Radar apparatus
A beat signal normalizing section in a correction control section normalizes a group of sampling data of an input beat signal in one processing group. A phase amount measuring section calculates an amount of phase change of each sampling data. A correction control value calculating section compares the actually measured amount of phase change of each sampling data with an ideal amount of phase change of each sampling data and generates correction voltage data such that the actually measured amount of phase change matches with the ideal amount of phase change. Correction control data provided as the correction voltage data at each sampling time is applied to a transmission control section. The transmission control section generates transmission control data based on the correction control data and applies the transmission control data to a VCO through a DAC.
1. A radar apparatus comprising:
a transmitter that changes a frequency over time in a predetermined frequency band width to generate a transmission signal and transmits the transmission signal;
a receiver that receives a reflected signal resulting from the transmission signal and generates a reception signal;
target detector that detects a target based on a beat signal obtained from the reception signal and the transmission signal;
a beat signal normalizing section that holds an amplitude of the beat signal constant and removes an offset component;
an actually-measured phase change amount calculating section that calculates an actually measured amount of phase change of the normalized beat signal per unit time; and
a correction control value calculating section that calculates a correction control value per unit time, which makes the actually measured amount of phase change matched with a preset amount of phase change per unit time,
the transmitter generating the transmission signal while correcting the transmission signal based on the correction control value.
2. The radar apparatus according to claim 1 , wherein the actually-measured phase change amount calculating section uses an average value of the actually-measured phase change amounts, which are obtained from plural lots of beat signals resulting from reflection of the transmission signal by the target at a particular unit distance.
3. The radar apparatus according claim 1 , wherein the actually-measured phase change amount calculating section comprises:
a peak spectrum detecting section that executes a Fourier transform process on the beat signal and detects a peak spectrum; and
a partial beat signal obtaining section that executes an inverse transform process on spectrum data within a predetermined frequency range including the detected peak spectrum and obtains a beat signal component corresponding to the predetermined frequency range,
the actually measured amount of phase change being calculated based on the obtained beat signal component.
4. The radar apparatus according to claim 1 , further comprising an ideal phase change amount calculating section that calculates an ideal amount of phase change per unit time based on a total amount of phase change derived from both a distance to the target and the predetermined frequency band width,
wherein the correction control value calculating section calculates the correction control value per unit time such that the actually measured amount of phase change matches with the ideal amount of phase change.
5. The radar apparatus according to claim 1 , further comprising a normalized ideal phase-change amount calculating section that calculates a normalized ideal amount of phase change per unit time for a preset reference distance based on a total amount of phase change derived from both a distance to the target and the predetermined frequency band width,
wherein the correction control value calculating section calculates the correction control value per unit time such that the actually measured amount of phase change matches with the normalized ideal amount of phase change.