Vtech Telecommunications Limited

Vtech Communications Limited

Stephen George Kropp

Ralph Tischler

Gordon Ryley

Allan Chi-Yun Wong

Jagjit Grewal

A multi handset telephone system with a wireless telecom/doorbell module. The telecom/doorbell module has similar electronics as a cordless handset that includes audio and RF link with a base unit. A speakerphone functionality of a wireless telecom/doorbell audio processor is used to provide an intercom audio conversation. The wireless intercom/doorbell module is battery powered that is either charged by an AC adapter or by an existing doorbell wiring. The wireless intercom/doorbell module also work in parallel with the existing bell wiring. When a page key is pressed, the module pages the telephone system and shorts the doorbell wiring to make an existing bell ring. The doorbell module is coupled with a camera.

Intercom/wireless door bell for multi-handset telephone system

A sidetone level reduction circuit for reducing the sidetone level in digital cordless telephones incorporating continuously variable slope delta modulator/demodulator (CVSD) digital to analog technology is disclosed comprising a CVSD encoder for converting an analog voice signal to a digital signal, a CVSD decoder for converting a digital signal to an analog signal voice signal, and coupling means connecting the coincidence output of the CVSD encoder and the coincidence output of the CVSD decoder in a manner such that the coincidence output of the CVSD decoder can affect the CVSD encoder but the CVSD encoder cannot affect the CVSD decoder.

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Surrey, Canada

Stephen George Kropp