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Author Topic: High Frequency Global Communications System  (Read 22798 times)

Offline 4405486

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Re: High Frequency Global Communications System
« Reply #15 on: June 15, 2010, 2343 UTC »
Best information I have found so far: Google- EAM (Emergency Action Message) Monitoring Times Article
Evidently, the Echo effect is intentional; for reasons that escape me?
I'm new at this c'mon you guys with decades of Monitoring and Analysis experience, you can do better than that. I'm all Ears.
Behind that lack of context, lies an extraordinary System. Cheers.

Offline 4405486

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Re: High Frequency Global Communications System
« Reply #16 on: June 18, 2010, 2121 UTC »
I tend to be a skeptic and critical thinker; Have to find out for myself. While waiting for my lower back to unsieze, have been spending time looking into this. This Alpha/Numeric combination does show up enough to reasonably satisfy me that this is used for command and control. Have been looking at some of these systems. I have taken the AMTRAC Train through Vandenburgh AFB and wondered about some of those structures, now I know. Appears to be a new openess; amazing what you can find on the Internet; furthermore, if It's there for public consumption I'm going there. The exception appears to be the NSA, very disappointing <YAWN>.

I hope those involved in decision and policy making know what the Hell they are doing? I for one am not so sure.

Cheers.

Offline SW-J

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Re: High Frequency Global Communications System
« Reply #17 on: June 20, 2010, 0401 UTC »
I tend to be a skeptic and critical thinker; Have to find out for myself. While waiting for my lower back to unsieze, have been spending time looking into this. This Alpha/Numeric combination does show up enough to reasonably satisfy me that this is used for command and control. ...

You know, those used to be go/no go 'codes' for the SAC B-52 bombers that were third 'prong' on the triad of nuclear deterrence (the other two prongs being nuke subs and the missiles in silos)

One would hear the words: "Skybird skybird, do not answer message follows" followed by groups of characters and then an authentication block ...

Those messages used to be as prolific as grackles ... anybody who was SWLing in the 80's and 90's can confirm.

A good example would the Peter Sellers movie "Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb" where they are seen decoding messages.

In case anybody is wondering what we are talking about:

http://www.wizzler.com/video/fTZuJQ4xtE0/HF-GCS-EAM-Emergency-Action-Message.html

o Icom IC-756ProII, ProIII, Alinco DX-70, Kenwood TS-680s
o WinRadio G303e, Degen/Kaito 1103/DE1103, Stoddart NM-25
o 1/2 wave 80m Dipole used with several tuners
o Tuned loops from 2' thru 16' diam. capable of 160m thru 10m

Offline Token

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Re: High Frequency Global Communications System
« Reply #18 on: June 21, 2010, 1927 UTC »

Evidently, the Echo effect is intentional; for reasons that escape me?


The echo is caused most commonly in this specific system by sending the same signal from multiple transmitters at the same time.  The different distances to each transmitter from you mean different arrival times to your location.  Arrival times differing by as little as 2 milliseconds can be detected by the human ear.  6.18 microseconds is the time it takes RF to travel one mile.  Distances differing to two transmitter sites by 300 miles (one transmitter being 300 miles further form the receiver than the other transmitter) would result in about 2 milliseconds difference in arrival time.  Greater distance deltas equate to larger timing deltas.

Echos can also be caused by differing paths from one transmitter to a given receiver.  RF can take more than one path from point A to point B.
T!
Mojave Desert, California USA

Offline 4405486

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Re: High Frequency Global Communications System
« Reply #19 on: June 21, 2010, 2247 UTC »
Thank you all for the information and recording. I am finding this quite interesting.
Youtube is very helpful. Might want to see: "How to Launch a Nuclear Missile"(5:12 long) note the Tour Guide, when he mentions the preamble: "Birds of the Air, or something like that".

Also, old documentary: "First Strike" with authentic personnel is insightful; especialy (part1).

Evidently, I am reading too much into this "echo" effect; however in the Monitoring Times article: " What is an EAM?" there is a reference made that I don't understand, but is nonetheless interesting. Near the bottom in the 04 APRIL 2005 update section it says in reference to the echo rotation callup: " they were no longer 'aliased' (as in IDing) and at least two new stations were added to the echo rotation callup." The term "aliased" as it is used here, I for some reason can't quite grasp. Oh well, it's not important; but it is that reference that made me think there possibly might be something more to this echo effect.

Do to the fact that this is part of an extraordinay System, and in the interests of obtaining some sense of this. I mentioned in reply #14 a illustration that contains numerous miliatary platforms (politicaly correct way of saying it, I still can't bring myself to say the "N" word;
NU[. . .]LEAR) at any rate, as deficient as this drawing is I have looked into some of these systems that are depicted and found it interesting. As a treat, I recommend the youtube video: "JointSTARS.wmv (2:54 long). This features the nondescript looking airplane in the depiction- gets my juices flowing- enjoy. Cheers.

Offline SW-J

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Re: High Frequency Global Communications System
« Reply #20 on: June 22, 2010, 0007 UTC »
(Ref. a) Evidently, I am reading too much into this "echo" effect;


(Ref b) As a treat, I recommend the youtube video: "JointSTARS.wmv (2:54 long). This features the nondescript looking airplane in the depiction- gets my juices flowing- enjoy. Cheers.

Ref. to (a) above - Anybody here heard 'round the world echo on 20 Meters ? ... it's an awesome phenom to behold, and today with propagation 'in the ditch' so to speak it will be hard to demonstrate 'live', but when things are good it's not that rare. The echoes from the DOD's multisite-originated multicast/simulcast system are due to the time delay the other poster pointed out; the delays could also be due to satellite echo delay, I say, I do not know as a certainty, but, if using geostationary sats for links the time delay to and from the geo sats are not insignificant either ...

For some HF echo, round-the-earth paths of recordings check out:  http://www.aa5tb.com/recordings.html the section titled: "Radio Echoes - Short and Long Path"

Ref. to (b) above - JSTARS is pretty impressive, it is quite amazing the detail that can be 'rendered' when you pepper a target area with a nearly continuous barrage of short, interspersed RADAR pulses then work with both the Doppler shifts imposed plus the amplitudes returned and integrating the returns over time ... the effect is as if you had a much larger, more sharply defined RADAR antenna, leading to the term SAR (Synthetic Aperture RADAR)  ... the rendered detail can be quite amazing ...

Just to be clear: JSTARS <> AWACS

AWACS - rotating dish on top, meant for detection and control/direction of aircraft in the 'theater'

JSTARS - longish stationary pod attached/beneath the aircraft, meant to look at targets (kinda sideways to the aircraft, not straight down) on the ground ..

Edit: Update JSTARS desrip.
« Last Edit: June 22, 2010, 0129 UTC by SWJ »
o Icom IC-756ProII, ProIII, Alinco DX-70, Kenwood TS-680s
o WinRadio G303e, Degen/Kaito 1103/DE1103, Stoddart NM-25
o 1/2 wave 80m Dipole used with several tuners
o Tuned loops from 2' thru 16' diam. capable of 160m thru 10m

Offline Token

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Re: High Frequency Global Communications System
« Reply #21 on: June 22, 2010, 1547 UTC »

Ref. to (a) above - Anybody here heard 'round the world echo on 20 Meters ?


Often in the past, and several times recently.  I even have some recordings of it around someplace, including SDR recordings that allow you to see it happening on multiple stations.

The most interesting echo or delay I have ever seen happened a couple of years ago on 80M.  Conditions were extremely long and a few of us noticed very, very, heavy echos on each others transmissions, far heavier and longer than I have ever heard on 20M.  Playing around I found that I could slap the desk mic switch making a very audible "crack" during a very short transmission.  I could hear my own "crack" echoing back, like a radar pulse.  At times I could hear multiple copies echoing back.  Unfortunately I got no recordings of that, it would have been very interesting to measure the delay.  I am convinced the delay was possibly more than the ~135 msec max of circling the Earth at the longest distance.  While only a guess, as no measurements were taken, it felt closer to half a second.
T!
Mojave Desert, California USA

Offline SW-J

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Re: High Frequency Global Communications System
« Reply #22 on: June 22, 2010, 1627 UTC »

Ref. to (a) above - Anybody here heard 'round the world echo on 20 Meters ?


Often in the past, and several times recently.  I even have some recordings of it around someplace, including SDR recordings that allow you to see it happening on multiple stations.

The most interesting echo or delay I have ever seen happened a couple of years ago on 80M.  Conditions were extremely long and a few of us noticed very, very, heavy echos on each others transmissions, far heavier and longer than I have ever heard on 20M.  Playing around I found that I could slap the desk mic switch making a very audible "crack" during a very short transmission.  I could hear my own "crack" echoing back, like a radar pulse.  At times I could hear multiple copies echoing back.  Unfortunately I got no recordings of that, it would have been very interesting to measure the delay.  I am convinced the delay was possibly more than the ~135 msec max of circling the Earth at the longest distance.  While only a guess, as no measurements were taken, it felt closer to half a second.
Interesting observations ... I've only heard personally the phenom on 20 M some years back ...

This last winter 80 Meters got really, really long on a regular basis, the time station from S. America on 8410, as noted here, was easily heard:

   http://www.hfunderground.com/board/index.php/topic,823.0.html

... but no long distance echo effects were observed/heard.

On the subject of LDE (Long Duration Echoes), here's some info on Wikipedia I had not seen before and so I'll post a link (so I can come back later and do some deeper reading when I have time too):

  http://en.wikipedia.org/wiki/Long_delayed_echo

And another personal observation from an individual, with his own theories, perhaps a bit outside the 'mainstream' view, but hey, that's how science progresses (observe a phenomenon, propose a hypothesis, prove it or disprove it and possibly it becomes a theory):

  http://www.eskimo.com/~nanook/radio/2006/12/long-delayed-echo-radio-phenomena.html

o Icom IC-756ProII, ProIII, Alinco DX-70, Kenwood TS-680s
o WinRadio G303e, Degen/Kaito 1103/DE1103, Stoddart NM-25
o 1/2 wave 80m Dipole used with several tuners
o Tuned loops from 2' thru 16' diam. capable of 160m thru 10m

Offline outhouse radio

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Re: High Frequency Global Communications System
« Reply #23 on: June 22, 2010, 1732 UTC »
>>Long delayed echo<<    Now that is a really interesting thing to witness first hand   I personally have heard 4 repeats on of all things 11 meters !!!  Also around the same time a cb op had set up a simplex repeater(MFJ) in the 11m band    Late at night it would start picking up the Long delayed Echo it would retrasmit the echo and keep going until they shut it off or the LDE would fade out   I wish i had a recording of it    BTW the simplex repeater was in mexico

WrongwayCorrigan

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Re: High Frequency Global Communications System
« Reply #24 on: July 23, 2010, 0640 UTC »
Receiver: Grundig G6 Aviator
Anntenna: Telescoping Rod
Place of Reception: Northeastern United States
Date: 07/23/2010
Time: 0540 UTC
Frequency: 8992 kHz SSB

http://www.zshare.net/audio/78596027bcd2fc06/

Offline Seamus

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Re: High Frequency Global Communications System
« Reply #25 on: July 23, 2010, 1537 UTC »
Sounds like yours are much more intelligible than the ones I receive here. 
On your recording, you have one transmitter that is clearly dominant, with the other one being a weak echo.  Here in upstate NC, on a wire with a predominantly north-south pattern, I usually receive two strong signals with very similar strengths, making them somewhat difficult to read at times.

http://www.zshare.net/audio/78607374b381097a/

Offline L Cee

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Re: High Frequency Global Communications System
« Reply #26 on: July 23, 2010, 2010 UTC »
Heard 7/23/10 on 8.992, 11.175, 13.200, and 15.016 at 20:00 UTC. Best reception on 15.016 at my location.
« Last Edit: July 23, 2010, 2027 UTC by L Cee »
L Cee
East Coast - USA