On Sun, 23 Jul 2006 07:20:16 GMT, Dave S
wrote:

thejim wrote:
Can someone explain me what do we mean by the term frequency pairing?
I met the term in an avionics book.The phrase is the following;
The DME interrogation and reply frequency are paired with VOR
frequency.
Thank you



VOR's are in the VHF band (108-118 mHz approx)
DME's are in the UHF band (up in the 400's mHZ)

When you tune a DME, the VHF frequency you enter on the device (or have
channeled to it from the nav) is a paired frequency, established years
ago by international convention.


Dave

It's even more complex than it first looks:

There are 200 VHF channels allocated for NAV/DME of which 40 are also
paired with the ILS. That means when you tune to a VHF NAV frequency
you also tune the DME transmitter, DME receiver and ILS receiver. Each
part of the system uses a separate range of frequencies but for
simplicity selecting one automatically selects the rest.

These a

108-117.95MHz VOR/LOC
1041-1150MHz DME Transmitter
978-1213MHz DME Receiver
328-336 MHz Glideslope Receiver
(Glideslope selected by the VHF range up to 111.95MHz)

Being mere pilots all we need to know is when you tune the NAV
everything else should follow as it is 'paired'.

David