Design And Construction Of A Digital Voice Recorder And Playback

Electrical Electronics Engineering

The design and construction of a digital voice recorder and playback system involve integrating various components such as microphones, analog-to-digital converters (ADCs), digital signal processors (DSPs), memory modules, and audio output circuits. Beginning with the acquisition stage, high-quality microphones capture audio signals, which are then converted into digital format through ADCs for processing. The DSP handles tasks like noise reduction, compression, and storage management, optimizing the recording quality and efficiency. Memory modules store the digitized audio data, utilizing flash or SD card technology for storage capacity and flexibility. Playback involves retrieving stored audio data from memory, decoding and processing it through the DSP, and finally converting it back to analog form for output through speakers or headphones. This construction requires careful consideration of component selection, circuit design, and software implementation to ensure seamless recording and playback functionality, meeting the demands of users in various applications such as meetings, lectures, interviews, and personal memos, thereby enhancing productivity and communication efficiency.

ABSTRACT

Voice recorder and playback system is a made for the purpose of recording those messages and playback which required frequently at some places like platform, train, instruction, mobile, etc.

This work is based on IC ISD1700 which is DIP package and 2.4-5 volt operating voltage. It is a multi-message voice record. It can be operated standalone or by microcontroller (SPI) mode. Recording are stored into on-chip flash memory, providing zero power message storage.

TABLE OF CONTENT

COVER PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

TABLE OF CONTENT

CHAPTER ONE

INTRODUCTION
BACKGROUND OF THE PROJECT
AIM OF THE PROJECT
OBJECTIVE OF PROJECT
OBJECTIVE OF PROJECT
APPLICATION OF THE PROJECT
SCOPE OF THE PROJECT
PROJECT WORK ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

2.1 OVERVIEW OF SOUND RECORDING AND REPRODUCTION

2.2 HISTORICAL BACKGROUND OF SOUND RECORDING

2.3 OVERVIEW DIGITAL AUDIO

CHAPTER THREE

DESIGN METHODOLOGY

3.1 BLOCK DIAGRAM

3.2 SYSTEM OPERATION

3.3 PIN DESCRIPTION

3.4 SYSTEM CIRCUIT DIAGRAM

3.5 HOW TO USE THE SYSTEM

3.6 NONPRESCRIPTION

3.7 FEATURES OF ISD 1700

3.8 SYSTEM DESIGN PICTURE

CHAPTER FOUR

RESULTS ANALYSIS

CONSTRUCTION PROCEDURE
CASING AND PACKAGING
ASSEMBLING OF SECTIONS
PACKAGING
MOUNTING PROCEDURE
TESTING
RESULT ANALYSIS

CHAPTER FIVE

5.1 CONCLUSION

5.2 RECOMMENDATION

5.3 REFERENCES

CHAPTER ONE

1.0 INTRODUCTION

In digital recording, audio signals picked up by a microphone or other transducer or video signals picked up by a camera or similar device are converted into a stream of discrete numbers, representing the changes over time in air pressure for audio, and chroma and luminance values for video, then recorded to a storage device. To play back a digital sound recording, the numbers are retrieved and converted back into their original analog waveforms so that they can be heard through a loudspeaker. To play back a digital video recording, the numbers are retrieved and converted back into their original analog waveforms so that they can be viewed on a video monitor, television or other display.

This technology is mostly useful in day to day life, the voice recorders which gets recorded from the wrist watch voice recorder and pen voice recorder can be easily transferred to the computer through the USB key. This allows creating the audio or voicing recorded files of conversations, which can be copied and forwarded easily. These can be placed in some other devices like’s hard disks, CD drives, pen drive and this copied files are easily forward able within few minutes this applications are mostly helpful for students, you can send this conversations as notes to those who has missed their previous classes. This device consumes less amount of power supply.

1.1 BACKGROUND OF THE PROJECT

Sound recording and reproduction is an electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording.

Acoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record (in which a stylus cuts grooves on a record). In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current, which is then converted to a varying magnetic field by an electromagnet, which makes a representation of the sound as magnetized areas on a plastic tape with a magnetic coating on it. Analog sound reproduction is the reverse process, with a bigger loudspeaker diaphragm causing changes to atmospheric pressure to form acoustic sound waves.

Digital recording and reproduction converts the analog sound signal picked up by the microphone to a digital form by the process of sampling. This lets the audio data be stored and transmitted by a wider variety of media. Digital recording stores audio as a series of binary numbers (zeros and ones) representing samples of the amplitude of the audio signal at equal time intervals, at a sample rate high enough to convey all sounds capable of being heard. A digital audio signal must be reconverted to analog form during playback before it is amplified and connected to a loudspeaker to produce sound.

Prior to the development of sound recording, there were mechanical systems, such as wind-up music boxes and, later, player pianos, for encoding and reproducing instrumental music.

1.2 AIM OF THE PROJECT

The main aim of the work is to design a device that records and playback of voice messages. With this device users can leave a voice message for their family or friends whenever you go out, which they can hear by pressing the ‘play’ button.

1.3 OBJECTIVE OF PROJECT

At the end of this work, the student involved will be able to built and operate this device, and a little display of the application shall also be demonstrate by the student.

1.4 SIGNIFICANCE OF THE PROJECT

Digital voice recorders are the solution for busy business people or anyone with a need to record notes, meetings, presentations, lectures, and dictation. For musicians and other professionals, better quality recorders have additional features that, for example, allow them to make high fidelity stereo recordings. Yes, a modern multifunction device such as the iPhone can provide voice recording functionality. However, compared to dedicated voice recorders, multifunction devices can be limited in recording quality, battery life, audio storage capacity, and may lack features like voice activation and index markers.

1.5 APPLICATION OF THE PROJECT

This device can be used in different types of applications such as door bells, railway announcement systems and automatic telephone answering devices.

1.6 SCOPE OF THE PROJECT

This voice recorder and playback system is built around a recording and playback chip that supports voice recording for 16 seconds to 1minute and reproduces it clearly. This work is based on IC ISD1700 which is DIP package and 2.4-5 volt operating voltage. It is a multi-message voice record. It can be operated standalone or by microcontroller (SPI) mode. Recording are stored into on-chip flash memory, providing zero power message storage. IC ISD1700 is a high-quality voice recording and playback IC.

1.7 PROJECT WORK ORGANISATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to this study. In this chapter, the background, significance, objective limitation and problem of the study were discussed.

Chapter two is on literature review of the study. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.