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What color is your problem?

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WKetel
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re: What color is your problem?
WKetel   2/2/2011 8:21:19 PM
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Signals and noise can be a difficult mixture to deal with, that is certain. Unfortunately, it is a challenge to measure the amplitude of a signal with a resolution greater than the amplitude of the noise surrounding the signal. That means that if your signal is about half a volt, and the high frequency noise surrounding your signal is a 5 millivolt band, the uncertainty of any measurement is 10 millivolts. This winds up being a fatal problem if you are using a scope to measure the signal and there is no way to know the instant value of the noise signal at the instant of reading the signal amplitude. The result tells you that the signal of interest varies, when in reality it is the noise measurement that varies. When the application does not allow estimation, it is assured that the results will be wrong. This is why the parameters of measurement, including frequency response, are so important.

WKetel
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re: What color is your problem?
WKetel   1/19/2011 4:48:54 PM
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"Things" having problems generally are in one of two categories, being either they used to function as desired, but now do not, or else, they have never been known to function as desired. The second category includes new product designs, and concepts, by extension. Relating this to the original detection discussion is a bit of a stretch, but it does relate to the remarks following. If a "thing" once worked but now does not, the evaluation can be based on discovering what has changed as the cause. Efficient analysis requires understanding how the system is supposed to function. If it never functioned as desired, then the challenge is to relate the capabilities of what you have to the possibility of providing the desired function, which requires even a bit more understanding of how the desired function is obtained. Both require not only knowledge, but also some creativity, which is often actively discouraged in some environments.

Bob Lacovara
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re: What color is your problem?
Bob Lacovara   1/17/2011 6:55:43 PM
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Since I work in R&D, I get plenty of the unknowns ... and too many of the unknown unknowns. That's the game, though. You can sometimes squeak by on the unknowns, by brute force, or an unhappy compromise, or, as a last resort, moving the goalposts, err, I mean, updating the requirements. But the unknowns are the place where the rubber meets the road. You may or may not come up with a solution, but you also have the chance to find out something new. That's always neat, even if the new thing isn't directly related to the unknown problem at hand. I once worked on an instrument that incorporated a visible-light absorption analyzer. We put blue light into water with some iodine in it. The blue light would be absorbed. The light source was an incandescent, and on top of the power use, we chopped the darn thing with a flag mounted on a stepper motor! Couldn't have been harder. LEDs were becoming more common in the blue: I suggested that we go to an LED, and chop electronically. This met with an amazing amount of pushback, and even some ridicule. Anyway, for a variety of reasons, I quit and went elsewhere. One day I got a call from one of my lead detractors, who politely and even humbly told me that they now had to get rid of the incandescent/stepper motor... He tried to find an LED, but there was no LED bright enough. Did I have any thoughts. Hm. Yes, I did. But instead, I said, "use two LEDs". Silence on the phone. Finally he said only, "so you aren't just a pretty face," and signed off. Few months later, he called again with the grace to tell me that he easily found a company who mounted 6 of the LEDs into a single package: case closed.

kdboyce
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re: What color is your problem?
kdboyce   1/12/2011 5:55:13 AM
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In my early years in Silicon Valley, I had the good fortune to work on a project that required pulling a digital signal out of the noise, i.e. the Detection issue. Two things complicated the problem. (1) The signal was deliberately buried in the noise, and (2) it was never on the same frequency for any length of time. Today, we know this as signal correlation techniques and frequency hopping to avoid interference. We did it to deliberately hide sensitive military transmissions below the in-band noise levels and used signal correlation techniques which worked on the basis of always knowing at what frequency and what time the signal was going to be there. You could scan the RF band the signals were in, but you could never find it without prior knowledge about it. Furthermore, the signal was "encrypted" by a psuedo-random number sequence, the key to which was also transmitted and had to be retrieved then locked in the receiver in order to know what to look for when. My role involved assisting in the design of the digital frequency synthesizer, and in designing and building very narrow band cascaded microwave filters which shifted in frequency based on the expected time of arrival of the signal. For a young engineer, this bordered on magic to watch it work successfully, and gave me a much deeper respect for the mathematical underpinnings of the techniques. In other words, electronics ain't just about resistors, capacitors, and active devices. It can also be all about the numbers.

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