Talk:Distance measuring equipment

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Accuracy[edit]

What is the todays standard accuracy of a DME? — Preceding unsigned comment added by 83.76.251.6 (talk • contribs) 10:40, December 7, 2005‎

According to the DME section of the 2001 Federal Radionavigation Systems (2001 FRS) publication released by the DOD and DOT, Page 3-29:

Accuracy (2 sigma)

Predictable - The ground station errors are less than ±0.1 nm. The overall system error

(airborne and ground RSS) is not greater than ±0.5 nm or 3 percent of the distance, whichever is greater.

Relative - Although some errors could be introduced by reflections, the major relative

error emanates from the receiver and flight technical error.

Repeatable - Major error components of the ground system and receiver will not vary

appreciably in the short term.

Hope this helps -- Dual Freq 01:01, 10 December 2005 (UTC)[reply]

Doppler indicators forgotten ?[edit]

Shouldn't this article include Doppler indicators, under historical parts ? They were commonly used on the first generation of Transatlantic jet airliners, like Boeing707 and DC8, possibly even later models.Boeing720 (talk) 21:06, 12 March 2015 (UTC)[reply]

Doppler radar navigation? As discussed in this article? That sounds like an aircraft based radar coupled with an inertial navigation system. Wikipedia could probably use an article about doppler navigation if some decent sources could be found. Doppler_radar#navigation has some items. Green Satin radar might be similar or an earlier model. Sounds like a dead reckoning system that uses doppler radar for a more accurate ground speed. How does it fit in with DME? DME wouldn't be useful in transatlantic flights many miles from land or comparable to that system. --Dual Freq (talk) 21:44, 12 March 2015 (UTC)[reply]

Hello, Doppler has no real connection to this DME technology. DME relies on a ground transponder, interrogated by pulse pairs, and then the time divided by 12.36us to determine nMile distance (slant range to the beacon). the doppler change in frequency is not able to be calculated by the interrogator (airborne equipment) and then displayed. Also the distance available is only used to around 200 nm, so it would be useless across the atlantic more than that distance from a ground-based transponder. just my 2cents, Read-write-services (talk) 01:40, 13 March 2015 (UTC)[reply]

DME Operates in the L-Band (960-1215 MHz)[edit]

The term UHF, although used by ICAO, is confusing to some, who would prefer the term L-band. I added this, and made a few other edits. NavigationGuy (talk) 14:52, 3 February 2019 (UTC)[reply]

Also, the third figure (caption: 'DME distance and VOR/ADF cockpit display instruments') is misleading. A reading of 567.8 is clearly erroneous.

Strangely the frequency entered in the aircraft is typically in the hundreds of MHz, for example, the JFK VOR/DME is 115.9 MHz (refer to skyvector.com). But the actual text refer to 1000's MHz, which ends up in the GHz band? Can somebody clarify this?

--Mgouin (talk) 01:40, 21 March 2019 (UTC)[reply]

VOR and DME are (a) separate systems, but (b) used together. Thus, their frequencies are paired. Paired means that if 'you' tune to a VOR frequency (108 - 118 MHz), the DME is automatically tuned to the paired channel (defined by ICAO). You don't have to know the DME frequency. NavigationGuy (talk) 15:24, 20 April 2019 (UTC)[reply]