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Hearing myself respond to my Call

Discussion in 'Amateur Radio News' started by KE0VH, Oct 21, 2002.

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  1. KE4PJW

    KE4PJW Premium Subscriber QRZ Page

    </span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (w1it @ Oct. 31 2002,18:37)</td></tr><tr><td id="QUOTE">If somehow a radio wave could exceed the speed of light, than BINGO it would travel backwards in space/time and maybe become an LDE ?
    [/QUOTE]<span id='postcolor'>

    Maybe it's because I have a rudimentary understanding of space/time, but I don't see how the velocity of ANYTHING can be FTL using space/time. It is my understanding that in order for this to happen, you need more than the 4 known dimensions of space/time. (Think string theory)

    </span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (w1it @ Oct. 31 2002,18:37)</td></tr><tr><td id="QUOTE">
    In any event the theories that these signals travel to the Sun and are reflected is silly. Even if they could they would be so weak on return, they could not be heard.[/QUOTE]<span id='postcolor'>


    I never heard anyone say that the signals traveled to the sun and back. Heck the sun is 8.3 light minutes away. That's almost a 17 minute round trip. I guess I could do the math and see what the path loss would be of objects 4 light seconds away. If the object has a 100% HF radio reflective quality, there might be a chance of it being possible.

    My next best guess as to what LDEs are, is the radio signal keeps hopping around the globe on paths that eventually make it back to the source several seconds later.

    -- Terry
     
  2. K4LEM

    K4LEM Ham Member QRZ Page

    </span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (K2KVS @ Nov. 01 2002,20:00)</td></tr><tr><td id="QUOTE">[True only for an isotropic source (point source). With a properly shaped antenna (parabolic dish) the only dimunition in signal strength with distance is caused by the imperfections in the dish and internal radiation pressure. The "dish" at Areceibo can get to the other end of the Milky Way (takes a while, though&#33[​IMG]


    Incidentally, one of the papers proposes a mechanism whereby a signal would be "trapped" in the ionosphere and could release it later, anywhere from seconds to hours later. It seems a little bogus to me. Nice convenient explanation, but the physics seemed very vague. [​IMG]

    73

    Larry K2KVS[/QUOTE]<span id='postcolor'>
    Larry, I want to argue one of your points. Yes, a large antenna can act as a lens and direct energy in a specific direction. This is what allows for the engineering term Effective radiated Power. One of our local FM stations has a 7 kw transmitter, yet boasts 50 kw ERP. The reason is the antenna is essentailly non directional in azimuth ( wouldn't want to exclude any listeners), but as compared with the isotropic antenna, the antenna takes all that high vertical plane energy and concentrates it within a few degrees of the horizon. Thus the 50 kw figure is realative and uses an isotrpic antenna for that (big gain) increase. BUT.. the fact we live in what appears as a three space Universe, means any light or radiowaves etc. departing an antenna spread out inverse squarely with range. This the big antenna in KP4 gives a very large ERP, but the radiated energy is still subject to inverse square law. It just squirts more energy at a given point in space.

    Now, even with ERP such and ten power to 9 in watts or better, after traveling 50,000 light years, that signal is quite faint. In fact I think if a dish were on opposite side of galaxy it would need be same size as Acricebo to detect it ! In communications rx and tx antenna gains may be added as in simple alegra or arthimetic. [​IMG]
     
  3. K4LEM

    K4LEM Ham Member QRZ Page

    </span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (ke4pjw @ Nov. 01 2002,20:11)</td></tr><tr><td id="QUOTE">Maybe it's because I have a rudimentary understanding of space/time, but I don't see how the velocity of ANYTHING can be FTL using space/time. It is my understanding that in order for this to happen, you need more than the 4 known dimensions of space/time. (Think string theory)

    [[/QUOTE]<span id='postcolor'>
    I don't think you need string theory, which as I understand it is on good theoretical ground but very shacky empirical ground since it cannot be accomdated with other basic laws in physics. As for velocity, and time, distance being related recall velocity is only a concept and equals D/T, in other words so many units distance per unit of time.
    Einstein posulated and it has since found quite a bit of experimental evidence time is NOT unique. Time just says clocks in one frame of reference tick faster or slower than other clocks in relative motion to each other.
    The amazing thing here is if two space craft traveling at near speed of light pass each other and the one traveling opposite direction tries to measure the speed of a light beam or radio wave sent from the craft that just passed it, BOTH craft get same value for light speed.

    You might think that since light travels at light speed and the space craft also is traveling at light speed, the craft traveling in opposite direction would measure light at light speed MINUS its own velocity. But Einstein found otherwise. That's why time is unique to each and every frame of reference.
    No such thing as saying its such and such a time on Mars right now!
    [​IMG]
     
  4. W5HTW

    W5HTW Ham Member QRZ Page

    </span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (K2KVS @ Nov. 01 2002,20:00)</td></tr><tr><td id="QUOTE"></span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">his is thought to possibly be exploited for space "sailing"  starships.

    If somehow a radio wave could exceed the speed of light, than BINGO it would travel backwards in space/time and maybe become an LDE ?
    [/QUOTE]<span id='postcolor'>
    No, photons have zero mass. By definition, photons (light) travel at the speed of light. The notion of light travelling faster than light is a little confusing to me!

    Particles that travel faster than light (tachyons) have been conjectured but no proof of their existence is forthcoming as yet. If they did exist, and caused an LDE, wouldn't YOUR signal be an echo of the tachyon signal, which happens BEFORE you send?

    Hmmm.

    Incidentally, one of the papers proposes a mechanism whereby a signal would be "trapped" in the ionosphere and could release it later, anywhere from seconds to hours later. It seems a little bogus to me. Nice convenient explanation, but the physics seemed very vague. [​IMG]

    73

    Larry K2KVS[/QUOTE]<span id='postcolor'>
    If any of you get The NewScientist Newsletter, you may recall within the past month or so, an announcement that light waves have been propagated through something (I have forgotten what medium) at I think four times the accepted speed of light. Seems it's actually a technique that has been around a while, and I don't claim to understand it. If someone subscribes to that, in print edition, they may can look it up. I will try to research it on the New Scientist website, but I have not tried before to access back issues.

    Regarding "not having permission to access the Stanford U articles" - Yeah, I don't either. You have to, as the email says, "order them," which I believe means buy them. They are not available on line but are print articles you purchase, and I'm sure you pay for the time to dig them out and print them and mail them. Which is why this old retired fella isn't going to provide them here!! I just pointed out the location of them for you young rich guys and gals with the money to burn.

    And I can't tell ya what time it is on Mars right now? Nuts. Sure I can. It is exactly 12:56[​IMG]8 PM MST. Oh? You mean Martian Time? Nah, that's "many moons," and since Mars has more than one moon, that's multiple-moons of times. Time is arbitrary. It relates to where you are. If I could convince all of you folks (and the rest of the world) out there that this is Thursday at midnight, then that is what it would be. It is what we call it. This is Saturday 'cuz we sez so. Tain't written in the heavens above us. So if I land on Mars and I say "It's 9 AM" then, by gosh, it's 9 AM. Unless I found a Little Green Man who was bigger than me and he said it wasn't that way at all.

    But I can tell you what time it is right nowright here, and that that happens to be the time I am observing Mars. So I need a frame of reference and I become that frame. Where I am. From that I can pretty well figure out how long it took the image I am seeing to actually get here. But that isn't Martian time, at least not in my definition? It's my viewing Mars in MY time.

    Anyway, I don't think LDEs come from Mars! Or via Mars. Or a space ship coming from there, unless it's been one heck of a long time on the road. My guess is LDEs (the real ones, not Mr. Lid/DigicordEr) are a natural physics phenomena we simply haven't explored enough to figure it out. No one has enough interest in it to dedicate the millions of bucks it would take to reach some definitive answer.

    Anyway, it's a fun subject, and I'm glad everyone has enjoyed it. I have. Brought back some memories from years ago. And in saying that I should point out, though I am active on 20 meters almost daily, I have not heard a real LDE since at least 1970 or 72 or so. That isn't to say they don't exist anymore, but I am not in the right place at the right time, or am not sitting there sorting out the noise in the background.

    If I find the article on faster-than-light, from New Scientist, I may come back here and post a reference to it. Otherwise, I think the subject is running dry.

    Have fun

    73
    Ed
     
  5. K4LEM

    K4LEM Ham Member QRZ Page

    </span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (W5HTW @ Nov. 02 2002,13:04)</td></tr><tr><td id="QUOTE">If I find the article on faster-than-light, from New Scientist, I may come back here and post a reference to it.  Otherwise, I think the subject is running dry.  

    Have fun

    73
    Ed[/QUOTE]<span id='postcolor'>
    Yes, nice post and thanks for references. As a PhD student once told me when I told him a friend of mine ( not me) just got a C in physics, he said, " yes good, physics is HARD"

    But time is more than just an arbitrary saying its this or that. For time to exist in even the barest sense it has to relative to something. For example the ancients used seasons etc. Now, WWV and NBS uses atomic clocks and pulses of quanta (potons) from cesium atoms.

    The part I want to clarify is Einstein said clocks in different accelerated frames say time is different. For example if you took the best atomic clock to Mars and set it with an atomic clock on Earth before leaving, the two would not point to the same numbers. Sound strange yes, but our Universe is both wonderful and awesome at the same time. Its a wonder our puny minds comprehend as much as they do.
    That's what I met by no such thing as time on Mars when you're on Earth watching your WWV clocks!

    For example Einstein also said the Sun distorts space and time. Time runs slower and is curced in a gravitational field. Recall Newton's first law about linear motion in straight line unaccelerated forever unless acted upon by a force? Well, ever wonder why the Earth travels in a closed path about the Sun instead of running off in a straight line? Einstein said the Earth is traveling in a straight line relative to the Universe, but is in a closed curve ( orbit ) about the Sun because the Sun's gravity curves space and slows time.

    Now, I wonder if you were in empty space, would time have any meaning at all? If so relative to what? Think about it.
     
  6. WM5R

    WM5R Ham Member QRZ Page

    I, too, have heard a Long Delayed Echo. My admittedly small amount of research into the topic resulted in a 45-minute presentation at my local radio club. There is something of bibliography of QST articles at the end:

    Long Delayed Echoes
     
  7. K4LEM

    K4LEM Ham Member QRZ Page

    </span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (wm5r @ Nov. 05 2002,14:52)</td></tr><tr><td id="QUOTE">Long Delayed Echoes[/QUOTE]<span id='postcolor'>
    Of all the possibilities advanced, hoaxes and people not correctly interpreting what they hear are first line.
    Signals that travel long distances would be so faint upon return no HF receiver would hear them. The idea of an alien repeater is interesting, but IMHO not correct. If there are intelligent aliens they would not think as we do. That was brought into a rather scary frontline by the BORG. If there be aliens that can communicate with us two things are very clear, they are much more advanced than we, and entirely different in thought process. Thats why to expect a friendly or even communicating alien is a bit far fetched. [​IMG] [​IMG] [​IMG]
     
  8. WA4PTZ

    WA4PTZ XML Subscriber QRZ Page

    This condition is the result of LONG PATH propagation.
    Usually in the Spring and fall during the planets orbital
    transitions this condition occurs. In other words you can
    point your antenna in the opposite direction of the
    station you wish to work. Since there is a time delay
    it is sometimes enough to hear yourself, at least short
    bursts of yourself . This is not a new condition but is
    caught by being in the right place at the right time.
    It's fun and you can work some rare ones during long
    path.  Enjoy and 73 -  Tim
    [​IMG]
     
  9. VA6ZO

    VA6ZO Ham Member QRZ Page

    i had the same experience about 9 years ago on ten meters. very strange. my friend who i was talking to also heard the same thing, he heard the last few words of my transmission after i was done talking.could it be something like a scatter signal ? i have heard of airplane scatter , something to think of!
     
  10. N7DC

    N7DC Ham Member QRZ Page

    Its quite simple to do this. You record a wave file, and then play it back with a voice keyer. You can do it on the run at a moments notice. No its not LDEs , which are a real rarity, and would not include more than a few keyclicks, cw tones, or parts of words, if you were to ever hear them.
    [​IMG]
     
  11. N9WOS

    N9WOS Ham Member QRZ Page

    I read most of the thread and i have an idea.
    (Yes it's time to run and hide.) [​IMG]

    Think of the magnosphere that surrounds the planet.
    The densest magnetic fields are close to the planet but
    there is flux lines from the earth that extend way past the moon.

    They are part of the disturbance that the earth causes in space around it.

    If the solar wind hits one of the outer flux lines but isn't
    strong enough to obliterate it.
    You will have a nice parabola formed by the impact zone
    where the solar wind hits the flux line.

    It could be many times farther out than the moon and it will
    reflect a decent portion of the signal back with a delay of
    many seconds.

    (How's that for crackpot science?)  [​IMG]
     
  12. AC7WS

    AC7WS Guest

    If you tune into baseband audio (elf antenna and audio amp) you can hear "whistlers," "hooks," and other sounds that are lighting strikes (burst of RF) being delayed several seconds. The lowering tone of some of these is, I believe, dispersion in the transmission medium such that the lower frequencies are delayed more (and arrive later) in the "echo." Since this "long path" of several seconds is in a duct (not free space) the signal strength does not follow the square law for free space attenuation.

    It seems to me, all it takes to explain most all of the effects presented in these posts is assuming that HF signals can follow the same geomagnetic (and ionization?) ducts that are producing the ELF audio effects. Yes, the path lengths are quite long but the LDE for these low frequency signals is almost an "all the time" occurence. Searching "ELF signals" will lead you to some sites where you can listen in. Interesting!!

    N9WOS is on the same basic idea in his post.
     
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