How to get envelope from AM signal without phase shift
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From: WWalker on 27 Mar 2010 21:58 Eric, Sorry, the last post I made to you was sent prematurely. I will try again. I simply mean the dipole pulse arrives indistorted 0.16ns earlier than if the pulse had propagated at the light speed. I have made an FTP site where I have uploaded JPG pictures of my simulation results. This should help make things clearer. Copy and paste the following web address into your browser and it should take you to the folder: LPF_Pulse_Exp . I hope it works. ftp://REM:signal(a)132.230.139.154/LPF_Pulse_Exp Regarding how I calculated the theoretically predicted time difference from light speed, refer to the file: Mod_time_delay_from_c_Calc.jpg on the FTP server at: ftp://REM:signal(a)132.230.139.154 I am simply using the dispersion curve slope of the magnetic field component to calculate the time delay of the modulation and then I compare it to the time delay of a light speed signal. Regarding your request that I interrupt the input signal, isn't this what I did in the LPF Pulse simulation I just posted? The pulse is turned on and off and both edges arrive ealier than if it propagted at the speed of light. I guess I could do it without the LPF, but the signal would be wideband and distort in the nearfield. But the discontinuity in this signal would appear to propagate at the speed of light, because the high frequency components comprising the discontinuity would propagate at light speed, since they are in the farfield. Remember that the speed of the field is only superluminal in the nearfield and reduces to the speed of light (c) as the field propagates about a wavelegth from the dipole source, and continues to propagate at c into the farfield. If the detector is located at 1/6 carrier wavelength from the dipole, then higher frequency components with wavelengths a lot shorter than this distance will propagate at speed c. William >On 3/27/2010 3:47 AM, WWalker wrote: >> Eric, >> >> Since a pulse distorts in the nearfield, one can not determin it's group >> speed in the nearfield. But if you take the same pulse and send it through >> a low pass filter, mix it with a carrier, and send it though a dipole you >> get the same superluminal results. Because the filtered pulse is narrow >> band, it propagates undistorted and arrives sooner than a light propagated >> pulse. > >I'm not following this argument, especially the last statement. > > >> I have done a Vee Pro simulation and it clearly shows this. In this program >> I used a pulse with the following characteristics: 1Hz Freq, 50ns pulse >> width, 10ns rise and fall time, 1V amplitude. the Lowpass filter had the >> following characteristics: 50MHz cutoff frequency (fc), 6th order, Transfer >> function: 1/(j(f/fc)+1)^6. Then I multiplied this narrowbanded signal with >> a 500MHz carrier and sent it though a light speed propagating transfer >> function [e^(ikr)] and though the magnetic component of a electric dipole >> transfer function [e^(ikr)*(-kr-i)]. Finally I extracted the modulation >> envelopes of the tranmitted signal, light speed signal, and the dipole >> signal. To extract the envelopes I squared the signal and then passed it >> through a 300MHz cutoff (fc), 12th order LPF with the following transfer >> function [1/(j(f/fc)+1)^12]. The pulse envelope from the dipole arrives >> 0.16ns earlier than the light speed propagated pulse. This corresponds >> exactly with theoretical expectations (0.08/fc=0.16ns). >> >> I think perhaps this is the evidence you have all been looking for. >> >> William > >Although I probably shouldn't be, I was thinking about this a bit more >and wanted to add some thoughts. > >Although the following is certainly not a rigorous analysis, in general >as the signal bandwidth goes up the time resolution one can achieve in >correlation measurements gets smaller. The information update rate for >typical comm systems is the symbol period, Ts, and generally Ts = 1/BW >where BW is the 3dB signal bandwidth. It is possible to resolve time >more finely than Ts and synchronization systems have to do this to >recover the symbols, but a reasonable benchmark for how fast information >is updating is Ts = 1/BW. I think it is arguable that if one wants to >measure how fast information is propagating with very fine time >resolution one needs to use a signal with a very wide bandwidth. >Otherwise one risks measuring a phase offset due to phenomena like >negative group delay rather than accelerated information propagation. > >You said: > > > The pulse envelope from the dipole arrives > > 0.16ns earlier than the light speed propagated pulse. This corresponds > > exactly with theoretical expectations (0.08/fc=0.16ns). > >What theory creates an expectation that the signal propagates faster >than light? I don't know of any. > >Since you've filtered your signal to 50 MHz BW there will be no >significant frequency components with periods shorter than 20ns. You're >claiming that a time difference of 0.16ns (or 1/125th of the length of >the smallest period in the signal) is a difference in information >propagation. I think it's far more likely to be a phase shift due to >the dispersion (as shown in the Sten paper), since that is only 360/125 >= 2.88 degrees of phase advance. A signal experiencing 2.88 degrees of >phase advance through a dispersive medium is far more believable than >propagation faster than light. This is what I've been saying, what >Andor's blog demonstrates, and what my reading of the Sten paper indicates. > >As mentioned long ago, I think a good experiment would be to interrupt >the input signal at some point, perhaps even the modulated signal at a >carrier zero crossing. The propagation of the interruption (which has >infinite bandwidth if it's a hard stop) should be revealing. > > >-- >Eric Jacobsen >Minister of Algorithms >Abineau Communications >http://www.abineau.com >
From: Eric Jacobsen on 27 Mar 2010 22:33 On 3/27/2010 6:58 PM, WWalker wrote: > Eric, > > Sorry, the last post I made to you was sent prematurely. I will try again. > > I simply mean the dipole pulse arrives indistorted 0.16ns earlier than if > the pulse had propagated at the light speed. I have made an FTP site where > I have uploaded JPG pictures of my simulation results. This should help > make things clearer. Copy and paste the following web address into your > browser and it should take you to the folder: LPF_Pulse_Exp . I hope it > works. > > ftp://REM:signal(a)132.230.139.154/LPF_Pulse_Exp Looks just like Andor's and Sten's plots, which aren't due to propagation faster than c. > Regarding how I calculated the theoretically predicted time difference > from > light speed, refer to the file: Mod_time_delay_from_c_Calc.jpg on the FTP > server at: > > ftp://REM:signal(a)132.230.139.154 > > I am simply using the dispersion curve slope of the magnetic field > component to calculate the time delay of the modulation and then I compare > it to the time delay of a light speed signal. Yes. And how do you distinguish the advance between what is easily explained by the effects of negative group delay and the less likely explanation of propagation faster than c? Why do you think the less likely explanation is the correct one? How do you plan to prove that the less likely explanation should be accepted? > Regarding your request that I interrupt the input signal, isn't this what I > did in the LPF Pulse simulation I just posted? The pulse is turned on and > off and both edges arrive ealier than if it propagted at the speed of > light. I guess I could do it without the LPF, but the signal would be > wideband and distort in the nearfield. Are you trying to say the nearfield distortion of the wideband component would suggest that the propagation is less than or equal to c? That's pretty much the point. The expectation is that you'll see something similar to Figure 7 in Andor's blog article. You're seeing essentially Figure 5 now, or Fig. 2a. in Sten's paper. > But the discontinuity in this signal > would appear to propagate at the speed of light, because the high frequency > components comprising the discontinuity would propagate at light speed, > since they are in the farfield. Yup. Which suggests that the signal isn't really propagating faster than c after all, it's just dispersing in a way that advances the phase and makes it appear to accelerate, like the citations we've been quoting over and over and over. > Remember that the speed of the field is > only superluminal in the nearfield and reduces to the speed of light (c) as > the field propagates about a wavelegth from the dipole source, and > continues to propagate at c into the farfield. I think most disagree with you here, and think that the pulse just distorts in the near field due to the dispersion and advances the phase, just like it does in Andor's negative group delay filter and Sten's paper. You're the only one I know of claiming the explanation is propagation faster than c. Everybody else seems to think it's just the phase advance due to the dispersion. Your results appear consistent with Andor's and Sten's so far as far as I can tell, but you insist on a different explanation. Eric > If the detector is located > at 1/6 carrier wavelength from the dipole, then higher frequency components > with wavelengths a lot shorter than this distance will propagate at speed > c. > > > William -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com
From: WWalker on 28 Mar 2010 07:24 Eric, I think you are missing the point. Refering to the Low Pass Filtered Pulse simulation I posted, the simulation clearly shows that if I transmit a pulse, the pulse edge arrives sooner than if it had propagated faster than light. If my detector at the receiving end is threshold detector which is set to look for anything above the noise level, it will fire earlier than if the pulse had propagated at light speed. In other words, it shows that if I push a button launching the narrowband pulse signal and propagate it via a dipole to a nearfield receiver with the threshold detector, the pressed button will be detected sooner than a light propagated signal. This clearly shows that an action (informaton) in this nearfield dipole system can be detected faster than light. If this is true than I have proven my point that information propagtes faster than light in the nearfield of a dipole. William >On 3/27/2010 6:58 PM, WWalker wrote: >> Eric, >> >> Sorry, the last post I made to you was sent prematurely. I will try again. >> >> I simply mean the dipole pulse arrives indistorted 0.16ns earlier than if >> the pulse had propagated at the light speed. I have made an FTP site where >> I have uploaded JPG pictures of my simulation results. This should help >> make things clearer. Copy and paste the following web address into your >> browser and it should take you to the folder: LPF_Pulse_Exp . I hope it >> works. >> >> ftp://REM:signal(a)132.230.139.154/LPF_Pulse_Exp > >Looks just like Andor's and Sten's plots, which aren't due to >propagation faster than c. > > >> Regarding how I calculated the theoretically predicted time difference >> from >> light speed, refer to the file: Mod_time_delay_from_c_Calc.jpg on the FTP >> server at: >> >> ftp://REM:signal(a)132.230.139.154 >> >> I am simply using the dispersion curve slope of the magnetic field >> component to calculate the time delay of the modulation and then I compare >> it to the time delay of a light speed signal. > >Yes. And how do you distinguish the advance between what is easily >explained by the effects of negative group delay and the less likely >explanation of propagation faster than c? Why do you think the less >likely explanation is the correct one? How do you plan to prove that >the less likely explanation should be accepted? > > >> Regarding your request that I interrupt the input signal, isn't this what I >> did in the LPF Pulse simulation I just posted? The pulse is turned on and >> off and both edges arrive ealier than if it propagted at the speed of >> light. I guess I could do it without the LPF, but the signal would be >> wideband and distort in the nearfield. > >Are you trying to say the nearfield distortion of the wideband component >would suggest that the propagation is less than or equal to c? That's >pretty much the point. > >The expectation is that you'll see something similar to Figure 7 in >Andor's blog article. You're seeing essentially Figure 5 now, or Fig. >2a. in Sten's paper. > > >> But the discontinuity in this signal >> would appear to propagate at the speed of light, because the high frequency >> components comprising the discontinuity would propagate at light speed, >> since they are in the farfield. > >Yup. Which suggests that the signal isn't really propagating faster >than c after all, it's just dispersing in a way that advances the phase >and makes it appear to accelerate, like the citations we've been quoting >over and over and over. > >> Remember that the speed of the field is >> only superluminal in the nearfield and reduces to the speed of light (c) as >> the field propagates about a wavelegth from the dipole source, and >> continues to propagate at c into the farfield. > >I think most disagree with you here, and think that the pulse just >distorts in the near field due to the dispersion and advances the phase, >just like it does in Andor's negative group delay filter and Sten's >paper. You're the only one I know of claiming the explanation is >propagation faster than c. Everybody else seems to think it's just the >phase advance due to the dispersion. Your results appear consistent >with Andor's and Sten's so far as far as I can tell, but you insist on a >different explanation. > >Eric > > >> If the detector is located >> at 1/6 carrier wavelength from the dipole, then higher frequency components >> with wavelengths a lot shorter than this distance will propagate at speed >> c. >> >> >> William > > >-- >Eric Jacobsen >Minister of Algorithms >Abineau Communications >http://www.abineau.com >
From: Rune Allnor on 28 Mar 2010 12:22 On 28 Mar, 16:12, "WWalker" <william.walker(a)n_o_s_p_a_m.imtek.de> wrote: > Rune, > > If you are going to be rude, don't bother posting. I will not answer your > posts if you continue. I am sure you have interesting things to say and I > am interested in discussing it, but not if your going to be rude. You have been met here with far more respect than you deserve. In fact, your inflated ego is the only issue standing beteen you and some real insights. You *think* what you dabble with is difficult. It is not. It's nothing more than the basics most other people did away with during their first semester of wave theory. You have spent a decade and a half messing with the basics. *Read* my posts. *Contemplate* what I say. *Search* *up* *the* *basics* on the trivial stuff you dabble with. Then find a new vocation. Rune
From: Eric Jacobsen on 28 Mar 2010 12:44
On 3/28/2010 4:24 AM, WWalker wrote: > Eric, > > I think you are missing the point. Refering to the Low Pass Filtered Pulse > simulation I posted, the simulation clearly shows that if I transmit a > pulse, the pulse edge arrives sooner than if it had propagated faster than > light. If my detector at the receiving end is threshold detector which is > set to look for anything above the noise level, it will fire earlier than > if the pulse had propagated at light speed. In other words, it shows that > if I push a button launching the narrowband pulse signal and propagate it > via a dipole to a nearfield receiver with the threshold detector, the > pressed button will be detected sooner than a light propagated signal. This > clearly shows that an action (informaton) in this nearfield dipole system > can be detected faster than light. If this is true than I have proven my > point that information propagtes faster than light in the nearfield of a > dipole. > > William I get the impression that you either haven't read or haven't understood any of our previous dialogue. What you are seeing appears consistent with a phase advance of a bandlimited signal, not accelerated propagation. The same sort of bandlimited pulse is shown, and I'm sure everybody is getting weary of me citing these same references over and over again, with apparent acceleration in Andor's blog (Figures 4 and 5) and in Sten's paper (Fig. 2.a). Both show apparent arrival of the output pulse before the input, but it is only a small phase advance of the signal due to the nature of the medium (i.e., an unusual group delay). Both authors acknowledge this. You do not. Andor demonstrated, pretty clearly, that the system is, in fact, causal, by turning off the input signal and observing the output signal end in Fig. 7. This is why people here have been trying to get you to do something similar, because otherwise the logical explanation is that there's just a slight phase advance in the signal. -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com |