A digital hardware correlation system for fast ultrasonic data acquisition in peak power limited applications

Abstract

The theoretical and experimental evaluation of a digital hardware correlation system for low-power ultrasonic applications is presented. The system, which incorporates dual Golay code matched filtering, is capable of 20-MHz processing rates with a signal-to-noise-ratio enhancement (SNRE) of 23 dB over a conventional pulse-echo system operating at the same peak power levels. The effects of digitization have been investigated, and a TTL (transistor transistor logic)-based hardware correlator has been developed. For many applications, low-voltage driving followed by differential detection is sufficient, permitting the system to be used in a number of power-limited environments. Sample tests conducted on three different transducers have demonstrated that the system is operational over a wide variety of probe configurations.

3d Indoor Localization Through a Wireless Acoustic sensor Networks

“…The inter-correlation function between the transmitted and received signal during period T t is obtained by the integration between the products of these signals [15]:…”

Ultrasonic-Based Distance Measurement Through Discrete Extended Kalman Filter

“…By considering the inherent error of the time-to-digital conversion (i.e. the quantization error), it can be written (4) In order to read the distance in a straightforward way in length units, its value should be expressed in decimal order of tens. In order to lower the discretization error, the working frequency of the clock is chosen sufficiently high (as a rule, tens of MHz are used).…”

“…Although several solutions providing good accuracy can be conceived, for example optical solutions which are based on lasers or position sensitive devices, such solutions are usually rather expensive. In addition, in several cases the use of lasers or other high-power systems cannot be accepted in hazardous environments or when low energy devices are prescribed [4]. In these cases low-power ultrasonic sensors are a cost-effective solution, especially when low-frequency devices (30-50 kHz) are used [5]- [7].…”

“…An original use of discrete extended Kalman filter (DEKF) is presented in the following to face the aforementioned problems. The novelty of the method mainly relies upon its capability of jointly estimating the whole set of parameters (A 0 , α, T, and ) that characterize the wellknown model of echo envelope, A(t): (2) A 0 accounts for echo amplitude, α and T are peculiar to the specific ultrasonic transducer, and is the desired TOF [4]- [6]. The main advantage of the new approach is that TOF estimation inherently accounts for distortions the ultrasonic echo eventually undergoes, with a consequent positive effect on bias reduction.…”

Pulsecompression in Pulse-Echo-Mode with Splitted Chirp Signals

“…Instead of short pulses, signals with a large time-bandwidth-product (e.g. chirp-signals 4 , pseudo-random-signals 5 ) are applied. As these exhibit a single-peaked autocorrelationfunction, they can be compressed to short pulses by appropriate correlation-or pulsecompression-filters.…”