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Very short distance Ms

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    Very short distance Ms

    I wonder how short Ms can get in terms of distances. The Geminids were quite active here, with catches from the usual places -- the Dakotas, Carolinas, Arkansas, and such. But what really grabbed my attention this time is the short-haul nature of some catches. MP3 audio files are attached, with written descriptions below. Times EST, from Burnt River ON (100 miles northeast of Toronto).

    101.7 CKNX ON Wingham – Dec 13 at 2210: “104 Suncoast Drive in Goderich and online”. There is such an address in Goderich ON, so this without doubt is CKNX. But CKNX is the semi-local I have managed to nicely null to create an open channel that did well throughout the Geminids. For whatever reason, CKNX seemed weaker than usual, likely due to unstable weather, and thus unusually easy to null. I even managed a nice ID out of 720-watt WGOG in Walhalla SC. The voice is familiar. Note the sudden, choppy nature of this burst. It’s certainly not groundwave or troposcatter. The question is, is it meteor scatter, or some other scatter — say airplane? It’s roughly 144 miles.

    101.7 WLOF NY Elma — Dec 13 at 2258: “Station of the Cross” ID in this burst. WLOF is also a minor pest on 101.7. Usually when CKNX is nulled, WLOF is usually in second place. But this, like CKNX above, is a clear burst. It’s roughly 131 miles.

    101.7 WHOF OH North Canton — Dec 13 at 2123: “…station Sunny 101 point…” I’ve had this one by tropo once or twice. But northeast Ohio is a place I associate more with troposcatter than with meteor scatter. Roughly 297 miles.

    101.7 WOWY PA Central City — Dec 12 at 2143: A pretty sudden “Wowie” and the start of a Billy Joel song. At about 318 miles this starts to feel more like the usual very short-end of typical Ms mileage.

    Curious if this sparks any discussion. I’m counting WOWY as actual meteor scatter. But I’m still a little unsettled about categorizing the others. Troposcatter almost always presents as a fade up. Sometimes these fade-ups happen pretty quickly. But never so abruptly and choppy in nature as in these clips. I did record other channels. Nothing IDed on those other channels of this short-haul nature. Thoughts, anyone?​
    Attached Files

    #2
    I've had meteor scatter as close as 282 miles but nothing closer. Based on that I'd be inclined to think WHOF could be meteor scatter as well.

    Comment


      #3
      I would first classify all of these receptions as meteor scatter. Definitely Ms on CKNX. I opened the file in Wavepad because I wanted to see the graphical appearance of how the signal arrived. Way too abrupt to be any other mode of reception. Ditto on the others.

      Comment


        #4
        I'm inclined to agree about it not being TrS. But I wonder what other factors create scatter like this. I'll quickly and decidedly rule out Lightning Scatter. I've actually IDed for stations by Ls. These are even more abrupt than Ms, and very brief -- they time pretty neatly to observed lightning flashes and crackling on the radio (I use indoor antennas for this). But there were no storms and the signals also do not even closely resemble Ls. But what about airplane scatter? Or perhaps other causes of a mode that sounds and presents like Ms? I know there's often talk of back-scatter. But I've never really read anything that has - to my mind at least - satisfactorily explained what it sounds like, what causes it, how it presents, and such.

        Comment


          #5
          It seems the only viable alternative would be airplane scatter. The signals arrive quickly and aren't chopped up the way a lot of meteor scatter signals sound. IF that is the case, this type of reception should occur often and not in connection with regular meteor showers. I would be checking the dial during noted times of reception for repeats. Airplanes are on a schedule for flights.

          Comment


            #6
            I also have comparable receptions from other years. The Buffalo area, for instance, at about 122 miles (clip from 107.7 Wethersfield NY). And these two clips from CIQM London ON, at about 172 miles. These are rough distances between towns/cities via mapping tools, not actual coordinates but close enough for discussion purposes here. I know I'm not alone. Andrew Knafel from OH was at his Kingston ON area DX site and recorded 103.5 in Orangeville ON via a clear burst-type I would agree sounds very much like Ms (and probably is).
            Attached Files

            Comment


              #7
              This is an area where FM DXers might well be able to contribute to the scientific literature and understanding of meteor scatter propagation.

              If you start with Google searches, the majority of your sources will be from those involving amateur radio communications or military applications. These communications are based on experience and scientific studies on two-way communication. Most will cite 500 KM (210 miles) as the minimum distance.

              I personally have dozens of signals under 200 miles that are meteor scatter on the FM band.

              A better source for study might be findings related to the SNOTEL system. The United States Department of Agriculture (USDA) used meteor scatter extensively to report snow water totals system for over 40 years but discontinued this use in 2023.
              Some of these transmitters were within 120 miles of the receiving data center.

              Airplane scatter can also be responsible for many of the short-haul receptions that we attribute to Ms. Unlike, lightning scatter (Ls) they don't have a distinctive sound so it's almost impossible to eliminate them except through repeated receptions of short range Ms signals (pattern recognition).

              Lots of great books on the subject for those who are truly interested:

              Meteor Science and Engineering by D.W.R. McKinley

              Meteor Burst Communications by Jacob Z. Schanker

              Meteors by Charles P. Oliver

              and many, many more. Considerable scientific literature has also been published online. Reading all this material led me to devote an FM6 antenna to full-time Ms work, tilting it at 45° for optimum reception and to reduce the noise floor by pointing the antenna at 'cold sky.' This was based on experiments conducted by a Japanese PhD candidate.

              FM DXers might be able to contribute more information in this field. As it pertains to optics, there is no "minimum" angle; the angle of reflection will always be equal to the angle of incidence, regardless of how small the angle is.

              Does that hold true for ionized particles of a meteor trail reflecting radio signals? It's not clear. But I would hazard a guess that if it isn't zero, it's very close to it. It hasn't been widely studied because there are no practical applications for meteor burst communication at those distances. No applications means very little impetus for a study.

              But amateurs and hobbyists can afford to indulge their own curiosity and that can contribute to science too. This is my favorite form of radio propagation, can you tell?​

              Comment

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