Re: GPS tracking device allowed in commercial flights?

From: Meindert Sprang (mhsprang_at_NOcustomSPAMware.nl)
Date: 08/17/04 

Date: Tue, 17 Aug 2004 18:50:45 +0200

"Alan Browne" <alan.browne@FreeLunchVideotron.ca> wrote in message
news:1voUc.85710$sk2.1721793@wagner.videotron.net...
> The risk to interference in avionics is at many places, including
> antennas. Given the large variety of aircraft configurations,
> wiring runs and many unknowns, it has been deemed unsafe to
> operate any kind of transmitter aboard an aircraft. Commercial
> aircraft antennas range from fairly low frequency (ADF receivers)
> to very high (weather radar in x-band). Some antennas have
> filters at the mounting area, some do not but rely on in-chassis
> filtering.

Oh please! What about the aircraft's own transmitters? And now don't tell me
their RF stays out of the cockpit...
Every decent receiver (and you can count on aircraft stuff being decent) has
all the proper filtering they need, effectively blocking 900,1800 or 1900
MHz cellphone signals to a very low level.

Really, if aircraft electronics were so sensitive to RF interference, it
would be impossible to have HF and VHF transmitters on board used for
navigation and communication.

> Your test is hardly exhaustive or conclusive. See RTCA DO-160D
> for guidance.

Sorry, don't have that at hand. My job only deals with EN/IEC61000-6-1
and -6-3 and the likes.

> When my cell phone (on, but not in use) is under my car radio
> there are occasional bursts of modulation lasting 5 seconds or so
> when the cell and phone conduct some back channel communication.

You can hardly compare a car radio with a professional VHF radio.

> Interference does not occur uniquely via an antenna. Poor
> chassis shielding, poor wiring harness/connector shielding and
> filtering are among the many ways that signals get into receivers
> and can interfere.

Isn't that what I said too?

Meindert