Radar detector detector

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A radar detector detector (RDD) is a device used by police or law enforcement in areas where radar detectors are declared illegal.

Radar detectors are built around a superheterodyne receiver, which has a local oscillator that radiates slightly, it is therefore possible to build a radar-detector detector, which detects such emissions (usually the frequency of the radar type being detected, plus about 10 MHz for the intermediate frequency). Some radar guns are equipped with such a device.

However, like any device that detects stray emissions from electronic equipment, it is easily defeated by using adequate shielding.


The VG-2 Interceptor was the first device developed for this purpose, although more current technology such as the Spectre III (Stalcar in Australia) is now[when?] available.[1] This form of "electronic warfare" cuts both ways and since detector-detectors use a similar superheterodyne receiver, many early "stealth" radar detectors were equipped with a radar-detector-detector-detector circuit, which shuts down the main radar receiver when the detector-detector's signal is detected, thus preventing detection by such equipment.[citation needed] In the early 1990s, BEL-Tronics, Inc. of Ontario, Canada (where radar detector use is prohibited) found that the local oscillator frequency of the detector could be altered to be out of the range of the VG-2 Interceptor. This resulted in a wave of detector manufacturers changing their local-oscillator frequency. Today, practically every radar detector on the market is immune to the VG-2 Interceptor[citation needed]. The VG-2 is no longer in production.

The Spectre III detected almost every radar detector certified for operation in the United States by the Federal Communications Commission as of December 2004; however counter technology has evolved rapidly, so that by July 2008, even budget radar detectors were able to avoid detection by the device.[2] Then, in late 2008, the Spectre IV (Elite) was released, citing improved range and reliability over the Spectre III. Radar detector manufacturers produce some models undetectable by the Spectre Elite beyond a distance of a few inches, making them immune in real-world situations.


  1. ^ Radar Detector Detector (RDD) Archived June 20, 2010, at the Wayback Machine
  2. ^ Asher Moses (2008-07-23). "Police grapple with defective detectors". Sydney Morning Herald. Retrieved 2008-10-13.