Radar device for detecting response signal

• US 6,507,310 B2
• Filed: 09/10/2001
• Issued: 01/14/2003
• Est. Priority Date: 05/01/2001
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Nishiguchi, Kenichi, Takase, Kazuyosi, Matuura, Kioo
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/948,797
• Publication Number:
  US 20020163462A1
• Time in Patent Office: 491 Days
• Field of Search: 342/42, 342/43, 342/44, 342/45, 342/46, 342/47, 342/48, 342/49, 342/50, 342/51, 342/175, 342/195, 342/41, 342/187
• US Class Current: 342/43
• CPC Class Codes: G01S 13/767 Responders; Transponders teaching or practice apparatus for gun-aiming or gun-laying using reflecting targets or active targets F41G3/26
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals

Abstract

When a question signal of a transmitting frequency band ΔF1 output from a radar device is received in search and rescue radar transponder (SART) of a wreck ship, a response signal is sent from the SART to the radar device. In the radar device, the response signal and an echo of the question signal are received as a reception signal, intensity of components of the reception signal placed in almost the same frequency band as the transmitting frequency band ΔF1 of the question signal is suppressed to produce a filtered response signal, and components of he filtered response signal placed in a receiving frequency band ΔF2, which does not overlap with the transmitting frequency band ΔF1 of the question signal, are extracted from the filtered response signal as an image signal. Therefore, sea clutter and ground clutter indicated as the echo of the question signal is hardly included in the image signal, and a position of the wreck ship can be detected by using the image signal excellent in a signal-to-noise ratio. Accordingly, the radar device excellent in a detection performance of the position of the wreck ship can be obtained.

Claims

1. A radar device comprising:

a signal producing unit for producing an interrogation signal;

an antenna for outputting the interrogation signal produced in the signal producing unit and receiving both an echo of the interrogation signal and a response signal sent from a search and rescue radar transponder in response to the interrogation signal;

a filtering unit for receiving both the echo of the interrogation signal and the response signal received in the antenna and suppressing intensity of components of both the echo of the interrogation signal and the response signal placed in almost the same frequency band as that of the interrogation signal to produce a filtered response signal;

a circulator unit for sending the interrogation signal produced in the signal producing unit to the antenna and sending both the echo of the interrogation signal and the response signal received in the antenna to the filtering unit; and

a signal receiving unit for receiving the filtered response signal produced in the filtering unit and extracting components of the filtered response signal placed in a receiving frequency band, which does not overlap with the frequency band of the interrogation signal, from the filtered response signal to obtain a position indicating signal displayed on a display device.

2. A radar device according to claim 1, wherein intensity of components of both the echo of the interrogation signal and the response signal placed in a frequency band other than the receiving frequency band is suppressed in the filtering unit to produce the filtered response signal.

3. A radar device according to claim 1, further comprising:

a fixed attenuator for receiving a part of both the echo of the interrogation signal and the response signal from the circulator unit and sending the part of both the echo of the interrogation signal and the response signal to the signal receiving unit,

wherein intensity of components of the other part of both the echo of the interrogation signal and the response signal placed in almost the same frequency band as that of the interrogation signal is suppressed in the filtering unit to produce the filtered response signal, the image signal is produced from the filtered response signal in the signal receiving unit, and the part of both the echo of the interrogation signal and the response signal sent from the fixed attenuator and the position indicating signal are combined with each other in the signal receiving unit.

4. A radar device according to claim 1, further comprising:

a fixed attenuator for receiving a part of both the echo of the interrogation signal and the response signal from the circulator unit and sending the part of both the echo of the interrogation signal and the response signal to the signal receiving unit,

wherein intensity of components of the other part of both the echo of the interrogation signal and the response signal placed in a frequency band other than the receiving frequency band is suppressed in the filtering unit to produce the filtered response signal, the position indicating signal is produced from the filtered response signal in the signal receiving unit, and the part of both the echo of the interrogation signal and the response signal sent from the fixed attenuator and the position indicating signal are combined with each other in the signal receiving unit.

5. A radar device according to claim 1, further comprising:

a variable attenuator for receiving a part of both the echo of the interrogation signal and the response signal set to an adjusted electric power level from the circulator unit and sending the part of both the echo of the interrogation signal and the response signal to the signal receiving unit to adjust an electric power level of the other part of both the echo of the interrogation signal and the response signal sent from the circulator unit to the filtering unit,

wherein intensity of components of the other part of both the echo of the interrogation signal and the response signal placed in almost the same frequency band as that of the interrogation signal is suppressed in the filtering unit to produce the filtered response signal, the position indicating signal is produced from the filtered response signal in the signal receiving unit, and the part of both the echo of the interrogation signal and the response signal sent from the fixed attenuator and the position indicating signal are combined with each other in the signal receiving unit.

6. A radar device according to claim 1, further comprising:

a variable attenuator for receiving a part of both the echo of the interrogation signal and the response signal set to an adjusted electric power level from the circulator unit and sending the part of both the echo of the interrogation signal and the response signal to the signal receiving unit to adjust an electric power level of the other part of both the echo of the interrogation signal and the response signal sent from the circulator unit to the filtering unit,

wherein intensity of components of the other part of both the echo of the interrogation signal and the response signal placed in a frequency band other than the receiving frequency band is suppressed in the filtering unit to produce the filtered response signal, the position indicating signal is produced from the filtered response signal in the signal receiving unit, and the part of both the echo of the interrogation signal and the response signal sent from the fixed attenuator and the position indicating signal are combined with each other in the signal receiving unit.