Audio Receiver Watermark Encoding for Reliable Detection
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Solution Overview
Problem
Existing audio watermarking systems face challenges in reliably tracking audience ratings without degrading the listenability of audio signals, due to distortions caused by pre-transmission processing, lossy transmission mediums, and signal filtering, which can hinder the detection of watermarks by listening devices like the Nielsen Portable People Meter (PPM).
Innovation Solution
A method and system for locally generating a Nielsen Portable People Meter (PPM) technology ratings watermark in an audio receiver, where the watermark information is separately transmitted and decoded, then embedded into the audio signal without degrading the signal quality, ensuring higher decodability rates and robustness against signal distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If audio watermarking is embedded in the audio signal before transmission, then audience tracking can be performed, but the watermark detection reliability deteriorates due to distortions from pre-transmission processing, lossy transmission, and signal filtering
Solution Approach 1:
The patent applies preliminary action by generating the watermark signal in advance at the receiver end, before the audio signal undergoes transmission and processing. The receiver locally generates a watermark using station information obtained from the broadcast signal, embedding it into the received audio signal before further processing. This ensures the watermark is created at the optimal point in the signal chain, avoiding degradation from transmission distortions and pre-transmission processing that would occur if watermarking were done at the transmitter end.
2Object-affected harmful factors
If psychoacoustic masking is used to keep the watermark inaudible, then user listenability is maintained, but the watermark encoding complexity increases
Solution Approach 1:
The patent applies self-service by utilizing the station information that is already being received and processed by the audio receiver for normal broadcast functionality. The same station identification data is reused to generate the watermark signal, eliminating the need for separate watermark generation equipment or additional complex encoding processes. The receiver's existing signal processing resources are leveraged to create the watermark, reducing overall system complexity while maintaining inaudibility through the natural audio signal characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the reliability of watermark detection by audio receivers, improving the accuracy of audience tracking without affecting the listenability of the audio signal, even in the presence of signal processing and transmission-related distortions.
Implementation Method 1
applies a Fourier transform 12 to each windowed signal to obtain its representation in the frequency domain and identify its frequency components
Implementation Method 2
A reverse Fourier transform 17 is applied to convert the encoded audio signal back to the time domain
Data Source
AI summary
A method operable in a receiver comprises the steps of: receiving an audio signal from a broadcaster; obtaining digital information comprising an identifier associated with the broadcaster; retrieving an audio watermark associated with the identifier; encoding the audio watermark in the audio signal; and outputting an acoustic signal based on the encoded audio signal so that the audio watermark can be sensed by a listening device without being audible by a human listener.