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Author Topic: "Flutterly" CW sound  (Read 4336 times)
AF3Y
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« on: November 18, 2011, 02:19:10 PM »

I guess that is as good a way to describe it as any.  I hate to admit I dont know what is causing this, but I am sure one of you antenna gurus can enlighten me.

For the past few days, I have been hearing some rather strange "chirpy" or "fluttery" sounding CW signals. Yesterday I think it was a station from Barbados and just a few minutes ago, ZD8ZZ on Ascension Island. I did a search on DX Summit and saw that several others had noted the 8P9MS as "Chirpy" also. So, maybe its not my wire vertical.  I was wondering if I was getting signals from both paths..... By the way, these two contacts were on different bands 30m and 10m. Probably NOT my antenna, as other stations are fine. I worked the ZD8ZZ a couple days ago and the signal was OK, but could be a different antenna there, I guess. Huh
« Last Edit: November 18, 2011, 03:34:36 PM by AF3Y » Logged
AF3Y
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« Reply #1 on: November 18, 2011, 03:33:58 PM »

Since posting, I went over to the CW forum (Where I probably should have gone to begin with) and did a little reading. Seems the chirp is from the transmitter, which is logical.  

By the way I saw one of our regulars  Shocked here on the DX forum stating he got one of those "OO" cards for a chirper signal some years ago.. Grin

73, Gene AF3Y
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NU1O
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« Reply #2 on: November 18, 2011, 06:04:54 PM »

Chirp from the rig is one thing, but a "fluttery" sound on CW or SSB from Central and South American stations, like you might hear on a signal from Asia going through a polar path is a different story entirely.  I often hear "fluttery" sounds on stations from those locations in the late afternoon or evening but I have not been able to find out what caused it.

On October 25th 20111 I was working Central and South American stations on 10 Meters from 03:00 to 04:00 (PY, LU, CX , KP4) when the band is normally dead, and they had very strong signals. Before I could ascertain their QTH I though they might be Asian stations coming in over the pole.  I have experienced this on numerous times over the years.

73,

Chris/NU1O
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AB4ZT
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« Reply #3 on: November 18, 2011, 06:11:18 PM »

Not necessarily.  If the CW sounds "chirpy"...that is the end of the element is a little higher in pitch than the beginning of the element...then that is likely the transmitter.  I still hear chirp now and then but not very often.  If it sounds "fluttery", or "watery"...then that is more propagation, either backscatter (strong signals being refracted back towards the transmitter because of strong ionization), or perhaps multipath, which is like an echo.  Being heaing a lot of multipath lately when my dipole is pointed towards Europe.  Not so much on the band where I have front-to-rear directivity.

73,

Richard
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AB4ZT
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« Reply #4 on: November 18, 2011, 06:14:59 PM »

NU1O posted the relevant point on polar paths while I was typing.  Also a cause of "watery" or "fluttery" CW.

73,

Richard
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K9AIM
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« Reply #5 on: November 18, 2011, 07:58:22 PM »

If it sounds "fluttery", or "watery"...then that is more propagation, either backscatter (strong signals being refracted back towards the transmitter because of strong ionization), or perhaps multipath, which is like an echo.  Being heaing a lot of multipath lately when my dipole is pointed towards Europe.  Not so much on the band where I have front-to-rear directivity.

73,

Richard

I have been hearing it off and on for a few months now.  Is multi-path flutter due to the difference in distance of each respective path that causes the flutter? (shorter path signals arriving sooner and longer path signals arriving slightly later?  If so, then multi-directional antennas for both the station transmitting and receiving would seem to maximize its occurrence(?)   
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AB4ZT
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« Reply #6 on: November 19, 2011, 05:38:08 AM »

Yes.  My TA-33 has dipoles for 12 and 17 meters, which of course hear equally from both sides.  When pointed toward strong signals, such as Europe, there is sometimes a long path, or off-bearing signal which arrives just after and not much weaker than the short-path signal, just like you said.  The effect is a slight echo, which sometimes sounds like a there is a LID on frequency with almost impeccable timing! It can make for interesting copy.  It is an artifact of the good propagation we have had the past couple of months - which is good enough to support strong long-path signals.

73,

Richard
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K3NRX
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« Reply #7 on: November 19, 2011, 05:44:35 AM »

I love the sound of fluttery signals....that means that the propagation is weird and makes for a very intriguing qso experience.....In the old days of the cold war (my ham radio infancy), I used to love working into the old Soviet Union.....those guys would have the flutteriest of signals coming over the pole and it made for a very mysterious qso because at the time, tensions were high (actually they were kind of easing as I started DXing in the mid to late 80s)....but still, the fluttery signals coming out of USSR added to the mystique...there was no question.....Chirpy signals on the other hand (as in the Cuban Chirp) were just plain annoying....

V
KA3NRX

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W7ETA
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« Reply #8 on: November 19, 2011, 09:14:20 AM »

You maybe hearing "back scatter"?
Bob
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WD4ELG
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« Reply #9 on: November 19, 2011, 07:30:47 PM »

KA3NRX, you have brought back some good memories!  One of the things I listened for back around 1980 during my first days of DXing was the flutter of the polar path to the east coast.  It meant "juicy DX" a la SE Asia, Asiatic Russia, Mongolia, or central Asia.  It still does mean that, at least for late night US East Coast time for me.  Early mornings I hear the stations coming over Europe on skewed path, loud and with no flutter.

Nothing more exciting than a quite 15 meter CW band and a flutter happening around 2300 local.  Gets the blood going like a cup of strong java.  Thanks for the reminder, OM!
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NU1O
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« Reply #10 on: November 20, 2011, 08:41:39 AM »

NU1O posted the relevant point on polar paths while I was typing. 
Richard

Do you have any idea how many times I was typing in an answer and somebody beat me to the punch?

73,

Chris
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NU1O
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« Reply #11 on: November 20, 2011, 08:43:02 AM »

You maybe hearing "back scatter"?
Bob

Back scatter has a unique sound of its own, but it does not sound like a polar signal.

73,

Chris/NU1O
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W2IRT
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« Reply #12 on: November 20, 2011, 09:02:15 AM »

This morning I was listening to stuff on 10 and 12m and it was very echo-y but no flutter. I'd originally thought backscatter but even the DX was echoing. Everything was, for about 2-3 hours after SR.
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WD4ELG
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« Reply #13 on: November 20, 2011, 09:30:18 PM »

W2IRT, I did some reading on this and have observed the same thing around SR.  I suspect it is multipath (either LP and SP, or SP and skewed path).  Definitely not fluttery, as you said.
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AF3Y
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« Reply #14 on: November 21, 2011, 01:43:06 PM »

Perhaps I mis-described it.  Have not heard it again, but thinking back, I guess it was echo-y, rather than fluttry, with somewhat of a chirpy sound as well.  Gene
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