How to get envelope from AM signal without phase shift
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From: Vladimir Vassilevsky on 22 Mar 2010 21:16 Randy Yates wrote: > Rune Allnor <allnor(a)tele.ntnu.no> writes: > >>[...] >>I can guarantee that you will find that the transients >>propagate down range with a speed exactly equal to c. > > > <chuckle> It looks like there is more and more of them every day. Scarry. VLV
From: Eric Jacobsen on 23 Mar 2010 02:35 On 3/22/2010 5:12 PM, WWalker wrote: > I dissagree. > > Simulation results show that if you add two signals with different > frequencies and differnt amplitudes, the resultant signal changes in a > random way as far as a detector is concerned. If the signal is modulated > with a carrier and transmitted by a dipole antenna to another dipole > antenna in the nearfield, the envelope of the received signal arrives > undistorted, faster than light. This is because for a narrowband AM signal, > the dispersion curve (phase and amplitude) is linear over the bandwidth of > the signal. Provided the SNR is high enough, the random modulation > information can then be decoded by dividing by the carrier. Comparing the > transmitted modulation to the received modulation clearly shows that the > modulation propagates undistorted, faster than light in the nearfield. > > But if a pulse is transmitted in the nearfield the pulse will distort > because the dispersion curve (phase and amplitude) is not linear over the > bandwidth of the signal, so group speed has no meaning in the nearfield. > But in the farfield, the pulse will realign and propagate without > distortion at the speed of light, so the pulse group speed only has meaning > in the farfield. > > William Mixing top and bottom posting is very bad form and makes your responses difficult to read, or at least very difficult to sort out the logic train you're responding to. So what carries the information faster than light? Clearly it can't be an EM photon, since they're inherently limited to c. If it's not via EM photons, how does the energy get from the transmit to the receive antenna? > >> On 22 Mar, 22:43, "WWalker"<william.walker(a)n_o_s_p_a_m.imtek.de> >> wrote: >>> Hi Rune, >>> >>> What ever the the reason for this phenomina, given the known and > excepted >>> transfer function of a dipole source, It should be possible to transmit >>> information faster than light by transmitting an AM signal in the > nearfield >>> and decoding the modulation. Simmulations clearly show that the envelope > of >>> an AM signal will arrive faster than light and undistorted in the >>> nearfield. What is needed now is to find a way to decode the modulation >>> within a fraction of (<1/10) a carrier cycle. >> >> Wrong. >> >> Your simulations use fixed-parameter sinusoidals and have >> as such nothing to do with information, only steady states. >> Everything is known all the time; there is nothing new to >> be learned from observing the wave field. Hence, no >> information is transmitted. >> >> If you want to transmit *information*, you need to change >> something in the wavefield: The amplitude, the frequency >> or the phase. Something that is not known, that the reciever >> has to lock on to, detect and quantify. It is this *transient* >> change to an *unknown* state that carries the information down >> range between transmitter and reciever. >> >> I can guarantee that you will find that the transients >> propagate down range with a speed exactly equal to c. >> >> Rune >> -- Eric Jacobsen Minister of Algorithms Abineau Communications http://www.abineau.com
From: Rune Allnor on 23 Mar 2010 04:57 On 23 Mar, 01:12, "WWalker" <william.walker(a)n_o_s_p_a_m.imtek.de> wrote: > I dissagree. > > Simulation results show that if you add two signals with different > frequencies and differnt amplitudes, the resultant signal changes in a > random way as far as a detector is concerned. That's the interference. In a steady-state condition. Interference is hard to quantify because it is chaotic: Make the slightest change in any of the initial conditions or environmental parameters, and it causes a total chance of the resulting interfernce pattern. > If the signal is modulated > with a carrier and transmitted by a dipole antenna to another dipole > antenna in the nearfield, the envelope of the received signal arrives > undistorted, faster than light. No, it doesn't. The amateur might have a look at the interference and get such ideas, but the professional will be aware of observations of the wave field at oblique angles from the propagation. This is a simple excercise, that can even be simulated: Start out with a 2D plane wave propagating in the x direction: s(t,x,y) = sin( 2pi f(t - x/c) ) Then observe it along a line through (0,0) that intersects the wavefield at an angle with the x axis, phi. If phi = 0, you will see an apparent wavelength, lambda', along the line that equals the free field wavelength lambda = c / f. Change the angle of the observation line, and find that the apparent wavelength equals lambda' = lambda / cos(phi) Run a simulation of how the observation changes with time, and find that the *apparent* speed c' of the wave along the observation line equals c' = lambda' f = lambda f / cos (phi) = c / cos(phi). It's a ridiculously simple trap, but it seems you have fallen into it. Rune
From: Rune Allnor on 23 Mar 2010 05:04 On 23 Mar, 02:16, Vladimir Vassilevsky <nos...(a)nowhere.com> wrote: > Randy Yates wrote: > > Rune Allnor <all...(a)tele.ntnu.no> writes: > > >>[...] > >>I can guarantee that you will find that the transients > >>propagate down range with a speed exactly equal to c. > > > <chuckle> > > It looks like there is more and more of them every day. > Scarry. I don't know if you have looked at the paper he has referred to a couple of times. He claims that he at some time was affiliated with NTNU. I am not at all surprised - this kind of stuff is just what I would expect from that place. Once upon a time I asked what the procedure is to hand back my PhD diplomas etc, as I didn't want more affiliations with them than absolutely necessary. Cut as many ties as possible. It turned out there were no such procedures. So one needs to be acutely cautious about whose company one seeks - their stain might last a lifetime. Rune
From: steveu on 23 Mar 2010 05:29
>On 23 Mar, 02:16, Vladimir Vassilevsky <nos...(a)nowhere.com> wrote: >> Randy Yates wrote: >> > Rune Allnor <all...(a)tele.ntnu.no> writes: >> >> >>[...] >> >>I can guarantee that you will find that the transients >> >>propagate down range with a speed exactly equal to c. >> >> > <chuckle> >> >> It looks like there is more and more of them every day. >> Scarry. > >I don't know if you have looked at the paper he has referred >to a couple of times. He claims that he at some time was >affiliated with NTNU. I am not at all surprised - this kind >of stuff is just what I would expect from that place. > >Once upon a time I asked what the procedure is to hand back >my PhD diplomas etc, as I didn't want more affiliations with >them than absolutely necessary. Cut as many ties as possible. > >It turned out there were no such procedures. So one needs to >be acutely cautious about whose company one seeks - their stain >might last a lifetime. You're being too negative. I think he's on to something, and will produce the ideal advanced communications system to showcase my new infinite gain bandwidth amplifier. Steve |