Quadrature demodulation based circuit implementation of pulse stream for ultrasonic signal FRI sparse sampling

Abstract

Converting ultrasonic signal to ultrasonic pulse stream is the key step of finite rate of innovation (FRI) sparse sampling. At present, ultrasonic pulse-stream-forming techniques are mainly based on digital algorithms. No hardware circuit that can achieve it has been reported. This paper proposes a new quadrature demodulation (QD) based circuit implementation method for forming an ultrasonic pulse stream. Elaborating on FRI sparse sampling theory, the process of ultrasonic signal is explained, followed by a discussion and analysis of ultrasonic pulse-stream-forming methods. In contrast to ultrasonic signal envelope extracting techniques, a quadrature demodulation method (QDM) is proposed. Simulation experiments were performed to determine its performance at various signal-to-noise ratios (SNRs). The circuit was then designed, with mixing module, oscillator, low pass filter (LPF), and root of square sum module. Finally, application experiments were carried out on pipeline sample ultrasonic flaw testing. The experimental results indicate that the QDM can accurately convert ultrasonic signal to ultrasonic pulse stream, and reverse the original signal information, such as pulse width, amplitude, and time of arrival. This technique lays the foundation for ultrasonic signal FRI sparse sampling directly with hardware circuitry.

Image reconstruction based on frequency domain feature extraction for EMT

“…Step 2, New measurement equation. Combining with ( 7) and (26), a new measurement equation can be obtained as (28).…”

“…Recently, the sampling of signals composed of short pulse streams with known pulse shapes has become a hot research topic. This kind of signal is called the finite rate of innovation (FRI) property [28][29][30], that is, it has limited degrees of freedom in unit time. This kind of signal can be uniquely reconstructed with a suitable sampling kernel and a sampling rate not less than the rate of innovation.…”

FRI-based sparse sampling for ultrasonic array signals based on pulse-positive sequence delay synthesis

“…Formula ( 12) is a Yule-Walker equation [20], which needs at least 2L continuous Fourier coefficients to obtain a unique solution.…”

“…For more general applications, Eldar et al developed a sum of sinc (SoS) sampling kernel with compact time-domain support, and applied it to ultrasonic imaging [5]. Our team has recently conducted research in the fields of ultrasonic signal FRI sampling and parameter reconstruction [6][7][8], proposed an ultrasonic-signal FRI sampling circuit implementation method based on the Non-Ideal Low Pass Filter (NI-LPF) sampling kernel, and, for the first time, realized single-channel ultrasonic signal sparse sampling by using a circuit [9]. Some scholars have proposed the multichannel FRI sampling theory, which is another FRI sampling framework for a single transducer signal, rather than multichannel transducer signals.…”