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1. 发明授权

US3975686A Loss signal generation for delta-modulated signals 失效
标题翻译： Delta调制信号的丢失信号产生
公开(公告)号：US3975686A
公开(公告)日：1976-08-17
申请号：US560422
申请日：1975-03-20
申请人： Ulrich Appel
发明人： Ulrich Appel
IPC分类号： H03M3/02 , G10L19/00 , H04B3/20 , H04B14/06 , H04J3/17 , H03K13/22
CPC分类号： G10L19/012 , H04B3/20 , H04J3/172
摘要： A digital communication system employs delta-modulation coders and decoders for voice signal conversion. Signal inequalities at remote ends of a coder-decoder connection, due to unscheduled momentary interruptions of the transmission channel, are adjusted by insertion of a special pseudo-random "noise" signal at the remote demodulator. Voice Activity Compression (VAC) processing circuits, operating upon integrated digital signals which represent the analog (voice) input to the delta-modulation coder, are utilized to develop line activity indications. These indications are processed to produce VAC "channel use" information which is sent over a separate channel for remote demultiplexing control. The same activity indications are used to control remote demodulation handling and line level restoration. The remote control circuits insert the special pseudo-random signal at the remote demodulator during interruptions of the voice transmission (indicated as inactivity). The inserted signal adjusts the demodulator output level to correspond to the noise level at the input to the modulator. The demodulator signal is thereby reproducible as "natural" audible noise, consequently avoiding leaving the remote listener with the unnatural and disconcerting impression of a "dead" connection.
摘要翻译：数字通信系统采用增量调制编码器和解码器进行语音信号转换。通过在远端解调器处插入特殊的伪随机“噪声”信号来调整由于传输信道的非计划的瞬时中断而在编码器 - 解码器连接的远端处的信号不等式。用于表示向delta调制编码器的模拟（语音）输入的集成数字信号的语音活动压缩（VAC）处理电路用于开发线路活动指示。这些指示被处理以产生通过单独的信道发送的用于远程解复用控制的VAC“信道使用”信息。相同的活动指示用于控制远程解调处理和线路级恢复。遥控电路在语音传输中断（表示为不活动）的情况下，将遥控解调器中的特殊伪随机信号插入。插入的信号调整解调器输出电平以对应于调制器输入端的噪声电平。因此，解调器信号可以被再现为“自然”的可听见的噪声，因此避免了使远程监听器对“死”连接的不自然和令人不安的印象留下。

2. 发明授权

US4005276A Digital voice signaling with digital echo detection and voice activity compression used to cancel echo 失效
标题翻译：具有数字回声检测和语音活动压缩的数字语音信号用于消除回波
公开(公告)号：US4005276A
公开(公告)日：1977-01-25
申请号：US560423
申请日：1975-03-20
申请人： Paul Abramson , Ulrich Appel
发明人： Paul Abramson , Ulrich Appel
IPC分类号： H04J3/17 , H04B3/20
CPC分类号： H04B3/20
摘要： A connection system for varied distance digital communication capable of handling telephone signals utilizes Voice Activity Compression (VAC) to effectively share a given number of digital transmission channels among a greater number of virtual telephone connections. The telephone signals are delta-modulated and demodulated in system connection stations. The VAC processing circuits with a small increment of decision logic provide echo suppression. Echo suppression is thereby rendered as a "value-added" service at a relatively small increment of station cost over the cost of VAC processing. Echo interference with original telephone signal activity in the send channels is reduced by digital control of gain in the demodulation stage. The system also provides connections without VAC handling subject to echo control.
摘要翻译：用于处理电话信号的不同距离数字通信的连接系统利用语音活动压缩（VAC）在更多数量的虚拟电话连接中有效地共享给定数量的数字传输信道。电话信号在系统连接站中进行增量调制和解调。具有小增量决策逻辑的VAC处理电路提供回波抑制。因此，以VAC处理成本为基础，以台站成本相对较小的增量将回波抑制作为“增值”服务。通过对解调阶段增益的数字控制，减少了发送信道中原始电话信号的回波干扰。该系统还提供无VAC处理的连接，可进行回波控制。

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