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The requirement for an efficient method for noise-robust detection of Dual-tone Multi-frequency (DTMF) signals keeping in mind the continuous evolution of telecommunication equipment is conspicuous. A machine learning based approach has been proposed in this research article to detect DTMF tones under the influence of various noises and frequency variations by employing the K-Nearest Neighbor (KNN) Algorithm. In order to meet accurate classification/detection requirements for various real-world requirements, a total of four KNN models have been created and compared, and the best one proposed for real-time deployment. Two datasets have been amassed, a clean dataset without noise and a noisy augmented dataset with perturbations that are observed in telecommunication channels such as additive white gaussian noise (AWGN), amplitude attenuation, time shift/stretch etc. Mel-Frequency Cepstral Coefficients (MFCC) and Goertzel’s Algorithm (used to estimate the absolute Discrete Fourier Transform (DFT) values for the fundamental DTMF frequencies) are employed to calculate features to be fed to the KNN models. The four models differ in being trained with and without the augmented data using the two aforementioned feature extraction algorithms, namely MFCCs calculation and the Goertzel’s algorithm. The proposed models have been verified and validated with unseen noisy testing data and it was found that the proposed KNN model D outperformed all the other models with a macro recall, precision and F1 classification score of 97.7, 97.70625 and 97.70046 respectively. The proposed model is also computationally inexpensive and showcases relatively low computing time and complexity.

Purpose Due to the continuous and rapid evolution of telecommunication equipment, the demand for more efficient and noise-robust detection of dual-tone multi-frequency (DTMF) signals is most significant. Design/methodology/approach A novel machine learning-based approach to detect DTMF tones affected by noise, frequency and time variations by employing the k-nearest neighbour (KNN) algorithm is proposed. The features required for training the proposed KNN classifier are extracted using Goertzel's algorithm that estimates the absolute discrete Fourier transform (DFT) coefficient values for the fundamental DTMF frequencies with or without considering their second harmonic frequencies. The proposed KNN classifier model is configured in four different manners which differ in being trained with or without augmented data, as well as, with or without the inclusion of second harmonic frequency DFT coefficient values as features. Findings It is found that the model which is trained using the augmented data set and additionally includes the absolute DFT values of the second harmonic frequency values for the eight fundamental DTMF frequencies as the features, achieved the best performance with a macro classification F1 score of 0.980835, a five-fold stratified cross-validation accuracy of 98.47% and test data set detection accuracy of 98.1053%. Originality/value The generated DTMF signal has been classified and detected using the proposed KNN classifier which utilizes the DFT coefficient along with second harmonic frequencies for better classification. Additionally, the proposed KNN classifier has been compared with existing models to ascertain its superiority and proclaim its state-of-the-art performance.

Obtaining information is one of the most important requirements for intelligence works, spy surveillance cameras and listening devices are among the important means for this. One problem of using these means is a mechanism of controlling them to sustain their work efficiently for the perpetuating of achieving the purpose of their installation. In this research, the problem of controlling these devices has been overcome, by designing a system dependent on the dual tone multi frequency (DTMF) and global system for mobile (GSM) networks. In the proposed work, designing and implementing a system to remotely and wirelessly control of the movement of spy cameras in all directions as well as the ability to control the on/off listing audio device anytime and anywhere. The proposed mechanism is implemented by dividing the work into nine modes, with each one performing one specific function. These work modes are used to control all system activities such as control the horizontal directional motor (HDM) to change the spy camera in different horizontal directions, control the vertical directional motor (VDM) to change the camera in vertical directions and control the working status of the listening device.

Smart Home Systems have achieved great interest in the recent years to make people’s life easier and more comfortable. Smart home system offers people to control home environment in efficient and comfortable manner. Technological advancement in recent years resulted in producing a large number of smart and sophisticated systems which promoted smart living technology. This paper presents complete analysis of various smart and intelligent home automation systems. Comparative analysis of existing smart home system has been made which provides a clear idea of the pros and cons of the existing systems. Working principle of different types of smart home systems such as Dual Tone Multi Frequency based, Global System for Mobile based, voice recognition based, Zigbee based, Bluetooth based, Internet and Wi-fi based, and Gesture based smart home systems has been studied. Comments according to different aspects and features have been made for the studied smart home systems which enable users to select suitable technology according to budget and needs.

This paper is concerned with the improvement of the Dual Tone Multi Frequency (DTMF) identification where the signals were transmitted via real communication channels. The frequencies of the DTMF signals are tracked using particle filtering method, a method that rely on the numerical computation in approximating the posterior probability density function (PDF) of the underlying state parameters, to identify which pad was pressed at the transmitter end. We propose and implement the adaptive resampling to improve the performance of the DTMF identification. The method enhances the quality of resampling stage generating a better set of particles which will be used for posterior PDF of the tones of the DTMF signals. Results reveal the advantage of using the proposed method in comparison to the conventional resampling scheme.

In this study, we investigate the design and simulation of an electronic system for remote controlling the level of light intensity of an electrical lighting system used for a certain desired application. The remote controlling is done using the keypad of any Dual Tone Multi Frequency (DTMF) based telephone handset. A DTMF tone command sent from a transmitting fixed or mobile phone terminal will be used to activate a system of relays that control the required level of light intensity. An appropriate active bandpass filters are designed for recognition of the DTMF tones of the transmitted digit. The bandpass filters and the additional subsequent stages of the overall electronic system are simulated and tested using MULTISM. Light intensity controlling is useful to avoid unnecessary electrical power wastage and the remote controlling eliminates the physical presence of a person for adjusting the required level of lighting at the desired location.

This technical paper aims at bringing about a huge development in this domestic and agriculture sectors to protect the farmer's interest thereby ensuring the overall growth of this country's economy. The topic is all about introducing a toll-free automation system for farmers who are considered to be the lifeline of India. Automation plays an important role in every field of work and segment of human life in helping the human beings to improve their functioning. Dual-Tone Multi-Frequencies has numerous applications and utilization in a broader perspective. The usage of DTMF touch tones by customer service has increasingly gained its importance and attention in the field of automation albeit it is not free of cost. Considering the poor economical background and condition of majority of Indian farmers, the automation system should be so designed to save their money in a cost effective manner as a onetime investment device. To put it in a nutshell the technicality involved in this project is that DTMF beep ringtone is set as a ringtone in a mobile phone rather than its being used in any distant automation system. The function of DTMF Decoder is to decode DTMF tone in binary numbers that would be received through a missed call. Thus the code generated in the previous step activates the microcontroller that would trigger the relays to operate appropriate appliance that was intended. The whole aim of this project is to design and install a high secured distant controlled toll-free automation system that would empower the farmers to take care of the entire needs in one stroke in their day-to-day agriculture activity.

Aims: This article reports the development and the experimental results of the acceptability testing and comparison of speech and dual tone multi frequency (DTMF) for interacting with a speech application for carrying out banking transactions. Study Design: A within-subjects experiment where each of the participants tested both the DTMF only and speech only modalities was carried out. Each one filled a questionnaire after testing each modality Place and Duration of Study: Department of Computer and Information Sciences, Covenant University, Ota, Nigeria, between May 2013 and June 2013. Methodology: Voice Objects 11 was used as the development platform. Voxeo Prophecy 9 was used as the implementation platform while MySQL 5.5 was used as the database management system for storing each customer's account details. X-Lite soft phone 3.3 was used for testing the system. 50 undergraduates of Covenant University, Ota, Nigeria participated in the evaluation. Each one tested the system using DTMF and speech separately. After each round of the tests, each one filled a questionnaire for the modality tested in a bid to measure the acceptability and user satisfaction with the modality. Results: The entire system’s satisfaction ratings for DTMF were significantly higher (M=36.18) than for speech (M=34.76), t(49)= -1.46, tcrit =2.0, P=.05. For modality evaluation, speech was more satisfying (M=12.22) than DTMF (M=12.18), t(49)= 0.14, tcrit =2.0, P=.05. For modality entertainment, both speech and DTMF were rated equal (M=13.94), t(49)=0, tcrit =2.0, P=.05. For modality naturalness, speech was more natural (M=10.2) than DTMF (M=9.44), t(49)=- 2.41, tcrit =2.0, P=.05. 52% of the subjects chose DTMF modality, whereas 48% chose speech (p = .05). Conclusion: Dialogue systems are a widely acceptable technology for carrying out banking transactions in Nigeria. It will provide a cost-effective and easily accessible means of carrying out banking transactions

The goal of this project is to use DTMF decoders, sand micro-controllers to control autonomous navigation of a robot between a start and end point along a fixed path. This has very practical applications, eg. a mobile phone can be used to start the car and allow it to autonomously drive itself to a pick up point and vehicles in warehouses to carry goods fro m point A to point B, etc. A DTMF decoder is interfaced with the microcontroller , and a phone on auto answer mode is connected to t he decoder. When the robot is called and a number on the user’s phone is press ed, the tone is sent to the decoder, which decodes and sends a signal to the microcontroller, and the robot is started. To avoi d obstacles the robot has inbuilt Infrared sensors which detect obstacles and inform the microcontroller, which accordingly guides the r obot. In this setup only three sensors were used gi ven the limitation in terms of input ports. However, a greater number of sensors w ould allow for the robot to be aware of more specif ic situations. Therefore, it can be made more adaptable in varying situations. The t est robot was programmed using Embedded C with AVR Studios. This approach uses existing technologies and is very inexpensive.

Introduces a system design scheme of the telephone dialer based on Arduino, including the design principle, hardware and software design and the experimental results in this paper. The scheme is based on the dual tone multi frequency (DTMF) dialing mode, using the Arduino UNO as the main controller, the serial port send out the telephone number to be dialed, speaker synthesize the voice.

The paper represents a smart gadget to avert the calamitous effects of pest bugs in the farming land as well as in household commodities. In this paper, development and performance analysis of smart ultrasonic insects repellent device has been demonstrated. This device is able to generate different types of frequencies which are very helpful to repel different types of insects. It can be controlled from any distance with DTMF (Dual Tone Multi Frequency) technology. Besides, manual control with night mode via LDR (Light Dependent Resistor) has also been employed. The device would be charged through solar energy system which is a cost effective approach. A power amplifier along with a microcontroller known as Arduino Uno as well as solar charger circuit regulator and solar panel are used. The implementation of this device in farmland has shown a great reduction of bugs attack compared to the other land which doesn't have one.

The intelligent telephone alarm system is designed with a single chip microcomputer as the core of system,and the intelligent system is controlled by AT89C51. A telephone network is used as transmission of voice digital information in the system. The telephone alarm is composed of a single-chip microcomputer control, sensor and signal input circuit, and DTMF send and receive circuit, voice controlling and receiving circuit, alarm telephone circuit. According to the different sensor output signal, it can send out different alarm information to realize remote monitoring function.

Interactive Voice Response System (IVRS) is an automated system which is multi-lingual and makes use of text-to-speech (TTS) technology. This paper describes the implementation of an Interactive Voice Response System personalized especially for students to obtain any information desired by them in a reliable and timely manner by just placing a normal call, thus being a building block of a smart city. It works on a 24/7 basis and is very user friendly. The IVRS system comprises of ring detector hardware, dual tone multi frequency decoder (DTMFD), microcontroller, serial interface unit, computer and cell phone. It includes a ring detector hardware which identifies the caller and connects the identified caller to a computer. When a caller presses a key from their cell phone the input is produced in the form of dual tone multi frequency signal. The computer generates voice response dynamically based on the key pressed by the caller. A "Text to Speech Converter" converts the database into a voice format as per the response given by the caller.

In this paper, based on the traditional fixed telephony features to increase the short message processing module. To meet the voice communication between users, the fixed telephone can realize mutual development between the SMS function .The main telephone lines in the completion of the CAS signal detection, and traditional communications in FSK and DTMF signal reception and transmission.

Extremely long distance control, hardly reachable actuator/target and costly network development are some concerns within a distance control system. Such control is computer control for advertisements placed in tricky areas as locations over the bridge, at a junction, etc. The provider usually performs system inactivation in order to save energy. But until now, it is still difficult to find a system that can be turned on and off in remote manner. That is why the distant control using telephone can be the best alternative solution. Not only can the telephone be used in wide range of area, but also easily operated. The developed circuit in this research uses dual tone multiple frequency (DTMF). It is operated by pressing telephone button as control input for microcontroller. The microcontroller processes the input and controls the computer via relay and serial port. The result of experiment shows that the developed application is able to shut down and turn on computer as well as to apply software remotely.

DTMF (Dual Tone Multi Frequency) is a system of signal tones used for telecommunications. DTMF uses two tones to represent each key on the touch pad. DTMF data transfer technique has advantages such as high reliability, constant speed, and high signal to noise ratio, low cost and optimal utilization of existing resources. These features make DTMF an attractive Data Transfer Technique. It finds application in home and car security systems, robot control, SMS and voice call controlled industrial applications. In this paper, we discuss the use of DTMF data transfer in a voice call to control a toy car. Cell phone 1(CP 1), which is at user end, makes a call to cell phone 2(CP 2) at the machine end and establishes a connection. A key is pressed at the user side. Two tones corresponding to one key are encoded and sent through the cell phone network. Both tones are tapped through the earphone jack of cell phone at machine end and are decoded. The output is fed to a Micro-controller. The Micro-controller is connected to the remote control unit of the toy car, which in turn controls the motion of the car. The car moves in various directions according to the key pressed user. The electronic circuit is divided into 2 parts. The transmitter side consisting of Cell phone 1 with an inbuilt encoder and the receiver side consisting of Cell Phone 2, 8870 DTMF decoder and Atmega 16 micro-controller. The programming has been carried out on AVR Bascom®.

Home automation or known as smart home is a home which is equipped by a system for controlling and integrating electronic devices, such as lighting, home theather, CCTV (closed-circuit television), HVAC (heating, ventilation, and air conditioning), motion sensor, security lock sensor for gates or doors, and etc. Its main purpose is to provide the improved simplicity, energy efficiency, higher security, and better feelings at home for the user benefits. Smart phone could be integrated as part of ring tone sensor for security door lock automation system. Therefore in this work, locking automation system using smart phone polyphonic tone sensor has been designed and implemented. A simple unlocking mechanism is explained as follows. The DTMF (Dual Tone Multi Frequency) module which has simply been programmed with Arduino was used to receive the polyphonic tone signal which is embedded in smart phone system. Then that signal will be processed by Arduino Uno, so the solenoid will automatically unlock the door. But, after three seconds delay, it will lock again (protection system). However, this system still has some drawbacks, such as low security system, short working-range of sensitivity, and limited amount of password digits. Moreover, those limitations could be improved/solved in the near future.

In the design, the MCU AT89C52 is the core of the system. The system can send and receive the DTMF signal, which can identify the city telephone number or the long-distance telephone number. According the number, it can billing and show call duration and call cost. It can realize automatically the conversion between the full price and the discount price. It can billing accurately and conveniently query ticket information. It is configurable product and resets rate by pressing a button. It is low cost and low power consumption.

Interactive Voice Response (IVR) Systems have been developed by enterprises to provide better services to the customers by allowing an automated machine to interact with humans through the use of voice or Dual Tone Multi Frequency (DTMF) keypad tones. But the IVR systems being developed today do not provide ease of use to the customers as they are monotonous. The present IVR systems lack dynamism, have very less degree of failure recovery and use APIs that are system dependent. In this paper we are proposing an Intelligent Interactive Voice Response System (IIVR) that generates a context-based dialogue using semantic web service composition and Expert System. This approach provides quality service to the customer by reducing the conversation time and by providing maximum information needed by the user. We use Java Expert System Shell (JESS) Rule Engine for generating the dialogue based on the context and thus optimizing the request-reply dialogue process between the service provider and consumer of the IVR systems. Furthermore, we use Ontology-based knowledge representation and we extract the necessary information from the ontology using semantic web services to further refine the dialogue generated by the IVR system.

Dual Tone Multi Frequency signal detection is an important to developing for telecommunication equipment. "This is a standard where keystrokes from the telephone keypad are translated into dual tone signals over the audio link". FPGA has gains very popularity in recent years due to their reprogram ability and flexibility. This paper presents a new type of ZYBO Board ZYNQ 7000 series FPGA based efficient DTMF detection. FFT based technique is, one of the approaches for DTMF detection but which requires more hardware and also power consuming type. Split Goertzel algorithm itself is an area optimized solution comparison with FFT based technique, but in this project we initiate efforts to further makes it low power by building lot of serialism in the design. Since DTMF based applications don't require high speed tone detection the resource sharing approach can be used. In this approach very minimal set of hardware is scheduled as inputs and outputs at appropriate clock edges, for implementing the algorithm. This paper divided into three phases. In the first phase, FFT based DTMF detection is done using Xilinx FFT core. The area, timing and power results are analyzed. In the second phase the split Goertzel algorithm is implemented and analysis is carried out. In the third phase, the resource sharing approach is studied and suitable state machine based scheduling will be carried with limited resources to implement split Goertzel algorithm. It will be demonstrated that the novel resource sharing based approach consumes less power and can still efficiently detect the DTMF tones. To test the project at various stage DTMF tone generator module also will be implemented with digital carrier generators. Mentor Graphics Modelsim Software is used for functional verification and Xilinx ISE is used for simulation and synthesis respectively. The Xilinx Chipscope is used to test the FPGA inside results while the logic is running on FPGA. The ZYBO board ZYNQ 7000 series FPGA Family board is used in this paper.

Since 2007, high quality IP telephone service has been provided over a Next Generation Network (NGN) developed by Nippon Telegraph and Telephone Corporation (NTT) Group of Japan. Prior to the commencement of service provision, a wideband telephone handset was developed on an experimental basis and tested in a field trial to verify service validity. The handset demonstrated improved characteristics over those of conventional telephone handsets.

In this paper, a visible light communication (VLC)-based indoor positioning system (IPS) employing a dedicated algorithm and using the dual-tone multi-frequency technique is proposed. Unlike the time-division multiplexing based VLC-IPS, the proposed positioning system doesn't require synchronization between the transmitter and receiver, which makes it a simple, robust and cost effective. To test the accuracy of the proposed method, an experimental test-bed using 3 white light-emitting diodes and a photomultiplier tube is developed. The results show that the proposed VLC-IPS is highly accurate with an average positioning error of about 1.6cm, which far lower than many existing indoor position systems.

Electromagnetic interference to electronic equipment by mobile telephone handsets is well known. We present an automatic screening gate that detects concealed mobile telephone handsets and classifies them by type. The screening method used in the gate does not require any additions to or reconstruction of mobile telephone systems.

This paper describes the design and development of a phone-based remote controller for home and office automation. The circuit is designed based on the Turkish telephone standards and connected to the telephone network just like any normal telephone sets. Any tone dialing dual tone multiple frequency (DTMF) telephone set or hand-held tone dialer may be used to send commands to the control unit, and remotely control, a wide range of mains appliances in homes and offices. The designed circuit can also detect the user identification number for preventing non-authorized use of the control unit. The feedback signal informs the user about the results of the commands.

In this paper, we propose a visible light communication (VLC)-based indoor positioning system (IPS) and algorithm using dual-tone multi-frequency (DTMF) technique. Compared with the existing VLC-based IPS algorithms, our algorithm does not need clock synchronization to separate signals from different time slots. With simple procedures, the coarse position or specific position of the mobile can be obtained by analyzing both the time and frequency domain of the received signal. The simulation result shows that the average positioning error is 18 mm at the signal-to-noise ratio (SNR) of 10 dB.

Dual-Tone Multi-Frequency (DTMF) signaling is used in telecommunication systems for dialing telephone numbers and sending commands to equipment such as interactive voice response (IVR) systems. There are two types of signalings to transmit DTMF digits: in-band and out-of-band. Since many systems use in-band signaling, equipment that uses DTMF signaling needs to support in-band signaling. Media servers that provide IVR services must process a huge number of sessions in parallel. The load of decoding in-band DTMF digits needs to be reduced to increase in the number of sessions processed by media servers. This paper presents load reduction methods with adaptive omission of frequency analysis and simulation results showing that the presented methods reduced the load of DTMF decoding by more than 50%.

This paper proposes a model of variable rate automatic microcontroller based irrigation system. Solar power is used as only the source of power to control the overall system. Sensors are placed on the paddy field and these sensors continuously sense the water level and give the message to the farmer informing the water level. Without visiting the paddy fields, farmers can get the information about the water level. Based on the water level, a farmer can control the motor by sending a message from his cellular phone even from a remote place. However, if the water level reaches to the danger level; the motor will automatically start without confirmation of farmer to ensure the proper water level in the site. At the end of this paper, a complete hardware implementation of this proposed automated irrigation system is presented.

Short span notifications or acknowledgment of events plays a major criterion in our world. Henceforth this module can be rigged up with any system in order to control the activity and acknowledge the user at any preconfigured parameter. Approximated that t oxic chemicals are mixed every 14.7 seconds Over 2 million Aquatic Creatures are affected every year. About 65% of reported water pollution resulted from Tanneries and Chemical factories. The pH-COP bestows the solution for these catastrophic events. This module being robust can be attached to any system viz. Voltage monitor, Security system, Fluid level/ pressure cont roller, pH sensor cum controlle r,.etc. The pH-COP primarily comprises of a microcontroller and a DTMF transceiver .This control systems which is efficient enough to be interfaced with the TELE-ALERT MODULE or the pH-COP. Key word: PH-COP, Tele-alert module, DTMF, telephone, interfacing control systems 1. INTRODUCTION The pH-COP primarily comprising of a microcontroller and a DTMF transceiver whose sole responsibility lies in the course of memory storage and communicating interface with the telephone line respectively which is sufficiently adequate to report the user when the in terfaced system is triggered. The current trend fusing on w ith the DTMF (Dual Tone Multi Frequency) logic, which decreases the time span of session activity, is the basic media or technology behind the communication of this system. The PH-COP can accumulate five sets of telephone numbers. The memory module can be increased by using an industrial or higher grade microcontroller. Additionally the advantage of PH-COP is that telephone or mobile numbers can be programmed using a telephone ,connected parallel across the telephone line. Though the GSM-ALERT is faster consisting of an integral wireless device, the module comes up with a foremost disadvantage that the wireless signals are detectable. In case of the interface between the Monitoring system and the module, Pollution Control Board (PCB) are now proficiently alert that they are capable of sniffing the GSM signals and becoming vigilant. They are able to lacerate the signals and take action against the violating industries, tanneries. Though the Tele-Alert Module’s link to the PCB can be harmed either by natural / artificial catastrophe a cut line detector can be placed, which aids or notifies the user or the telephone exchange in the event of a damaged line. Henceforth the pH-COP is comparativel y beneficial than the scenario comprising the GSM. In the upcoming sections, the paper elucidates the topi cs stated below such as sec 2. pH - COP

The inter communication signal system and signal control method on HMP are searched. One model of communication using HMP, which combines SIP and MS RCT as communication protocols, is proposed. The procedure of improving the identification of DTMF and the methods of reducing the transporting time under this model are provided.

The intelligent building system integration is a hot topic in the construction sector currently. The processing decision required to give in emergency, is to achieve the controlling, linkage, coordination and optimization goals, providing the time of escaping and passages for supervisors. In this paper, the mutual controlled monitoring and communication technology which is based on dual tone multi-frequency (DTMF) is utilized to achieve intelligent building safety. This method has many advantages such as the long information collection distance, wide range, large density, reliable, low cost, do not occupancy additional radio frequency resources and so on.

In this paper, we propose a PC application remote control system via mobile phones. Recently, mobile phones have been used to remotely control systems such as home automation systems. However, users are inconvenienced when using remote control systems because existing remote control systems require specific devices and software. Thus, in this paper, we propose a PC application remote control system that does not rely on specific devices and software by using the Dual Tone Multi Frequency (DTMF) of mobile phones.

A novel method is proposed which is effective in preventing malfunction in the DTMF (dual-tone multifrequency) signal decoder caused by the holding melody. When the monitoring time is one second, the probability of a malfunction is at most 0.01. The proposed approach is a double DTMF signal monitoring method using the statistical characteristics of a DTMF signal decoder for a holding melody. >

Equipment and technique for the lab demonstrating information protection against its leak through telephone channels are presented.

This chapter discusses Dual-Tone Multi-Frequency (DTMF) signaling digital signal processing (DSP) system, which is designed using LabVIEW. DTMF signaling is used extensively in voice communication applications such as voice mail and telephone banking. A DTMF signal is made up of two tones selected from a low and a high tone group. Each pair of tones contains one frequency from the low group and one frequency from the high group. The implementation of the DTMF receiver system is done using the Goertzel algorithm. In terms of the number of operations and amount of memory usage, Goertzel algorithm is much more efficient than the fast Fourier transform (FFT) algorithm for DTMF detection. In addition, this algorithm does not require access to the entire data frame thus leading to faster execution. Each Goertzel filter detects a DTMF tone. The output from each filter is then squared and fed into a threshold detector, where the strongest signals from the low and high frequency groups are selected to identify a pressed digit on the keypad.

A microcontroller-based enhanced telephone set designed and developed using the Inter-IC (I/sup 2/C) bus system is described. Besides functioning as a subscriber telephone, this feature phone incorporates a software-controlled ringer function, pulse and DTMF (dual-tone multifrequency) dialing, redial and extended redial features, direct dialing for emergencies, on-chip memory for 10 repertory dial numbers of 18 digits, direct access repertory dialing, and a liquid-crystal display. >

Dual tone multi-frequency (DTMF) receiver based on modified Goertzel algorithm is developed. Performance of receiver is assessed under the ITU Q.24 standard specifications. The algorithm was tested with a variety of signals including speech, music, and DTMF tones. We found that this detector was efficient, reliable, and exceeded Bellcore standards

Most selectors use the infamous trio in their business: application form, references and interviews. References are still used but with much more careful examination through fear of litigation.

This chapter explores the Dual-Tone Multi-Frequency (DTMF) digital processing system built in the LabVIEW graphical programming environment. For creating a keypad or cluster control as shown in block diagram (BD) of a DTMF system, the buttons are grouped into a cluster so that their outputs are wired via a cluster wire. This is achieved by placing a cluster shell on the front panel (FP), and then by locating the text buttons in the cluster area. The keypad cluster control is shown as an icon on the BD of DTMF system. The virtual instrument (VI) generates a tone depending on the number pressed on the keypad in the FP. The DTMF decoder based on the Goertzel algorithm is present in the lower half of the BD. In order to build the BD, the output value of the cluster is wired to an array by using the cluster to array function.

The International Organization of Standardization (ISO) standard MPEG-I Layer-III, commonly known as MP3, is one of the most widely used standards for digital compression and storage of audio data. The MP3 standard was developed to provide compression of audio files without any major loss in audio quality. There are many other software tools in addition to portable MP3 players that are capable of playing MP3 files. This chapter focuses on a LabVIEW software implementation of single channel MP3 player. It also discusses the building components or blocks associated with MP3 decoding. The first functional block associated with the MP3 player is the synchronization block. This block receives the incoming bitstream, extracts certain information from it, and passes the extracted information to the succeeding blocks. An MP3 file is divided into smaller units called frames. Each frame is further divided into five sections—header, cyclic redundancy check (CRC), side information, main data, and ancillary data. The scale factor decoding block decodes the scale factors to allow the reconstruction of the original audio signal. Furthermore, chapter highlights LabVIEW implementation of the entire MP3 decoding system and the steps taken for the real-time implementation of the system.

We report on research aimed at gaining an improved understanding of how issues such as language, literacy and previous exposure to technology affect citizens’ ability to access government services of different complexity via ordinary telephony. We discuss user interface issues in conditions of low literacy and where previous exposure to technology is low. The results are based on field experiments with citizens using a real government application. The experimental set-up is described and the experimental procedure and results reported.

In the current implementation of the CT2 systems in Singapore, only handset initiated calls are allowed. This paper will describe a design to allow two-way calling for the CT2 system with minimal modification to the current CT2 infrastructure as well as the public switched telephone network (PSTN). The design makes use of centralized databases in the home location register (HLR) and visitor location register (VLR) to track the location of the handsets. We carried out a computer simulation of the proposed system to determine the potential area of congestion in the system. >