Process for generating synthetic aperture radar interferograms

• US 5,332,999 A
• Filed: 02/05/1993
• Issued: 07/26/1994
• Est. Priority Date: 02/05/1993
• Status: Expired due to Fees

• Current Assignee: Agence Patiale Europeenne Intergovernmental Organization
• Original Assignee: Agence Spatiale Europeenne
• Inventors: Rocca, Fabio, Prati, Claudio
• Primary Examiner(s): TUBBESING, THEODORE
• Application Number:
  US08/014,240
• Time in Patent Office: 536 Days
• Field of Search: 342/25
• US Class Current: 342/25.00F
• CPC Class Codes: G01S 13/24 using frequency agility of carrier wave
• CPC Class Codes: G01S 13/9023 combined with interferometric techniques
• CPC Class Codes: G01S 13/904 SAR modes

Abstract

A process for generating synthetic aperture radar interferograms comprises the following steps. First and a second radar images of a scene from a first and a second position spaced apart by a given baseline are generated. A first signal of said first image within a first radio frequency band of the spectrum is recorded. A second signal of said second image within a second radio frequency band of the spectrum having a frequency shift relatively to the first detecting band is recorded. The frequency shift being such that it ensures or maximizes correlation between the first and the second images. The first and second signals are combined for generating an interferogram of said scene.

Claims

1. A process for generating synthetic aperture radar interferograms comprising the steps of:

generating a first and a second radar image of a scene from a first and a second position spaced apart by a given baseline,

recording a first signal of said first image within a first radio frequency band of the spectrum,

recording a second signal of said second image within a second radio frequency band of the spectrum having a frequency shift relatively to said first detecting band, said frequency shift being such that it ensures or maximizes correlation between the first and the second images,

combining said first and second signals for generating an interferogram of said scene.

2. A process as in claim 1 wherein said first and second radar images are generated on two separate passes by a first and a second satellite on two separate orbits and wherein at least one of said satellites has tunable reception means whereby said frequency shift may be produced.

3. A process as in claim 1 or 2 wherein the step of recording a second signal includes said frequency shift as:

##EQU34## ω

o=2π

fo, fo being the central frequency of an image generator, θ

=mean value of the off-nadir angles of the first and second positions,

Δ

θ

=difference between the off-nadir angles of the first and second positions.

4. A process as in claim 1 or 2 wherein the step of combining said first and second signals also comprises a step of shifting a phase of the second signal relatively to the first signal.

5. A process as in claim 4 wherein said shifting a phase is by a constant term which maximizes the absolute value of this image.

6. A process as in claim 4 wherein the shifting a phase is for each point y_o of the scene, ##EQU35## c=speed of light z₀₁, z₀₂ =distance between respectively said first and second positions and a given point y_O on the ground surface. ##EQU36## u=y-y_o y=ground range variable

y_o =abscissa of said given point.