Speech Recording System

SPEECH RECORDING SYSTEM

ABSTRACT

A speech recorder is a digital handheld device that used to record short reminders or we can define speech recorder is a portable device for recording and playing back speech, usually equipped with a built in flash memory element. Sound recording and reproduction is an electronic or mechanical inscription and recreation of sound waves .such as spoken voices and instrument music or singing or other sound effect. The two main class of sound recording systems are analog and digital recording system. From the two of them we are going to built a digital recording system using ISD2560P.

In many cases the recording system have fulfill the recording process effectively due to many factors such as noise. Now in this project our aim is to reduce the complexity using simple circuit elements and ISD series to build up a digital recording system which lead us to hear clear out of noise with play back method.

Digital recording information begin in 1937 with idea of pulse code modulation patented by Alec Revel. The next was in 1943 Bell Telephone laboratory developed the first digital sampled speech transmission system. In 1957 the first sound recording through computes was created. This was the period of start for digital recording.

1.Introduction

A speech recorder is a digital handheld device that used to record short reminders or we can define Speech recorder is a portable device for recording & playing back speech ,usually equiped with a built in flash memory element. Sound recording & reproduction is an electronic or mechanical inscription & re-creation of sound waves . Such as spoken voices,singing,instrument music or sound effects.The two main class of sound recording technology are analog and digital recording system.From the two class we are going to built a digital recording system. In many cases recording syetm have no full satisfying full recording due to many factors.From these facteros the simplicity of recoding device can be considerd .Now in this project our aim is to reduce this complexity using simple circuit elements to build up a digital recoding system leads us to hear clear voice of playing back with avoiding noises.

2.Backgroung information

The earliest methods of recording arbitrary sounds involved the live recording of the performance directly to the recording medium. This was an entirely mechanical process, often called "Acoustical recording". The sound of the performers was captured by a diaphragm with the cutting needle connected to it. In 857,Edwouard-leon Scott de Martinuille invented the phonautograph, the first device that could record sound waves as they passed through the air. It was intended only for visual study of the recording and could not play back the sound. The Phonograph expanded on the principles of the phonautograph Perfected by Thomas Edison in 1878, the phonograph was a device with a Cylinder covered with an impressionable material such as tin foil, lead, or wax on which a stylus etched grooves. A disadvantage of the early phonographs was the difficulty of reproducing the phonograph cylinders in mass production. Next to this the gramophone (phonograph inAmerican -English), which was patented by Emile Berliner in 1887. By 1902, successful molding processes for cylinder recordings were developed. The material used was eventually changed to Electrical recording.Both phonograph cylinders and gramophone discs were played on mechanical devices most commonly hand wound with a clockwork motor. The advent of electrical recording in 1925 drastically improved the quality of the recording process of disc records. There was a period of nearly five years, from 1925 to 1930, when the premiere technology for home sound reproduction consisted of a combination of electrically recorded. Electrically powered phonographs were introduced in 1930, but crystal pickups and electronic reproduction did not become common until the late 1930s.The advent of electrical recording made it possible to use microphones to capture the sound of the performance. Electrical recording increased the flexibility of the process and the sound quality of the recordings. Magnetic recording was demonstrated in principle as early as 1898 by Valdemarpoulsen in his telegraphone. Magnetic wire recording, and its successor, magnetic tape recording, involve the use of a magnetizeable medium which moves with a constant speed past a recording head. An electrical signal, which is analogous to the sound that is to be recorded, is fed to the recording head, inducing a pattern of magnetization similar to the signal. A playback head can then pick up the changes in magnetic field from the tape and convert it into an electrical signal.The reproduction quality of wire recorders was significantly lower than that achievable with phonograph disk recording technology. Engineers at AEG, working with the chemical giant IG Farben, created the world's first practical magnetic tape recorder, the 'K1', which was first demonstrated in 1935. The next major development in magnetic tape was multitrack recording, in which the tape is divided into multiple tracks parallel with each other. The first development in multitracking was stereo sound, which divided the recording head into two tracks. First developed by German audio engineers ca. 1943.Multitrack recording was immediately taken up in a limited way by Ampex, who soon produced a commercial 3-track recorder. The next important development was 4-track recording. The advent of this improved system gave recording engineers and musicians vastly greater flexibility for recording and overdubbing, and 4-track was the studio standard for most of the later 1960s .In the 1980s, digital recording methods were introduced, and analog tape recording was gradually displaced, although it has not disappeared by any means. (Many professional studios, particularly those catering to big-budget clients, use analog recorders for multitracking and/or mixdown.) Digital audio tape never became important as a consumer recording medium partially due to legal complications arising from piracy fears on the part of the record companies. They had opposed magnetic tape recording when it first became available to consumers, but the technical difficulty of juggling recording levels, overload distortion, and residual tape hiss was sufficiently high that magnetic tape piracy never became an insurmountable commercial problem. With digital methods, copies of recordings could be exact, and piracy might have become a serious commercial problem. Digital tape is still used in professional situations and the DAT variant has found a home in computer data backup applications. Magnetic soundtracks can be joined with the moving image but it creates an abrupt discontinuity because of the offset of the audio track relative to the picture. Whether optical or magnetic, the audio pickup must be located several inches ahead of the projection lamp, shutter and drive sprockets. There is usually a flywheel as well to smooth out the film motion to eliminate the flutter that would otherwise result from the pull-down mechanism. If you have films with a magnetic track, you should keep them away from strong magnetic sources, such as televisions. These can weaken or wipe the magnetic sound signal. Magnetic sound on an acetate base is also more prone to vinegar Syndrome than a film with just the image. For optical recording on film there are two methods utilized. Variable density recording uses changes in the darkness of the soundtrack side of the film to represent the sound wave. Variable area recording uses changes in the width of a dark strip to represent the sound wave. Within a few years after the introduction of digital recording, multitrack recorders (using stationary heads) were being produced for use in professional studios. In the early 1990s, relatively low-priced multitrack digital recorders were introduced for use in home studios; they returned to recording on videotape. In the consumer market, tapes and gramophones were largely displaced by the Compact Disc (CD) and a lesser extent the minidisc. These recording media are fully digital and require complex electronics to play back.

CHAPTER 3

3.Statements of the problem /Objective/Significance of the project/limitation of the project

3.1.Statement of the problem

-for reminding the useful speeches,music,data

-for preserving information for example for pilot in black box

-For getting detail information via play back.

- For removal of noise at the out put with filter

-For getting clear signal out put

3.2.Objectitive

T o design speech recording using ISD2560P,resistors,capacitors,mic,speaker and switches in simple way for recording purpose . One of the benefit of this technology is the use of On-chip non-volatile memory ,producing Zero power message storage .The message retained for up to 100 years typically with out power. In addition the device can be re-recorded typically over 100,000 times.

3.3.Significance of the project

This project lead us in simple way to record speech using simple material to get recording process. For example Recording music is a great way to allow people to experience our art, because a recording of a song is easily distributed. Especially today, when websites like Myspace allow people to put their recordings up online for everyone to listen to. It's certainly easier than booking/playing concerts and relying on people hearing your music that way. Recording can also be an art form of its own - the recording often makes the song, and a good music producer can make a badly written song sound great in a recording. provide accurate records of the agency’s contact with the client and aid in continuity of case management between co-workers aid /jog memory as time it can be difficult to recall the specifies of each case lend credibility. particularly if one is called to give evidence of a particular fact or matter may add credence to claim by a client –especially about sexual abuse or domestic violence incidents protect the worker and the agency ,particularly from the later claims of negligigence.On the other hand our recording project aim is on the behave of teaching-learning activity may be applied to check back the speech of the teacher and to check up the students interview for exam or their case.

3.4.Limitation of the project

Flaws are easily detected in recordings. Probably because people don't expect to hear anything in a song that isn't perfect. Mistakes are acceptable when people see bands live, but in a recording every little error stands out. Because of this, recording often takes a long time to perfect. It can be extremely frustrating and tedious at times, because it often involves playing the same thing over and over, just to get it right. Technical problems are also very frequent and frustrating, especially today when nearly all recording is done with computers. A computer problem isn't as easily fixed as a broken cassette player.

Non-privileged records may be used against the client (e.g. in court cases) if it exists, file notes may disclose negligence on the part of the worker clients may be loathe to seek assistance if they know that an agency maintains records which they fear may later be used against them or which they fear somehow may end up in the hands of a violent spouse or government agency.

From the time limitation of the duration of recording is 60 second we must use external ISD card to extend the duration if we want more record .

CHAPTER 4

4.METHODOLOGY

4.1.ISD2560P

Winbond’s ISD2500 Chip order Series provide high-quality, single-chip, Record/Playback solutions for 60- to 120-second messaging applications. The CMOS devices include an on-chip oscillator, microphone preamplifier, automatic gain control, antialiasing filter, smoothing filter, speaker amplifier, and high density multi-level storage array. In addition, the ISD2500 is microcontroller compatible, allowing complex messaging and addressing to be achieved. Recordings are stored into on-chipnonvolatile memory cells, providing zero-power message storage. This unique, single-chip solution is made possible through Winbond’s patented multilevel storage technology. Voice and audio signals are stored directly into memory in their natural form, providing high-quality, solid-state voicereproduction.

4..1.1.BASIC futures of this ISD

-High-quality, natural voice/audio reproduction

-Ease –to-use single-chip, voice record/play back solution

-Single-chip with duration of 60, 75, 90, or 120 seconds

-Manual switch or microcontroller compatible

-Playback can be edge- or level-activated

-Directly cascade able for longer durations

-Automatic power-down (push-button mode)

-Zero power message storage

-Eliminates battery backup circuits

-Fully addressable to handle multiple messages

-100-year message retention (typical)

-100,000 record cycles (typical)

-one chip clock source

-single +5v supply

4.1.2.ISD2560P Pin configuration and and internal block diagram

4.1.2.1.Pin configuration

4.1.2.2.Internal block diagram

Fig1.internal block diagram of ISD2560P

4.1.2.3.Description for the pins

1. XCLK:-external clock-for clock rating should not be varied because of ant aliasing and smoothing filters are fixed
2. AN in: Analog input-transfers the analog signal to the chip for recording .for microphone inputs the ANAOUT pin should be connected via an external capacitor to the ANA IN pin. this capacitor value together with 3.kΩ input impedance of ANA IN is selected to give additional cutoff at the low frequency end of the voice pass band .if the desired input is derived from a source other than a microphone ,the signal can be fed ,capacitive coupled in to the ANA pin directly.
3. AN outputs. Analog outputs-This provides the preamplifier output to the user .The voltage gain of the preamplifier is determined by the voltage level at the AGC pin.
4. Mic: microphone –transfers the input signal to the on chip pre-amplifier. An external MIC should be AC coupled to this pin via a series capacitor. The capacitor value with this 10kΩ resistance on this pin determines the low-frequency cutoff for the ISD series pass band.
5. Mic ref: microphone reference- input is the inverting input to the microphone This provides a noise-canceling or common-mode rejection input to the device when Connected to a differential microphone

6.AGC: Automatic control gain- The AGC dynamically adjusts the gain of the preamplifier to compensate for the wide range of microphone input levels. The AGC allows the full range of whispers to loud sounds to be recorded with minimal distortion. The “attack” time is determined by the time constant of a 5 KΩ internal resistance and an external capacitor (C2 on the schematic of Figure 5 in section 11) connected from the AGC pin to VSSA analog ground. The “release” time is determined by the time constant of an external resistor (R2) and an external capacitor (C2) connected in parallel between the AGC pin and VSSA analog ground. Nominal values of 470 KΩ and 4.7 µF give satisfactory results in most cases

7.Pre-amp:amplifies before going to the voice to the out put.

8.Internal clock: for clock rating should not be varied because of ant aliasing and smoothing filters are fixed.the internal clock is connected to oscillator which is used to generate rectangular pulses.

9.Timing:time variation and duration limiter.

10. Sample clock:is adevice used to generate clock pulses

11.Analog transistors:

12.pole active antialiasing filter

13.Automatic gain control (AGC):is used to amplify the gain of the preamplifier of the operational amplifier to a level which enables to allow wide range input levels of the microphone.

14.Decoders 480 cell non volatile multistorage array is an addressable 480k byte memory chip which is used to store the recorded signals with their self address.

15.Address buffers:-this buffers used to interface the non volatile memory chip to the micro controller of the ISD2560p.

17.Power conditions: A power conditioner (also known as a line conditioner or power line conditioner) is a device intended to improve the quality of the power that is delivered to electrical load equipment. While there is no official definition of a power conditioner, the term most often refers to a device that acts in one or more ways to deliver a voltage of the proper level and characteristics to enable load equipment to function properly. In some usages, power conditioner refers to a voltage regulator with at least one other function to improve power quality (e.g. power factor correction, noise suppression, transient impulse protection, etc.).

18.SP-All devices in the ISD2500 series include an on chip differential speaker driver. Capable of driving 50mw into 60ohm from AUX IN(12.2mW from memory).The speaker outputs are held at VSSA

19.Sp+ speaker out put: All devices in the ISD2500 series include an on chip differential speaker driver. Capable of driving 50mw into 60ohm from AUX IN(12.2mW from memory).The speaker outputs are held at VSSA

20.Amp:amplify low level signals

21.Mux:selects one of several analog or digital input signals and forwards the selected input into a single line & used to select which input line to send the out put.

22.Smooth filter:to capture important patterns in the data, while leaving out noise or other fine-scale structures/rapid phenomena. In smoothing, the data points of a signal are modified so individual points (presumably because of noise) are reduced, and points that are lower than the adjacent points are increased leading to a smoother signal.

23.Pd: power down-when neither record nor play back operation ,the PD pin should be pulled High to place the part in the standby mode. when overflow condition ,PD should be brought

24.OVF:Over Flow-this signal pulses LOW at the end of memory array, indicating the device has been filled and the message has overflowed.The overflow output then follows the CE input until a PD pulses has reset the device .this pin can be used to cascade the several ISD2500 devices together to increase the record/playback durations.

25.P/R:play back /record-the play back record is latched by the falling edge of the CE pin .A high level selects a play back cycle while a low level selects a record cycle .For record cycle the address pins provide the starting address and recording continues until PD or CE is pulled High or an overflow is detected that means the chip is full. when the record cycle is terminated by pulling PD or CE HIGH, then EOM marker is stored at the current address in memory .For the play back cycle the address inputs provide the starting address and the device will play until an EOM marker is encountered .The device can continue to pass an EOM marker if CE is held LOW in address mode, or in an operational MODE.