gerrcoin wrote in message ...
Larry Dighera wrote:
On Wed, 19 May 2004 00:42:13 +0100, gerrcoin
wrote in Message-Id:
:


The effects on a magnetic compass could be significant however.


At what distance?


--

Irrational beliefs ultimately lead to irrational acts.
-- Larry Dighera,

Don't rightly know, but as everything that emitts an electric field
also emitts a magnetic field there has to be some effect, even though
it may not be significant or even noticable. That's why you have to
swing a compass in an aircraft, because the pressence of other
magnetic fields (avionics, gyros, even plain steel) can influence the
heading indicated.

Bluetooth operates within a signal range of 10m or so, so in
comparison to a mobile phone (which is a fairly powerful transmitter)
it's a pretty weak signal. If anything were going to cause
interferience to avionics it would be your cell phone, but a lot of
prople use them during GA flights with no ill effects that I've heard
of. It should be remembered that all avionics are built with such
effects in mind. They have shielded cases and recieve their signals
through shielded cables from outside the aircraft.

I'm no electronics engineer, but I do know that compasses respond to
steady-state magnetic fields, where North and South stay put, more or
less. A direct-current flow in a wire will generate such a field, but
an alternating-current flow will generate a field that switches
polarity at the frequency of the AC. Since all radio transmissions are
AC, the compass won't respond to them. It WILL respond to stronger DC
flows within a radio box, such as the DC voltage feed, panel lighting
and so on. More typical compass interference (deviation) is caused by
nav and landing lights or the DC bus flow.

Dan