Eureka beacon

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The Eureka beacon was a simple radio homing beacon used in combination with the airborne Rebecca receiver.

[edit] Operation

The airborne Rebecca receiver transmitted 300 3-4 uSec pulses per second on a frequency between 170 and 234 MHz, upon receiving this signal the ground based Eureka rebroadcast the pulses on a different frequency. This rebroadcast signal was picked up by two aerials on the aircraft carrying the Rebecca unit. The difference in reception time between the two aerials gave the bearing of the Eureka beacon, while the delay between transmission and reception of the return pulses gave range.

There were a large numbers of the versions of the system, early models were limited to a single frequency - later ones could switch between 5 frequencies.