公开(公告)号：US4354248A

公开(公告)日：1982-10-12

申请号：US98093

申请日：1979-11-28

申请人： David R. L. Conger ,  Ira A. Gerson ,  Richard E. White

发明人： David R. L. Conger ,  Ira A. Gerson ,  Richard E. White

IPC分类号： H04L27/30 ,  H04Q1/457 ,  G06F15/31

CPC分类号： H04Q1/4575 ,  H04L27/30

摘要： A multifrequency tone receiver is disclosed for detecting simultaneous tone signals in a sampled digital signal. The tone receiver includes a microprogrammed sequence controller, a time-multiplexed digital filter and a signal processing microcomputer. For each sample of the digital signal, the sequence controller is programmed to time multiplex the digital filter for performing three cascaded second order filtering operations (two bandpass filter operations and one low pass filter operation) for each of six tone signals to provide corresponding energy estimates and one additioal filtering operation to provide a total energy estimate. The signal processing microcomputer processes a number of sets of the seven energy estimates and provides an indication when a multifrequency toner pair has been detected. The digital filter, when enabled by a filter start signal from the sequence controller, asynchronously performs a single multiplication-like filtering operation to implement each second-order filter, and provides a filter done signal upon completion of the filtering operation. Full-wave rectifying capability is provided during low pass filtering operations by logically complementing the digital filter input signal. Limit cycles may be suppressed in the digital filter output signal by rounding the output signal and clamping positive and negative overflows to the largest allowable positive and negative signals, respectively. The tone receiver may be advantageously utilized in a PCM communication system for detecting multifrequency tone signalling used for dialing and supervisory control. Moreover, the inventive tone reciver may be adapted to receive many different types of tone signalling simply by changing firmware therewithin.

摘要翻译： 公开了一种用于检测采样数字信号中的同时音调信号的多频音频接收机。 音调接收机包括微程序序列控制器，时分复用数字滤波器和信号处理微计算机。 对于数字信号的每个样本，序列控制器被编程为对数字滤波器进行时间复用以对六个音调信号中的每一个执行三个级联二阶滤波操作（两个带通滤波器操作和一个低通滤波器操作），以提供相应的能量估计 以及一个额外的滤波操作来提供总能量估计。 信号处理微处理器处理多个七个能量估计组，并且当检测到多频调色剂对时提供指示。 数字滤波器在通过序列控制器的滤波器起始信号使能时，异步地执行单个类似乘法的滤波操作来实现每个二阶滤波器，并且在完成滤波操作时提供滤波器完成信号。 通过逻辑互补数字滤波器输入信号，在低通滤波操作期间提供全波整流能力。 数字滤波器输出信号的限制周期可以通过对输出信号进行舍入，并将正和负的溢出分别钳位到最大允许的正和负信号。 音调接收机可以有利地用于PCM通信系统中，用于检测用于拨号和监督控制的多频音调信令。 此外，本发明的音调调谐器可以适于仅通过在其中更改固件来接收许多不同类型的音调信号。