How to get envelope from AM signal without phase shift
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From: Rune Allnor on 26 Mar 2010 17:31 On 26 Mar, 22:02, Jerry Avins <j...(a)ieee.org> wrote: > Rune Allnor wrote: > > On 24 Mar, 01:20, Eric Jacobsen <eric.jacob...(a)ieee.org> wrote: > >> On 3/23/2010 4:51 PM, Rune Allnor wrote: > > >> You sim doesn't run very well under my version of Octave, but the bit > >> about the phase velocity on oblique angles is fundamental. > > I don't think the illusion is based on obliquity. Walter is wrong about > faster-than-light signaling, but he's not naive. Agreed. He seems to be far worse off than that. > Close in, the near > field predominates, but it fades faster than the far field, so there's a > transition as the distance from the antenna increases. There's a net > shift of pi/2 when shifting between the two field components. That's > subtle enough to take someone in without engendering too much embarrassment. There are two main factors at play in the near field: - Interefernce between the fields emanated by the two monopoles - The evanecent components of the plane-wave expansion of the spherical wave field. The former is wave theory 101 material; the latter is wave theory 102. The fundamental effect is intereference: The dipole is a superporsition of monopoles (wave theory 101). There is nothing else at play. The definition of a dipole, is a pair of monopoles that emits the same signal at the same time - possibly with different scalar weights. Again, WT 101. Th edefinition of 'near field' is the space where wave form arrive forms arrive from the two dipoles at notably different directions - WT 101. The analytic study of this interefernce, is a mess, for a number reasons: 1) The analytic study of spherical Bessel functions is messy 2) Converting the Bessels to plane waves is even more messy 3) By 1) and 2) it becomes difficult to decomose the field at (x,y,z) in terms of components arriving form the individual monopoles 4) Since no one decomoposes the wavefield in said way, no one obtain the detailed understanding of what exactly goes on. So there are no convenient ways to find out the detailed behaviour of the field. But there is no need to, since the basic mechanism is so simple: Interference, possibly combined with oblique observation. Again, except for the plane-wave representation of the spherical Bessel functions, all of this is wave theory 101. Rune
From: Eric Jacobsen on 26 Mar 2010 18:19 On 3/26/2010 2:31 PM, Rune Allnor wrote: > On 26 Mar, 22:02, Jerry Avins<j...(a)ieee.org> wrote: >> Rune Allnor wrote: >>> On 24 Mar, 01:20, Eric Jacobsen<eric.jacob...(a)ieee.org> wrote: >>>> On 3/23/2010 4:51 PM, Rune Allnor wrote: >> >>>> You sim doesn't run very well under my version of Octave, but the bit >>>> about the phase velocity on oblique angles is fundamental. >> >> I don't think the illusion is based on obliquity. Walter is wrong about >> faster-than-light signaling, but he's not naive. > > Agreed. He seems to be far worse off than that. > >> Close in, the near >> field predominates, but it fades faster than the far field, so there's a >> transition as the distance from the antenna increases. There's a net >> shift of pi/2 when shifting between the two field components. That's >> subtle enough to take someone in without engendering too much embarrassment. > > There are two main factors at play in the near field: > > - Interefernce between the fields emanated by the two monopoles > - The evanecent components of the plane-wave expansion of > the spherical wave field. > > The former is wave theory 101 material; the latter is wave > theory 102. > > The fundamental effect is intereference: The dipole is a > superporsition of monopoles (wave theory 101). There is > nothing else at play. The definition of a dipole, is > a pair of monopoles that emits the same signal at the > same time - possibly with different scalar weights. > Again, WT 101. > > Th edefinition of 'near field' is the space where wave > form arrive forms arrive from the two dipoles at notably > different directions - WT 101. The analytic study of this > interefernce, is a mess, for a number reasons: > > 1) The analytic study of spherical Bessel functions is messy > 2) Converting the Bessels to plane waves is even more messy > 3) By 1) and 2) it becomes difficult to decomose the field > at (x,y,z) in terms of components arriving form the > individual monopoles > 4) Since no one decomoposes the wavefield in said way, > no one obtain the detailed understanding of what > exactly goes on. > > So there are no convenient ways to find out the detailed > behaviour of the field. But there is no need to, since the > basic mechanism is so simple: Interference, possibly > combined with oblique observation. > > Again, except for the plane-wave representation of the > spherical Bessel functions, all of this is wave theory 101. > > Rune That also explains why it can be simulated numerically. If there was something funky going on, like virtual photons, one would think a numerical simulation wouldn't show it because it wouldn't be included in the math. The first yellow flag here was that numerical simulations were being used to demonstrate the effect of something unknown and unexplained. -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com
From: WWalker on 26 Mar 2010 20:35 Rune, Are the insults really necessary! This is a serious discussion and the concepts are not easy. It is a complex system. I garentee no one knows exactly what is going on in this system. Insults and ridicule are simply childish and unbecomming in an intelectual discussion. Regarding your two monopole model, this is a mathematical approximation. Remember this is modelling an oscillating electron, which is not really composed of two charges spaced a fixed length apart. This is just a mathematical model which enables one to calculate the fields at a distance much larger than oscilation amplitude of the oscillating charge. As you get near the electron, this model breaks down and is not valid. To determine the filds near a dipole, one can use the Liénard-Wiechert potentials. William >On 26 Mar, 22:02, Jerry Avins <j...(a)ieee.org> wrote: >> Rune Allnor wrote: >> > On 24 Mar, 01:20, Eric Jacobsen <eric.jacob...(a)ieee.org> wrote: >> >> On 3/23/2010 4:51 PM, Rune Allnor wrote: >> >> >> You sim doesn't run very well under my version of Octave, but the bit >> >> about the phase velocity on oblique angles is fundamental. >> >> I don't think the illusion is based on obliquity. Walter is wrong about >> faster-than-light signaling, but he's not naive. > >Agreed. He seems to be far worse off than that. > >> Close in, the near >> field predominates, but it fades faster than the far field, so there's a >> transition as the distance from the antenna increases. There's a net >> shift of pi/2 when shifting between the two field components. That's >> subtle enough to take someone in without engendering too much embarrassment. > >There are two main factors at play in the near field: > >- Interefernce between the fields emanated by the two monopoles >- The evanecent components of the plane-wave expansion of > the spherical wave field. > >The former is wave theory 101 material; the latter is wave >theory 102. > >The fundamental effect is intereference: The dipole is a >superporsition of monopoles (wave theory 101). There is >nothing else at play. The definition of a dipole, is >a pair of monopoles that emits the same signal at the >same time - possibly with different scalar weights. >Again, WT 101. > >Th edefinition of 'near field' is the space where wave >form arrive forms arrive from the two dipoles at notably >different directions - WT 101. The analytic study of this >interefernce, is a mess, for a number reasons: > >1) The analytic study of spherical Bessel functions is messy >2) Converting the Bessels to plane waves is even more messy >3) By 1) and 2) it becomes difficult to decomose the field > at (x,y,z) in terms of components arriving form the > individual monopoles >4) Since no one decomoposes the wavefield in said way, > no one obtain the detailed understanding of what > exactly goes on. > >So there are no convenient ways to find out the detailed >behaviour of the field. But there is no need to, since the >basic mechanism is so simple: Interference, possibly >combined with oblique observation. > >Again, except for the plane-wave representation of the >spherical Bessel functions, all of this is wave theory 101. > >Rune >
From: Eric Jacobsen on 26 Mar 2010 23:34 On 3/26/2010 4:42 PM, WWalker wrote: > Eric, > > Figure 2 in the Sten paper clearly shows that the pulse distorts in the > nearfield making it impossible to say anything about the speed of the > pulse. Only a narrowband signal will propagate undistorted from the > nearfield to the farfield. I asked about this previously and you did not respond. If you cannot say anything about the speed of the pulse in the near field due to "distortion", how can you claim that it is faster than c? The "distortion" appears to be understood according to the Sten paper, and not inconsistent with group delay effects. > Regarding your comments on adding nonharmonic signals to create the > modultion, even Mathematica cannot curvefit to the known equation. Check it > for yourself. The Mathematica curvefitting code is below. Note there are > many parrameters to fit and it is not able to do it, so it is not so easy! I don't have Mathematica, and don't have any intent to use it, so I don't really care about its shortcomings. > fn = Ao Cos[Wo*t + phc]*(Cm + A1*Cos[W1*t + phm1] + A2*Cos[W2*t + phm2]) > > Curvefit = > FindFit[points, fn, {Ao, A1, A2, phc, phm1, phm2, Cm, Wo, W1, W2}, t] > > Never the less, we do not need to discuss this any further because the same > superluminal behavior is observed in my newest simulation which uses a > random noise generator with a low pass filter. This latest test signal is > clearly nondeterministic. That's an improvement, but probably still not sufficient. It seems to me you're not paying attention to advice here. Good luck. > > > ----------------Mathematica Curvefitting Program---------------- > Gen Sig > AM = Cos[Wc*t + 0.1]*(3 + Am1*Cos[Wm1*t + 0.2] + Am2*Cos[Wm2*t + 0.2]) > Wc = 2 Pi fc; Wm1 = 2 Pi fm1; Wm2 = 2 Pi fm2; > Am1 = 1; Am2 = 1.7; > fc = 500*10^6; fm1 = 50*10^6; fm2 = 22.7*10^6; > Amp = 1; DT = 100*10^(-9); T = 100*10^(-9); > Envelope = (3 + Am1*Cos[Wm1*t + 0.2] + Am2*Cos[Wm2*t + 0.2]); > Plot[{Envelope, AM}, {t, 0, DT}] > Plot[AM, {t, 0, T}, PlotPoints\:f0ae2000] > points = Table[{t, N[AM]}, {t, 0, DT, T/2000}]; > plotpoints = ListPlot[points, PlotStyle -> PointSize[0.016/2]] > Curve Fit Sig > fn = Ao Cos[ > Wo*t + phc]*(Cm + A1*Cos[W1*t + phm1] + A2*Cos[W2*t + phm2]) > Curvefit = > FindFit[points, fn, {Ao, A1, A2, phc, phm1, phm2, Cm, Wo, W1, W2}, t] > Compare Sig with Curve Fit Sig > PlotCurve = Plot[fn /. Curvefit, {t, 0, T}, PlotPoints -> 10]; > Show[plotpoints, PlotCurve] > DetEnvelope = > 3 + A1*Cos[Wm1*t + phm1] + A2*Cos[Wm2*t + phm2] /. Curvefit > Plot[DetEnvelope, {t, 0, DT}] > Plot[{DetEnvelope, AM}, {t, 0, DT}] > Plot[{Envelope, DetEnvelope}, {t, 0, DT}] > -----------------End Mathematica Curvefitting Program------------ > > Regading your comment that the dipole is a filter, it is not a filter. The > dipole system has a dispersion curve. A signal can be decomposed into > frequency components and when the signal is sent through a dipole each > frequency component experiences a different wave phase speed. If the wave > phase speed is different for different frequencies then the signal will > distort as it propagates, as it does for a wideband pulse. If the wave > phase speed is the same for all the frequency components of the signal, > then the signal will not distort as it propagates. This is what happens for > a narrow band AM signal. > > Regarding your comment on Andor's paper, the circuit is not predicting the > signal, it is just phase shifting it. The filter has a phase curve and each > frequency component of the signal is being phase shifted. If each frequency > component is phase shifted the same amount, then the signal will phase > shift undistorted. This is very different from a time delay due to wave > propagation, as is observed in the dipole system. > > William > > >> On 3/25/2010 9:01 AM, WWalker wrote: >>> Jerry, >>> >>> I have tested real dipole antennas using a RF Network analyser and > after >>> compensating for the electrical filter characteristics of the antenna, > I >>> get the nonlinear dispersion curves shown in my paper. The nonlinear >>> dispersion is a real observable and measureable phenomina. >>> >>> Here is another paper that presents an NEC RF numerical analysis on a >>> dipole and shows the nonlinear nearfield dispersion is real and >>> observable: >>> http://ceta.mit.edu/pier/pier.php?paper=0505121 >>> >>> William >> >> FWIW, a quick read of that paper seems to support exactly what Jerry and >> I and others have been saying. The phase response of the near-field >> makes it behave similarly to a filter with negative group delay. The >> author even points this out about Fig. 2b, where the pulse appears to >> accelerate. >> >> It is not at all hard to believe that dispersion that leads to apparent >> non-causal behavior in passive or active filters could also seem to >> appear as signal propagation faster than c. >> >> >>>> Eric Jacobsen wrote: >>>> >>>> ... >>>> >>>>> Dipoles are actually bandpass filters with a center frequency > determined >>> >>>>> by the length of the dipole as related to the wavelength of the > carrier. >>> >>>>> Efficiency drops off significantly as the wavelength changes >>>>> substantially from the resonant length of the dipole. >>>> >>>> Herein lies the fallacy that is at the heart of what I see as self >>>> deception. Eric describes a real dipole, while Walter's simulation is >>>> constructed around an ideal one. An ideal dipole is a limit as the >>>> length of a real dipole goes to zero while the power it radiates > remains >>>> constant. (Compare to an impulse: a pulse whose width goes to zero > while >>>> its area remains constant.) Such abstractions are useful for brushing >>>> aside irrelevant details while retaining relevant relationships. They >>>> remain useful only so long as the ignored details remain irrelevant. > For >>>> example, it is inappropriate to inquire about the voltage gradient > along >>>> an ideal diode. >>>> >>>> An example might clarify the limit of an abstraction's utility. > Consider >>>> a ball bouncing on a flat surface, such that every bounce's duration > is >>>> 90% of that of the previous bounce. The ball is initially dropped from >>>> such a height that the first bounce lasts exactly one second. It is > not >>>> difficult to show that the ball will come to rest after ten seconds. > In >>>> that interval, how many times will the ball bounce? >>>> >>>> In dipoles, the extents of the near field are related to the > dimensions >>>> of the dipole. We can expect an ideal dipole, having zero length, to >>>> have a very peculiar calculated near field. >>>> >>>> ... >>>> >>>> Jerry >>>> -- >>>> Discovery consists of seeing what everybody has seen, and thinking > what >>>> nobody has thought. .. Albert Szent-Gyorgi >>>> > ����������������������������������������������������������������������� >>>> >> >> >> -- >> 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 27 Mar 2010 06:47
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 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 >On 3/26/2010 4:42 PM, WWalker wrote: >> Eric, >> >> Figure 2 in the Sten paper clearly shows that the pulse distorts in the >> nearfield making it impossible to say anything about the speed of the >> pulse. Only a narrowband signal will propagate undistorted from the >> nearfield to the farfield. > >I asked about this previously and you did not respond. If you cannot >say anything about the speed of the pulse in the near field due to >"distortion", how can you claim that it is faster than c? > >The "distortion" appears to be understood according to the Sten paper, >and not inconsistent with group delay effects. > >> Regarding your comments on adding nonharmonic signals to create the >> modultion, even Mathematica cannot curvefit to the known equation. Check it >> for yourself. The Mathematica curvefitting code is below. Note there are >> many parrameters to fit and it is not able to do it, so it is not so easy! > >I don't have Mathematica, and don't have any intent to use it, so I >don't really care about its shortcomings. > >> fn = Ao Cos[Wo*t + phc]*(Cm + A1*Cos[W1*t + phm1] + A2*Cos[W2*t + phm2]) >> >> Curvefit = >> FindFit[points, fn, {Ao, A1, A2, phc, phm1, phm2, Cm, Wo, W1, W2}, t] >> >> Never the less, we do not need to discuss this any further because the same >> superluminal behavior is observed in my newest simulation which uses a >> random noise generator with a low pass filter. This latest test signal is >> clearly nondeterministic. > >That's an improvement, but probably still not sufficient. It seems to >me you're not paying attention to advice here. > >Good luck. > > >> >> >> ----------------Mathematica Curvefitting Program---------------- >> Gen Sig >> AM = Cos[Wc*t + 0.1]*(3 + Am1*Cos[Wm1*t + 0.2] + Am2*Cos[Wm2*t + 0.2]) >> Wc = 2 Pi fc; Wm1 = 2 Pi fm1; Wm2 = 2 Pi fm2; >> Am1 = 1; Am2 = 1.7; >> fc = 500*10^6; fm1 = 50*10^6; fm2 = 22.7*10^6; >> Amp = 1; DT = 100*10^(-9); T = 100*10^(-9); >> Envelope = (3 + Am1*Cos[Wm1*t + 0.2] + Am2*Cos[Wm2*t + 0.2]); >> Plot[{Envelope, AM}, {t, 0, DT}] >> Plot[AM, {t, 0, T}, PlotPoints\:f0ae2000] >> points = Table[{t, N[AM]}, {t, 0, DT, T/2000}]; >> plotpoints = ListPlot[points, PlotStyle -> PointSize[0.016/2]] >> Curve Fit Sig >> fn = Ao Cos[ >> Wo*t + phc]*(Cm + A1*Cos[W1*t + phm1] + A2*Cos[W2*t + phm2]) >> Curvefit = >> FindFit[points, fn, {Ao, A1, A2, phc, phm1, phm2, Cm, Wo, W1, W2}, t] >> Compare Sig with Curve Fit Sig >> PlotCurve = Plot[fn /. Curvefit, {t, 0, T}, PlotPoints -> 10]; >> Show[plotpoints, PlotCurve] >> DetEnvelope = >> 3 + A1*Cos[Wm1*t + phm1] + A2*Cos[Wm2*t + phm2] /. Curvefit >> Plot[DetEnvelope, {t, 0, DT}] >> Plot[{DetEnvelope, AM}, {t, 0, DT}] >> Plot[{Envelope, DetEnvelope}, {t, 0, DT}] >> -----------------End Mathematica Curvefitting Program------------ >> >> Regading your comment that the dipole is a filter, it is not a filter. The >> dipole system has a dispersion curve. A signal can be decomposed into >> frequency components and when the signal is sent through a dipole each >> frequency component experiences a different wave phase speed. If the wave >> phase speed is different for different frequencies then the signal will >> distort as it propagates, as it does for a wideband pulse. If the wave >> phase speed is the same for all the frequency components of the signal, >> then the signal will not distort as it propagates. This is what happens for >> a narrow band AM signal. >> >> Regarding your comment on Andor's paper, the circuit is not predicting the >> signal, it is just phase shifting it. The filter has a phase curve and each >> frequency component of the signal is being phase shifted. If each frequency >> component is phase shifted the same amount, then the signal will phase >> shift undistorted. This is very different from a time delay due to wave >> propagation, as is observed in the dipole system. >> >> William >> >> >>> On 3/25/2010 9:01 AM, WWalker wrote: >>>> Jerry, >>>> >>>> I have tested real dipole antennas using a RF Network analyser and >> after >>>> compensating for the electrical filter characteristics of the antenna, >> I >>>> get the nonlinear dispersion curves shown in my paper. The nonlinear >>>> dispersion is a real observable and measureable phenomina. >>>> >>>> Here is another paper that presents an NEC RF numerical analysis on a >>>> dipole and shows the nonlinear nearfield dispersion is real and >>>> observable: >>>> http://ceta.mit.edu/pier/pier.php?paper=0505121 >>>> >>>> William >>> >>> FWIW, a quick read of that paper seems to support exactly what Jerry and >>> I and others have been saying. The phase response of the near-field >>> makes it behave similarly to a filter with negative group delay. The >>> author even points this out about Fig. 2b, where the pulse appears to >>> accelerate. >>> >>> It is not at all hard to believe that dispersion that leads to apparent >>> non-causal behavior in passive or active filters could also seem to >>> appear as signal propagation faster than c. >>> >>> >>>>> Eric Jacobsen wrote: >>>>> >>>>> ... >>>>> >>>>>> Dipoles are actually bandpass filters with a center frequency >> determined >>>> >>>>>> by the length of the dipole as related to the wavelength of the >> carrier. >>>> >>>>>> Efficiency drops off significantly as the wavelength changes >>>>>> substantially from the resonant length of the dipole. >>>>> >>>>> Herein lies the fallacy that is at the heart of what I see as self >>>>> deception. Eric describes a real dipole, while Walter's simulation is >>>>> constructed around an ideal one. An ideal dipole is a limit as the >>>>> length of a real dipole goes to zero while the power it radiates >> remains >>>>> constant. (Compare to an impulse: a pulse whose width goes to zero >> while >>>>> its area remains constant.) Such abstractions are useful for brushing >>>>> aside irrelevant details while retaining relevant relationships. They >>>>> remain useful only so long as the ignored details remain irrelevant. >> For >>>>> example, it is inappropriate to inquire about the voltage gradient >> along >>>>> an ideal diode. >>>>> >>>>> An example might clarify the limit of an abstraction's utility. >> Consider >>>>> a ball bouncing on a flat surface, such that every bounce's duration >> is >>>>> 90% of that of the previous bounce. The ball is initially dropped from >>>>> such a height that the first bounce lasts exactly one second. It is >> not >>>>> difficult to show that the ball will come to rest after ten seconds. >> In >>>>> that interval, how many times will the ball bounce? >>>>> >>>>> In dipoles, the extents of the near field are related to the >> dimensions >>>>> of the dipole. We can expect an ideal dipole, having zero length, to >>>>> have a very peculiar calculated near field. >>>>> >>>>> ... >>>>> >>>>> Jerry >>>>> -- >>>>> Discovery consists of seeing what everybody has seen, and thinking >> what >>>>> nobody has thought. .. Albert Szent-Gyorgi >>>>> >> ����������������������������������������������������������������������� >>>>> >>> >>> >>> -- >>> Eric Jacobsen >>> Minister of Algorithms >>> Abineau Communications >>> http://www.abineau.com >>> > > >-- >Eric Jacobsen >Minister of Algorithms >Abineau Communications >http://www.abineau.com > |