Thursday, October 26, 2006

Guess what? Technology proliferates

...and sometimes, it proliferates way, way faster than you'd like it to.

Case in point: electronics. This story at DefenseTech points out that
The computer which runs the F-22 is an absolute design marvel for its time, for example: 700 MIPS (Millions of Instructions per Second), approximately 300 Megabytes of memory, and some 20 billion DSP [digital signal processing] style operations.

Yet its time was the late 80s and early 90s, when much of the hardware was finalized. Today, a Playstation 3 meets or exceeds this performance, for $600 instead of perhaps $30,000,000. (Of course, the F22's avionics are considerably more robust and presumably more reliable.)
This has more relevance than simply comparing hardware. Stealthy aircraft like the F-117 scatter radar signals away from the receivers. (Other aircraft, like the B2, either absorb or are transparent to Radar.) If you've got multiple receivers, and decent computing power, you can still put a signal back together - a trick the Chinese are said to have taught some countries. But it gets much, much worse (if you've invested heavily in stealth technologies):
There are a few prerequisites for multipath radar. The broadcasters, although simple, need to transmit an identifier as part of their signals, and be at known locations. The receivers, on the other hand, need to be very sophisticated. This requires sophisticated radio antennas and, more importantly, "serious DSP magic," which, when networked together, can compute a cohesive picture of the defender's airspace.

Yet the hardware to perform such DSP operations is becoming commonplace and commercially prevalent. GNU radar and other designs can receive the signals, and conventional computers and DSPs can then process the results, extract the features, and create an overall picture. There have been prototypes built in the United Kingdom, able to track commercial aircraft by observing the reflected signals from cell-phone towers.
Most modern countries are awash in radio signals, and it would not be difficult for a well-organized insurgent group - much less a government - to get precise coordinates for things like FM towers and cell phone towers - and disperse the receivers throughout the countryside. With modern technology, putting them on the backs of the ubiquitous Toyota 4x4 shouldn't be hard.

Most importantly, the vast majority of militarily-useful targets are not very stealthy. Even if this technology didn't let you see F-22s and F-35s, you could certainly spot the flotillas of heavy-lift cargo planes that fly in and out of Iraq every day. Once you've got a bearing and a vector, putting a guy in place with a decent chance of firing a shoulder-mounted SAM is much easier.

(This would allow insurgents to fire on incoming aircraft well away from the airports themselves, which is what the Iraqis have been doing. This makes controlling the airspace one more task that falls to the army, ironically. It also makes occupation even more labour-intensive.)

That bit about using local cellphone towers is particularly difficult for someone like the US in Iraq. Your options at that point are probably limited to trying to hunt down every insurgent receiver (and the USAF hasn't had much luck finding SCUDs, remember) or shutting down a country's cellphone service somehow, an action which wouldn't endear them to the locals.

It would be interesting to speculate if some countries might start regulating civilian radio broadcasts to take these kinds of technologies in to consideration. There are large parts of the spectrum that commercial broadcasters use as buffers between channels, after all. A government that wanted to expand it's radar options could mandate a specific time/space code in these buffer zones to link every transmission with a place and time and make it easier to put all these signals together.

If I were Iran, I'd be thinking about it.

3 comments:

Hamilton Lovecraft said...

Most importantly, the vast majority of militarily-useful targets are not very stealthy. Even if this technology didn't let you see F-22s and F-35s, you could certainly spot the flotillas of heavy-lift cargo planes that fly in and out of Iraq every day. Once you've got a bearing and a vector, putting a guy in place with a decent chance of firing a shoulder-mounted SAM is much easier. (This would allow insurgents to fire on incoming aircraft well away from the airports themselves, which is what the Iraqis have been doing.)

Shoulder-mounted SAMs aren't very good at high altitude intercepts -- that's the other reason the shooter wants to be near the airfield. The newer Russian man-portables (SA-14,-16,-18) are thought to be effective up to about 3500m altitude (~12000 feet) and are probably less reliable that high up.

All in all, it seems like setting up a distributed "passive radar" system like you describe would be more trouble than it's worth for Iraqi insurgents, though I can see North Korea and Iran being interested in the technology.

john said...

Hmmm. I wonder if larger missiles - say, something that could be launched from a truck - would be a better fit.

I agree about the Iraqi insurgents as they exist today - I suppose I was thinking someone more like Hezbollah could pull this off. They at least have demonstrated the ability to fire missiles in defiance of overwhelming airpower.

auntiegrav said...

You know how you sometimes click on an icon in Windows (even on a super fast computer), and shit just doesn't happen immediately?
That's the $30,000,000 difference. When you push the auto-track, or the flare ejection, or the missile launch button on the F-22, it HAS to work RIGHT NOW. Sometimes the technology is better, even if it isn't as fast. For example, the hardware/software mix on the F-14 was run by a 42-bit computer of early 1970's technology, and when you needed something to happen, it happened, multitasked, distributed computing and all. We think we need all those MIPS to get things done, but in reality, most are wasted on color displays and pretty graphics to represent targets which could just as easily be represented with a caret or a dot, and signal processing is sometimes done better with analog circuits and filters than with DSP which is prone to deception by harmonics and intermediate frequency incompatibilities.
China (our future adversary), doesn't care if they impress anyone with the sophistication of the fighter jet. They can use Intel processors from our old designs, jet engines from our old blueprints that work just fine, and plain old steel and aluminum to build THOUSANDS of fighter jets that go fast and shoot actual bullets. All our high tech crap is only good against other high tech crap in similar numbers. Each plane can only carry so many missiles and bullets (at least until the lasers and plasma weapons come into service), and only so much fuel (until Area 51 is opened up for business). The more sophisticated the system, the less likely it is that the system will be error free and 100% mission capable all the time. You end up with squadrons that can only fly 2 planes at any one time because of backordered parts and corroded wiring or stress cracks in the tupperware that have to be glued back together under UV light, etc.
There is no terrorist threat except the one we have bought and paid for. If there was, we would see the unprotected things in our own country falling down every day. Since we don't, we can assume that the reason GW didn't stop reading "My Pet Goat" was because he knew the only terrorists out there were ours. ("Dick told me to sit tight, no matter what happened today...")
Common sense beats technology any day. Monopulse radars beat stealth. Passive infrared beats radar at night under most circumstances, especially in the desert.
The 'nuclear' option in Bagdad is not atomic, but the Spectre gunships. Nobody wants to do it, but that's the choice; either walk away now or kill 'em all. "They can run, but they will only die tired."--squadron motto.