Diversity circuit for magnetic communication system

Abstract

A magnetic communication system includes a transmitter have a single coil transducer, and a receiver having a three orthogonally oriented coil transducers. The signal processing circuitry in the receiver adjusts the phases of the signals received by the three transducers to produce signals which are in-phase. The signals are then summed to provide an output signal from the receiver. The processing circuitry adjusts the phases of the incoming signals either serially or in parallel. Transmissions from the receiver to the transmitter are also phase adjusted in accordance with the same adjustments used in reception.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This is a continuation-in-part of U.S. patent application Ser. No. 08 / 444,017, filed May 18, 1995.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to magnetic communication systems. More particularly, it relates to a magnetic communication system which eliminates nulls in a mutual inductance field through a combination of signals from multiple transducers.[0004]2. Discussion of the Related Art[0005]When using a telephone, continually holding the handset to one's ear can be awkward. Also, holding the telephone interferes with the use of both hands for other work while trying to talk. In particular, the use of cellular telephones, which has increased dramatically, can interfere with the user's proper operation of an automobile. Various techniques have been used to overcome these difficulties.[0006]Speaker phones allow one to talk while roaming around a room and using one's hands. However, speaker ...

AI Technical Summary

Benefits of technology

[0012]The deficiencies of prior art systems are overcome in great part by the present invention which, in one aspect, includes a short-range, wireless communication system including a miniaturized portable transceiver and a base unit transceiver. The miniaturized portable transceiver sends and receives information through magnetic induction to the base unit, which may also be portable. Similarly, the base unit sends and receives information through magnetic induction to the portable transceiver. The information can be voice, data, music, or video. Use of magnetic induction fields reduces the power requirements and thus allows a smaller size and greater convenience.

[0013]In another aspect of the present invention, the base unit or portable device may include multiple, orthogonally arranged transducers for generating multiple magnetic fields. The multiple fields substantially eliminates mutual inductance nulls between the base unit and portable unit which result at certain positions in a generated field. In another aspect of the present invention, the multiple transducers may be selectively operated based upon a strongest signal, in order to limit power consumption and improve signal reception. The signals from the transducers are electronically scanned. The signals are then phase adjusted and combined to achieve a maximum signal level. In another aspect of the invention, the same phase information is used for a transmitted signal. This allows the other device to use a single transducer while maintaining a high signal to noise ratio.

Problems solved by technology

When using a telephone, continually holding the handset to one's ear can be awkward.

Also, holding the telephone interferes with the use of both hands for other work while trying to talk.

In particular, the use of cellular telephones, which has increased dramatically, can interfere with the user's proper operation of an automobile.

However, speaker volume can disturb others around the user.

They also cannot be used in close proximity to other speaker phones due to interference.

They have limited privacy since the speaker broadcasts the conversation to all within earshot.

Also, they tend to have poor sound quality because the user is not near the microphone and acoustics in the room are poor.

Headsets have the disadvantages of being bulky and somewhat awkward to use.

Although they permit hands free use of the telephone, the user has limited mobility due to the connecting wire.

The need for communications circuitry and sufficient power to communicate with the base unit increases the bulk and weight of the headset.

This increased weight can become tiresome for the user.

As with wired headsets, the wire can become inconvenient and interfere with other actions by the user.

However, magnetic induction fields suffer from signal nulls at certain positions and orientations between the transmitter and receiver.

However, this system cannot compensate for changes in position and orientation of the transmitter, and, thus, requires a stationary transmitter.

Also, the mercury switch array is large, costly, and sometimes unreliable.

Furthermore, switching transients occur as different coils are selected, which causes degradation of the signal and possible loss of information.

While this system eliminates switching transients, it has other deficiencies.

Furthermore, the simple summing of signals from all three transducers can increase noise levels.

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