« "Alone In Paris: a Bit of Autobiography" By Richard Sale | Main | Eric Holder's progress. »

03 October 2013

Comments

Feed You can follow this conversation by subscribing to the comment feed for this post.

nick b

I will now be adding 'boffins' to my SST vocabulary list, along with 'camarilla' and 'Principate'. One learns something new here every day.

Allen Thomson


As far as I know, the guidance systems in question are hybrid inertial/GPS. If GPS jets jammed or significantly spoofed, the inertial part detects that and takes over. The resultant accuracy depends on how long the weapon has to fly on inertial-only after the last valid GPS fix, but isn't as bad as the article says.

walrus

Jamming of civilian GPS frequencies has been demonstrated with ease many times in the last Ten years with very cheap , home made, readily available gear. I would expect the encrypted military signal to be just as vulnerable.

While not being a tech head, I am sure this situation has not been lost on the U.S. defence forces, and since a complete digital inertial reference system now weighs about Three ounces and takes up Two cubic inches, I imagine that these missiles don't need GPS to get to an initial point to acquire terrain.

Asia Times is likely wrong.

VietnamVet

Colonel,

With the front lines in the Damascus suburbs, the city is pretty much being blown apart. It is not a suitable environment for stationary high value targets. There is nothing clean or impressive about the Syrian Civil War.

The rebels have released a video of a purported Chemical Weapons missile launch:

http://rogueadventurer.com/2013/08/29/alleged-cw-munitions-in-syria-fired-from-iranian-falaq-2-type-launchers/

The only thing colorful and big enough for targeting by the US military is the Mercedes Benz truck that delivered the missile. But the transport truck is likely always on the move or hidden. Not one mobile Scud missile and launcher was found and destroyed during Desert Storm.

To me this is a typical scene of war with soldiers standing around in the rear with locked and loaded rifles watching at the tech guys preparing a missile for launch. I didn’t see any gas masks so I assume it was a daylight launch of a thermobaric (fuel air explosive) missile at rebel held districts.

scott s.

If I'm not mistaken, we fired a couple hundred Tomahawks in Desert Storm, none of which had GPS. The possibility of jamming GPS is not some new discovery either.

confusedponderer

The interesting part about TERCOM is that it achieves its accuracy by combination of sensor data.

The article states "GPS jamming zone can start over water, where TERCOM and DSMAC" - true, but the launching platform, usually an Arleigh Burke class destroyer or a Ticonderoga cruiser or a submarine, does have GPS, and a highly accurate inertia guidance system, and, considering the 1650 km range of the Tomahawk Block IV, the launch platforms probably are out of jamming range.

What the article misses is that, beyond TERCOM, Tomahawks have TAINS (TERCOM Assisted Inertial Navigation System) i.e. inertial navigation. The more modern ones probably do have fibre optic gyros which are cheap and small and around for, what, two decades or so.

Using inertial navigation, the cruise missile can 'carry on' based on the navigation information received from the launch platform until they find identifiers for TERCOM and DSMAC. IMO the article by missing that generates a misleading impression.

Tomahawk Block IV does have an anti-jam GPS receiver, so the odds are that, if the jamming signal is too far off to be plausible, the missiles are programmed to ignore it.

So GPS jamming will probably reduce bombing accuracy from metres to tens of metres, or may lead a cruise missile astray. However, the other features of TERCOM my be able to compensate for that.

Tomahawk Block I, according to Wiki, had a CEP of 50–80 m (plenty accurate enough if you have that <150 KT warhead), Block II 30–50 m, Block IV, thanks to the addition of GPS, 10–15 m.

GPS jamming may make a difference as far as preserving high value targets is concerned, even though it would probably lead to collateral damage.

GPS jamming would probably reduce sortie efficiency. In that regard it is probably worthwhile. What it will not be able to prevent is explosives dropping in the general area.

The simplest countermeasure to GPS jamming would likely be assigning more sorties (cruise missiles) to one target. The US arsenal is big enough for that.

In a setting where US and opposition forces are close to each other, GPS jamming may succeed in preventing GPS weapons from being used in a close air support role because US forces may be hit due to the enlarged CEP. That then goes for GPS guided artillery also.

That's my stupid wild-ass guess on it.

shanks

@walrus,

Mostly likely the author is incorrect.

http://en.wikipedia.org/wiki/GPS-aided_geo-augmented_navigation

within it....

In 2012, the Defence Research and Development Organisation received a "miniaturised version" of the device with all the features from global positioning systems (GPS) and global navigation satellite systems (GNSS). The module weighing just 17 gm, can be used in multiple platforms ranging from aircraft (e.g. winged or rotor-craft) to small boats, ships. Reportedly, it can also assist "survey applications". It is a cost-efficient device and can be of "tremendous" civilian use. The navigation output is composed of GPS, GLONASS and GPS+GLONASS position, speed and time data. According to a statement released by the DRDO, G3oM is a state-of-the-art technology receiver, integrating Indian GAGAN as well as both global positioning system and GLONASS systems.

This is the basis for navigation for India's nukes, the defence version anyway.

Lee

http://rt.com/news/syria-sarin-saudi-provocation-736/

This has been percolating through the social networks this morning.

Neil Richardson

Walrus:

"While not being a tech head, I am sure this situation has not been lost on the U.S. defence forces, and since a complete digital inertial reference system now weighs about Three ounces and takes up Two cubic inches, I imagine that these missiles don't need GPS to get to an initial point to acquire terrain."

In addition to what Allen Thompson pointed out about backup INS, aren't there tactical solutions? A comprehensive GPS jamming line sounds impressive, but how difficult would it be to create a corridor (or several more as decoys) with HARMs? Sure it could sacrifice tactical surprise, but I'm sure there are many ways to spook an adversary by prepping him if there's a bit of time prior to the start of an operation. And if they only try to protect a limited number of sites with GPS jammers, well that also tells you something.

Basilisk

Allen,
I concur. Perhaps that writer should seek out the advice that begins with, "A little knowledge is a dangerous thing...".

Phil Cattar

I believe the original version was "A little learning is a dangerous thing"...............Alexander Pope

Marquetta Raddatz

After reading through the article, found that it contains some useful knowledge about it and like your way of writing , i will pay more attention to your article and hope that you can also pay more attention to my website.

The comments to this entry are closed.

My Photo

February 2020

Sun Mon Tue Wed Thu Fri Sat
            1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
Blog powered by Typepad