Russian woodpecker

[NN3W]

A few months back I stumbled across an audio file of the actual Russian Woodpecker.

Anybody know the url for this? BTW, it is different than from of the more recent vintage OTH radar systems.

[n2cfj]

Don't know the url but I grew up listening to it since my father's shack was in the room right next to my bedroom. he was first licensed in the early 60's

[WA2ZDY]

Never stopped me from making contacts. Just had to dial in some filter. 400 Hz worth worked just fine.

[wa9cwx]

Ok,

Everyone chuckle...but I remember when the 'theory' was that if you matched the speed of the woodpeckers 'dits'. and sent several seconds worth of them on the 'center' of the signal, it would QSY a few hundred Kcs away.

I did that many times on 20.....

AND it often "SEEMED" to work.

Any comments,

Coincidence, silly, sound, what?


All I can say is I am glad it is gone, and for those of you who never heard it, it really DID sound like a woodpecker, and was just as irritating.

[N5PVL]

I remember hearing the woodpecker, and there was another weird signal that sounded just like a sawmill going at full tilt. I was six years old and thought that the "log" scale at the top of the dial was for tuning in those sawmill stations.

[W4HAY]

The 'matching the dits' technique seemed to work for me also. We used to joke that we might trigger a nuclear attack! #http://www.qrz.com/iB_html/non-cgi/emoticons/laugh.gif

You can still hear those 'sawmills' coming from places like Castro's Carribbean Communist Paradise, North Korea, and various other 'free' states as they attempt to block 'anti-revolutionary' broadcasts from the outside.

Passport To World Band Radio's 'blue pages' depict jamming as (you guessed it!) a sawtooth waveform superimposed over the bars detailing the time and language of a station's broadcasts.

[N2RJ]

Some people recorded the woodpecker and played it back. I heard that was more effective than just sending spaced dits.

[K7FE]

Sending the dits back with a 5 element 20 meter beam and a Kilowatt worked just fine.

73,
Terry, K7FE

[WA2ZDY]

So all you guys sending dits to that darn woodpecker are why it kept landing on ME huh?

Now I know who my friends are.

[kg4kww]

If I were you I would be careful, I hear those Russian Woodpeckers leave splinters. http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif

Check This Out (http://www.qsl.net/n1irz/woodpeck.html)

[W5HTW]

The "sawmill" was often referred to as a B17 flying along, the constant drone of the engines.

Actually, it was *probably* MUX. Multiplex. Two, four, or 8 channel Independent Sideband AFSK. I spent several years running one of those sawmills! Ours were all four channel, two upper, two lower, narrow-shift AFSK.

The two channel ones sounded more like the sawmill while the four channel ones sounded like riding in a B17. There weren't many 8 channel ones. I knew they existed but I never ran one, never heard one.

Ours was a pilot carrier with two 170 hertz shift AFSK signals on each sideband. Not much way to describe it except the sawmill or the four engined bomber! With a broad receiver it seemed to occupy a lot of bandwidth, but actually it was well under the 6 kc of a normal double sideband transmission. The total bandwidth of a sideband might be 2 khz, for a resultant 4 khz spectrum. Many times it was actually much narrower. We could fit two 170 hertz shift signals in a 1 khz bandwidth, but we didn't normally start close to the carrier, so the first signal might be one khz above or below the carrier, and the second signal 1.5 khz above or below. Four independent channels, all carrying different RTTY.

While we didn't operate them in the US ham bands, some foreign nations did, especially on 40 meters, in the phone band, which was not allocated to hams in some portions of the planet.

The gradual rise and fall of the sawmill sound was from the very low beat notes of the multiple signals. Varied, depending upon what kind of TTY was being sent, but the beat was typically two seconds or so, as I recall. Been a long time.

Incidentally, we ran 16 and 32 channel MUX on microwave, with 85 hertz shift AFSK. Now that, if you could tune it in on an AM receiver, REALLY sounded bad - a whole fleet of B17s coming in!

Ed

[WA2ZDY]

Ahhh now I know what you're talking about. I remember hearing the "B17's" flying across the bands.

Another mystery solved. Thanks Ed.

[K0RGR]

I was spinning through the 60 meter channels the other evening, and lo and behold, on the lowest frequency channel, I heard something that sounded very much like the Russian Woodpecker.

I wonder who's running over-the-horizon radar on 5 Mhz ?

[N2RJ]

Quote[/b] (K0RGR @ Nov. 17 2006,13:26)]I was spinning through the 60 meter channels the other evening, and lo and behold, on the lowest frequency channel, I heard something that sounded very much like the Russian Woodpecker.

I wonder who's running over-the-horizon radar on 5 Mhz ?
That's probably why we're secondary users on the band.

[ka5piu]

Hello.

The Russian woodpecker is actually a complex waveform, that
is why a recording works better.
The Chinese OTH RADAR emits a very complex signal indeed.
it is part AM and part FM all rolled up into one.
The signal is confined to places like 5 MHz, China not wanting to upset anyone.
I am now experimenting with this AM/FM cross to see what it is all about.