Binary Sneeze

In this tutorial we are writing a code in MATLAB for amplitude modulation of a signal and understanding the different cases of modulation in context of modulation index.

Steps to Follow:

• Generate a message signal of frequency 1Hz with m(t) = A + Amcos(2πfmt), and |m(t)|>0
• Generate a carrier signal of frequency 20Hz
• Plotting both the signals and their spectrum.
• Plotting the modulated signal and it’s spectrum
• Amplitude modulation of the message signal with µ = 0.5, µ = 1, µ = 1.5
• Mention the case of over modulation.

Description:

Message Signal: To generate the message signal, the values of amplitude Am, frequency fm, offset value A and time axis have been defined. The value of fm is chosen as specified and values of Am and t are taken arbitrarily. A>Am to satisfy the condition |m(t)|>0. t is chosen such that sampling frequency is 500 samples/sec

m(t) = A + Am cos(2πfmt)

Carrier Signal: For generation of carrier signal fc is taken as specified. The Amplitude Ac is taken arbitrarily. Read the rest of this entry »

Introduction:

This is an ironic twist in terminology. The term “intelligence” refers to processing capability; therefore, every computer is intelligent. However, artificial intelligence implies human-like intelligence.
Possibly we can say that it means “un-natural understanding”.

Artificial intelligence in some sense is engineering inspired by biology. It is a branch of Science which deals with helping machines to find solutions to complex problems in a more human-like fashion.

In AI, an “intelligent system” is one that exhibits behaviors normally associated with human intelligence.

Definition:

Defining “intelligence” in a computer system can be problematic since intelligence can be defined as something that humans possess and computers do not. In AI, however, an “intelligent system” is one that exhibits behaviors normally associated with human intelligence. Systems that perform complex diagnostic procedures and pattern matching are considered intelligent.

Artificial intelligence (AI) is a branch of computer science and engineering that deals with intelligent behavior, learning, and adaptation in machines.

The ability of a computer or other machine to perform those activities that are normally thought to require intelligence and which brings common sense, expert knowledge, and superhuman reasoning to computers.

Schools of thought:

AI divides roughly into two schools of thought: Conventional AI and Computational Intelligence (CI), also sometimes referred to as Synthetic Intelligence to highlight the differences. Read the rest of this entry »

The techniques earlier used for interpolation were the approximations of arbitrary functions on closed intervals by the use of polynomials. However we experienced two problems there:

• The oscillatory nature of high degree polynomials and
• The property that a function over a small portion of the interval can induce large fluctuations over the entire range restricts their use.

Piecewise-Polynomial Approximation:

An alternative approach is to divide the interval into a collection of subintervals and construct a different approximating polynomial on each subinterval. Approximation of functions by this type is called piecewise-polynomial approximation.

Spline:

A piecewise polynomial function that can have a locally very simple form, yet at the same time be globally flexible and smooth. Splines are very useful for modeling arbitrary functions, and are used extensively in computer graphics. Read the rest of this entry »

Programmable Logic Controller

Control engineering has evolved over time. In the past humans were the main method for controlling a system. More recently electricity has been used for control and early electrical control was based on relays. These relays allow power to be switched on and off without a mechanical switch.It is common to use relays to make simple logical control decisions. The development of low cost computer has brought the most recent revolution, the Programmable Logic Controller (PLC). The advent of the PLC began in the 1970s, and has become the most common choice for manufacturing controls.

Advantages

• Cost effective for controlling complex systems.
• Flexible and can be reapplied to control other systems quickly and easily. Read the rest of this entry »

Phase Hits

Definition:
A phase hit is the unwanted and significant shifting in phase of an analogue signal, as defined by Bell, any instance when the phase of a 1, 004-Hz test signal shifts more than 20 degrees. These are sudden large changes in the received signal phase (20 degrees) or frequency lasting longer than 4 mSec. The telephone company standard allows no more than 8 phase hits in any 15 minutes.

Causes and Effects:
Phase-hits can cause burst error and synchronization problems in high speed communication systems. The root cause of phase-hits results from the material’s thermal expansion mismatch. Read the rest of this entry »

Undersampling is generally known to have no benifits and is known to make the signals distorted. The main objective of this tutorial is to understand the phenomenon of sampling and the use of under sampling to extract a band-pass signal.

Section 1: Introduction

The sampling theorem states that for a limited bandwidth (band-limited) signal with maximum frequency fmax, the equally spaced sampling frequency fs must be greater than twice of the maximum frequency fmax, i.e.,

fs > 2•fmax

In order to have the signal be uniquely reconstructed without aliasing.

The frequency 2•fmax is called the Nyquist sampling rate. Half of this value, fmax, is sometimes called the Nyquist frequency.

When this theorem is not followed and fs < 2•fmax, the concept of undersampling arises.

This undersampling results aliasing of the signal, which causes many problems while the reconstruction of the signal. But a band-pass signal can be successfully retrieved back by using undersampling.

Section 2: Low Pass Sampling

Sampling (C to D)

Sampling is a principle that engineers follow in the digitization of analog signals. For analog-to-digital or discreet-to-continuous conversion, to result in a faithful reproduction of the signal slices called samples, of the analog waveform. The number of samples per second is called the sampling rate or sampling frequency fs.

A continuous time signal I(x) (where x is the time) can be sampled at a sampling rate of fs by replacing x with n/fs which implies that I[n] = I(n/fs)

Nyquist’s Theorem

The Nyquist’s Theorem is also known as the sampling theorem. Read the rest of this entry »

Extend

The Extend lines, extends the original length of the line to a new length.

• Select objects
• Press ENTER
• Select object to be extended Read the rest of this entry »

Line Types:

• Center lines are used to represent symmetry, and to mark the centers of circles and the axes of symmetrical parts, such as cylinders and bolts.

• Break lines are freehand lines used to show where an object is broken to reveal interior features.

• Hidden lines are used to represent features that cannot be seen in the current view. Read the rest of this entry »

Book Review: “The Myth of Independence” By Zulfikar Ali Bhutto

Author’s note:

“The reader will discover for himself in the pages of this book what opinions I hold, what my attitude is to world problems, what mistakes I believe were committed by Pakistan in dealing with foreign powers__particularly with Global Powers __and how those mistakes may be remedied; what my proposals are for a foreign policy adequate to avert the dangers which now threaten the country.”

Pakistan had been under military rule by a government headed by Ayub Khan since 1958. Bhutto, who served as minister of foreign affairs until asked to resign in 1966. In December 1967 Bhutto formed his own political party, the Pakistan People’s Party.

During his student days, Zulfikar Ali Bhutto had acquired an anti-Imperialist view of the world. He was a firm believer in economic self confidence and political independence, themes he illustrated in this book The Myth of Independence. This book is a conclusion of the events, and experiences of Zulfikar Ali Bhutto as foreign minister.

The book is dedicated to The Sovereign People of Pakistan, and was released in 1969.

Review:

The selected book has twenty chapters. The first one is devoted to ‘The Struggle for Equality’ describing the conflicts between groups, seeking their own interests and the fact that, for centuries Europe was the centre from which conflicts spreaded out but now the eye of the storm has shifted to Asia for example, Vietnam war. The writer has discussed that the fighting between the Arab states and Israel put west Asia and south-east Asia together in the same furnace of war. He has discussed the domination of countries which has been given the name of ‘White Man’s Burden’. He has also discussed the one dimensional approach to diplomacy, the nature of Pak-US relations, the US decision of termination of military assistance to Pakistan, affect of chains of colonialism and has concluded that the struggle of Pakistan and India to attain sovereign equality continues unsettled. He says that:

“Twenty years of independence have revealed to the people of Pakistan and India the sharp difference that really exists between independence and sovereign equality”. Read the rest of this entry »

Definition:

In some sense it is engineering inspired by biology. In AI, an “intelligent system” is one that exhibits behaviors normally associated with human intelligence.

Technology:

In some cases, early expert systems success led to inflated claims and unrealistic expectations: while the technology produced many highly effective systems. Here are the time slots of various developments in the field of AI.

• 1950s
• 1960s-1970s
• 1970s-1980s
• 1990s & turn of the century

Recent Developments in Artificial Intelligence:

Some recent achievements have been included such, speech dialog systems, expert systems, machine translation, fuzzy controllers and other appliances. Read the rest of this entry »