Frequency domain low time-bandwidth product chirp synthesis for pulse compression side lobe reduction

Virolainen, Teemu; Eskelinen, Joona; Hæggström, Edward

doi:10.1109/ultsym.2009.5441618

Cited by 9 publications

(6 citation statements)

References 5 publications

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“…Hence, we selected the frequency range from 39 to 41 kHz. We selected linear chirp signals as they are robust in terms of Doppler sensitivity and frequency selective fading [32]. Non-linear chirp signals give better results when the time-bandwidth product is higher, which was 14 in our experiments.…”

Section: Proposed Methodsmentioning

confidence: 99%

A Multi-Path Compensation Method for Ranging in Wearable Ultrasonic Sensor Networks for Human Gait Analysis

Ashhar

Khyam

Soh

2019

Sensors

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Gait analysis in unrestrained environments can be done with a single wearable ultrasonic sensor node on the lower limb and four fixed anchor nodes. The accuracy demanded by such systems is very high. Chirp signals can provide better ranging and localization performance in ultrasonic systems. However, we cannot neglect the multi-path effect in typical indoor environments for ultrasonic signals. The multi-path components closer to the line of sight component cannot be identified during correlation reception which leads to errors in the estimated range and which in turn affects the localization and tracking performance. We propose a novel method to reduce the multi-path effect in ultrasonic sensor networks in typical indoor environments. A gait analysis system with one mobile node attached to the lower limb was designed to test the performance of the proposed system during an indoor treadmill walking experiment. An optical motion capture system was used as a benchmark for the experiments. The proposed method gave better tracking accuracy compared to conventional coherent receivers. The static measurements gave 2.45 mm standard deviation compared to 10.45 mm using the classical approach. The RMSE between the ultrasonic gait analysis system and the reference system improved from 28.70 mm to 22.28 mm. The gait analysis system gave good performance for extraction of spatial and temporal parameters.

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Section: Proposed Methodsmentioning

confidence: 99%

A Multi-Path Compensation Method for Ranging in Wearable Ultrasonic Sensor Networks for Human Gait Analysis

Ashhar

Khyam

Soh

2019

Sensors

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“…These signals are usually preferred because they are easy to generate and the results obtained with them are easy to interpret and process, but they are very limited in terms of energy and bandwidth [23]. Therefore, if our goal is to produce ultrasonic signals with high energy and wide bandwidth, the best option is to use spread spectrum (SS) signals [24]- [27], such as these based on arbitrary waveforms [28], [29], chirp (FM-CW, LFM) [24], [30], non-linear chirp (NLFM) [20], [31] and PSK sequences [32]. The use of SS signals offers significant advantages over conventional signals:…”

Section: Introductionmentioning

confidence: 99%

On the Optimization of Spread Spectrum Chirps Into Arbitrary Position and Width Pulse Signals. Application to Ultrasonic Sensors and Systems

et al. 2022

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This work presents in detail a new method for the optimization of rectangular spread spectrum excitation signals for its use in simple and low-cost ultrasonic pulsers, but that could be extended to other applications based on spread spectrum signals. Starting from rectangular linear frequency modulated (RLFM) chirps, it uses the transfer function of the transmitted signal and received echoes from reference specimens to iterate through a recursive algorithm to obtain arbitrary position and width pulse (APWP) signals with the desired bandwidth, maximizing the energy and the flatness of the spectrum, and enhancing the resolution and dynamic range of conventional chirp excitation signals. This optimization procedure can be repeated for any transducer and material, so that it achieves the best performance in each experimental environment. Such characteristics are ideal for Time-of-Flight estimation, imaging, and applications in which spectral regularity is needed, such as the Split Spectrum Processing (SSP) algorithm, which is used as example to test the performance of the proposed excitation signals. It also allows to specify and change the bandwidth reducing the need to change the transducers. The method is tested with different transducers (2 and 5 MHz focused transducers) and complex composite materials (aluminum-carbon aviation composite and high porosity GFRP composite) in immersion setup for imaging applications using SSP algorithm.INDEX TERMS Ultrasound, Spread Spectrum, chirp, arbitrary position and width pulses, Split Spectrum Processing, non destructive testing.

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“…The obvious solution is to employ a spread spectrum signal [4]- [6] if wideband measurement channel is available: a processing gain allows for both resolution and accuracy improvement. Multiple spread spectrum techniques can be used: phase manipulated sequences [7], linear frequency modulation signals (chirp) [8]- [10], or arbitrary waveform signals [11], [12]. The phase-coded sequences do not offer flexibility in spectral content management [9], [13].…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic System Models for Pulse Trains Excitation Tuning

Svilainis¹,

Rodríguez²,

Aleksandrovas³

2016

ElAEE

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Quality of the ultrasonic imaging depends on probing signal. Application of the spread spectrum (SS) signals offers significant advantage over conventional signals: higher signal-to-noise ratio can be achieved and spectral content can be programmed. Yet, such SS signals like chirp and coded sequences suffer for the sidelobes which are induced by compression processing. Arbitrary position and width pulse (APWP) trains is a new class of SS signals which are expected to maintain advantages of the square pulse and the SS signals. Usual approach of SS signals application does not assume signal optimization. The novelty of the APWP approach is the optimization of the APWP train accounting of the signal transmission through system. In order to speed up the optimization iterations, a mathematical model of the APWP signal transmission through ultrasonic system is needed: instead of doing the iterations in real environment, those can be accomplished mathematically, using the system transmission model in order to sustain the experiment conditions. The development of the transmission model of the system is presented; the models are compared using the correlation properties. The results of the investigation are presented.

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Frequency domain low time-bandwidth product chirp synthesis for pulse compression side lobe reduction

Cited by 9 publications

References 5 publications

A Multi-Path Compensation Method for Ranging in Wearable Ultrasonic Sensor Networks for Human Gait Analysis

A Multi-Path Compensation Method for Ranging in Wearable Ultrasonic Sensor Networks for Human Gait Analysis

On the Optimization of Spread Spectrum Chirps Into Arbitrary Position and Width Pulse Signals. Application to Ultrasonic Sensors and Systems

Ultrasonic System Models for Pulse Trains Excitation Tuning

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