Distributed intercom system with audio bus
First Claim
1. An intercom system comprising:
- a hub unit;
a plurality of zone units having respective local speakers;
the hub unit and zone units interconnected by a cable with four twisted pair wires, with one of the twisted pairs serving as a control bus for sending control messages, and another designated one of the twisted pairs in the same cable serving as an audio bus for distributing, in two directions, intercom system audio signals between at least two of the zone units;
wherein the hub unit controls connection of the zone units to the audio bus such that a first zone unit is connected to the audio bus to transmit intercom system audio to be received by multiple ones of the zone units in first direction, and so that a second zone unit is connected to the audio bus to transmit intercom system audio to be received by multiple ones of the zone units in a second direction; and
wherein the hub unit also sends a control message to the receiving zone units to couple their respective local speakers to the audio bus, so that only a designated one or more zone units that are an intended receiver of the intercom system audio provide an output that is audible to a user.
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Accused Products
Abstract
A distributed intercom system that interconnects a hub and various keypad and door zone units having microphones and/or speakers via CAT5 or similar cable having multiple twisted pairs. Audio is carried between all devices over a first audio wire pair, in analog signal format, forming an audio bus. Audio twisted pair acts as a data communication bus for control messages. One or more of receiver units may be active, while only one keypad device can be individually instructed to connect its corresponding microphone circuit to the audio bus. Determination of which unit is selected to be the transmitter occurs under the control of the hub. For example, in a case where a first user wishes to speak to another user in a different room, the first user presses a “talk” button at his keypad, causing that keypad to send out a message on a data communication bus to the hub. The hub unit then sends a reply on the data communication bus that grants permission to the first user'"'"'s keypad to couple its microphone to the audio bus. The message is interpreted by the other stations as an instruction to keep their own microphones disconnected from the bus. A message is also sent to the desired receiving station(s) to couple their speakers to the bus to receive the audio signal.
28 Citations
11 Claims
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1. An intercom system comprising:
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a hub unit; a plurality of zone units having respective local speakers; the hub unit and zone units interconnected by a cable with four twisted pair wires, with one of the twisted pairs serving as a control bus for sending control messages, and another designated one of the twisted pairs in the same cable serving as an audio bus for distributing, in two directions, intercom system audio signals between at least two of the zone units; wherein the hub unit controls connection of the zone units to the audio bus such that a first zone unit is connected to the audio bus to transmit intercom system audio to be received by multiple ones of the zone units in first direction, and so that a second zone unit is connected to the audio bus to transmit intercom system audio to be received by multiple ones of the zone units in a second direction; and wherein the hub unit also sends a control message to the receiving zone units to couple their respective local speakers to the audio bus, so that only a designated one or more zone units that are an intended receiver of the intercom system audio provide an output that is audible to a user. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification