Nortel Networks Corporation

Northern Telecom Limited

Christopher Michael Forrester

Andre John Van Schyndel

Larry Edward Hawker

Laura A Mahan

Michael Brown

Frederic J Simard

Paul Vincent Coverdale

Paul Provencal

Hugh M Collins

David A Pepper

Norbert J Diesing

W J McCready

Guy J Fortier

A voice-switching device for use in a telephone terminal which applies an optimal amount of switched loss to a plurality of distinct receive transducers. The voice-switching device detects speech signals on the transmit and receive paths to determine a mode of operation. Based on the mode of operation the device applies optimal amount of loss to the transmit path and each output path separately. This system eliminates excessive attenuation of non-dominant receive transducers as well as optimizes the transition time from active to quiescent mode for all receive transducers.

Voice-switching device and method for multiple receivers

A wireless terminal for personal communication systems is provided with handsfree and handset receive modes of operation utilizing a single transducer. The transducer is mounted within a specially designed enclosure having front and back chambers separated by a partition. The partition contains strategically located internal vents and the front chamber contains strategically located acoustic ports for shaping the frequency response and providing good audio quality in each mode. The back chamber may also contain strategically located acoustic ports. Amplification and equalization circuitry may be employed to further adjust the amplifier gain and shape the frequency response for dual mode operation. The terminal may additionally be equipped with a proximity detector to assist in switching between operating modes of operation. The transducer may also be used to generate the alerting (ringing or buzzing) signal.

Handset with a single transducer for handset and handsfree functionality

A method of increasing the terminal coupling loss in a digital half-duplex handsfree terminal is provided. When the terminal receive channel is active an idle code which is effectively zero is transmitted by an idle code generator. When the terminal transmit channel is active a normal speech signal is transmitted. To determine which channel is active, a receive speech signal level is measured at the receive channel input, and a 'virtual' transmit speech signal is computed from a signal in the transmit channel before the idle code generator.

System and method for providing high terminal coupling loss in a

Portable wireless telephone handset with a flap movable upon a housing. In a first position the flap is close to a speaker to enable the flap to be disposed near to a user's ear for the user to receive personal low volume sound from the speaker. In a second position, the flap is further from the speaker to detract from use of the speaker near to the user's ear. In the second position of the flap, the speaker operates in loudspeaker mode. A switch is provided to change the speaker between loudspeaker and low volume sound mode, the switch operation being dependent upon flap position.

Wireless telephone handset

A wireless terminal for personal communication systems is provided with selective handsfree or handset receive mode of operation utilizing a single transducer. The transducer is mounted within a specially designed enclosure having front and back chambers each with strategically located acoustic ports for shaping the frequency response and providing good quality audio in each mode. Electronic equalization may be employed to further adjust the amplifier gain and shape the frequency response for dual mode operation.

Communications terminal having a single transducer for handset and

Sidetone in a four-wire telephone station set that is coupled to a two-wire telephone line through a four-to-two wire hybrid circuit is automatically and cancel the phase 'to a predetermined value', set by incrementally adjusting a balancing impedance connected to the circuit until an optimum impedance match between the telephone set and line is achieved. Under software control, during idle intervals between dialed digits when a call is initiated, a microcontroller mutes the telephone transmitter and receiver on the telephone side of the circuit and substitutes for these components a tone signal generator to produce a sidetone signal that is applied to a full-wave rectifier and therefrom to a peak voltage detector to generate a sidetone envelope. Individual ones of several impedance balancing networks are then sequentially connected to the telephone side of the circuit and the sidetone envelope for each balancing impedance is digitally encoded and stored. A mutual comparison of the stored data indicates a minimum sidetone value which corresponds to an optimum impedance match that is retained unless a subsequent telephone call results in a change of balancing impedance.

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Ottawa, Canada

Christopher Michael Forrester