Abstract: Electro-static discharge protection for sensitive circuitry in devices, which have exposed metallic contacts for accessing such circuitry, is achieved by providing switching apparatus in these devices. The switching apparatus isolates the sensitive circuitry from static electricity which may be impressed upon the exposed metallic contacts. In operation, when a first device is placed in engagement with a second device for transferring data, charging a battery or the like, the switching apparatus relies on the weight exerted by the first device on the second device for establishing a conducting path between the contacts and the sensitive circuitry in each device. This conducting path is interrupted when the first device is removed from the second device thereby providing isolation for the sensitive circuitry from any static electricity which may be impressed upon the exposed metallic contacts.

Abstract: A microphone selection process is made relatively constant in terms of processing requirements through use of combination values which provide a measure of the quality of the speech signal received in each one of a plurality of microphones. Such combination values are derived in a manner which provides an indication of which one of the plurality of microphones, that provide area coverage for a conference room, for example, best receives the speech signal. In operation, the microphone selection process selects the microphone which best receives the speech signal by comparing a signal energy value received in each one of the microphones to that received in each of the other microphones. More specifically, pairs of microphones are examined, to determine the direction of origin for the speech, by seeking a microphone pair where the speech is strong in the microphone directed toward the source of speech, and weak in an associated microphone directed away from the source of speech.

Abstract: A telephone message system overcomes the problems and limitations of presently available systems that seek to enhance inter-and intra-premises communications. The system advantageously comprises a controller unit with Caller ID capabilities and one or more adjunct units that are bridged onto a single wire-pair at a user's residential location in a parallel electrical connection. These customer installable units are merely plugged into any telephone jack and share a telephone wire-pair with existing telephone extensions without interference. Such operation is possible since communication between the controller unit and the adjunct units is limited to a frequency band different from the audio frequency band used by the existing telephone extensions on the single wire-pair. The controller unit, in one configuration, operates as an answering machine with multiple mailboxes. This functionality is advantageously combined with Caller ID, intercom and speakerphone capabilities.

Abstract: A cordless telephone arranged for operation in a frequency hopping system quickly establishes communications between a base unit and an associated handset unit in the telephone. Synchronization between the base unit and the handset unit is achieved through a process in which first the base unit sends a start hopping message contiguously for a specific number of frames or time slots. The handset unit, in turn, responds by sending a staff hopping acknowledge message to the base unit in a frame each time it receives the start hopping message in a frame. In response to the handset unit sending the start hopping acknowledge message, the base unit sends to the handset unit an acknowledge hopping message, also for a specific number of frames. If either the base unit or handset unit fails to receive a message in a specific frame, the synchronization process advantageously continues since each one of the messages contained in the specific number of frames linearly decreases in value with each succeeding frame.