|This is from a while back: http://www.agitprop.org.au/stopnato/19991201stealt.htm
THE CIA and Pentagon fear that China may be on the verge of perfecting a new anti-aircraft technology that can locate and track the stealth fighters and bombers that form a central plank of US air power.
The US defence establishment is so concerned that China may be forging a PCL, or “passive coherent location” system, that America’s military planners have been summoned to a meeting in Washington next month to examine the strategic implications of such a breakthrough, Newsweek reported yesterday.
Existing anti-aircraft early-warning systems rely on conventional radar, which the bat- shaped Stealth fighters are designed to evade. Such radars are also vulnerable to jamming and attack by missiles which follow the path of radar beams to transmitters.
The new Chinese system, by contrast, simply monitors civilian radio and television broadcasts and analyses the minute fluctuations caused by the passage of an aircraft through commercial wavelengths.
Relying on a network of receivers similar to television aerials, the “silent” PCL system does not emit a tell- tale radar signal and is therefore much harder to locate and destroy.
US military strategy could be dramatically undermined if US stealth aircraft, including the F117 fighter and the F22 fighter now in development, become vulnerable to Chinese interception, particularly given China’s more aggressive recent stance over Taiwan.
“Everyone is wondering about the cost of defending Taiwan,” one senior intelligence official was quoted as saying.
The US is developing a similar system, the “silent sentry”, which monitors energy reflected from commercial TV and radio signals to track aircraft.
The shooting down of a US Air Force F117 fighter in March during the Kosovo conflict has added to US fears that the stealth technology, developed amid intense secrecy during the 1970s, may no longer be the asset that it was.
Yugoslavia is believed to have sold on the wreckage of the F117, probably to China or Russia, and defence experts say that while the stealth technology used in that aircraft is now out of date, the wreck may still be useful for perfecting a means to track it. The Pentagon has refused to discuss how the aircraft was brought down, but defence officials say that the F117 was probably shot down by a Serb SA3 surface-to-air missile.
The B2 bomber, first deployed during the Kosovo conflict, uses a more advanced type of stealth technology than the F117, but it could still leave a “signature” detectable by a Chinese PCL system.
The US is the only country with stealth technology in use, and both Russia and China have been researching a means of tracking the “invisible” aircraft since the early 1970s. On conventional radar, if the technology is working correctly, a stealth aircaft is impossible to detect, but a PCL system may be able not only to “see” the incoming aircraft, but identify the make by its disruption of television and radio signals permanently in the atmosphere.