Radar apparatus and signal processing method
There is provided a radar apparatus capable of emitting a transmission wave relating to a transmitting signal which is frequency-modulated, and receiving a reflection wave coming from a target at which the transmission wave is reflected as a receiving signal, to derive at least position information of the target based on the receiving signal. A deriving unit derives a fluctuation value of a signal level relating to the receiving signal for a stationary target among the targets. A calculating unit calculates a fluctuation integrated value integrated by the fluctuation value. A judging unit judges the stationary target as a target other than a control subject if the fluctuation integrated value is below a predetermined threshold.
1. A radar apparatus capable of emitting a transmission wave relating to a transmitting signal which is frequency-modulated, and receiving a reflection wave coming from a target at which the transmission wave is reflected as a receiving signal, to derive at least position information of the target based on the receiving signal, the radar apparatus comprising:
a deriving unit configured to derive a plurality of fluctuation values of a signal level of the receiving signal for a stationary target among the targets;
a calculating unit configured to calculate a fluctuation integrated value by integrating the plurality of fluctuation values of the signal level of the receiving signal; and
a judging unit configured to judge the stationary target as a target other than a control subject if the fluctuation integrated value is below a predetermined threshold.
2. The radar apparatus according to claim 1 , wherein the plurality of fluctuation values are derived from a maximum value and a minimum value of the signal level of the receiving signal.
3. The radar apparatus according to claim 2 , wherein the deriving unit derives the plurality of fluctuation values from the maximum value to the minimum value if the stationary target exists at a position which is above a predetermined distance, and derives the plurality of fluctuation values from the minimum value to the maximum value if the stationary target exists at a position which is below the predetermined distance.
4. The radar apparatus according to claim 1 , wherein the judging unit is configured to judge the stationary target as the target other than the control subject when a moving target exists at a distance closer than the stationary target.
5. The radar apparatus according to claim 1 , wherein the calculating unit increases an integration rate of the plurality of fluctuation values when the signal level is high.
6. The radar apparatus according to claim 1 , further comprising a target judging unit configured to judge, on the basis of comparison of horizontal and vertical distances between the stationary target and an other stationary target, whether or not the other stationary target is a diverged target belonging to the same object as the stationary target.
7. The radar apparatus according to claim 1 , further comprising a continuous target judging unit configured to judge, on the basis of comparison of horizontal and vertical distances between the stationary target and an other stationary target, whether or not the stationary target and the other stationary target are a continuous stationary target which continuously exists in a traveling direction of a vehicle mounted with the radar apparatus at a side of a traffic lane on which the vehicle is traveling.
8. The radar apparatus according to claim 6 , further comprising a continuous target judging unit configured to judge whether or not there is a continuous stationary target which continuously exists in a traveling direction of a vehicle mounted with the radar apparatus at a side of a traffic lane on which the vehicle is traveling,
wherein the target judging unit changes a judgment condition of the diverged target if the continuous stationary target exists.
9. A signal processing method of emitting a transmission wave relating to a transmitting signal which is frequency-modulated, and receiving a reflection wave coming from a target at which the transmission wave is reflected as a receiving signal, to derive at least position information of the target based on the receiving signal, the signal processing method comprising:
deriving a plurality of fluctuation values of a signal level of the receiving signal for a stationary target among the targets;
calculating a fluctuation integrated value by integrating the plurality of fluctuation values of the signal level of the receiving signal; and
judging the stationary target as a target other than a control subject if the fluctuation integrated value is below a predetermined threshold,
wherein the deriving, calculating and judging are performed by a processor.
10. The radar apparatus according to claim 3 , wherein the predetermined distance is a predetermined vertical distance.