Pulse compression radar

• US 6,067,043 A
• Filed: 03/23/1999
• Issued: 05/23/2000
• Est. Priority Date: 03/23/1998
• Status: Expired due to Fees

• Current Assignee: Alcatel SA (Nokia Corporation)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Suinot, Noel, Faure, Alain
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US09/274,471
• Time in Patent Office: 427 Days
• Field of Search: 342/174, 342/168, 342/169, 342/172, 342/196, 342/202, 342/203, 342/204, 342/189, 342/134, 342/135, 342/145, 342/159, 342/162
• US Class Current: 342/174
• CPC Class Codes: G01S 13/282 using a frequency modulated carrier wave G01S13/286 takes precedence
• CPC Class Codes: G01S 13/90 using synthetic aperture techniques , e.g. synthetic aperture radar [SAR] techniques
• CPC Class Codes: G01S 7/4052 by simulation of echoes
• CPC Class Codes: G01S 7/4082 using externally generated reference signals, e.g. via remote reflector or transponder

Abstract

The invention concerns a method of synthesizing a replica used in the compression filter of pulse compression radar.

The replica is calculated from the spectrum of a required impulse response.

The required impulse response is preferably obtained from an analytical function, such as a sinc function or a weighted sinc function, and a template.

It is preferable to use calibration signals of the instrument to calculate the replica.

The invention also applies to synthetic aperture radar.

Claims

1. A method of synthesizing a replica used in the compression filter of pulse compression radar wherein the replica is calculated from a required impulse response, wherein the required impulse response is obtained from an analytic function such as a sinc function or a weighted sinc function and from a template, wherein calibration signals of the instrument are used to calculate the replica, and wherein the replica is defined by the following equation:

space="preserve" listing-type="equation">R(f)=RI.sub.obj (f)/S.sub.cal (f)

in which RI_obj (f) is the spectrum of the required impulse response and S_cal (f) is the spectrum of a calibration signal, in particular a calibration pulse.

2. A method according to claim 1, wherein, in the required impulse response spectrum, an upper frequency band of approximately 10% to 100% of the active band is adopted to obtain the required resolution.

3. A method according to claim 1, wherein a calibration signal or pulse is used to synthesize the replica which is measured and/or estimated and which represents the distortion introduced by the radar.

4. A method according to claim 3, wherein the replica is periodically measured and/or estimated in order to adjust it periodically.

5. A method according to claim 3, wherein measuring the calibration pulse consists in acquiring a signal that has passed through the transmit and receive subsystems of the radar.

6. A method according to claim 2, wherein the spectrum of the required impulse response is obtained by applying a discrete Fourier transform algorithm to the required impulse response in the time domain.

7. Application of the method according to claim 1 to coherent radar over the time to integrate a plurality of pulses.