Orthogonal Periodic Sequences for the Identification of Functional Link Polynomial Filters

Carini, Alberto; Orcioni, Simone; Terenzi, Alessandro; Cecchi, Stefania

doi:10.1109/tsp.2020.3021244

Cited by 13 publications

(11 citation statements)

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“…A novel approach for nonlinear system identification was proposed in [49], [50], where the concept of orthogonal periodic sequence (OPS) was introduced. OPS can be used for the identification of any Functional Link Polynomial filter (FLiP), which is a broad class of nonlinear filters comprising also LN, WN, and Volterra filters [51].…”

Section: Introductionmentioning

confidence: 99%

A Room Impulse Response Measurement Method Robust Towards Nonlinearities Based on Orthogonal Periodic Sequences

Carini¹,

Cecchi²,

Terenzi³

et al. 2021

IEEE/ACM Trans. Audio Speech Lang. Process.

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An open problem in room impulse response (RIR) measurement is the effect of nonlinearities, especially those with memory, present in the measurement system, specifically in the power amplifier and in the loudspeaker. The nonlinearities can corrupt the measurement introducing artifacts. The paper discusses a RIR measurement method that is robust towards these nonlinearities. The proposed methodology allows measuring the RIR using the cross-correlation method, i.e., computing the cross-correlation between the output signal and an appropriate sequence. In contrast to other cross-correlation based methods, the proposed approach directly estimates the first-order kernel of the Volterra filter modeling the measurement systems, i.e., the system impulse response for small signals. The proposed approach exploits the concepts of orthogonal periodic sequences, recently proposed in the literature. The input signal can be any periodic persistently exciting sequence and can also be a quantized sequence. Measurements performed both on an emulated scenario and in real environments illustrate the validity of the approach and compare it with other competing RIR measurement methods.

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Section: Introductionmentioning

confidence: 99%

A Room Impulse Response Measurement Method Robust Towards Nonlinearities Based on Orthogonal Periodic Sequences

Carini¹,

Cecchi²,

Terenzi³

et al. 2021

IEEE/ACM Trans. Audio Speech Lang. Process.

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“…The experimental results, when considering both an emulated scenario, involving signals that are affected by a real nonlinear device, and a real room impulse response measurement, highlight the effectiveness and the robustness towards nonlinearities of the proposed RIR measurement technique. Future research will be dedicated to the study and development of further periodic sequences suitable for RIR measurement, as the recently introduced orthogonal periodic sequences [59].…”

Section: Discussionmentioning

confidence: 99%

Robust Room Impulse Response Measurement Using Perfect Periodic Sequences for Wiener Nonlinear Filters

2020

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The paper discusses a measurement approach for the room impulse response (RIR), which is insensitive to the nonlinearities that affect the measurement instruments. The approach employs as measurement signals the perfect periodic sequences for Wiener nonlinear (WN) filters. Perfect periodic sequences (PPSs) are periodic sequences that guarantee the perfect orthogonality of a filter basis functions over a period. The PPSs for WN filters are appealing for RIR measurement, since their sample distribution is almost Gaussian and provides a low excitation to the highest amplitudes. RIR measurement using PPSs for WN filters is studied and its advantages and limitations are discussed. The derivation of PPSs for WN filters suitable for RIR measurement is detailed. Limitations in the identification given by the underestimation of RIR memory, order of nonlinearity, and effect of measurement noise are analysed and estimated. Finally, experimental results, which involve both simulations using signals affected by real nonlinear devices and real RIR measurements in the presence of nonlinearities, compare the proposed approach with the ones that are based on PPSs for Legendre nonlinear filter, maximal length sequences, and exponential sweeps.

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“…These large values are due to the short length of the OPS input sequences. The effect of noise on short length OPSs, i.e., with length similar to those used for HRTF measurements, is much larger than that experienced on room impulse response (RIR) measurements [19]. In the experiment, the best results are obtained by the PPSs, which have a noise gain 1, in particular the PPSs for WN filters are the less affected by nonlinearities and are good candidate for HRTF measurements.…”

Section: B Emulated Scenariomentioning

confidence: 96%

“…Volterra filters do not admit PPSs, but they can still be identified with the cross-correlation method using OPSs. Given any persistently exiting periodic input sequence x(n) of sufficiently large period P , it has been shown in [19] that an orthogonal periodic sequence z(n) of period P can be developed such that…”

Section: Orthogonal Periodic Sequencesmentioning

confidence: 99%

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Using Periodic Sequences for HRTFs Measurement Robust Towards Nonlinearities in Automotive Audio Applications

Cecchi

Bruschi

Nobili

et al. 2022

2022 IEEE International Workshop on Metrology for Automotive (MetroAutomotive)

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Head Related Transfer Functions (HRTFs) are a mathematical representation of the acoustic transfer functions between a sound source and the listener's ears. They play an important role for both creating immersive audio scenarios and evaluating the perception of a sound system from human being point of view. These applications are also important for automotive scenario, since the car is nowadays the most used audio listening environment. Automotive audio has been attracting a great deal of attention in recent years as well as the use of HRTFs inside the car for creating these immersive scenarios. In this context, we proposed a technique for HRTFs measurement based on perfect or orthogonal periodic sequences that allows an effective measurement robust towards system nonlinearities. Experiments with an emulated scenario and measurements performed in real environments illustrate the validity of the approach in comparison with other competing HRTFs measurement methods of the state of the art.

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Orthogonal Periodic Sequences for the Identification of Functional Link Polynomial Filters

Cited by 13 publications

References 50 publications

A Room Impulse Response Measurement Method Robust Towards Nonlinearities Based on Orthogonal Periodic Sequences

A Room Impulse Response Measurement Method Robust Towards Nonlinearities Based on Orthogonal Periodic Sequences

Robust Room Impulse Response Measurement Using Perfect Periodic Sequences for Wiener Nonlinear Filters

Using Periodic Sequences for HRTFs Measurement Robust Towards Nonlinearities in Automotive Audio Applications

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