Talk:Radio direction finder
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Does anyone know what this refers to, from Ralph Hartley:
- During World War I he established the principles that led to sound-type directional finders
Aircraft (automated) ADF have a separate 'sense' antenna and the receiver compares the phase of the sense signal with the (apparently) rotating directional antenna. If the signals match phase, direction must be 'forward', if the signals are 180 out of phase, must be the other direction. Manual style systems (like the hand-held one illustrated) require 'procedural' methods - find the direction (or could be opposite), walk across the direction, take another bearing ... the intersection of those two bearings should be the real direction ... so move in that direction, monitoring signal strength and perhaps try the two bearing procedure again. I'll take the automated ADF any day :) Drpixie (talk) 08:39, 9 October 2008 (UTC)
The pictures "On-board ADF Display" and "An aircraft RMI" in this article are identical. A picture should contribute to an article it in some way, so the same picture twice in the same article is usually redundant at best - confusing at worst. I do not have a picture of an ADF myself, and could not find one with the necessary rights attached - but please insert one if you can, thanks! Tungstic (talk) 20:55, 17 October 2012 (UTC)
It's highly questionable, I think, whether it is true to say that RDF "... makes a particularly good navigation system for ships, small boats, and aircraft that might be some distance from their destination." Certainly, in the context of small boat navigation, it was never more than a short-medium range navigation aid, whose range was limited to (usually) less than 100 miles and whose accuracy was such that even at ranges of a few tens of miles, its practical value was extremely limited. It was cheap and reasonably easy to integrate with traditional navigation techniques, so until the late 70's/early 80's, many/most seagoing small craft carried an RDF receiver. But it was largely a device of last resort, and was quickly rendered obsolete by hyperbolic systems such as Decca and Loran and (later) by GPS. AFAIK, all marine radiobeacons have now been decommissioned. Tim Bartlett 220.127.116.11 (talk) 17:15, 23 March 2010 (UTC)
"The act of measuring the direction is known as radio direction finding or sometimes simply direction finding (DF)."