31 January 20

Is Cobra Mist a movie line or Magnetic Drum Radar
A. Movie Line
B. Magnetic Drum Radar

Answer B… Cobra Mist was the US Airforce code name for its over the horizon radar based on the Navy Research Labs magnetic drum radar equipment (aka “MADRE”). The US Airforce placed it in Orford Ness, Great Britain.

Key to the operation of any backscatter radar is the ability to filter out the huge return from the ground and sea and capture only the objects of interest. This is accomplished using the Doppler effect and gating out the vast majority of the signal. In the case of Cobra Mist, the signal was first gated for range by eliminating any signals lying outside a particular time window; thereby selecting targets within a particular area. Then it was fed into a series of frequency filters tuned to the expected frequency shifts from various sorts of common targets: lower speed for ships, high-speed for aircraft, and constant-acceleration for missiles.

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