Good radar detectors, like good AM/FM radios, are super-heterodyne receivers, and they all share a common trait. They receive, but they also transmit a signal; it's called "local oscillator emissions." This transmitted signal can be found by another radio if it's tuned to the right frequency. A radar-detector detector is merely a radio tuned to the right frequency range for most detectors.

VG2 is the most famous of the radar-detector detectors.

A little history: Escort was the first X-K super-heterodyne detector. Jim Jaeger and I invented it, working out of his basement in the mid-seventies. Since then, other detector makers have taken the easy way and copied Escort's frequency scheme, which means they have the same L-O frequency. So VG2 knows right where to tune for them.

The one detector that's apart from the pack is V1. I didn't copy myself. So VG2 misses Valentine One. In our tests, Valentine One is better than all others for VG2-proofing. Our best competitors are pretty good, maybe good enough. Some others resort to a dubious strategy; they switch off their radar protection when they sense VG2 nearby.

Recently, we've been hearing of another radar-detector detector, the Spectre RDD. Used first in Canada, enforcers of detector bans in Virginia and Washington, DC, and the nationwide ban in heavy trucks, surely have this tool on their must-have list. It claims to have been designed specifically "to detect the latest state of the art stealth-type radar warning receivers." Does it find V1? Very likely, according to reports we've been hearing from a few V1 users. One participant in an internet chat room, who claimed to be a Canadian enforcer, said "I've snagged a Valentine 1 already." We've been unable to acquire a Spectre RDD for testing. Until we can do so, be advised that no super-heterodyne receiver is perfectly undetectable, and that includes V1.