302 not receiving GPS satellites

On Jul 11, 11:44*am, jcarlyle wrote:
I'd be surprised if GPS antennas had oscillators, they're most likely
to be inside the unit itself and signal shouldn't leak out. Some GPS
antennas have preamps, for sure, and of course the only difference
between an amp and an oscillator is feedback. My own experience is
that active GPS antennas close enough to touch one another work
perfectly well. Naturally, keeping a transmitter (like FLARM or a VHF
radio antenna) at a distance from a GPS antenna is a wise idea to
prevent front end overload.

Perhaps a preamp experienced a thermal runaway once, and this led to
the legend of keeping GPS antennas separated? Are there any documented
instances to show that GPS antennas must be separated from one
another?

-John

On Jul 11, 1:31 pm, Darryl Ramm wrote:







Concerns about GPS antennas placed close to each other seem largely a
non-issue. e.g. there is really no local oscillator leakage from these
antennas. More common antenna problem are likely just good sky view/
obstruction issues.

Right, I should have been clear. They don't have local oscillators in
the active antennas, just pre-amps. And the good back-isolation means
the local oscillator in the GPS units themselves does not leak back to
the antenna.

Darryl

On Jul 11, 2:03*pm, Darryl Ramm wrote:



Thanks Darryl and others on your replies...
I spoke to CAE today and they believe it is one of 2 problems and most
likely the GPS board. I'm sending the unit back for repair and will
update the result as I find out.

Stephen

On Jul 11, 5:34*pm, Stephen Michalik
wrote:
On Jul 11, 2:03*pm, Darryl Ramm wrote:



Thanks Darryl and others on your replies...
I spoke to CAE today and they believe it is one of 2 problems and most
likely the GPS board. I'm sending the unit back for repair and will
update the result as I find out.

Stephen

The GPS engine hardware board in the unit failed. Jeff said likely
from age.

Stephen

On Jul 14, 2:48*pm, Stephen wrote:
On Jul 11, 5:34*pm, Stephen Michalik

wrote:
On Jul 11, 2:03*pm, Darryl Ramm wrote:

Thanks Darryl and others on your replies...
I spoke to CAE today and they believe it is one of 2 problems and most
likely the GPS board. I'm sending the unit back for repair and will
update the result as I find out.

Stephen

The GPS engine hardware board in the unit failed. Jeff said likely
from age.

Stephen

I had the same thing happen to me. You will find the new GPS engine
locks in much faster when you turn it on.

Clay

On Jul 16, 6:49*am, wrote:
On Jul 14, 2:48*pm, Stephen wrote:









On Jul 11, 5:34*pm, Stephen Michalik

wrote:
On Jul 11, 2:03*pm, Darryl Ramm wrote:

Thanks Darryl and others on your replies...
I spoke to CAE today and they believe it is one of 2 problems and most
likely the GPS board. I'm sending the unit back for repair and will
update the result as I find out.

Stephen

The GPS engine hardware board in the unit failed. Jeff said likely
from age.

Stephen

I had the same thing happen to me. You will find the new GPS engine
locks in much faster when you turn it on.

Clay

New GPS engine? Huh? The Cambridge 302 IGC approval document describes
a Garmin GPS25-LVC GPS receiver. The manufacturer cannot just change
this themselves and keep IGC approval of the flight recorder.

The actual time to get a GPS fix depends on if it was recently
operated at a different location far enough away and whether it has a
currently valid satellite almanac (and a few more things I'll
ignore). Typically when a GPS receiver like this is returned from a a
repair facility you'll see them need to get a cold fix and therefore
slower than the usual warm fix many people would see before a flight.

The time to get a cold fix times with newer generation GPS receivers
will be a lot faster than the rather old GPS engine used in the C302.

Darryl