No Sidebands? 1

[Skogsgurra]

Was Shannon and the other guys wrong?

http://mwrf.com/Articles/Index.cfm?Ad=1&ArticleID=23644&cid=ed_newsletter&NL=1&YM_RID=gunnar@gke.org

I am not in communications, so I do not understand much of what is said.

Anyone that can comment on this?

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[MikeHalloran]

I think the first sentence in the second paragraph should refer to 'FM', not 'AM', but I can't make enough sense of the rest to point out any more possible typos.

I have asked an RF guru friend to join and comment.

Mike Halloran
Pembroke Pines, FL, USA

 

[robertjo24]

Basically what this article discusses is using a pulsed carrier, not a modulated carrier. Without modulation, there are no side bands. The information would be modulated to turn the carrier on and off very rapidly. Think of it like a CW key (morse code) happening very fast.

This isn’t earth shattering or new, just applied in a new way.

 

[VEBill]

The article gets off to a very bad start where the author states some practical problems with transmit filters, but not with receive filters.

So he should take the output *after* the receive filters, put it in a coax cable, and mark the middle of the cable with the word "HERE!". Then he can discuss his purported violation of Shannon's Law with respect to the signal at that exact point.

The article triggers off other alarm bells. I'll need to have a drink and try again.

 

[VEBill]

It doesn't appear that he is explicitly claiming that one can send information through a sub-Shannon (zero?!?!) bandwidth channel. He mostly refers to radar. But he almost speculates in that direction when he mentions various communications systems (IFF, TACAN) that *do* require information to be transmitted. That part has to be wrong.

Shannon's Law is derived from pure math. It doesn't depend upon a particular type of filter. A channel cannot carry any more information than the limit, no matter what filters are used. One can do worse, but not better.

 

[Comcokid]

Note that most of what is discussed is radar, which is extremely low in terms of actual information (pulse out, delay, pulse received). In fact, the main information used in radar is the delay, which is not actually transmitted information but a measurement made at the receiver and is not a part of the signal information. [Hummm - I wonder if radar is the simplest example of minimal information - single bit out, single bit back?]

Also, the statement: This present article shows near-perfect reception without usable sidebands for AM pulses, although the method does not work for ordinary AM audio, where the sideband energy is essential to the operation of the system. Translated, I think it means: 'This doesn't work if there is any information in the signal'.

Also, the statement: The approach can also be used to extend the range of UWB signals when applied to UNB communications systems. is self contradictory!

I thought April 1st was still a few months off!

 

[MacGyverS2000]

Also, the statement: This present article shows near-perfect reception without usable sidebands for AM pulses, although the method does not work for ordinary AM audio, where the sideband energy is essential to the operation of the system. Translated, I think it means: 'This doesn't work if there is any information in the signal'.

That's my take on it...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[VEBill]

Even on-off keying "CW" Morse code has a known, predictable, real, actual, non-zero bandwidth.

It's not clear that the author understands that the Fourier equivalence isn't something you have to do; it just is. In other words, he should (not really) have been able to do this experiment in pure math (or math sim) and derive the exact same result. Using a practical hardware-based experiment to try to amend Information Theory is just plain weird.

Also, his so-called "transmitter" is a bit of a strawman. It's junk and the emitted spectrum is a violation of All That Is Holy in the radio world.

The Nobel prize committee should probably hold-off for a while, until this finding is deciphered and aligned with theory. If the theory requires an amendment, then crack open the champange.

 

[Skogsgurra]

OK. I will not bring this to the Nobel Prize Committee meeting then.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[Brad1979]

See "Comments on spectral efficiency of VMSK" in IEEE Transactions on Broadcasting for a paper on ultranarrow bandwidth modulation techniques. Abstract:

"This article demonstrates that no ultra narrow band modulation (UNBM) method, which includes very minimum shift keying (VMSK) and VPSK, can have substantially greater efficiency than conventional methods, such as quadrature amplitude modulation (QAM), in transmission in the same frequency band."

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=992858

 

[waross]

I'm thinking that his system would require some type of code to transmit data. hmm What to name it? The name "Morse code" is already taken. grin

Bill
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"Why not the best?"
Jimmy Carter