Wireless earphone and cordless phone (1997-08-20)

1. General Information

The wireless earphone combined with antenna connected to a sound system would increase mobility and privacy to users. We would discuss other applications using similar method in the following sections

2. Marketing Analysis

This system would be sold to all users using a sound system such as

·        Music listeners, TV users

·        Technical support personnel

·        Car alarm system

·        Cordless phone or ear phone

3. Product Analysis

3.1 System Overview

There are wireless earphones and cordless phones in the market that have interference problems, e.g. a user uses a wireless earphone listen to music might hear unwanted sound/message/music coming from a neighbouring wireless sound system. To eliminate this problem, we may want to encrypt voice data before sending it on the air from a sound system to the wireless earphones.

3.2 Voice Encryption

If we planned to use voice encryption method and CAVE algorithm designed for cellular telephony, cost of each earphone would be very high. The processing power of each earphone is also slow. Therefore, it is recommended to use in cordless phone handset.

Assuming that user is only listening to music from his sound system, but he is not concerned with eavesdropping. Thus, the earphones will only focus on decoding voice data sent from his sound system, but ignoring data sending over the air by other sound system. The same principle applies to his sound system.

3.3 Implementation Proposal

Encoding/digitizing voice data and adding some pre-defined (product) identification code at the beginning of each voice message frame. This unique code must be stored in both sound system (cordless phone, music receiver, etc.) relayed via the antenna as well as the earphone. Therefore, the antenna and earphones will only accept and decode messages which convey the same predefined identification code.

A manufacturer would set the product identification code in both devices. It may contain

·        Serial number

·        Manufacture code allocated to each manufacturer

·        Model number

The diagram above illustrates how system would add and remove identification code. It must be implemented on both sound system and ear phones.

(a) When interference detected either the earphone or radio-based antenna system will order changing frequency of transmitted carrying waves.

(b) The receiving unit will perform verification on identification code, parity bits, frame alignment bits, etc. to ensure quality of the receiving messages.

4. Other applications

The above procedure could be implemented in car alarm system using remote key.