SECURITY SINUSOIDAL TRANSFORM OF SPEECH CODING FOR MOBILE COMMUNICATION
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
The introduction of speech
coding for mobile communication through security sinusoidal transformation. Speech coding is the application of data
compression of digital audio signal containing speech. Speech coding uses speech-specific parameter estimation
using audio signal processing techniques to model the speech signal, combined with generic data compression
algorithms to represent the resulting modeled parameters in a compact bitstream. The two most important
applications of speech coding are mobile telephony and voice over IP.
The techniques employed in speech coding are similar to those used in audio data compression and audio coding
where knowledge in psychoacoustics is used to transmit only data that is relevant to the human auditory system. For
example, in voice band speech coding, only information in the frequency band 400HZ to 3500Hz is transmitted but
the reconstructed signal is still adequate for intelligibility. Speech coding differs from other forms of audio coding in that speech is a much simpler signal then most other audio
signals, and a lot more statistical information is available about the properties of speech. As a result, some auditory
information which is relevant in audio coding can be unnecessary in the speech coding context. In speech coding, the
most important criterion is preservation of intelligibility and pleasantness of speech, with a constrained amount of
transmitted data. The intelligibility of speech includes, the actual literal content, speaker identity, emotions, intonation,
timbre etc. In addition, most speech applications require low coding delay, as long as coding delays interfere with
speech interaction
Communication is the exchange of thoughts, messages or information, as by speech, signals, writing or behaviour. It
is derived from the latin word.
“Communis”, which means to share. Communication requires a sender, a message and a recipient, although the
receiver need not be present or aware of the sender’s intent to communicate at the time of communication, thus
communication can occur across vast distances in time and space. Communication requires that the communicating
parties share an area of communicative commonality. The communication process is complete once the receiver has
understood the message of the once the receiver has understood the message of the sender. Feedback is critical to
effective communication between participants. Bandwidth is a key concept in many telephony applications. In radio
communications, for example, band width is the frequency range occupied by a modulated carrier wave, whereas in
optics, it is the width of an individual spectral line or the entire spectral range.
In many signal processing contexts, bandwidth is a valuable and limited range of frequencies. A government agency
may apportion the regionally available bandwidth to broadcast license holders so that their signals do not mutually
interfere.
For different applications there are different precise definitions for bandwidth. It could be defined as the range of
frequencies beyond which the frequency function is zero. This would correspond to the mathematical notion of the
support of a function. Bandwidth can also be referred to as the frequencies where the frequency function is small.
Bandwidth typically refers to base band or as a pass band for communication systems.
1.2 CHARACTERISTICS OF MOBILE COMMUNICATION WITH RESPECT TO SPEECH CODERS
There are a number of additional characteristics of mobile communication, some of which are closely linked with
handover.
The most important characteristics includes:
a) Adaptive frame Alignment: Mobile staggers is transmitted by three timeslots after a burst from the base
station. This means that there is a nominal delay of three TDM slots between transmit and receive frames at the base
station
SECURITY SINUSOIDAL TRANSFORM OF SPEECH CODING FOR MOBILE COMMUNICATION