• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11C
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• pp.133-139
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• 2001

The economical detection of dual-tone multi-frequency(DTMF) signals is an important factor when developing cost-effective telecommunication equipment. Each channel has independently a DTMF receiver, and it informs the detected signal to processors. In order to detect the DTMF signals, this paper analyze the power spectra of the DTMF receiver by using the QFT algorithm. As experimental result, by analyzing 2$\^$M/ real data in terms of ITU-T specification, it show that the QFT algorithm improve the performance of the DTMF receiver and can save memory waste and can the real-time processing.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.9
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• pp.21-28
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• 2001

The economical detection of dual-tone multi-frequency(DTMF) signals is an important factor when developing cost-effective telecommunication equipment. Each chanel has independently a DTMF receiver, and it informs the detected signal to processors. In order to detect the DTMF signals, the receiver use algorithm such DFT, FFT and Goertzel methods. This paper analyze the power spectra of the DTMF receiver by using the QFT algorithm. As experimental results, it show that can the improved performance of the DTMF receiver and can reduce memory waste and the real time processing.

• The Journal of the Korea Contents Association
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• v.6 no.1
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• pp.8-13
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• 2006

In this thesis, an automatic door lock system using a dual tone multiple frequency(DTMF) signal generated as pushing the key button of mobile phone is proposed and implemented. This system consists of a transmitter module and a receiver module for processing the DTMF signal of mobile phone. The DTMF signal of mobile phone connected with ear-phone jack enter into the input terminal of DTMF receiver and those are encoded by a code-converter with 4-bits binary format in the DTMF receiver. The encoded output signals are transmitted to the amplitude shift keying(ASK) modulator of transmitter module and the modulated ASK signals which are converted into radio frequency(RF) signals propagate in a free space. The RF signals passed through a free space are demodulated by the ASK demodulator of receiver module and the demodulated ASK signals are sent to a micro-controller unit(MCU). The output signals processed by the MCU are compared with the secreted identification number which is prerecorded in a microprocessor and are transferred to a power relay. If the result is the same, the automatic door lock system opens a door. In the opposite case, it maintains closing the door. The implemented automatic door lock system operates well in mobile environments.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.10
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• pp.21-31
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• 1994

This paper describes the multichannel combined R2MFC/DTMF/CCT reciver which provides a signaling service functions for call processing control in digital switching system. Using the TMS320C25 DSP chip, we have implemented multi-function receriver shich processes 8 channels of R2MFC, DTMF, and CCT signals simultaneously. In order to increase the channel multiplicity of the combined receiver. R2MFC and CCT receiver were employed by discrete Fourier transform(DFT) method using Goertzel algorithm, and DTMFreceiver was employ by infinite impulse reponse(IIR) filtering method using 4KHz subsampling technique. The combined receiver has 4 function modes for each channel such as R2MFC, DTMF, CCT, and Idle modes. The function mode of each channel may be selected at any time by single-chip micro-controller(.mu.C). Hence, the number of channels assigned for each function mode can be adjusted dynamically according to the signaling traffic variations. From the experimental test results using the test-bed, it has been proved that the combined receiver statisfies all receiver satisfies all receiver specifications, and provides good channel multiplicity and performance, Therefore, it may give a great improvement than existing receiver in cost, reliability, availability, and serviceability.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.2
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• pp.196-200
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• 1987

The following methods are proposed for implementing digital dual tone multi-frequency (DTMF) receiver: using infinite impulse response(IIR) digital filters, period-counting algorithm, discrete Fourier transform(DFT), and fast Fourier transform(FFT)[2]. The PARCOR(Partical Correlation) analysis method which has been widly used in the speech signal processing area is applied to the dual tone multi-frequency(DTMF) signal detection. This method is easy to implement digitally and stronger to digit simulation of speech than any other methods proposed up to date. Since sampling rate of 4KHz is used in the DTMF receiver for the detection of input DTMF signal originally sampled at 8KHz, it effects two times higher multiplexing efficiency.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1638-1642
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• 2003

In this paper, we have analyzed the power spectra and evaluate the performance of DTMF receiver by using the quick Fourier transform(QFT) algorithm. The economical signals detection of dual-tone multifrequency(DTMF) receiver is an important factor when developing cost-effective telecommunication equipment. In experimental results, it shows that reducing memory waste and can process the real-time.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.449-452
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• 2000

The economical detection of dual-tone multifrequency(DTMF) signals is an important factor when developing cost-effective telecommunication equipment. Each channel has independently a DTMF receiver, and it informs the detected signal to processors. This paper analyze the power spectra and evaluate the performance of DTMF receiver by using the quick Fourier transform(QFT) algorithm. As experimental results, it show the improved performance to the DTMF receivers and reduce memory waste and process the real-time.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.105-108
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• 2000

The economical detection of dual-tone multifrequency(DTMF) signals is an important factor when developing cost-effective telecommunication equipment. Each channel has independently a DTMF receiver, and I t informs the detected signal to processors. This paper analyze the power spectra and evaluate the performance of DTMF receiver by using tile quick Fourier transform(QFT) algorithm. As experimental results, it show the improved performance to the DTMF receivers and reduce memory waste and process the real-time.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.10
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• pp.26-32
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• 1997

The economical detection of dulal-tone multifrequency(DTMF) signals is an important factor when developing cost-effective telecommunication equipment. Each channel have independently a DTMF receiver, and it informs the detected signal to processors of the TDX. This paper proposes the linear prediction algorithm for the spectrum analysis. As a experimental resutls, it can obtain the improved performance to the DTMF receivers and reduce the real-time processing and memory waste.

• The Journal of the Acoustical Society of Korea
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• v.22 no.4
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• pp.276-285
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• 2003

In this paper, we present real-time implementation of a R2MFC/DTMF (R2 Multi Frequency Combinations/Dual Tone Multiple Frequency) tone receiver/sender using a high performance DSP (Digital Signal Processor) and apply it to a carrier class VoIP (Voice over Internet Protocol) gateway system. The Receiver utilizes the Goertzel filter and the sender adopts the harmonic resonant filter. We describe, in detail, the techniques of multi-channel real-time implementation on a Texas Instruments TMS320C62x DSP such as effective PCM (Pulse Code Modulation) in/out by means of DMA (Direct Memory Access) and McBSP (Multi Channel Buffered Serial Port) and message communication via HPI (Host Port Interface), etc. From experimental results, we confirmed that the optimized code provided 780 channel capacity at 250㎒ C6202, and the our R2MFC/DTMF receiver/sender met ITU-T (International Telecommunication Union-Telecommunication) specifications.