Originally Posted by
chevvron
I agree DRDF was useful as one of your 'tools' for discovering aircraft, especially where radar couldn't see and even in some circumstances for FISOs which might (for instance) be unable to transmit speech but could receive carrier wave only transmissions.
In this case it is called ''High Resolution DF' and the examples I have are at Little Rissington and Manston.
I believe HRDF refers specifically to those DF sites that form part of the D&D Auto-Triangulation network. The two examples you mentioned are both part of this network. The other term is DRDF
but I believe this is used in the military airfield context rather than part of the auto-T network in the sense that it has both UHF and VHF whereas VDF would be VHF only as is commonly the case at a civil unit.