The sci. prefix makes me a little uncertain about posting here, as the
questions from this GPS newbie hardly rise to the dignity of an sci.
level. However, as I've found no other group that seems to discuss
GPS issues, I hope you will indulge me.

I have recently acquired a Garmin GPS-18 receiver with their nRoute
software. I had been having extreme signal loss problems (driving in
residential neighborhoods and on a divided highway with no buildings
taller than six stories, and those at least 100 yards from the
roadway); during a 30-minute drive I lost reception 14 times, and in
total was without a signal for about 15 of the 30 minutes.

I wrote to Garmin's customer support and was referred to a driver
update which I downloaded and installed (or attempted to instal; I
don't know how to tell whether I succeeded or not). Since then, the
lapses in reception have been less lengthy (none over fifteen seconds
and most only a second or two), but no less frequent.

In many cases of both the momentary and the long losses of reception,
the "satellites" screen has shown from six to nine satellites in
green.

My questions are
1) How can I tell whether I have, indeed, successfully installed the
driver update?
2) If I have done so, should I delete the old driver and, if so,
where do I find it?
3) Is this frequent, even if momentary, loss of reception normal for
a GPS receiver, or is the GPS 18 a piece of junk? (Here may be a
chance for you to get back to the science of GPS: once locked on to a
satellite, wouldn't the software always know where the satellite is
and will be five seconds or five minutes from now, the orbits being
either geosynchronous or of known speed and direction?)
4) If this degree of loss of reception is not normal, can you think
of anything I might do to improve it. I have been placing the
receiver beneath an unobstructed windshield; low or high seems to make
little difference. (Garmin was quick with a response to my first
query, but has not responded after several days to my follow-up
email.)
5) If the GPS 18 is a piece of junk, are there other receivers I can
use with nRoute? (I like the software pretty well, and in the
majority of respects better than the ALK, which I have also had.)


Thank you very much.

Gary Williams

The GPS 18 should work fine if it has a good view of the sky. Try
mounting it outside on your roof and see if the situation improves.
The previous comments are "right on".

I may try the roof-mounting thing, but only as an experiment; I don't
think I should have to crack open my sunroof in the middle of winter.

Here's a more general question: is it usual behavior for a receiver
to lose the signal, then regain it in a few seconds?

I have seen this [frequent losses of satellite signal and signal regained in >from a moment to ten seconds or so] but I live in mountains country (BC, >Canada).

Does that unit have facilities for an external antenna?

Sometimes nearby electronic equipment can interfere with reception.
If ... there are no radar or microwave antennas in the area, etc. and > you still get a lot of breaks, then maybe the GPS-18 has an internal
problem and you should get it replaced.

Thanks. I'd wondered whether electromagnetic interference could be an
issue for GPS receivers. The breaks seem quite frequent in and around
my residential neighborhood. I'm not aware of big antennas nearby,
but you never know. Maybe I should check into it.

And today, driving the same route as on which I've done most of my
tests, I had only a very few and momentary lapses.

But if we come to the latter option...from what I've read, I think
maybe Garmin software, which would include nRoute, doesn't conform to
NMEA standards, so I'd have to get another Garmin receiver. To your
knowledge, are there any other than the GPS 18 that work with nRoute?
(I rather like the software in most respects.)

The sci. prefix makes me a little uncertain about posting here, as the
questions from this GPS newbie hardly rise to the dignity of an sci.
level. However, as I've found no other group that seems to discuss
GPS issues, I hope you will indulge me.

I have recently acquired a Garmin GPS-18 receiver with their nRoute
software. I had been having extreme signal loss problems (driving in
residential neighborhoods and on a divided highway with no buildings
taller than six stories, and those at least 100 yards from the
roadway); during a 30-minute drive I lost reception 14 times, and in
total was without a signal for about 15 of the 30 minutes.

I wrote to Garmin's customer support and was referred to a driver
update which I downloaded and installed (or attempted to instal; I
don't know how to tell whether I succeeded or not). Since then, the
lapses in reception have been less lengthy (none over fifteen seconds
and most only a second or two), but no less frequent.

In many cases of both the momentary and the long losses of reception,
the "satellites" screen has shown from six to nine satellites in
green.

My questions are
1) How can I tell whether I have, indeed, successfully installed the
driver update?
2) If I have done so, should I delete the old driver and, if so,
where do I find it?
3) Is this frequent, even if momentary, loss of reception normal for
a GPS receiver, or is the GPS 18 a piece of junk? (Here may be a
chance for you to get back to the science of GPS: once locked on to a
satellite, wouldn't the software always know where the satellite is
and will be five seconds or five minutes from now, the orbits being
either geosynchronous or of known speed and direction?)
4) If this degree of loss of reception is not normal, can you think
of anything I might do to improve it. I have been placing the
receiver beneath an unobstructed windshield; low or high seems to make
little difference. (Garmin was quick with a response to my first
query, but has not responded after several days to my follow-up
email.)
5) If the GPS 18 is a piece of junk, are there other receivers I can
use with nRoute? (I like the software pretty well, and in the
majority of respects better than the ALK, which I have also had.)


Thank you very much.

Gary Williams