Method and apparatus for identifying audio accessory through two pin connection in a two way radio

Patent metadata

Field	Value
Publication number	US-10014842-B2
Application number	US-201414228903-A
Country	US
Kind code	B2
Filing date	Mar 28, 2014
Priority date	Mar 28, 2014
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

A method and apparatus for detecting the connection of an external audio accessory to an audio device via a two-wire audio jack includes providing a DC bias on the output of the audio circuit connected to the audio jack. The audio jack is such that, when a plug is inserted into the audio jack, the DC bias is removed from an internal routing pin of the audio jack. The change in DC voltage at the internal routing pin indicates connection of the external audio accessory. Furthermore, upon detection, the AC response of the external audio accessory can be determined, and used to select a set of audio settings to be applied to the audio components of the audio device to optimize the performance of the external audio accessory.

First claim

We claim:

1. A method for identifying an audio accessory through a two-wire audio jack, comprising:
biasing a positive output line and a negative output line of an audio power amplifier with a direct current (DC) bias voltage, the negative output line being connected to a negative pin of an audio jack, the positive output line being connected to a break/short pin of the audio jack, and wherein the audio jack has an internal routing pin that is connected to the break/short pin in the absence of an audio plug in the audio jack and that is disconnected from the break/short pin when the audio plug is inserted into the audio jack;
detecting removal of the DC bias voltage from the internal routing pin;
selecting an audio profile for an external audio accessory responsive to detecting removal of the DC bias voltage from the internal routing pin;
reconfiguring audio settings of an audio processor that provides an audio signal to the audio power amplifier in accordance with the selected audio profile;
wherein selecting the audio profile comprises determining an alternating current (AC) response of the external audio accessory to determine a plurality of parameters comprising: impedance, quality factor and fundamental frequency and mapping the AC response to the audio profile which is one of a plurality of audio profiles based on the plurality of parameters;
wherein determining the AC response comprises applying tonal audio content to the external audio accessory and detecting a current and a voltage response at each of a plurality of tones, the current being sensed by a current sense resistance in series between the audio positive output line of the audio power amplifier and the break/short pin as part of an impedance measurement; and
wherein the impedance measurement of the external audio accessory at a given frequency is equal to the ratio of the output voltage of the audio power divided by the current minus the resistance of the current sense resistance:
Z freq =[V total /( V sense /R sense )]− R sense ,

where Z freq is the impedance at a given frequency, V total is total voltage output by the audio power amplifier between the audio positive output line and the negative output line, and R sense is resistance of the current sense resistance.

2. The method of claim 1 , further comprising, subsequent to reconfiguring audio settings, detecting removal of the external audio accessory and, in response, reconfiguring audio settings of the audio processor to default audio settings for an internal speaker.

3. The method of claim 1 , wherein detecting removal of the DC bias voltage from the internal routing pin comprises detecting the voltage across a grounded capacitor that is connected to the internal routing pin through a resistance.

4. A method of adjusting audio output of an audio device, comprising:
detecting connection of an external audio accessory at a two-wire audio jack of the audio device, the audio jack including a break/short pin coupled to a positive output line of an audio power amplifier, a negative output pin coupled to a negative output line of the audio power amplifier, and an internal routing pin that is connected to the break/short pin in the absence of a plug in the audio jack and disconnected from the break/short pin when a plug is inserted in the audio jack, detecting connection of the external audio device is based on a change of an electrical parameter on the internal routing pin;
selecting a set of audio settings of an audio processor in response to detecting connection of the external audio accessory;
applying the audio settings to at least one audio component of the audio device, wherein the audio settings are selected to optimize audio performance of the external audio accessory;
wherein selecting the set of audio settings comprises:

determining an alternating current (AC) response of the external audio accessory;
determining a plurality of parameters comprising: impedance, quality factor and fundamental frequency from the AC response of the external audio accessory; and
mapping the AC response to one of a plurality of audio profiles that corresponds to the AC response based on the plurality of parameters;
wherein determining the AC response comprises applying tonal audio content to the external audio accessory and detecting a current and a voltage response at each of a plurality of tones, the current being sensed by a current sense resistance in series on the positive output line between the audio power amplifier and the break/short pin as part of an impedance measurement; and
wherein the impedance measurement of the external audio accessory at a given frequency is equal to the ratio of the output voltage of the audio power divided by the current minus the resistance of the current sense resistance:
Z freq =[V total /( V sense /R sense )]− R sense ,

where Z freq is the impedance at a given frequency, V total is total voltage output by the audio power amplifier between the audio positive output line and the negative output line, and R sense is resistance of the current sense resistance.

5. The method of claim 4 , further comprising, subsequent to applying the audio settings, detecting removal of the external audio accessory and, in response, reconfiguring audio settings of the audio processor to default audio settings for an internal speaker.

6. The method of claim 1 , wherein the two-wire audio jack comprises a speaker jack and a microphone jack for insertion of a two-pin external audio accessory.

7. The method of claim 1 , wherein the audio profile indicates preferred audio settings comprising one or more of: gain compensation and equalizer settings to be used with the external audio accessory.

8. The method of claim 1 , wherein the audio profile is selected from a memory of a portable two-way radio.

9. The method of claim 4 , wherein the plurality of audio profiles are stored in a memory of the audio device.

Assignees

• Motorola Solutions Inc
• Motorola Solutions Inc

Inventors

• Teh Kheng Shiang
• Tan Cheah Heng

Classifications

• H04B1/3827

  Portable transceivers · CPC title

• H03G3/3026

  the gain being discontinuously variable, e.g. controlled by switching · CPC title

• H03G9/025

  frequency-dependent volume compression or expansion, e.g. multiple-band systems (H03G9/10, H03G9/18 take precedence) · CPC title

• H04R5/04

  Circuit arrangements, {e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments (combinations of amplifiers H03F3/68; stereophonic systems H04S)} · CPC title

• H03G3/3089

  Control of digital or coded signals · CPC title