Radio Noises in the Gulf Region on 121.50

[Panama Jack]

I was just reading the post Bleeps on VHF in France (http://www.pprune.org/forums/showthread.php?t=293682) which got me wondering about the strange radio noises that are pretty much constant on 121.50 MHz throughout the Gulf Region. At first I thought it was a radio problem the aircraft I was flying, but it seems to be constant on all aircraft, same sound, (and only on 121.50 MHz). Anybody know the origin of it?

Seems to be a flight safety concern, since the tendancy is to turn the volume of 121.50 down so that the noise is not so annoying (almost but not quite as bad as listening to HF), despite the operation need to monitor it, lest you get one of these transmissions:

“attention unidentified aircraft at position N27° en E051° squawking 3726, groundspeed 300 knots altitude 5000 ft. You are approaching a United States Naval Warship operating in International waters. . . . . . ”

[6853]

You mean this noise, "you are on guard mate"

[wastafarian]

is that what ausies say when they here “attention unidentified aircraft at position N27° en E051° squawking 3726, groundspeed 300 knots altitude 5000 ft. You are approaching a United States Naval Warship operating in International waters. . . . . . ” ?

[brassplate]

might have something to do with the navy's scramblers, though for whatever reason would they want to do that?

[SubsonicMortal]

I have often wondered the same thing. My theory is that there is some "spillover" jamming on this frequency from military presence in the region. Warships and military aircraft all have electronic warfare equipment that can jam almost any frequency spectrum. I'm guessing that they are to be blamed although I cant substantiate my theory.

[Wiley]

Someone (I can't rmember who) told me years ago that it was something to do with the US military.

I agree it's a pain, making it almost impossible to listen out on 121.5 when in the Gulf area, and I also agree that this has grave safety implications should, one day, you happen to be the target being painted when a US warship makes 'that' speech we've all heard more than once.

I believe a Gulf Air A320 went within 30 seconds of going the same way as the Iranian A300 out of Bandar Abas when they approached a US Navy ship one day and neither pilot was listening out on 121.5.

[GAGing in Bahrain]

It could also be freq harmonics. I doubt it's got anything to do with jamming. The real problem is that there is no real regulatory authority to complain to and investigate it. The GCC Frequency Board are a joke, literally. I can't name the times we have asked them to look at something and their response is "please tell us what we should be looking for" or better yet the age old blame game, "it's the Americans".

[forget]

The US Navy in the Gulf has a special interest in 121.5 being kept as it should be, quiet. They've got the airborne kit to pin down the source of any interference. Fixing it may be another problem, but you have to start somewhere. I'd say this is serious enough to warrant a call to your local US Navy Attache and explain the implications. I doubt very much it's the Navy causing the problem.

If any 'fix' does present an issue then the Navy also has a long range ability to switch things off.

[forget]

HARM ............. .............the Navy also has a long range ability to switch things off.

[CT7]

The Americans have nothing to do with 121.50.
And there is not an Area 51 either!
UFOs dont exist and Roswell was a weather baloon!

[wastafarian]

and what bout elvis?

[MTOW]

The Americans have nothing to do with 121.50.Like they had nothing to do with the major interference in the ILS signals at Dubai back in 2003 at the time of GW2? If, (as some claim), mobile phones can cause tumors, I wonder what effect the very high power radio/radar signals put out by warships equipped with Aegis and similar systems must be having on the crew. Are they sheilded in some way?

[411A]

and what bout elvis?

Elvis was at Roswell a few years ago, standing right beside his old red JetStar, that was parked right outside hangar 84...and was next in line to be scrapped as soon as the crew was finished with an old clapped out BAC 1-11.

Legends die hard.

[CT7]

I know the old Leander Class Frigates that the Uk and NZ had (AKA Warship 1970's tv show) couldnt use the big lattice work radar within 10nm of shore due to TV interference.

[brassplate]

if i'm not mistaken, the interference is strongest over dxb and bah, two places with the biggest us navy presence. coincidence?

[inverter]

I have noticed that if you have any frequency close enough to 121.5 would interfere with the transmission!
e.g: 121.10 OTBD
plus there are ample other frequencies within the area of operation,
for instance the OKBK GRD! You guys operate within the region, so figure it out.
Its a concern but I guess its just close proximity of the digits. ain't it. MATES.
:confused:
INV

[brassplate]

nope, didn't pick it up today in kwi.

[forget]

US Warships radars work a little differently than your average radar. All US warships use digital systems and satellites that don’t send signals like your standard radar. :p

Stealth carriers next. :bored:

PS. AN/SPY-1 Radar
The AN/SPY-l radar system is the primary air and surface radar for the Aegis Combat System installed in the Ticonderoga (CG-47) and Arleigh Burke (DDG-51)-class warships. It is a multi-function phased-array radar capable of search, automatic detection, transition to track, tracking of air and surface targets, and missile engagement support.

A conventional, mechanically-rotating radar "sees" a target when the radar beam strikes that target once during each 360 degree rotation of the antenna.

[forget]

major, you’re reading too many dodgy magazines. For RAdio Detection And Ranging to work it needs to squirt out RF energy. If it doesn’t do that - it’s not Radar.

Also, how do you hide an aircraft carrier? :confused: There’s stealth and there’s stealth. Is the picture below from one of you magazines?

From the US Department of Defenc(s)e. Caption says ‘Artists rendition of USS CVN-78 and her escort of five destroyers steaming through the Straits of Hormuz’.

http://i21.photobucket.com/albums/b270/cumpas/sco0871.jpg

[forget]

and MTI moving target indicator processed by a computer in combat areas and airborne assets.

:ugh::ugh: MTI needs a target - and the target comes from RADAR! Whether or not the 'scanner' moves - it's still RADAR

Here, if you still don't understand.

http://www.fas.org/man/dod-101/navy/docs/es310/advradrsys/AdvRadr.htm

[MTOW]

majorA, check your PMs.

The question remains - is there some form of shielding that protects the crew on such ships, particularly those out on deck and the upper superstructure?

Is some such shielding required?

[brassplate]

:hmm:Geeks!!!!!!!!!!!!!

[MTOW]

Brassplate, if wondering whether servicemen are being fried by high power radio/radar transmissions while going about their normal duties, then I'll gladly admit to being a geek, because we know no government would ever endanger their servicemen, don't we? (I can't see an 'irony' smiley in the list, but if there was one, I'd be inserting it here in double size and boldface.) I'm reminded of all those US soldiers who were positioned out in the open back in the 1940's and 50's, protected only a pair of goggles, to 'witness' nuke tests from what today would be considered grossly unsafe distances. The Brit and Australian airmen who worked on the Brit nuke tests in Australia were similaraly exposed.

So, getting back into my 'geekiness': given that if I have a chocolate bar in my pocket and walk in front of a civilian microwave transmission dish, said chocolate bar will melt poste haste, what would happen to a USN sailor's Hershey Bar if he had one in his pocket while on deck while all the ship's radar etc was on at full power?



majoramerica, I PM-ed you with the info I gave because I don't think (in fact, I know!) the people involved would want it on a public forum, even today, and I don't want them looking for me if I'm right, which they're quite capable of doing.