that determines a threshold by adding a predetermined value to the standard deviation or by multiplying the standard deviation by a predetermined coefficient, and that detects a presence or an absence of interference on the beat signal according to a presence or an absence of an amplitude greater than the threshold;
a high pass filter that allows high frequency components of the beat signal to pass through;
a second interference detecting unit that detects a presence or an absence of interference on the beat signal according to whether or not an amplitude of the high pass filtered signal exceeds a predetermined threshold;
a signal processing unit that performs processing on the beat signal according to the detection results of the first and second interference detecting units; and
a detecting unit that detects information of the target based on the amplitude greater than the threshold and/or the predetermined threshold.
4. A radar comprising:
a transmitter that transmits a transmission signal whose frequency gradually changes over time within a predetermined frequency range;
a receiver that receives a reception signal reflected from a target;
a frequency spectrum unit that determines a frequency spectrum of a beat signal of the transmission signal and the reception signal;
a high pass filter that allows high frequency components of the beat signal to pass through;
a standard deviation computing unit that determines a standard deviation of an amplitude of the high pass filtered signal for a predetermined period;
a threshold processing unit that determines a threshold by adding a predetermined value to the standard deviation or by multiplying the standard deviation by a predetermined coefficient;
an interference detecting unit that detects a presence or an absence of interference on the beat signal according to a presence or an absence of an amplitude greater than the threshold;
signal processing unit that performs processing on the beat signal according to the presence or the absence of the interference; and
a detecting unit that detects information of the target based on the amplitude greater than the threshold.
5. A radar comprising:
a transmitter that transmits a transmission signal whose frequency gradually changes over time within a predetermined frequency range;
a receiver that receives a reception signal reflected from a target;
a frequency spectrum unit that determines a frequency spectrum of a beat signal of the transmission signal and the reception signal;
a reference amplitude setting unit that sets a reference amplitude of the beat signal;
an interference detecting unit that detects a presence or an absence of interference on the beat signal according to whether or not an amplitude of the beat signal exceeds the reference amplitude by a predetermined ratio or a predetermined value;
a signal processing unit that performs processing on the beat signal according to the presence or the absence of the interference; and
a detecting unit that detects information of the target based on the amplitude greater than the reference amplitude.
6. The radar according to claim 5 , wherein the radar repeats scans of the transmission and reception signals in an azimuth direction, and wherein the reference amplitude is determined on the basis of the amplitude of the beat signal for a beam in the same direction used in a previous scan.
7. The radar according to claim 5 , wherein the radar directs the transmission signal to a plurality of different directions and receives a reception signal for each beam, and wherein the reference amplitude is determined on the basis of the amplitude of the beat signal for a beam neighboring a focused beam.
8. The radar according to claim 5 , wherein the reference amplitude is determined according to the beat signal in a neighboring modulation interval.