Multibeam radar based on linear frequency modulated waveform diversity

Kocjancic, Leon; Balleri, Alessio; Merlet, Thomas

doi:10.1049/iet-rsn.2018.5029

Cited by 13 publications

(8 citation statements)

References 22 publications

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“…Table I shows that the up-chirp and the down-chirp are the combination pair with the best isolation performance. This is in agreement with the results obtained in [5] that showed the isolation improves with the time-bandwidth product as…”

Section: B Comments On the Resultssupporting

confidence: 93%

“…Furthermore, for chirps with the same duration and different chirp rates, a lower bound on the isolation has been found as [5]…”

Section: B Comments On the Resultsmentioning

confidence: 99%

“…In addition to common modes of operation, a multibeam radar (MBR) with collocated antennas can be devised as well. This type of radar uses an orthogonal waveform for each of its beams to form separate radar channels with different properties [5], [6]. A linear combination of orthogonal waveforms is transmitted for each channel.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Characterisation of Quasi-Orthogonal Piecewise Linear Frequency Modulated Waveforms

Kocjancic

Balleri

Merlet

2019

2019 Sensor Signal Processing for Defence Conference (SSPD)

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This paper presents an analysis of the Doppler tolerance and isolation properties of five different sets of piecewise linear frequency modulated (PLFM) waveform triplets consisting of a combination of LFM subchirps. Different combinations of PLFM signals are used to produce waveforms with the same timebandwidth product and optimise them with respect to isolation. The performance of the proposed waveforms are numerically investigated and a comparison between sets is presented. Results confirm that the waveforms have quasi-orthogonal properties and exhibit a degree of Doppler tolerance.

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Section: B Comments On the Resultssupporting

confidence: 93%

“…Furthermore, for chirps with the same duration and different chirp rates, a lower bound on the isolation has been found as [5]…”

Section: B Comments On the Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Numerical Characterisation of Quasi-Orthogonal Piecewise Linear Frequency Modulated Waveforms

Kocjancic

Balleri

Merlet

2019

2019 Sensor Signal Processing for Defence Conference (SSPD)

Self Cite

View full text Add to dashboard Cite

show abstract

“…In addition to ensuring a constant envelope, the waveform also needs to have good waveform characteristics. It is well known that linear frequency modulation (LFM) signals are widely used in radar systems due to their good waveform characteristics [ 52 , 53 ]. Therefore, we can use similarity constraints to use LFM as a reference waveform to make the designed waveform share good waveform characteristics.…”

Section: Introductionmentioning

confidence: 99%

Joint Design of Colocated MIMO Radar Constant Envelope Waveform and Receive Filter to Reduce SINR Loss

Huang

Deng

Zheng

et al. 2021

Sensors

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In this paper, we aim at the problem that MIMO radar’s target detection performance is greatly reduced in the complex multi-signal-dependent interferences environment. We propose a joint design method based on semidefinite relaxation (SDR), fractional programming and randomization technique (JD-SFR) and a joint design method based on coordinate descent (JD-CD) to solve the actual transmit waveform and receive filter bank directly to reduce the loss of strong interference to the output signal-to-interference-plus-noise ratio (SINR) of the radar system. Therefore, the maximization of output SINR is taken as the criterion of the optimization problem. The designed waveforms take into account the radar transmitter’s hardware requirements for constant envelope waveforms and impose similarity constraints on the waveforms. JD-SFR uses SDR, fractional programming and randomization technique to deal with the non-convex optimization problems encountered in the solution process. JD-CD transforms the optimization problem into a function of the phase of the waveform and then solves the transmit waveform based on CD. Compared with other methods, the proposed method has lower output SINR loss under strong power interference and forms deep nulls on the direction beampattern of multiple interference sources, which indicates that it has better anti-interference performance.

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“…If both chirp-codes have a constant time duration, increasing the bandwidth can reduce the sidelobe levels. [243] gives a detailed account of investigations based on this idea. However, the sonar system in such a case would be limited to using only two codes at the most, restricting the area coverage and so increasing the time of surveys.…”

Section: Resultsmentioning

confidence: 99%

Code Optimisation Framework for Multicode Sonar Systems

Rashed¹

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<p>The ocean is a temporally and spatially varying environment, the characteristics of which pose significant challenges to the development of effective underwater wireless communications and sensing systems. An underwater sensing system such as a sonar detects the presence of a known signal through correlation. It is advantageous to use multiple transducers to increase surveying area with reduced surveying costs and time. Each transducers is assigned a dedicated code. When using multiple codes, the sidelobes of auto- and crosscorrelations are restricted to theoretical limits known as bounds. Sets of codes must be optimised in order to achieve optimal correlation properties, and, achieve Sidelobe Level (SLL)s as low as possible. In this thesis, we present a novel code-optimisation method to optimise code-sets with any number of codes and up to any length of each code. We optimise code-sets for a matched filter for application in a multi-code sonar system. We first present our gradient-descent based algorithm to optimise sets of codes for flat and low crosscorrelations and autocorrelation sidelobes, including conformance of the magnitude of the samples of the codes to a target power profile. We incorporate the transducer frequency response and the channel effects into the optimisation algorithm. We compare the correlations of our optimised codes with the well-known Welch bound. We then present a method to widen the autocorrelation mainlobe and impose monotonicity. In many cases, we are able to achieve SLLs beyond the Welch bound. We study the Signal to Noise Ratio (SNR) improvement of the optimised codes for an Underwater Acoustic (UWA) channel. During its propagation, the acoustic wave suffers non-constant transmission loss which is compensated by the application of an appropriate Time Variable Gain (TVG). The effect of the TVG modifies the noise received with the signal. We show that in most cases, the matched filter is still the optimum filter. We also show that the accuracy in timing is very important in the application of the TVG to the received signal. We then incorporate Doppler tolerance into the existing optimisation algorithm. Our proposed method is able to optimise sets of codes for multiple Doppler scaling factors and non-integer delays in the arrival of the reflection, while still conforming to other constraints. We suggest designing mismatched filters to further reduce the SLLs, firstly using an existing Quadratically Constrained Qaudratic Program (QCQP) formulation and secondly, as a local optimisation problem, modifying our basic optimisation algorithm.</p>

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Multibeam radar based on linear frequency modulated waveform diversity

Cited by 13 publications

References 22 publications

Numerical Characterisation of Quasi-Orthogonal Piecewise Linear Frequency Modulated Waveforms

Numerical Characterisation of Quasi-Orthogonal Piecewise Linear Frequency Modulated Waveforms

Joint Design of Colocated MIMO Radar Constant Envelope Waveform and Receive Filter to Reduce SINR Loss

Code Optimisation Framework for Multicode Sonar Systems

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