Well, I should have known that trying to keep my comments on the 9/2006 xMax patent brief, will only generate more questions. I really do not have the time (or desire) to go through and discuss all the statements in the patent which are wrong – there are simply too many of them. Let me give you just one example, which is related to questions asked by several readers. The patent has the following statements:
“ Thus noise can be overcome by a brief pulse of high amplitude while another signal of much longer duration and more total power can be well below the noise floor, making it virtually un-detectable.”
“ Thus we understand that it is possible to create a high-amplitude/short-duration signal that can rise above the noise floor, yet due to its short duration and low repetition rate the signal contains an average power that is much lower than the instantaneous peak power.”
This is sheer nonsense. A brief pulse of high amplitude and a long pulse of low amplitude which have the same energy (i.e. the same product of power times duration) are detectable to exactly the same degree. The detectability of the pulse has to do with its energy (power times duration), not power. This is because a long duration pulse which is well below the noise floor will be integrated to yield the same signal to noise ratio as the short pulse of high amplitude. The fact that when you look on an oscilloscope one pulse is visible (sticks up above the noise) and the other is invisible (obscured by the noise) is not relevant. The key point is that integrating over the pulse duration builds up the signal and reduces the noise! This is one of the many errors in this patent which reveal a surprising ignorance of basic concepts such as matched filtering and coherent integration.
The inventor is apparently just not getting this. In a 2005 article he is quoted as saying: “If that doesn’t help, think of the zenon strobe lamp. It’s very bright, but only flashes for a very short time. The average power consumed is quite low, yet the flash can be seen for miles.” This is a very nice story, but it completely misses the key point that long duration low power signals can be integrated to become as detectable as short duration high power signals!
The patent has many examples of wrong statements based on fundamental misconceptions by the inventor. If readers have specific questions related to this patent I will try to answer them. However, to try and do a complete line by line sorting of fact from nonsense is more work than I am willing to do. Sorry …