VOR-DME equations 2

[Slash67]

Hi all,

Can anyone help me by suggesting some references (books or links) related to the equations used for the VOR-DME equipment in order to determine distance?

Thanks

 

[CESSNA1]

SLASH67: Go to any basic flight instruction book such as Jeppesen or Kerschner. Try the public library, they may have them. VOR-DME stands for VHF Omni-Navigation Radio - Distance Measuring Equipment. DME measures straight line distance from the aircraft to the VOR-DME station. It is really a slant distance and is reasonably accurate up to the vicinity of the VOR_DME station. Depending on your altitude the closer you get to the station the less accurate the DME reading. One mile horizontal distance for each 1000 feet of altitude is typically accepted as being the edge of accuracy as you near the station. If you are 1000 feet above the station and one mile out the DME will read about 5400 feet Groundspeed readout is only accurate when flying directly to or from the station on a VOR-DME radial.

Hope this helps

Regards
Dave

 

[debodine]

There is a thorough discussion with the mathematics involved at:

http://www.pn.ewi.tudelft.nl/education/et4-022/sheets/20060310_vor-dme.pdf

if you want detailed analysis.

I don't know how deep you want to dive in.

debodine

 

[CESSNA1]

SLASH67: Sorry, I misinterpreted your question. The equations are very simple. A VOR has a omni-directional beacon and a rotating beacon. When the receiver in the plane detects the omni-directional signal it starts a clock. when the receiver detects the rotating signal it stops the clock. The radial the airplane is on can then be calculated by knowing the rpm of the rotating beacon (3600 rpm). The DME operation is similar. A single pulse is sent out from the airplane to the DME station. The DME station then responds with another signal and the time difference is used to calculate the distance, knowing the speed of the signal (186,000 miles/second).

Regards
Dave