Radar apparatus
View Patent ↗A pulse signal is produced in a pulse generating section, and repetitively transmitted from an antenna at constant time intervals. A reception signal, received through an antenna and including a reflective wave from an object, is amplified and gain-adjusted. Thereafter, a distance detecting section detects a reception pulse of the reflected wave, and calculates the distance to the object. The variable attenuator attenuates the reception signal by a gain adjusted in accordance with a gain control signal. The gain of the variable attenuator is controlled so as to be maximum immediately after the pulse signal is transmitted, and to be reduced with elapse of time. Based on a gain adjustment timing signal, a gain adjustment timing when the attenuation amount is changed is made different for each transmission of the pulse signal.
1. A radar apparatus comprising:
a transmission signal generator that generates a transmission signal which is an intermittent signal having a predetermined signal width and signal interval;
a RF transmitter that wirelessly transmits the transmission signal to a measurement space during a transmission period;
a RF receiver that receives a reception signal including a reflected wave from an object, from the measurement space;
a timing adjuster that adjusts a plurality of length of gain adjustment periods in the transmission period, each gain adjustment periods have different lengths, respectively for each transmission period of the transmission signal;
a gain adjuster that generates a gain control signal for increasing the level of the received signal in accordance with the plurality of adjusted gain adjustment periods;
a level adjuster that adjusts a level of the reception signal by a variable gain based on the gain control signal; and
an object detector that detects the object based on the level-adjusted reception signal.
2. The radar apparatus according to claim 1 , wherein the timing adjuster adjusts time which is longer than a response time required for the gain adjustment in the level adjuster as a difference between the gain adjustment periods in each transmission period.
3. The radar apparatus according to claim 1 , wherein the object detector includes an adder which adds the level-adjusted reception signals in each the transmission periods.
4. The radar apparatus according to claim 1 , wherein the object detecting section includes:
a reflected wave detector which detects a signal of the reflected wave from the object, from the level-adjusted reception signal; and
a distance calculator which calculates a distance from the object based on a result of the detection of the reflected wave.
5. The radar apparatus according to claim 4 , wherein the reflected wave detector includes a comparator which compares the level-adjusted reception signal with a predetermined threshold to detect the signal of the reflected wave from the object; and
wherein the comparator changes the threshold in conjunction with the level adjustment of the reception signal, in synchronization with the adjusted gain adjustment period.
6. The radar apparatus according to claim 1 , wherein the RF receiver includes a plurality of antennas which are arranged in an array manner, an antenna controller which generates an antenna switch timing signal for controlling the antenna switcher, and an antenna switcher which switches the plurality of antennas based on the antenna switch timing signal; and
wherein the antenna controller generates the antenna switch timing signal for switching the plurality of antennas in each period which is an integer multiple of amounts of the gain adjustment periods.
7. The radar apparatus according to claim 6 , wherein the gain adjuster performs an adjustment of the gain adjustment periods in preference to the antenna switching by the antenna controller.
8. The radar apparatus according to claim 6 , wherein the object detector includes:
a second adder which, based on the antenna switch timing signal, among the level-adjusted reception signals, adds signals which are received by a same antenna and which have a same delay time; and
a direction detector which detects an incoming direction of the reflective wave from the object based on a result of the addition of the second adder.
9. The radar apparatus according to claim 1 , wherein the level adjuster has a variable attenuator; and
wherein the gain adjuster adjusts an attenuation amount of the variable attenuator.
10. The radar apparatus according to claim 1 , wherein the level adjuster has a variable amplifier; and
wherein the gain adjuster adjusts an amplification amount of the variable amplifier.