A brief introduction into AWT3 technology
AWT3 technology is a direct extension of AWT2 and it uses the very same patented core approach. AWT3 has been designed to provide truly reliable robustness against over-the-air sound transducing and against strong room reverberations to allow digital codes transmission on several meters distances from the sound source in real acoustic environments.
While AWT2 uses the source audio content to carry and hide watermarks in it, AWT3 does not actually use the source audio content as a carrier, but adds additional sound ("beeps") into it that is used as a carrier. The frequency of the added carrier is configurable in a wide range.
AWT3 watermarks can survive 3-4-5 meters distance between sound source (speakers) and capturing device (phone/tablet). To achieve this goal, ultra-sonic frequencies (> 18 KHz) have to be used as a carrier because only high frequencies can withstand strong room reverberations. AWT2 watermarks cannot resist such reverberations, while AWT3 – can do. The drawback of AWT3 is that its codes not always survive lossy audio encoding. For example, if you try to compress AWT3-watermarked stream with Lame MP3 Encoder using its default encoding settings, it will most likely filter out all high frequencies above 16 KHz together with the watermarks. With some lossy coders (including Lame MP3) this problem can be solved by defining special parameters to force it preserving these frequencies. However, it may not be always possible with other audio codecs, especially when it comes to broadcasting equipment having special/fixed/non-configurable encoding settings. At that, this problem does not happen with, for example, iTunes AAC-LC codec (which is used by some broadcasters in UK) – AWT3 codes are preserved well under compression using this codec.
A typical application for AWT3 is a kick-shopping. For example, mini-speakers can be installed in shopping centers. Shoppers passing by can capture codes (coupons) using their mobile devices. There are of course many other uses for it.
You can send your inquiries to mailbox [at] audiowatermarking.com.
