Summaries of Research and Inventions from Science and Technology Journals
Lip-syncing isn't a problem just for pop performers and old martial arts films. Getting the sound and pictures to match is a real difficulty for digital video broadcasters. Because the audio and video signals can go through a different number of encoders and decoders in a viewer's receiver, they can wind up out of sync with each other. Anything more than a few milliseconds is bothersome to viewers, especially if they're watching something with a lot of speech, such as a newscast.
The usual method for checking synchronization requires special equipment and a test signal that interrupts the broadcast. So engineers at Kyungpook National University in Daegu, South Korea, have come up with a way of embedding an easy-to-read test signal that can be run during normal broadcasts. They embedded the test signal in the part of the video signal that is not normally displayed on televisions and, similarly, embedded an audio marker in the part of the digital audio signal used for transmitting in multiple languages. They then came up with a way of measuring the difference between the signals with an ordinary oscilloscope instead of the special equipment, so broadcasters can make adjustments more frequently and for less money.
DTV Lip-Sync Test Using Time-Indexed Audio and Video Signals Without Effect on Program , by Chan-Ho Han and Kyu-Ik Sohng, IEEE Transactions on Broadcasting, March 2005, pp. 62-68.
Solving A Knotty Problem
Human eyes can't determine the value of timber before it's cut, but microwaves can. Logs with fewer knots are more valuable, and knowing where the knots are ahead of time would let sawmills get the most value out of each log. Researchers have tried X-rays and ultrasound, but the former are expensive and potentially dangerous and the latter won't work in a noisy sawmill. So scientists from ETH Zurich and Halmstad University in Sweden are trying to use a new theory about how logs reflect microwaves.
By looking at different aspects of the reflected microwaves, the technology could glean information about the angle of the wood grain, the amount of moisture in it, how dense it is, and where defects exist. Applied to a test spruce log, the technology was able to locate all four of its knots.
Microwave Polarimetry Tomography of Wood , by Andres P. Kaestner and Lars B. Bååth, IEEE Sensors Journal, April 2005, pp. 209-15.