Metrological and Legal Traceability of Time Signals

2018 ◽  
Author(s):  
Demetrios Matsakis ◽  
Judah Levine ◽  
Michael Lombardi
Keyword(s):  
Time Signals

scholarly journals The VIT Transform Approach to Discrete-Time Signals and Linear Time-Varying Systems

Eng ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 99-125
Author(s):  
Edward W. Kamen
Keyword(s):  
Discrete Time ◽  
Initial Conditions ◽  
Linear Time ◽  
Order Term ◽  
Initial Time ◽  
Time Varying ◽  
Varying Coefficients ◽  
Time Signals ◽  
Time Varying Systems ◽  
Time Varying Coefficients

A transform approach based on a variable initial time (VIT) formulation is developed for discrete-time signals and linear time-varying discrete-time systems or digital filters. The VIT transform is a formal power series in z−1, which converts functions given by linear time-varying difference equations into left polynomial fractions with variable coefficients, and with initial conditions incorporated into the framework. It is shown that the transform satisfies a number of properties that are analogous to those of the ordinary z-transform, and that it is possible to do scaling of z−i by time functions, which results in left-fraction forms for the transform of a large class of functions including sinusoids with general time-varying amplitudes and frequencies. Using the extended right Euclidean algorithm in a skew polynomial ring with time-varying coefficients, it is shown that a sum of left polynomial fractions can be written as a single fraction, which results in linear time-varying recursions for the inverse transform of the combined fraction. The extraction of a first-order term from a given polynomial fraction is carried out in terms of the evaluation of zi at time functions. In the application to linear time-varying systems, it is proved that the VIT transform of the system output is equal to the product of the VIT transform of the input and the VIT transform of the unit-pulse response function. For systems given by a time-varying moving average or an autoregressive model, the transform framework is used to determine the steady-state output response resulting from various signal inputs such as the step and cosine functions.

scholarly journals Car2Car Communication Using a Modulated Backscatter and Automotive FMCW Radar

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3656
Author(s):  
Antonio Lazaro ◽  
Marc Lazaro ◽  
Ramon Villarino ◽  
David Girbau ◽  
Pedro de Paco
Keyword(s):  
Power Supply ◽  
Communication Systems ◽  
Microwave Frequency ◽  
Proof Of Concept ◽  
Driver Assistance ◽  
Switching Rate ◽  
Fmcw Radar ◽  
Time Signals ◽  
Video Sensors ◽  
24 Ghz

This work proposes the use of a modulated tag for direct communication between two vehicles using as a carrier the wave emitted by an FMCW radar installed in the vehicle for advanced driver assistance. The system allows for real-time signals detection and classification, such as stop signal, turn signals and emergency lights, adding redundancy to computer video sensors and without incorporating additional communication systems. A proof-of-concept tag has been designed at the microwave frequency of 24 GHz, consisting of an amplifier connected between receiving and transmitting antennas. The modulation is performed by switching the power supply of the amplifier. The tag is installed on the rear of the car and it answers when it is illuminated by the radar by modulating the backscattered field. The information is encoded in the modulation switching rate used. Simulated and experimental results are given showing the feasibility of the proposed solution.

scholarly journals Croonian lecture—Aspects of animal locomotion

1939 ◽  
Vol 128 (850) ◽  
pp. 28-62 ◽  
Keyword(s):  
Biological Activity ◽  
Animal Life ◽  
Intimate Contact ◽  
Animal Locomotion ◽  
Time Signals ◽  
Marine Engineers ◽  
Great Complexity

The power of locomotion is, perhaps, one of the most striking attributes of animal life. It occurs in all groups of animals and is characterized by two conspicuous features: (i) In no other biological activity is an animal brought into closer and more intimate contact with its environment. (ii) Closely related animals may display striking differences of locomotory pattern yet in every cast the animal is able to deal precisely and efficiently with mechanical problems of great complexity. For many years, the study of animal locomotion has been concerned with two, apparently distinct, types of problems. First, attention has been paid to the mechanical or kinematic principles which animals employ in order to progress from one place to another. In many terrestrial animals these principles are relatively simple, for their limbs represent levers of one type or another; in other cases the mechanical principles are more obscure—we know little concerning the kinematics of movement of a fish or a snail, and little or nothing of the forces which propel a bird actively through the air. These problems have long attracted attention and it is encouraging to know that they are now being attacked by methods as precise and as controlled as those employed by aeronautical or marine engineers. The second type of problem is of a different nature; it is concerned with physiological nature of the locomotory machine. What is the nature of the neuro-muscular mechanism which enables and animal to utilize its muscular energy with such conspicuous precision and efficiency? How far are the movements dependent on the higher nervous centres, and how far are they dependent on the receipt of time signals from the outside world?

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