ILS DME strength?

Does anybody know the typical range of the DME signal when DME is installed
in conjunction with a localizer or ILS?

I shot an ILS yesterday that had it's compass locator decommissioned some
time ago, so now the approach requires a VOR or DME, which is fine, because
we've got both in addition to the GPS. But the DME seemed to act pretty
flakey. Sometimes it indicated over one hundred DME out, when we were only
8-9 miles away. Outbound it flickered on and off, inbound it was dead on
perfect. It also worked perfect flying back to our home airport that has a
VOR/DME on the field.

Is the DME associated with an ILS a "low power" or special version that is
different from that installed in conjunction with VOR's?

Thanks,

Jim

Jim Burns wrote:

Is the DME associated with an ILS a "low power" or special version that is
different from that installed in conjunction with VOR's?

Some of them are low-powered when frequency protection is an issue. Others,
like those for the west runways at LAX are intended to be used far out to the
east.

You would have to get in contact with someone in the FAA at Airway Facilities
(a service organization within ATO) to obtain the definitive answer to your
question.

Even where power is reduced, all required DME fixes must pass flight
inspection.

It might be a combination of lower power and your aircraft's DME antenna and/or
avionics.

In article ,
Jim Burns wrote:
Does anybody know the typical range of the DME signal when DME is installed
in conjunction with a localizer or ILS?

Questions like this are best answered by reading the AIM, Chapter 1
(Navigation Aids). It's on line at http://www.faa.gov/ATpubs/AIM/.

A quick read of Section 1-1-7 says range is up to 199 nm, at altitudes
high enough to have line-of-sight to the ground station. There's
nothing in there that leads me to believe that a DME co-located with
an ILS is any different from one co-located with a VOR.

A quick read of Section 1-1-7 says range is up to 199 nm...

"You can get up to 85 miles per gallon with Belchfire Gasoline".

What I didn't see there is that the range is =no less than= some amount.

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.

Roy Smith wrote:
: Questions like this are best answered by reading the AIM, Chapter 1
: (Navigation Aids). It's on line at http://www.faa.gov/ATpubs/AIM/.

: A quick read of Section 1-1-7 says range is up to 199 nm, at altitudes
: high enough to have line-of-sight to the ground station. There's
: nothing in there that leads me to believe that a DME co-located with
: an ILS is any different from one co-located with a VOR.

Since DME requires bi-directional communication, it would seem that DME
station receiver sensitivity, atmospheric conditions, and aircraft DME
transmitter/antenna power would be the limiting factor beyond a certain point.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

Roy Smith wrote:

In article ,
Jim Burns wrote:
Does anybody know the typical range of the DME signal when DME is installed
in conjunction with a localizer or ILS?

Questions like this are best answered by reading the AIM, Chapter 1
(Navigation Aids). It's on line at http://www.faa.gov/ATpubs/AIM/.

A quick read of Section 1-1-7 says range is up to 199 nm, at altitudes
high enough to have line-of-sight to the ground station. There's
nothing in there that leads me to believe that a DME co-located with
an ILS is any different from one co-located with a VOR.

This is from AC-0031A (on Summit Aviation Reference Library CD). It is about
frequency protection for VOR, ILS and DMEs. Sort of technical but does show
they do a lot of tinkering depending upon circumstances:

b. Interference Protection of DME/TACAN. The following interference signal
protection ratios shall be provided within the operational service volume of all
DME/TACAN stations with a 95 percent time availability. This is done by
controlling the station separation in certain cases.
(1) The D/U signal ratio between co-channel DME/TACAN stations shall not be less
than +8 dB.
(2) The D/U signal ratio between adjacent channel DME/TACAN stations shall be as
follows. The various D/U ratios have been established recognizing the spectrum
control characteristics reflected in paragraph 124 and the spectrum differences
between DME and TACAN.
(a) When the undesired station is a TACAN, the D/U ratio shall not be less than
-42 dB.
(b) When the undesired station is an LDME (1000 W transmitter), the D/U ratio
shall not be less than -39 dB.
(c) When the undesired station is a TDME (100 W transmitter), the D/U ratio
shall not be less than -29 dB.
(3) The D/U ratio between DME/TACAN stations with more than 1 MHz separation
shall not be less than -50 dB.
(4) Some peak power deterioration is allowed before the system is shut down. In
order to account for this decrease in power, the actual D/U values used for
station separation calculations are 3 dB more protective, for example, +11 dB
vice +8 dB, -39 dB vice -42 dB, etc.
c. Protection of Service Volumes Which Extend Beyond National Borders. Stations
near the border are normally not frequency protected for that airspace which
lies beyond the national border. Standard service volume and expanded service
volume protection may be provided upon proper coordination with Canada or
Mexico. This must be done whenever specific airways, routes, or procedures
beyond the border are based on ground stations in the U.S.A.

Regarding frequency protection. The ILS I flew was at KCWA on 110.3, the
VOR at KSTE is on 110.6, and it's less than 15 miles away. The ILS DME was
flakey at 2000 ft agl, within 10 miles of CWA, while the DME from STE was
rock solid at the same location.
Jim

"Jim Burns" wrote in message
...
Does anybody know the typical range of the DME signal when DME is
installed
in conjunction with a localizer or ILS?

I shot an ILS yesterday that had it's compass locator decommissioned some
time ago, so now the approach requires a VOR or DME, which is fine,
because
we've got both in addition to the GPS. But the DME seemed to act pretty
flakey. Sometimes it indicated over one hundred DME out, when we were
only
8-9 miles away. Outbound it flickered on and off, inbound it was dead on
perfect. It also worked perfect flying back to our home airport that has
a
VOR/DME on the field.

Is the DME associated with an ILS a "low power" or special version that is
different from that installed in conjunction with VOR's?

Thanks,

Jim

Also, note LDME (1000 watts) and TDME (100 watts).

On 10/31/2005 10:57, Jim Burns wrote:

Regarding frequency protection. The ILS I flew was at KCWA on 110.3, the
VOR at KSTE is on 110.6, and it's less than 15 miles away. The ILS DME was
flakey at 2000 ft agl, within 10 miles of CWA, while the DME from STE was
rock solid at the same location.
Jim

Just out of curiosity, were you listening to the tone code from
the DME (in addition to the tone code from the ILS) while you were
experiencing this problem?


"Jim Burns" wrote in message
...
Does anybody know the typical range of the DME signal when DME is
installed
in conjunction with a localizer or ILS?

I shot an ILS yesterday that had it's compass locator decommissioned some
time ago, so now the approach requires a VOR or DME, which is fine,
because
we've got both in addition to the GPS. But the DME seemed to act pretty
flakey. Sometimes it indicated over one hundred DME out, when we were
only
8-9 miles away. Outbound it flickered on and off, inbound it was dead on
perfect. It also worked perfect flying back to our home airport that has
a
VOR/DME on the field.

Is the DME associated with an ILS a "low power" or special version that is
different from that installed in conjunction with VOR's?

Thanks,

Jim






--
Mark Hansen, PP-ASEL, Instrument Airplane
Sacramento, CA

I have noticed very similar issues with the ILS DME at APA. I either
get nor reading or it bounces all over the spectrum until I get quite
close. Switching over to several other VOR frequencies in the vicinity
creates no such problems. I can only assume that DMEs co-located with
ILSs are significantly less strong.