Development of the Doppler VOR in Europe

A new Doppler VOR system has been developed which provides site independence for users of conventional VOR receivers as well as increased accuracy when an airborne attachment is employed. Some essential features of a completed system are described. This system solves the siting problem in conventional receivers with present-day accuracy. Some basic receiver problems related to Doppler VOR engineering are discussed. Increased accuracy can be obtained with the new system when a conventional receiver is optimized for high instrumental accuracy. In another receiver improvement, a harmonic discriminator is used and offers the advantages of multilobe operation without any attachment to the ground station.