US 6,163,711 AGranted

Method and apparatus for interfacing a mobile phone with an existing audio system

AssigneeNokia Mobile Phones Ltd.

InventorsEsa Juntunen, Tapio Laurila

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Abstract

A hands-free adapter for interfacing a mobile phone handset with an existing audio system attaches to the handset by means of the accessory connectors that are generally located on the bottom or back of the handset. The adapter modulates the received audio from an in-coming call with a pre-selected FM or AM carrier frequency, and broadcasts the resulting, low power signal to the antenna of a receiver of the existing audio system, which may include a home stereo system, a portable stereo system, or a vehicle radio. The receiver is tuned to the carrier frequency used by the adapter so that the in-coming audio from the mobile phone can be heard over the audio system speakers. For Radio Data System (RDS)-capable radio receivers, a processor is provided within the adapter to generate channel data, which is then transmitted with the carrier signal. The RDS-capable radio receives the RDS signal and automatically tunes itself to the selected channel. An optional processor can be used to control internal and input/output signals through automatic functions which may include volume control, frequency search, and frequency tuning.

An adapter for interfacing a handset with an audio system having at least one speaker and at least one antenna for receiving an input signal to an AM/FM radio, said handset having a transceiver for receiving and decoding an incoming communication signal and for encoding and transmitting an outgoing communication signal, said handset further having a plurality of accessory connectors, said adapter comprising:

a connection means for connecting the handset to the adapter, the adapter receiving a decoded audio input signal from the handset;
a modulator circuit connected to said connection means, said modulator circuit for receiving said decoded audio input signal and for providing at least one level of modulation including modulation of said decoded audio input signal with a carrier frequency, and for generating an output signal comprising a modulated audio signal;
a transmission means for transmitting said modulated audio signal to the at least one antenna of said AM/FM radio, wherein said modulated audio signal is conducted to said at least one speaker;
a microphone connected to said connection means, said microphone for receiving a user's speech and generating a microphone audio output signal, wherein said microphone audio output signal is conducted to said connection means and to said modulator circuit;
a processor cooperating with said modulator circuit for conducting an automatic frequency search for an unused or a low-use frequency of the audio system, wherein said processor generates a short pulse to said modulator circuit and a modulated pulse is transmitted to the AM/FM radio, and wherein the processor then monitors a received pulse signal for the return of the short pulse via said microphone, and wherein the pulse is repeated over a sequence of AM and FM frequencies until said processor verifies the received pulse signal;
and
a power input means for providing at least one operating voltage to said modulator circuit, said transmission means and said microphone.

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Abstract

Claims12