Radar

• US 7,138,939 B2
• Filed: 01/06/2005
• Issued: 11/21/2006
• Est. Priority Date: 01/09/2004
• Status: Active Grant

• Current Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Original Assignee: Fujitsu Ten Limited (DENSO Corporation)
• Inventors: Honda, Kanako
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US11/029,463
• Publication Number:
  US 20050168378A1
• Time in Patent Office: 684 Days
• Field of Search: 342/27, 342/28, 342 70- 72, 342 82-103, 342/118, 342128-132, 342/175, 342188-197, 342134-137, 342/145, 180167-169, 375130-153
• US Class Current: 342/129
• CPC Class Codes: G01S 13/24 using frequency agility of carrier wave

Abstract

A radar has a transmission section, a reception section that receives a reflected wave of the transmission wave, a transmission switch section, a delay section that delays a predetermined timing, a reception switching section, a difference processing section, and a calculation section. The transmission section switches between a first frequency and a second frequency to transmit a transmission wave having one of the frequencies. The transmission switch section switches between turning-on and turning-off of an operation of the transmission section at the predetermined timing. The reception switching section switches between turning-on and turning-off of an operation of the reception section according to the timing delayed. The difference processing section outputs a difference between the transmission wave and the reflected wave. The calculation section calculates a distance on a basis of a delay amount, when a detection waveform has a difference frequency between the first frequency and the second frequency.

Claims

1. A radar comprising:

a transmission section that switches between a first frequency and a second frequency to transmit a transmission wave having one of the first frequency and the second frequency;

a predetermined schedule generated on a basis of a pseudo noise code;

a switch period between the first frequency and the second frequency in the transmission wave equal to or larger than a period determined by a code length of the pseudo noise code;

a reception section that receives a reflected wave of the transmission wave transmitted by the transmission section;

a transmission switch section that switches between turning-on and turning-off of an operation of the transmission section at the predetermined schedule;

a delay section that delays the predetermined schedule;

a reception switching section that switches between turning-on and turning-off of an operation of the reception section according to the predetermined schedule delayed by the delay section;

a difference frequency processing section that outputs a difference frequency between the transmission wave and the reflected wave as a detection waveform; and

a calculation section that calculates a distance to an object on a basis of a delay amount, which the delay section gives to the predetermined schedule, when the detection waveform has a difference frequency between the first frequency and the second frequency.

2. The radar according to claim 1, wherein the transmission section and the reception section share an antenna, the radar further comprising:

a transmission-reception selector switch that switches between a state where the transmission section uses the antenna and a state where the reception section uses the antenna; and

a transmission and reception path control section that controls the transmission-reception selector switch in synchronization with a switch period between the first frequency and the second frequency in the transmission wave.

3. The radar according to claim 1, wherein an integral multiple of a switch period between the first frequency and the second frequency in the transmission wave is equal to a period of the predetermined schedule.

4. The radar according to claim 1, wherein the difference frequency between the first frequency and the second frequency is larger than a Doppler frequency contained in the detection waveform.

5. The radar according to claim 1, wherein a switch period between the first frequency and the second frequency in the transmission wave is set to avoid the difference frequency between the first frequency and the second frequency.

6. The radar according to claim 1, further comprising:

a filter that allows the difference frequency between the first frequency and the second frequency to pass through, wherein;

the difference processing section outputs the detection waveform to the filter;

the filter outputs a waveform to the calculation section;

the calculation section detects whether or not the waveform output from the filter contains the difference frequency between the first and the second frequency; and

when the calculation section detects that the waveform output from the filter contains the difference frequency, the calculation section concludes that the detection waveform has the difference frequency.

7. The radar according to claim 1, wherein the transmission section and the reception section share an antenna.