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Author Topic: 9024 kHz, DSB, oddity, 03 April, 2020, 0420 UTC  (Read 1827 times)

Offline Josh

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Re: 9024 kHz, DSB, oddity, 03 April, 2020, 0420 UTC
« Reply #45 on: April 27, 2020, 1942 UTC »
Very nice on link11 tie in. Being the "jammer" in question is possibly naval in origin, using a dsb signal where link11 (used by most every NATO navy) is often sent in isb, the jamming might be at least somewhat effective. While they're not overtly jamming right now the use of the jammer precludes running link11 on those freqs, and allows the jammer to test for typical coverage. But who knows, could be some bored gopniks with an old transmitter.
« Last Edit: April 27, 2020, 2033 UTC by Josh »
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Offline KM0NAS

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Re: 9024 kHz, DSB, oddity, 03 April, 2020, 0420 UTC
« Reply #46 on: May 01, 2020, 1430 UTC »
I do wonder how effective it real is though. If you watch the video I posted I commended on how the signal was right on top of the link 11 signal. There didn't appear to be any attempt to switch the link 11 to another frequency due to interference. So while it has been appearing on those frequencies I haven't seen any effort to avoid the jamming which may indicate it is not effective. Then again...do you purposefully not move when someone is trying to jam to to make it look like it has no effect and thus you make them give up trying because they see you didn't flinch? Who knows. Not us.
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Offline Josh

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Re: 9024 kHz, DSB, oddity, 03 April, 2020, 0420 UTC
« Reply #47 on: May 01, 2020, 1823 UTC »
Link11 on hf is for los or near los only, not distant over the horizon like typical hf comms, wich is odd because they also have a uhf version of the protocol. I think they cover a cbg with it and that's all they want from it. The link sig might be strong enough for those within los to be unaware if the other signal.
Thus the jammers dilemma, how to jam the jam resistant.

https://us-browse.startpage.com/av/anon-image?piurl=https%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2F5%2F52%2FUS_Navy_070318-N-5961C-336_Ships_assigned_to_Ronald_Reagan_Carrier_Strike_Group_and_Japan_Maritime_Self-Defense_Force_%2528JMSDF%2529_steam_in_formation_during_a_photo_exercise_%2528PHOTOEX%2529.jpg&sp=1588357370T61451412d57c133541f95231bf971c7deb70dc483eec5a957b89419150757716
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Offline Token

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Re: 9024 kHz, DSB, oddity, 03 April, 2020, 0420 UTC
« Reply #48 on: May 01, 2020, 2210 UTC »
Link11 on hf is for los or near los only, not distant over the horizon like typical hf comms, wich is odd because they also have a uhf version of the protocol. I think they cover a cbg with it and that's all they want from it. The link sig might be strong enough for those within los to be unaware if the other signal.
Thus the jammers dilemma, how to jam the jam resistant.

Link-11 is more designed for regional use, beyond LOS but not really long range.  That is why you find it on the frequencies you do, most typically below 15 MHz with a real emphasis below 10 MHz.  It is often used it at beyond LOS, but seldom as far as 600+ miles.  At ranges where you could use the ground wave portion of a 2 to 6 MHz signal.  And yes, you can do Link-11 on VHF and UHF also, but that really is LOS.

Link-11 is for the entire battle group, whatever kind of group it is, and anyone attached to it.  Or it can be simply two (or more) ships independent steaming but supporting each other.  Push the pickets out to screening positions 75+ miles away and the battle group commander, or anyone else in the network, can see the radar / sonar / ESM picture from the pickets.  You can put up the Lamps 3 bird and push it out 200 miles (or more, but then he starts getting short on fuel), and watch his LN-66 picture.  Better yet, when prosecuting an ESM contact you can put the -3 out on a tangential bearing to get another ESM bearing cut on the target, giving you a position plot.  Since the link to the aircraft (this is a dedicated link, not Link-11) is on a tight beam and at UHF the chances of it being intercepted or giving your position away are lessened, so you can end up with a 2D location of a threat while not exposing yourself by lighting up any radars, and often at ranges beyond what your radar could see anyway.  That 2D position then goes out over Link-11 to the rest of the units.  And of course if it is a carrier battle group you can put up an E-2 Hawkeye and push him out several hundred miles with all the same advantages.

You can have the entire group in EMCON, using only passive systems, and one platform active and providing the tactical picture to everyone, obscuring details of who is in your group or where, exactly, you are (assuming you push the active platform outside the group).  This works particularly well with a helo or fixed wing aircraft as the active emitter.  Of course, your Link transmission gives you a way, but it is of limited use as many potential bad guys can't get as much information on an HF signal as VHF and up.

T!
« Last Edit: May 02, 2020, 1328 UTC by Token »
T!
Mojave Desert, California USA

Offline Token

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Re: 9024 kHz, DSB, oddity, 03 April, 2020, 0420 UTC
« Reply #49 on: May 04, 2020, 1326 UTC »
Just an FYI, this signal was last on the air on April 24, the day I put up that video on my YouTube channel.  Or at least that was the last time I saw it, and I checked every evening.

Until this morning, May 4.  The signal was observed on 9024 kHz, normal mode and content, before 0300 UTC.  At 0457 UTC it switched from 9024 kHz to 9008 kHz, same mode and content.  It turned off at off 0601 UTC.  I don't believe I have ever seen it shift frequency like that before, although it has used both those frequencies in the past.

Again, these frequencies are "close" to Link-11 freqs.  The entire time the signal was on 9024 kHz there was a Link-11 on 9022 kHz.  Although I did not see it active at the time of the frequency switch, by the time 9008 kHz went off the air there was a Link-11 on 9007 kHz.  I have no idea if the Link on 9007 kHz was there the whole time or not, and if propagation was just preventing me form seeing it at first.

T!
T!
Mojave Desert, California USA