Sunday, July 21, 2013

Examples of 1-bit hardware sensors

Here are two detectors that fits the 1-bit hardware [1,2] definition, In both cases, we observe the following:
  • there are now essentially "Do It Yourself" sensors thanks in part to Moore's law.
  • improvement based on these technologies, such as more discriminate detectors, are in fact, already mainstream detectors. One wonders however, how revisiting these 1-bit detectors with some rapid prototyping and the 1-bit or n-bit compressive sensing approach, could yield newer and cheaper detectors that would be in competition with current mainstream and more advanced detectors. 
First we have the Geiger-Muller counter

The second item is a Metal detector that is using the sum and difference between two frequencies to detect metal:


from the video description:
The basic BFO (Beat Frequency Oscillator) employs two radio frequency (RF) oscillators which are tuned to very nearly the same frequency. The frequency of each oscillator is usually determined by an L-C resonant circuit, that is, an inductor and a capacitor. One is called the search oscillator and uses the search coil as its inductor; the other is called the reference oscillator and uses an internal inductor. The outputs of the two oscillators are fed into a mixer which produces a signal that contains the sum and difference frequency components (plus other intermodulation components) of the two input signals. As we will see shortly, the difference frequency is what we are interested in, and a low-pass filter at the output of the mixer will remove the other components.
Note: No responsibility accepted due to injury or damage that may be caused in building or using this Metal Detector.


[1] Resources on Quantization
[2] Nuit Blanche blog entries on quantization

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