Detection and measurement of hypersonic target radial velocity in pulse Doppler radar

В работе предложен алгоритм обнаружения и однозначного измерения радиальной скорости воздушных объектов (ВО), летящих с абсолютной скоростью, превышающей скорость звука в несколько раз (гиперзвуковых целей). Область применения алгоритма – импульсно-доплеровские РЛС с линейно-частотно модулированным (ЛЧМ) зондирующим сигналом (ЗС). Приведено описание, обоснование использования и результаты моделирования обработки пачки принятых радиоимпульсов разработанным алгоритмом на модели современной импульсно-доплеровской РЛС. An algorithm for the detection and unambiguous measurement of the radial velocity of supersonic air objects is proposed. The scope of the algorithm is pulse-Doppler radars with a linear frequency modulation (LFM). The description, justification of the use and the results of modeling the processing of a packet of received radio pulses by the developed algorithm on a model of a modern pulse-Doppler radar are presented.

UNIFIED METHOD OF ADAPTIVE-ROBUST REDUCTION OF UNCERTAINTIES IN THE ELIMINATION OF BLIND SPOTS AND RANGING OF AIR OBJECTS IN PULSE-DOPPLER RADARS

A unified method of disclosing blind ranges, reducing or eliminating measurement ambiguity has been proposed and investigated, which allows, within the framework of a typical long-range detection session of an air object by a pulse-Doppler radar, to reduce time costs, expand information content, and unify algorithmic support of a detection session. At the heart of: unified adaptive-robust procedures for controlling radiation parameters (guaranteeing the observability of an object) and processing ambiguous quasi-measurements of range (in absence of detection) and real measurement (in initial detection).

Ocean Waves in K-distributed Clutter

<div> <div> <div> <p>Two examples of low grazing angle radar sea clutter, both well described by the compound K-distribution model, are studied. Pulse Doppler processing is applied to obtain two dimensional range-time textures for the intensity, centroid and width of the Doppler spectrum. The first example exhibits a monochromatic swell pattern, allowing phase averaging to be applied to the textures. The second example has a more typical ocean wave spectrum. The intensity textures are gamma distributed, consistent with the compound K-distribution model, but the Doppler spectrum centroid and width textures are also found to be gamma distributed. Based on this analysis, a new method for simulation of coherent radar sea clutter is proposed, where separate memoryless nonlinear transformations are applied to a simulated water surface to generate the spatially and temporally varying intensity, centroid and width of the Doppler spectrum. The method builds on the evolving Doppler spectrum model for radar sea clutter simulation and established methods for simulation of water surfaces. </p> </div> </div> </div>

Ocean Waves in K-distributed Clutter

<div> <div> <div> <p>Two examples of low grazing angle radar sea clutter, both well described by the compound K-distribution model, are studied. Pulse Doppler processing is applied to obtain two dimensional range-time textures for the intensity, centroid and width of the Doppler spectrum. The first example exhibits a monochromatic swell pattern, allowing phase averaging to be applied to the textures. The second example has a more typical ocean wave spectrum. The intensity textures are gamma distributed, consistent with the compound K-distribution model, but the Doppler spectrum centroid and width textures are also found to be gamma distributed. Based on this analysis, a new method for simulation of coherent radar sea clutter is proposed, where separate memoryless nonlinear transformations are applied to a simulated water surface to generate the spatially and temporally varying intensity, centroid and width of the Doppler spectrum. The method builds on the evolving Doppler spectrum model for radar sea clutter simulation and established methods for simulation of water surfaces. </p> </div> </div> </div>

Range Dividing MIMO Waveform for Improving Tracking Performance

A multiple-input multiple-output (MIMO) method that shares the same frequency band can efficiently increase radar performance. An essential element of a MIMO radar is the orthogonality of the waveform. Typically, orthogonality is obtained by spreading different signals into divided domains such as in time-domain multiplexing, frequency-domain multiplexing, and code domain multiplexing. This paper proposes a method of spreading the interference signals outside the range bins of interest for pulse doppler radars. This is achieved by changing the pulse repetition frequency under certain constraints, and an additional gain can be obtained by doppler processing. This method is very effective for improving the angular accuracy of the MIMO radar for a small number of air targets, although it may have limitations in use for many targets or in high clutter environments.

Fast-time and slow-time processing of the pseudorandom amplitude-phase-shift keyed signals

The two-dimensional raw data structure is used for modern pulse-Doppler radars. Fast-time and slow-time processing of radar return signals is performed. The matched filter compresses each received pulse in fast time. The FFT-based spectral processing of the compressed pulses is then performed in slow time. The two-dimensional structure of raw data has specific features in radars with the transmission and reception of pseudorandom amplitude-phase-shift keyed (APSK) signals to a common aerial. It is formed when the coherent processing interval of the APSK signal is divided into subintervals. The article describes the fast-time and slow-time processing of the APSK signal subintervals. The structure of the signal in the subintervals is also analyzed. The choice of the subinterval duration is discussed. The possible energy losses during the processing of the reflected signals are estimated. The results of the processing modeling of the additive sum of APSK signals with different Doppler frequencies are presented.

Large Amplitude Harmonic Vibration under Pulse Doppler Measurement

A flow velocity or tissue motion can be measured by pulse Doppler method. However, when the method is applied to a sinusoid motion or harmonic vibration, the estimation result is deviated. In this paper, the generalized theory of pulse Doppler measurement to the sinusoid motion is explained and the relation between the estimation deviation and the real value is given. Furthermore, a special case of binary velocity estimation is expanded and simulated with different parameters. This simulation result suggested that different selection of parameters may fundamentally affect the output of pulse Doppler estimation.

Recent Progress in Applying Advanced Computation Methods to Radar-Based Wave Measurements

High quality environmental data are critical for any offshore activity relying on data insights to form appropriate planning and risk mitigation routines under challenging weather conditions. Such data are the most significant driver of future footprint reduction in offshore industries, in terms of costs savings, as well as operational safety and efficiency, enabled through ease of data access for all relevant stakeholders. This paper describes recent advancements in methods used by a dual-footprint Pulse-Doppler radar to provide accurate and reliable ocean wave height measurements. Achieved improvements during low wind weather conditions are presented and compared to data collected from other sources such as buoys and acoustic doppler wave and current profiler (ADCP) or legacy. The study is based on comparisons of recently developed algorithms applied to different data sets recorded at various sites, mostly covering calm weather conditions.