Golay sequences

In this paper, an improved ultrasonic system for detection of falling objccts or alive beings intrusion in railways is presented. The basic ultrasonic array sensor is composed of four emitters and six receivers and can bc easily extendcd to a higher coverage area repeating this elementary structure. The rcceivers are able to distinguish among the signals coming from the four different emitters thanks lo the signal coding with complementaIy sets of sequences, which also gives to the reception module an excellent process gain. The signal proccssing has been accomplished by means of the Efficient Set of Scqriences Correlafor which has been recently developed by the authors.

Ultrasonic imaging and tissue characterization is a noninvasive technique widely used in medicine for many years to assess body conditions. However, the expertise required to operate the equipment and interpret the results is not always available. The medical ultrasonography project is developing a system concept for a remotely steerable, multibeam ultrasonic scanner that can be operated by skilled medical personnel. The properly chosen ultrasonic sensor and duration of signal play an important role in ultrasonography. The choice of the ultrasonic sensor is influenced by a variety of parameters among which are: type and frequency of the signal, spectrum width of the signal, which in turn depend on the environment and object under consideration. The most frequently used signals are short sine burst, Barker code, chirp signal and Golay sequences. Each signal has its own IHDWXUHV DQG SHFXOLDULWLHV WKDW GLVWLQJXLVK LW IURP WKH RWKHUV DQG FRQVLGHUDEO\ GHWHUPLQH WKH VHQVRU¶V properties.

The design of advanced sonar modules implies the use of more and more complex processing algorithms, in order to obtain as much information as possible from the environment. The use of simultaneous emission and reception techniques in certain transducers, that form an ultrasonic sensorial module, allows to increase the benefits and the performance of this type of systems. These developments make possible to obtain more information for every ultrasonic emission, diminishing the scanning time and improving the interpretation and usefulness of the obtained results. These techniques are usually based on the encoding of the ultrasonic emission, so the received signals can be correlated in order to search for possible echoes. As a consequence, the computational complexity necessary to carry out the implementation of the new algorithms increases considerably. The analysis of possible computing platforms for the real-time processing of the new algorithms becomes a task of great importance. In this work, some computing architectures are analysed and compared, in order to determine which scheme is most suitable for the ultrasonic signal processing.

The design of advanced sonar modules implies the use of more and more complex processing algorithms, in order to obtain as much information as possible from the environment. The use of simultaneous emission and reception techniques in certain transducers, that form an ultrasonic sensorial module, allows to increase the benefits and the performance of this type of systems. These developments make possible to obtain more information for every ultrasonic emission, diminishing the scanning time and improving the interpretation and usefulness of the obtained results. These techniques are usually based on the encoding of the ultrasonic emission, so the received signals can be correlated in order to search for possible echoes. As a consequence, the computational complexity necessary to carry out the implementation of the new algorithms increases considerably. The analysis of possible computing platforms for the real-time processing of the new algorithms becomes a task of great importance. In this work, some computing architectures are analysed and compared, in order to determine which scheme is most suitable for the ultrasonic signal processing.

This work presents a SOC-based (system-on-chip) architecture for ultrasonic imaging systems in airborne transmission which uses macro-sequences derived from complementary sets of sequences (CSS) to achieve simultaneous beam steering in several directions. By means of CSS concatenation and zero padding, a new macro-sequence can be obtained which achieves zero auto-and cross-correlation zones (ZCZ). These zones can be adjusted to provide interference-free CDMA (code division multiple access) within the scanning area. The correlation results with the proposed macro-sequences provide the A-scan lines for a final B-scan image. In contrast to other encoding schemes with similar sizes of ZCZ, the one proposed here allows an architecture design that further minimizes the computational load to make real-time processing feasible. The implementation of the proposed architecture in a FPGA (field-programmable gate array) device, including all the stages from the emission and reception modules of the imaging ultrasonic system, is presented. The ultrasonic phased array has 8 elements and permits the simultaneous analysis of 32 different angular sectors, for a maximum range of 1.5 m and an angular aperture of 64. Index Terms-Code-division multiple access (CDMA), field-programmable gate arrays (FPGA), System-on-Chip (SoC), ultrasonic phased array.

Multi-mode techniques reduce scanning times in ultrasonic systems, as they allow transducers in a sensor to simultaneously emit and receive without interference. In order to implement these techniques, it is necessary to encode each transducer's emission. The use of orthogonal pairs of Golay sequences associated with different emitters avoids crosstalk among them. However, these sequences imply an increase in the computational complexity required in the receiver. This paper presents the practical implementation of a system, with two emitters and four receivers, using a low-cost hardware architecture based on a FPGA. The ultrasonic signal processing is performed in real time. q

In the field of mobile robots ever more frequent use is being made of ultrasonic sensors composed of several transducers carrying out readings simultaneously and in a coordinated way. These sensors can read not only the distances but also listening angles, and they can also determine the reflector type (i.e. edge, plane or corner). To this end it is especially important that, after each emission of a pulse of ultrasound, each transducer can accurately detect the arrival of the echoes (providing accurate time-of-flight (TOF) readings). Another desirable feature is that the transducers be capable of discriminating between the echoes of simultaneous emissions (avoiding problems of crosstalk). This article describes the design and development of a correlation detector (implemented on a low-cost electronic system) allowing for both functions. ᭧

The design of advanced sonar modules implies the use of more and more complex processing algorithms, in order to obtain as much information as possible from the environment. The use of simultaneous emission and reception techniques in certain transducers, that form an ultrasonic sensorial module, allows to increase the benefits and the performance of this type of systems. These developments make possible to obtain more information for every ultrasonic emission, diminishing the scanning time and improving the interpretation and usefulness of the obtained results. These techniques are usually based on the encoding of the ultrasonic emission, so the received signals can be correlated in order to search for possible echoes. As a consequence, the computational complexity necessary to carry out the implementation of the new algorithms increases considerably. The analysis of possible computing platforms for the real-time processing of the new algorithms becomes a task of great importance. In this work, some computing architectures are analysed and compared, in order to determine which scheme is most suitable for the ultrasonic signal processing.

Multi-mode techniques reduce scanning times in ultrasonic systems, as they allow transducers in a sensor to simultaneously emit and receive without interference. In order to implement these techniques, it is necessary to encode each transducer's emission. The use of orthogonal pairs of Golay sequences associated with different emitters avoids crosstalk among them. However, these sequences imply an increase in the computational complexity required in the receiver. This paper presents the practical implementation of a system, with two emitters and four receivers, using a low-cost hardware architecture based on a FPGA. The ultrasonic signal processing is performed in real time. q

This work analyses the effect of the receiver movement on the pulse compression of the signals emitted by the beacons of an Ultrasonic Local Positioning System (ULPS). This analysis is first carried out by using a system model in order to obtain a set of results that are then experimentally validated with the help of an electric slider. The signals emitted by the ultrasonic beacons are encoded with Kasami sequences of four different lengths (15, 63, 255 and 1024 bits), and radial speeds of up to 2 m/s have been considered in the experimentation. The results derived from this study should be of interest to anyone performing matched filtering of ultrasonic signals with a moving emitter/receiver.

The design of advanced sonar modules implies the use of more and more complex processing algorithms, in order to obtain as much information as possible from the environment. The use of simultaneous emission and reception techniques in certain transducers, that form an ultrasonic sensorial module, allows to increase the benefits and the performance of this type of systems. These developments make possible to obtain more information for every ultrasonic emission, diminishing the scanning time and improving the interpretation and usefulness of the obtained results. These techniques are usually based on the encoding of the ultrasonic emission, so the received signals can be correlated in order to search for possible echoes. As a consequence, the computational complexity necessary to carry out the implementation of the new algorithms increases considerably. The analysis of possible computing platforms for the real-time processing of the new algorithms becomes a task of great importance. In this work, some computing architectures are analysed and compared, in order to determine which scheme is most suitable for the ultrasonic signal processing.

The design of advanced sonar modules implies the use of more and more complex processing algorithms, in order to obtain as much information as possible from the environment. The use of simultaneous emission and reception techniques in certain transducers, that form an ultrasonic sensorial module, allows to increase the benefits and the performance of this type of systems. These developments make possible to obtain more information for every ultrasonic emission, diminishing the scanning time and improving the interpretation and usefulness of the obtained results. These techniques are usually based on the encoding of the ultrasonic emission, so the received signals can be correlated in order to search for possible echoes. As a consequence, the computational complexity necessary to carry out the implementation of the new algorithms increases considerably. The analysis of possible computing platforms for the real-time processing of the new algorithms becomes a task of great importance. In this work, some computing architectures are analysed and compared, in order to determine which scheme is most suitable for the ultrasonic signal processing.

The design of advanced sonar modules implies the use of more and more complex processing algorithms, in order to obtain as much information as possible from the environment. The use of simultaneous emission and reception techniques in certain transducers, that form an ultrasonic sensorial module, allows to increase the benefits and the performance of this type of systems. These developments make possible to obtain more information for every ultrasonic emission, diminishing the scanning time and improving the interpretation and usefulness of the obtained results. These techniques are usually based on the encoding of the ultrasonic emission, so the received signals can be correlated in order to search for possible echoes. As a consequence, the computational complexity necessary to carry out the implementation of the new algorithms increases considerably. The analysis of possible computing platforms for the real-time processing of the new algorithms becomes a task of great importance. In this work, some computing architectures are analysed and compared, in order to determine which scheme is most suitable for the ultrasonic signal processing.

The design of advanced sonar modules implies the use of more and more complex processing algorithms, in order to obtain as much information as possible from the environment. The use of simultaneous emission and reception techniques in certain transducers, that form an ultrasonic sensorial module, allows to increase the benefits and the performance of this type of systems. These developments make possible to obtain more information for every ultrasonic emission, diminishing the scanning time and improving the interpretation and usefulness of the obtained results. These techniques are usually based on the encoding of the ultrasonic emission, so the received signals can be correlated in order to search for possible echoes. As a consequence, the computational complexity necessary to carry out the implementation of the new algorithms increases considerably. The analysis of possible computing platforms for the real-time processing of the new algorithms becomes a task of great importance. In this work, some computing architectures are analysed and compared, in order to determine which scheme is most suitable for the ultrasonic signal processing.

Multi-mode techniques reduce scanning times in ultrasonic systems, as they allow transducers in a sensor to simultaneously emit and receive without interference. In order to implement these techniques, it is necessary to encode each transducer's emission. The use of orthogonal pairs of Golay sequences associated with different emitters avoids crosstalk among them. However, these sequences imply an increase in the computational complexity required in the receiver. This paper presents the practical implementation of a system, with two emitters and four receivers, using a low-cost hardware architecture based on a FPGA. The ultrasonic signal processing is performed in real time. q

Multi-mode techniques reduce scanning times in ultrasonic systems, as they allow transducers in a sensor to simultaneously emit and receive without interference. In order to implement these techniques, it is necessary to encode each transducer's emission. The use of orthogonal pairs of Golay sequences associated with different emitters avoids crosstalk among them. However, these sequences imply an increase in the computational complexity required in the receiver. This paper presents the practical implementation of a system, with two emitters and four receivers, using a low-cost hardware architecture based on a FPGA. The ultrasonic signal processing is performed in real time. q

In the field of mobile robots ever more frequent use is being made of ultrasonic sensors composed of several transducers carrying out readings simultaneously and in a coordinated way. These sensors can read not only the distances but also listening angles, and they can also determine the reflector type (i.e. edge, plane or corner). To this end it is especially important that, after each emission of a pulse of ultrasound, each transducer can accurately detect the arrival of the echoes (providing accurate time-of-flight (TOF) readings). Another desirable feature is that the transducers be capable of discriminating between the echoes of simultaneous emissions (avoiding problems of crosstalk). This article describes the design and development of a correlation detector (implemented on a low-cost electronic system) allowing for both functions. ᭧

In many of the recent array ultrasonic applications, acquisition rate is a crucial issue. Many of those applications are even impractical due to the sequential nature of ultrasound systems scanning. Obviously, one way of increasing this rate is the use of multi-mode operation. This paper introduces the basic aspects of multi-mode ultrasonic operation, based on pulse compression techniques, by means of Golay complementary sequences. To take advantage of such sequences a QPSK modulation scheme is used so we transmit both complementary sequences simultaneously. Finally, some results using two modes simultaneously are shown.

In many of the recent array ultrasonic applications, acquisition rate is a crucial issue. Many of those applications are even impractical due to the sequential nature of ultrasound systems scanning. Obviously, one way of increasing this rate is the use of multi-mode operation. This paper introduces the basic aspects of multi-mode ultrasonic operation based on pulse compression techniques by means of binary sequences in a BPSK modulation scheme, and the advantages of Golay sequences, in multi-mode operation with respect to m-sequences, mostly used in recent works. Finally, some results of simulations using four modes simultaneously and a hardware architecture for testing these results are shown

Multi-mode techniques reduce scanning times in ultrasonic systems, as they allow transducers in a sensor to simultaneously emit and receive without interference. In order to implement these techniques, it is necessary to encode each transducer's emission. The use of orthogonal pairs of Golay sequences associated with different emitters avoids crosstalk among them. However, these sequences imply an increase in the computational complexity required in the receiver. This paper presents the practical implementation of a system, with two emitters and four receivers, using a low-cost hardware architecture based on a FPGA. The ultrasonic signal processing is performed in real time. q