RTW propagation or: Hearing my Own Signal LP

[Kim Elmore]

Since I'm at the radio and decided to look for my signal via RTW propagation again this morning. At 1634 UTC I can again hear my own dit with the same delay on 17, 15, 12, and 10 m! It's more apparent this morning when the antennas are pointed westward, it seems a bit stronger on beam headings about 70 deg, but clearly evident from NE to SE. I don't hear it as strongly on westerly headings. It is not evident on westerly headings on 12 or 10 m. I do not hear it on 20 m.

Have I been missing how common this is all these years? Are these conditions episodic and I'm just now noticing?

73,

Kim N5OP

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Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP SEL/MEL/Glider, UAS, N5OP, 2nd Class Radiotelegraph, GROL)

“People that make music together cannot be enemies, at least while the music lasts." – Paul Hindemith

[Ward Silver]

In my experience - just hamming and not researching - RTW is not uncommon but the radiated signal's elevation angle must be low, the GMF has to be relatively quiet, and the frequency will be on bands close to the MUF.  Under extraordinary conditions, multiple round-trips can be observed.  Once at the vernal equinox, I heard my QRP signal make it around 3 times, verified by a nearby friend, on 15 meter CW.  It's a really fun part of ham radio, experiencing the world in a way completely unknown to the vast majority of people!  Have fun!

73, Ward N0AX

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[Darrel]

In the last month or so I've been noticing a relatively strong RTW echo on my own signal at certain times of day, on both 20m and 17m.  Sometimes the echo has been so strong that at first I suspected QRM on top of me, but it was just the RTW echo.

A couple of years back, for a period I was receiving an echo with about 60 ms delay, measured on an oscilloscope.  [The RTW echo delay is about 140 ms.]  I never found out what was reflecting my signal back with that delay.

73
   Darrel aa7fv

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[Ward Silver]

Backscatter is another very common HF phenomenon with echoes delayed less than a full RTW trip.  For a 60ms delay, the reflection point would be something 30ms out and 30ms back.  That's about 1/5th a full trip - 5000 miles, perhaps.  Backscatter is usually terrestrial but there are lots of ionospheric scatter modes, too.

73, Ward N0AX

[Darrel]

Thanks, Ward.

  My memory was mistaken - the echo time delay was 30 ms, not 60 ms, after allowing for the time latencies in my rig.
  At the time (it was back in 2016 - time goes quickly!) I had some correspondence with Carl Luetzelschwab, K9LA about the reflection.  His suggestions were (1) auroral reflection, (2) northern crest of equatorial ionosphere to my southwest (Carl sent me an F2 region map), (3) ground scatter from North or Central America, or (4)  sea scatter to my east or out in the Pacific.  Unfortunately I could not rotate my antenna, which might have narrowed the possibilities, but my guess is that Auroral reflection may have been the most probable.  My antenna was a rhombic beam, pointing to an azimuth of +35 degs, from southern Arizona.

73
  Darrel aa7fv

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[Gedas V]

Reading these posts has been very enjoyable and something I have experienced as well. Years ago I had the HF station I always wanted here at my current QTH just south of Ft. Wayne IN. I had an AL-1200, my FT-1000 and a X7 at 75'. My good friend Jack, K8MA (now SK) lived north of me in Howell Michigan with a similar setup. On bands like 20m and higher we could have QSO's via brute-force ERP.  We were typically about S7 or so if we pointed at each other on 20-10m..

One evening around 9 PM - 10 PM Jack and I were taking advantage of the wonderful world-wide propagation of the solar max of 2002-2003. We were working JA's & Korean stations rock solid 5x9 on 20m sending SSTV images picture perfect. After an hour or so of fun we decided to QSY to a quiet frequency to chew the fat. We were playing around and I noticed rapid echo's on Jacks voice. He noticed them on my signal as well.  We decided to try a test so I had him point north over the pole and me south. Signals were even louder than direct and we each heard easily 4-5 echo's when we quickly spoke single test words like "TEST".  Each successive echo was weaker then the previous one. It was hard to count the echo's accurately as the entire train only lasted a second of so. I asked Jack to make recordings of this and he told me he was. Then as a test we went to 17m and we both heard the same thing. The same for 15m ! 12m was weak and only several echo's were heard and none were detected on 10m. I had never heard such a neat propagation event. Sadly Jack told me his recorder failed him and he was not able to produce any recordings at all of what we both experienced.  Something I will never forget. 73 Gedas W8BYA 

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[Gedas]

[Dick Bingham]

Greetings everyone

My experience with 'echo' events goes back to about 1978 +/- while  DXing  on 75M .

Conditions had been great for several nights, I was sleep deprived - fuzzy-headed - and realized

the station 'answering' my SSB CQ after several call sequences was ME.

I could hear my entire call at the end of the previous transmission. This was from at QTH in

Northern CA on a hilltop overlooking the ocean about 10-miles to the West. The antenna was

a vertical (insulated-base tower working against a well installed radial system) and ~1KW.

Have not experienced this effect again over the years.

73  Dick/w7wkr