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by roamingryan
1971 days ago
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Not necessarily. Watermarking an audio stream like this wouldn't require that high of a bit rate. It could easily be hidden "under" the content using coding techniques like direct-sequence spread spectrum. A real world example is GPS, which uses a spreading code to provide about 30 dB of gain. GPS signals aren't directly observable relative to the noise floor in many receivers. It's not until after the signal is "de-spread" that it becomes observable in a spectrogram. This process requires prior knowledge of the signal structure. In short, if you don't need to send data at high rate there are many ways to hide your signal. |
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We're also dealing with only 48KHz, which is 2-3 magnitudes less than what SDR people are accustomed to dealing with.
And we can also make our own detection systems by having a 3 person "meeting" with fake audio, with this fingerprinting on, and then comparing the 3 recordings.