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Acoustic feedback for signaling electro-magnetic field strength for mobile phones

IP.com Disclosure Number: IPCOM000183578D
Original Publication Date: 2009-May-28
Included in the Prior Art Database: 2009-May-28
Document File: 5 page(s) / 38K

Publishing Venue

IBM

Abstract

Mobile phones need a minimum signal strength to operate correctly, since communication between the mobile phone and the base station is critical for good audio signal quality with sufficient bandwidth. Otherwise data packets may be lost and/or the codec is changed to lower bandwidth thus reducing the audio quality or causing staggering of the audio signal. Instead the bar meter or acoustic signaling by request the user‘s intuitive reaction to white noise can be used for indicating the current signal-to-noise ratio on the voice signal. There are several possibilities of realtime feedback of SNR based on ambient noise.

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Acoustic feedback for signaling electro -magnetic field strength for mobile phones

Authors: Dr. Harry Barowski, Antje Mueller, Tim Niggemeier, Hagen Schmidt

Mobile phones need a minimum signal strength to operate correctly, since communication between the mobile phone and the base station is critical for good audio signal quality with sufficient bandwidth. Otherwise data packets may be lost and/or the codec is changed to lower bandwidth thus reducing the audio quality or causing staggering of the audio signal.

The signals strength is affected by the environment and physical facts like the distance between the sender and the receiver, the shielding effects of e.g. buildings, the user's head, polarization effects (caused by misaligned angles between the axes of the antennas), etc.

In the past the signal-to-noise ratio (SNR) in the receiver of analog mobile phones dropped, thus causing signal disturbance like white noise. Thus the user itself positioned for better signal quality by finding the (optimum) position with respect to the level of noise and minimum audio disturbance.

Today if the signal-to-noise ratio of digital mobile phones drops, there is no audio disturbance except reducing the codec quality to match the available communication bandwidth with respect to data correction. If the signal-to-noise ratio drops further, the redundancy of the channel codec is used up and then voice is chopped or connection is lost.

However there is no feedback available for poor signal-to-noise ratio except the bar meter on the display which is not available during phone calls. Thus in the end communication is lost abruptly without a prior warning.

PRIOR ART


Competitors introduced techniques to indicate the signal-to-noise ratio by using bar indicators representing the actual signal-to-noise ratio by a concrete n-stage bar on the display. Another option - so called "acoustic feedback signaling" translates the n-stage barmeter into several beeps which can be made available during phone calls when the display cannot be look at by pressing some dedicated key. The signal is integrated over some period of time and thus is not generated in realtime. The signal strength is given in request and in longer temporal distance, either the interaction with acoustic beeps is not intuitive and user friendly.

IDEA AND SOLUTION


Instead the bar meter or acoustic signaling by request the user's intuitive reaction to white noise can be used for indicating the current signal-to-noise ratio on the voice signal. There are several possibilities of realtime feedback of SNR based on ambient noise.

One option is using white noise which is modulated by amplitude. At lower volume levels white noise is not noted as disturbing - this matter of fact is already used as ambinet noise to indicate active phonecalls since digital communications will be free of white noise so that customers believe that communication is not established in

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