I hope you list our friend here in your references section. Plagiarism is for cowards.
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10. RFID BASED ROAD TOLL TAX USING LPC2148 PROCESSOR.
How about an echolocation aid? It could be advertised as either a mobility device for the blind or as a novelty for the sighted, depending on how well it performed. It might also double as a bat detector.
With sufficient practice, people can learn to echolocate well enough to avoid large obstructions, find curbs, and follow a wall. One experiment even showed that ordinary people could distinguish (with better-than-chance accuracy) the sound shadows cast by different geometric shapes.
The trouble with human echolocation, though, is that the smallest wavelengths we can hear are still too big to distinguish fine details (such as a thin pole). Ultrasound also has the advantage of being muffled more or less by its passage through air, depending on frequency. So how about building a device that lets humans hear a little more like bats?
Here's one possibility: An ultrasound emitter generates a continuous stream of intense chirps, each of which exponentially drops in frequency from 42KHz to 38KHz over the space of 200ms. (A guide on human echolocation I read suggested making no more than two clicks per second, but perhaps we could process chirps a bit faster. Bats certainly do.) Meanwhile, an ultrasound receiver continuously listens in the 43KHz to 37Khz range. The signal is filtered to remove or diminish frequencies that were just recently produced by the emitter, so as to ignore sounds that merely traveled straight from emitter to receiver. The frequency of the signal is then lowered by heterodyning to an audible 4100Hz through 100Hz range. Finally, the signal is output to an ordinary phono jack that one could plug an earbud into. There might be a knobs on the device to control the minimum detectable distance, chirp duration, and overall volume.
I'm not an electronics expert, but at first glance, this project does seem very doable to me. If you're interested in it, you might study the plans for some heterodyne-type bat detector kits; half the work is already done.