Abstract

DTMF(the Dual-Tone Multifrequency),is one kind of methods delivering signal in correspondence technique.The DTMF signal is the Stiring number signal of the audio frequency telephone.This text introduce a kind of method according to the creation and the examination method of the DTMF signal of the TMS320 C5402 series DSP chip.

This system’s hardware design uses TMS320VC5402 main controller that is a part of TI Company’5000 serial DSP and is high quality ang low prize .We use flash program memory extension in order to realize the system’s program. In the same time ,we use TLC320AD50C  and TMS320VC5402 to realize the siganal alternating .Then LCD is used to show measured data ang wave. The software aspect adoption Goertzel calculate way, the Goertzel calculate way is a kind of suitable method for CPU to carry out the examination  of the audio frequency signal efficiently  .The filter has a pair of extremities , can examine an audio frequency signal. Goertzel calculate way  carries out FFT,, this calculate way is simplify, and each frequency need a real amount coefficient then we can get the worth of flap.However, if we want to get the  right calculation number of flaps and mutually the demand plural coefficient,  complicated procedure is necessary,  if we only calculate a tone frequency flap but neglect the calculation of pulse, we can simplify the translating of DTMF signal.In addition, the Goertzel calculating way can handle immediately acquiring any sample , not after acquiring all samples .This way can raise speed .The Goertzel calculate way is the core of the DTMF signal examination, it uses  IIR filter of two extremities to compute FFT value, withdrawing a frequency chart information of  the inputing signal quickly and effectively.

Keywords

DTMF；TMS320VC5402；FLASH—AM29LV400B ；Goertzel；

TLC320AD50

摘要

DTMF(Dual-Tone Multifrequency)通信技术中的一种信号传输方法，DTMF信号是音频电话中的拨号信号. 本文介绍一种基于TMS320C5402系列DSP芯片的DTMF信号的产生和检测方法, 使得DTMF信号的产生和检测变准确、迅速和简单.

本系统的软件设计方面，采用TI公司的5000系列DSP中的高性能廉价的TMS320VC5402为主要控制器，进行了FLASH程序存储器的扩展，使用TLC320AD50C模拟接口电路与TMS320VC5402定点DSP接口电路的硬件设计方法。软件方面采用Goertzel算法，Goertzel算法是一种适合于CPU实现的高效音频信号检测方法。它是一个双极点滤波器,可以在噪声信道中清晰地检测出音频信号Goertzel 算法执行离散傅立叶变换（Discrete Fourier Transform）,这个算法较为精简，而且每个频率只需要一个实数系数就可以决定值的振幅；但是，正确计算数值振幅和相位时需要复数系数，故需要较复杂的程序，借助只计算音调频率的振幅而忽略相位的计算，我们可以简化DTMF信号的译码工作。此外，Goertzel算法只要获得任何采样就可以立刻处理，不必获得全部采样之后才处理，可明显地提高速度。Goertzel算法是DTMF信号检测的核心，它利用二极点的IIR滤波器计算离散傅立叶变换值，快速有效的提取输入信号的频谱信息。 

关键词

DTMF；TMS320VC5402；FLASH—AM29LV400B ；Goertzel算法；TLC320AD50C         1

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