Testing of airborne windshear radars

Claim 2

A portable test system, providing simulated radar returns for testing a radar system radiating radar pulse signals in a scanned antenna beam pattern, comprising: a test antenna suitable for positioning at a predetermined distance from said radar system for illumination by radar pulse signals of varying amplitude via said scanned antenna beam pattern; transmitter means for radiating simulated radar returns via said test antenna; receiver means, coupled to said test antenna, for processing received radar pulse signals of varying amplitude; modulator means, coupled to said test antenna, for providing simulated radar return signals to said transmitter in timed response to said received radar pulse signals; test data means, coupled to said modulator means, for storing test data to be included in said simulated radar return signals; memory means for storing radar data representative of selected characteristics of said radar pulse signals and scanned antenna beam pattern; and signal processing means, coupled to said receiver means and responsive to said radar data stored in said memory means, for controlling amplitude of said simulated radar return signals in inverse relation to said varying amplitude of said received radar pulse signals and for selectively controlling inclusion of test data in said simulated radar return signals; whereby, said simulated radar returns are time and inverse amplitude coordinated with said received radar pulse signals of varying amplitude.

Claim 3

A portable test system as in claim 1, wherein said test antenna is proportioned and arranged to be supported on an airport surface in front of an aircraft-mounted radar antenna in the vicinity of the beginning of the far field range of said radar antenna.

Claim 4

A portable test system as in claim 1, wherein said transmitter means comprises a mixer and filter combination coupled to a local oscillator.

Claim 5

A portable test system as in claim 1, wherein said receiver means comprises a crystal receiver providing a video frequency output directly from said received radar pulse signals.

Claim 6

A portable test system as in claim 1, wherein said modulator means comprises a surface acoustic wave delay line providing a plurality of time delayed pulses in response to each of said received radar pulse signals.

Claim 7

A portable test system as in claim 1, wherein said modulator means comprises a variable gain amplifier responsive to gain control signals inversely related to said varying amplitude of said received radar pulse signals.

Claim 8

A portable test system as in claim 1, additionally comprising an analog-to-digital converter, coupled to said receiver means, for sampling each pulse of said received radar pulse signals having an amplitude exceeding a predetermined threshold level to provide radar data representative of the relative amplitudes of said sampled pulses.

Claim 9

A portable test system as in claim 7, wherein said signal processing means utilizes said radar data from said analog-to-digital converter to derive a value representative of a least one of the following characteristics of said radar system: radar signal pulse width; radar peak power; antenna beam pattern; and antenna scan rate.

Claim 10

A portable test system as in claim 8, additionally comprising a display, coupled to said signal processing means, for displaying data representative of at least one of said characteristics derived by said signal processing means.

Claim 11

A portable test system, providing simulated windshear returns for testing a radar system radiating radar pulse signals in a scanned antenna beam pattern, comprising: a test antenna suitable for positioning at a predetermined distance from said radar system for illumination by radar pulse signals of varying amplitude via said scanned antenna beam pattern; transmitter means for radiating simulated windshear returns via said test antenna; receiver means, coupled to said test antenna, for processing received radar pulse signals of varying amplitude; modulator means, coupled to said test antenna, utilizing a tapped delay line providing a plurality of delayed pulse signals for providing simulated windshear return signals to said transmitter in response to said received radar pulse signals; test data means, coupled to said modulator means, for storing windshear test data to be included in said simulated windshear return signals; memory means for storing radar data representative of selected characteristics of said radar pulse signals and scanned antenna beam pattern; and signal processing means, coupled to said receiver means and responsive to said radar data stored in said memory means, for determining the amplitude of the largest received radar pulse signal as a reference amplitude, for controlling amplitude of said simulated windshear return signals in relation to a comparison of said varying amplitude with said reference amplitude, and for selectively controlling inclusion of windshear test data in said simulated windshear return signals.

Claim 12

A portable test system, providing simulated windshear returns for testing a radar system radiating radar pulse signals in a scanned antenna beam pattern, comprising: a test antenna suitable for positioning at a predetermined distance from said radar system for illumination by radar pulse signals of varying amplitude via said scanned antenna beam pattern; transmitter means for radiating simulated windshear returns via said test antenna; receiver means, coupled to said test antenna, for processing received radar pulse signals of varying amplitude; modulator means, coupled to said test antenna, utilizing a tapped delay line providing a plurality of delayed pulse signals for providing simulated windshear return signals to said transmitter in response to said received radar pulse signals; test data means, coupled to said modulator means, for storing windshear test data to be included in said simulated windshear return signals; memory means for storing radar data representative of selected characteristics of said radar pulse signals and scanned antenna beam pattern; and signal processing means, coupled to said receiver means and responsive to said radar data stored in said memory means, for determining the amplitude of the largest received radar pulse signal as a reference amplitude, for controlling amplitude of said simulated windshear return signals in relation to a comparison of said varying amplitude with said reference amplitude, and for selectively controlling inclusion of windshear test data in said simulated windshear return signals.

Claim 15

A method as in claim 11, wherein said step (b) base signal is provided as a plurality of pulses which are replicas of said first radar pulse signal.

Claim 16

A method as in claim 11, wherein step (c) comprises modifying said base signal by inclusion of test data representing a windshear effect.

Claim 17

A method as in claim 11, wherein step (d) comprises amplifying said simulated radar return signal by a gain value representative of the difference between said first amplitude and a reference amplitude representative of the largest radar pulse signal received during a complete scan of the radar antenna.

Claim 18

A method as in claim 11, including the additional step of observing radar performance on an in-aircraft radar display in order to evaluate radar system performance based upon receipt of said simulated radar return signals by said radar system.