Author Topic: Xaviers Latest Nonsense  (Read 2749 times)

Offline Allan F

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Re: Xaviers Latest Nonsense
« Reply #15 on: October 06, 2020, 07:58:37 AM »



The only reason they are able to detect the signal at all is because the light from the laser is monochromatic, but its not just a matter of looking for these photons and timing their arrival. The pulses are about 2cm deep, and even when detected, there is no way to determine where in the pulse the detected photon is - the leading edge, the trailing edge or somewhere in between. 



So when a sufficient large number of photons have been counted, the front and back end of the pulse can be determined? And thereby increase the accuracy of the measurement?
Well, it is like this: The truth doesn't need insults. Insults are the refuge of a darkened mind, a mind that refuses to open and see. Foul language can't outcompete knowledge. And knowledge is the result of education. Education is the result of the wish to know more, not less.

Offline Abaddon

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Re: Xaviers Latest Nonsense
« Reply #16 on: October 06, 2020, 09:35:51 AM »
Add to the list of things Hunchback doesn't understand: the inverse square law.
Maybe because he follows an inverse square law: the closer you look, the dimmer he appears.
Didn't he turn out to have the actual qualifications he claimed? I have some dim memory that somebody checked, although I have not spent any time on his ramblings for years (too much effort for no return).

Offline Allan F

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Re: Xaviers Latest Nonsense
« Reply #17 on: October 06, 2020, 04:52:59 PM »
He routinely trots out a paper, which is supposed to be a diploma from some french engineering school. But it is of so poor quality, it might as well have been typed on a C64 and then printed on a Commodore 801.
Well, it is like this: The truth doesn't need insults. Insults are the refuge of a darkened mind, a mind that refuses to open and see. Foul language can't outcompete knowledge. And knowledge is the result of education. Education is the result of the wish to know more, not less.

Offline JayUtah

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Re: Xaviers Latest Nonsense
« Reply #18 on: October 06, 2020, 05:03:31 PM »
The school is legit, but I doubt the diploma is.
"Facts are stubborn things." --John Adams

Offline Abaddon

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Re: Xaviers Latest Nonsense
« Reply #19 on: October 09, 2020, 03:41:49 PM »
The school is legit, but I doubt the diploma is.
Didn't someone check that out ages ago and it is legit?

Or have the memory worms struck again?

Offline ka9q

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Re: Xaviers Latest Nonsense
« Reply #20 on: November 30, 2020, 07:54:08 PM »
Yep. If I correctly recall my time working on TACAN ground stations, we used range gating to help detect interrogation pulses and separating them from things such as reference pulses, squitter pulses and reply pulse-pairs.
Right. My background is in radio communication rather than radar or optical ranging, but the underlying principles are the same. In radio, you tune a receiver to the transmitted signal, with filters excluding all frequencies other than those produced by the transmitter. Most radio signals are continuous in time but limited in bandwidth. Radar and optical signals are usually limited in time (for range resolution) which forces them to be wider (but still limited) in bandwidth. The famous uncertainty principle in physics is also fundamental to communications where it expresses the inverse relationship between frequency and time. Narrow in time means wide in frequency, and narrow in frequency means wide in time. You cannot have narrow in frequency and narrow in time, though numerous cranks have tried.

The basic aspects of any signal -- its structure, bandwidth and timing -- are usually at least partly known a priori -- before receiving it. Every communications engineer is taught to take advantage of as much a priori information as you possibly can when building and operating a receiver. If there's a radio program you want to hear (I know, pretty retro, but...) you tune into its advertised frequency at the proper time and with the right type of receiver. As Shannon explained, communication is all about reducing the receiver's uncertainty, so you eliminate as much of that uncertainty as you can at the start.

The technical term for all this is matched filtering, and there are well-established mathematical proofs that it is optimal. Yet that didn't keep one professor I know from claiming to research "mis-matched filtering", claiming it might work better. I guess the system for selecting professors isn't perfect.
« Last Edit: November 30, 2020, 07:58:49 PM by ka9q »