Pseudorandom Trigger Timing for Radar Interference Reduction

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Solution Overview

Problem

Conventional ET sampling systems are susceptible to interference from external energy sources and distant pulses, leading to increased radiated emissions and clutter, as they undersample external frequencies and correlate them with the pulse repetition rate, causing susceptibility spikes and interference.

Innovation Solution

Implementing a pseudorandom phase variation in trigger signal pulses to randomize the pulse repetition scheme, reducing susceptibility to interference by spreading the pattern of samples across the frequency spectrum and minimizing radiated emissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a constant pulse repetition rate is used in ET sampling systems, then the system achieves stable timing and simplified control, but the system becomes highly susceptible to interference from external energy sources at harmonic frequencies

Engineering Contradiction:

Improvetiming stabilityVSAvoidinterference susceptibility

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by transitioning from a static, constant pulse repetition rate to a dynamic, pseudorandomly varying pulse repetition rate. The trigger pulses are generated with pseudorandom phase variations that cause the pulse repetition intervals to change dynamically, thereby spreading spectral energy and reducing susceptibility to narrowband interference while maintaining timing stability through controlled randomness.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the transmitter power is increased to mitigate interference effects, then the radar can detect more distant targets, but the radiated emissions increase and cause more interference to other systems

Engineering Contradiction:

Improvedetection capabilityVSAvoidradiated emissions

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the temporal parameters of the pulse repetition scheme by introducing pseudorandom phase variations. This parameter change spreads the spectral density of the transmitted signal over a wider frequency range, reducing peak emissions at any single frequency while maintaining adequate detection capability through processed reception that exploits the known pseudorandom sequence.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If external energy sources are undersampled at constant pulse repetition rates, then the system operates at fixed sampling intervals, but external frequencies correlate with the pulse repetition rate causing susceptibility spikes

Engineering Contradiction:

Improvesampling efficiencyVSAvoidsusceptibility spikes

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potentially harmful correlation between external frequencies and constant pulse repetition rates into a benefit by using pseudorandom phase variations. The known pseudorandom sequence, which could be seen as introducing complexity, actually provides a benefit by enabling coherent processing that distinguishes transmitted signals from random interference, while the pseudorandom nature breaks harmful correlations with external periodic sources.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS9316729B2Systems and methods for providing trigger timing

Publication Date: 2016.04.19 NITEK INC

AI summary

A system for providing signal trigger pulses comprises an equivalent time sampling unit providing transmit and receive trigger pairs, and a control unit controlling the equivalent time sampling unit to provide pseudorandom delay length variations between the trigger pairs.