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Telephone conference circuit for delta modulated speech signals - sums speech inputs with 100 per cent attenuation for subscriber's own input
Telephone conference circuit for delta modulated speech signals - sums speech inputs with 100 per cent attenuation for subscriber's own input
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机译：电话会议电路，用于增量调制的语音信号-对语音输入求和，对用户自己的输入进行100％衰减
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摘要
The conference circuit comprises a sub unit for sampling the absolute magnitude of each speech input at a given clock rate and converting rising or falling amplitude levels into +1 or 0 digit outputs entered into shift registers and evaluated as to their aggregate incremental step value with the aid of a programmable memory register. The resulting step values, provided with the right sign (aggregate rising or falling trend representation) are applied to a conference incremental value step adding circuit from which emerges one single signal in digitised delta modulation form. Alternatively, to avoid effects from feeding to a participating subscriber his own speech contribution, a further subcircuit is provided from which n different signal outputs derive for then participating subscribers. In the 'Own Signal Subtraction' circuit is provided a signal inversion unit which deducts in the adding units the signal contribution from individual participants. In a supplementary circuit for each of the participants' channels, the instant signal is supplemented by aggregate incremental signals memorized in th e registers and then passed on to delta demodulator units and via low pass filters to the subscriber lines of each participant.
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