How to get envelope from AM signal without phase shift
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From: Jerry Avins on 24 Mar 2010 11:52 Eric Jacobsen wrote: > On 3/23/2010 9:02 PM, Jerry Avins wrote: >> steveu wrote: >> >>> ... only one person here doesn't seem to grasp >>> that this ain't gonna happen. >> >> It was the subject of his thesis and he passed his defence, so it must >> be valid. Isn't that how it goes? >> >> Jerry > > I'm struggling to believe that this is true. That's a pretty sad > indictment of that institution if this got by a PhD committee. > > I suspect there's more to this story. There's a number of things that > don't make sense here, beyond the obvious claims. From an earlier post of Walker's: "Many of the ideas being discussed in this thread are published in my Ph.D. thesis submitted in 1997 at ETH Zurich, Switzerland." True, id doesn't say that it's the basis of his degree, or even that he has one. Jerry -- Discovery consists of seeing what everybody has seen, and thinking what nobody has thought. .. Albert Szent-Gyorgi �����������������������������������������������������������������������
From: WWalker on 24 Mar 2010 17:21 Thank you for the interesting discussion, but some of you need to work on your manners. William >Eric Jacobsen wrote: >> On 3/23/2010 9:02 PM, Jerry Avins wrote: >>> steveu wrote: >>> >>>> ... only one person here doesn't seem to grasp >>>> that this ain't gonna happen. >>> >>> It was the subject of his thesis and he passed his defence, so it must >>> be valid. Isn't that how it goes? >>> >>> Jerry >> >> I'm struggling to believe that this is true. That's a pretty sad >> indictment of that institution if this got by a PhD committee. >> >> I suspect there's more to this story. There's a number of things that >> don't make sense here, beyond the obvious claims. > > From an earlier post of Walker's: "Many of the ideas being discussed in >this thread are published in my Ph.D. thesis submitted in 1997 at ETH >Zurich, Switzerland." True, id doesn't say that it's the basis of his >degree, or even that he has one. > >Jerry >-- >Discovery consists of seeing what everybody has seen, and thinking what >nobody has thought. .. Albert Szent-Gyorgi >����������������������������������������������������������������������� >
From: glen herrmannsfeldt on 24 Mar 2010 17:38 WWalker <william.walker(a)n_o_s_p_a_m.imtek.de> wrote: (snip) > This is not phase velocity, this is group velocity i.e. > time delay of the envelope. If the system is linear, w (omega) proportional to k (wave number) then group velocity and phase velocity are equal. If it is slightly non-linear then phase velocity is w/k and group velocity dw/dk. The works as long as the higher derivatives don't become too big. Optical materials away from resonance are pretty well described using w/k and dw/dk. Now, follow the dispersion (w vs. k) curve through a resonance. It goes up, limited by the loss term, and then goes down, and finally negative. Near resonance the index of refraction can go below 1, and even go negative. That doesn't mean that light travels faster than c, or backwards. Some years ago there was a long discussion on this, along with the corresponding DSP terms, group delay and phase delay. -- glen
From: Eric Jacobsen on 24 Mar 2010 18:42 On 3/24/2010 8:04 AM, WWalker wrote: > Eric, > > There is fundamental difference between a phase shift caused by a filter > and a time delay caused by wave propagation across a region of space. The > Op Amp filter circuit is simply phase shifting the harmonic components of > the signal such that the overall signal appears like it has arrived before > it was transmitted. The circuit is not really predicting the signal it is > only phase shifting it. Yes, this is fundamental. Still, of note, is that the way to distinguish between such a phase shift and an increase in propagation velocity is to introduce a perturbation, as Andor did, so that it can be seen whether the prediction is due to negative group delay or accelerated propagation. Andor's experiment is revealing in that it offers a method to demonstrate that what appears to be accelerated propagation is really narrow-band prediction. As far as I can tell you have not yet done the same, and are instead claiming the rather grandiose explanation of virtual photons (which cannot be used in the context of information transfer) and propagation faster than the speed of light. It could be cleared up pretty easily by demonstrating actual information transmission, but it seems to me that you resort to hand waving instead. > In my system, the time delay of the signal is completely due to wave > propagation across space. It is not a filter. You have not yet demonstrated that. > The simulation I presented simply shows the time delay of the modulation of > an AM signal transmission between two nearfield dipole antennas. If you > zoom in one can see that the modulations arrive earlier than a light > propagated signal. Except that with the signals you're using the propagation cannot be distinguished from a phase shift. Again, the point of Andor's paper is that there's a simple way to distinguish the difference. Until you do so you should not expect much respect of your grandiose claims when there's a much simpler explanation. > This is not phase velocity, this is group velocity i.e. time delay of the > envelope. > > William It doesn't matter which it is or whether the conditions are linear so that they're the same, you haven't demonstrated that the propagation has accelerated. Either demonstrate some actual information transmission or expect people to keep pushing back on you. You have a high burden of proof to make the claims that you're making, but you don't seem to want to offer anything substantial. > > > >> On 3/23/2010 6:06 PM, WWalker wrote: >>> Eric, >>> >>> Interesting article, but I don't see how it applies to my system. The >>> system described in the paper is a bandpass filter in a feedback loop, >>> where the bandpass filter phase function is altered by the feedback. > The >>> feedback forces the endpoints of the phase to zero, creating regions of >>> possitive slope, which yield negative group delays for narrow band > signals. >>> This causes narrow band signals at the output of the circuit appear to >>> arrive earlier than signals at the input of the circuit. Because the >>> information in the signals is slightly redundant, the circuit is able > to >>> reconstruct future parts of the signal from the present part of the >>> signal. >> >> Snipped context to allow bottom-posting. >> >> Feedback is not necessary to produce negative group delay. Here's >> another example with a passive notch filter that exhibits negative group >> delay. >> >> http://www.radiolab.com.au/DesignFile/DN004.pdf >> >> It doesn't matter what's inside a black box if it has a negative group >> delay characteristic if the transfer function is LTI. Whether there's >> feedback or not in the implementation is inconsequential. Consider >> that the passive notch filter could also be implemented as an active >> circuit with feedback, and if the transfer functions are equivalent they >> are functionally equivalent. This is fundamental. I don't think the >> feedback has anything to do with it. >> >> You're argument on the redundancy, though, is spot-on. Note that, as >> others have already pointed out multiple times, the signals you're using >> in your experiment are HIGHLY redundant, so much so that they carry >> almost no information. These signals are therefore not suitable for >> proving anything about information propagation. >> >> >>> First of all, this is a circuit which alters the phase function with >>> respect to time and not space, as it is in my system. The phase function > in >>> the circuit is not due to wave propagaton, where mine is. >> >> As far as I've been able to tell, your evidence is based on a >> simulation, in which case dimensionalities are abstractions. You are >> not performing anything in either time or space, you're performing a >> numerical simulation. Space-time transforms are not at all unusual and >> it is likely that a substitution is easily performed. Nothing has >> propagated in your simulation in either time or space. >> >>> Secondly,unlike the circuit, my system is causal. The recieved signal in > my >>> system arrives after the signal is transmitted. It just travels faster > than >>> light. >> >> Uh, the circuit is causal. That was the point. >> >> You have not demonstrated that your system is causal or not causal. >> That cannot be concluded using the waveforms you show in your paper due >> to the high determinism and narrow band characteristics. >> >>> Thirdly, the negative group delay in the circuit was accomplished by > using >>> feedback which does not exist in my system. >> >> As I stated above, this is inconsequential. >> >> >>> Information (modulations) are clearly transmitted using narrowband AM > radio >>> communication, just listen to an AM radio. The simulation I presented >>> simply shows that random AM modulations arrive undistorted across space, > in >>> the nearfield, earlier than a light speed propagated signal. >> >> Your simulation does not demonstrate that. Turn the signal off, even at >> a zero crossing if you want to minimize perturbations, and see what > happens. >> >>> Signal purturbations can not be used to measure the signal propagation > in >>> the nearfield because they distort in the nearfield, and group speed has > no >>> meaning if the signal distorts as it propagates. >>> >>> William >> >> If you cannot use a perturbation (i.e., information transmission) to >> measure signal propagation then you cannot demonstrate the speed of >> information propagation. Until you can actually demonstrate something >> other than phase velocity (which is NOT information transmission and >> many here have acknowledged can be faster than c, as do I), then you >> cannot make the conclusions that you are claiming. >> >> >> -- >> Eric Jacobsen >> Minister of Algorithms >> Abineau Communications >> http://www.abineau.com >> -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com
From: WWalker on 24 Mar 2010 19:56
Eric, The dicontinuity of a pulse from a dipole source propagates at light speed, but the pulse distorts in the nearfield because it is wideband and the dispersion is not linear over the bandwidth of the signal. In the farfield the pulse realigns and propagates with out distortion at the speed of light. Group speed only has meaning if the signal does not distort as it propagates. So in the nearfield one can not say anything about the propagation speed of a pulse, but in the farfield the pulse clearly propagates undistorted at the speed of light. Only a narrowband signal propagates without distortion in both the nearfield and farfield from a dipole source. This is because the dispersion is not very nonlinear and can approximately linear over the bandwidth of a narrow band signal. Since the signal does not distort as it propagates then the group speed can be clearly observed. The dipole system is not a filter. Wave propagation from a dipole source occurs in free space. There is not a medium which can filter out or change frequency components in a signal. The transfer functions of a dipole source simply decribes how the field components propagate. Clearly simple narrowband AM radio transmission contains information. Just turn on an AM radio and listen. The information is known to be the modulation envelope of the AM signal. My simmulation simply shows that in the nearfield, the modulation envelope arrives earlier in time (dt) than a light speed propagated modulation (dt=0.08/fc), where fc is the carrier frequency. William >On 3/24/2010 8:04 AM, WWalker wrote: >> Eric, >> >> There is fundamental difference between a phase shift caused by a filter >> and a time delay caused by wave propagation across a region of space. The >> Op Amp filter circuit is simply phase shifting the harmonic components of >> the signal such that the overall signal appears like it has arrived before >> it was transmitted. The circuit is not really predicting the signal it is >> only phase shifting it. > >Yes, this is fundamental. Still, of note, is that the way to >distinguish between such a phase shift and an increase in propagation >velocity is to introduce a perturbation, as Andor did, so that it can be >seen whether the prediction is due to negative group delay or >accelerated propagation. Andor's experiment is revealing in that it >offers a method to demonstrate that what appears to be accelerated >propagation is really narrow-band prediction. As far as I can tell you >have not yet done the same, and are instead claiming the rather >grandiose explanation of virtual photons (which cannot be used in the >context of information transfer) and propagation faster than the speed >of light. > >It could be cleared up pretty easily by demonstrating actual information >transmission, but it seems to me that you resort to hand waving instead. > >> In my system, the time delay of the signal is completely due to wave >> propagation across space. It is not a filter. > >You have not yet demonstrated that. > >> The simulation I presented simply shows the time delay of the modulation of >> an AM signal transmission between two nearfield dipole antennas. If you >> zoom in one can see that the modulations arrive earlier than a light >> propagated signal. > >Except that with the signals you're using the propagation cannot be >distinguished from a phase shift. Again, the point of Andor's paper is >that there's a simple way to distinguish the difference. Until you do >so you should not expect much respect of your grandiose claims when >there's a much simpler explanation. > >> This is not phase velocity, this is group velocity i.e. time delay of the >> envelope. >> >> William > >It doesn't matter which it is or whether the conditions are linear so >that they're the same, you haven't demonstrated that the propagation has >accelerated. Either demonstrate some actual information transmission >or expect people to keep pushing back on you. You have a high burden of >proof to make the claims that you're making, but you don't seem to want >to offer anything substantial. > > >> >> >> >>> On 3/23/2010 6:06 PM, WWalker wrote: >>>> Eric, >>>> >>>> Interesting article, but I don't see how it applies to my system. The >>>> system described in the paper is a bandpass filter in a feedback loop, >>>> where the bandpass filter phase function is altered by the feedback. >> The >>>> feedback forces the endpoints of the phase to zero, creating regions of >>>> possitive slope, which yield negative group delays for narrow band >> signals. >>>> This causes narrow band signals at the output of the circuit appear to >>>> arrive earlier than signals at the input of the circuit. Because the >>>> information in the signals is slightly redundant, the circuit is able >> to >>>> reconstruct future parts of the signal from the present part of the >>>> signal. >>> >>> Snipped context to allow bottom-posting. >>> >>> Feedback is not necessary to produce negative group delay. Here's >>> another example with a passive notch filter that exhibits negative group >>> delay. >>> >>> http://www.radiolab.com.au/DesignFile/DN004.pdf >>> >>> It doesn't matter what's inside a black box if it has a negative group >>> delay characteristic if the transfer function is LTI. Whether there's >>> feedback or not in the implementation is inconsequential. Consider >>> that the passive notch filter could also be implemented as an active >>> circuit with feedback, and if the transfer functions are equivalent they >>> are functionally equivalent. This is fundamental. I don't think the >>> feedback has anything to do with it. >>> >>> You're argument on the redundancy, though, is spot-on. Note that, as >>> others have already pointed out multiple times, the signals you're using >>> in your experiment are HIGHLY redundant, so much so that they carry >>> almost no information. These signals are therefore not suitable for >>> proving anything about information propagation. >>> >>> >>>> First of all, this is a circuit which alters the phase function with >>>> respect to time and not space, as it is in my system. The phase function >> in >>>> the circuit is not due to wave propagaton, where mine is. >>> >>> As far as I've been able to tell, your evidence is based on a >>> simulation, in which case dimensionalities are abstractions. You are >>> not performing anything in either time or space, you're performing a >>> numerical simulation. Space-time transforms are not at all unusual and >>> it is likely that a substitution is easily performed. Nothing has >>> propagated in your simulation in either time or space. >>> >>>> Secondly,unlike the circuit, my system is causal. The recieved signal in >> my >>>> system arrives after the signal is transmitted. It just travels faster >> than >>>> light. >>> >>> Uh, the circuit is causal. That was the point. >>> >>> You have not demonstrated that your system is causal or not causal. >>> That cannot be concluded using the waveforms you show in your paper due >>> to the high determinism and narrow band characteristics. >>> >>>> Thirdly, the negative group delay in the circuit was accomplished by >> using >>>> feedback which does not exist in my system. >>> >>> As I stated above, this is inconsequential. >>> >>> >>>> Information (modulations) are clearly transmitted using narrowband AM >> radio >>>> communication, just listen to an AM radio. The simulation I presented >>>> simply shows that random AM modulations arrive undistorted across space, >> in >>>> the nearfield, earlier than a light speed propagated signal. >>> >>> Your simulation does not demonstrate that. Turn the signal off, even at >>> a zero crossing if you want to minimize perturbations, and see what >> happens. >>> >>>> Signal purturbations can not be used to measure the signal propagation >> in >>>> the nearfield because they distort in the nearfield, and group speed has >> no >>>> meaning if the signal distorts as it propagates. >>>> >>>> William >>> >>> If you cannot use a perturbation (i.e., information transmission) to >>> measure signal propagation then you cannot demonstrate the speed of >>> information propagation. Until you can actually demonstrate something >>> other than phase velocity (which is NOT information transmission and >>> many here have acknowledged can be faster than c, as do I), then you >>> cannot make the conclusions that you are claiming. >>> >>> >>> -- >>> Eric Jacobsen >>> Minister of Algorithms >>> Abineau Communications >>> http://www.abineau.com >>> > > >-- >Eric Jacobsen >Minister of Algorithms >Abineau Communications >http://www.abineau.com > |