| Author |
c320: Loss of signal and generally odd GPS behaviour
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| romandvoskin@gmail.com 2006-12-16, 10:33 pm |
| All,
I've had c320 for about 6 months. Today in Boston and yesterday in
Framingham (30 miles West) the unit started to float around on the map
and eventually lost signal. This has never happened before while
driving thru the same areas. I have seen the unit loose signal when
going into a tunnel for example but today and yesterday this happened
less quickly (floating first) and with open sky. When this happens the
direction steps are correct but the unit does not have a clear idea of
location. The unit regained the signal later when I was out of the
city.
I just read there is a way to do a hard reset by removing the
faceplate. Will this help?
Is the unit defective?
Roman
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| mrichards 2006-12-17, 10:33 am |
| On Sat, 16 Dec 2006 18:42:08 -0500, <romandvoskin@gmail.com> wrote:
> All,
>
> I've had c320 for about 6 months. Today in Boston and yesterday in
> Framingham (30 miles West) the unit started to float around on the map
> and eventually lost signal. This has never happened before while
> driving thru the same areas. I have seen the unit loose signal when
> going into a tunnel for example but today and yesterday this happened
> less quickly (floating first) and with open sky. When this happens the
> direction steps are correct but the unit does not have a clear idea of
> location. The unit regained the signal later when I was out of the
> city.
>
> I just read there is a way to do a hard reset by removing the
> faceplate. Will this help?
>
> Is the unit defective?
>
> Roman
Never had that happen with my C320. I would try the reset first and if
that does not help I would contact Garmin.
MR
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| mike vore 2006-12-17, 12:33 pm |
| romandvoskin@gmail.com wrote:
> All,
>
> I've had c320 for about 6 months. Today in Boston and yesterday in
> Framingham (30 miles West) the unit started to float around on the map
> and eventually lost signal. This has never happened before while
> driving thru the same areas. I have seen the unit loose signal when
> going into a tunnel for example but today and yesterday this happened
> less quickly (floating first) and with open sky. When this happens the
> direction steps are correct but the unit does not have a clear idea of
> location. The unit regained the signal later when I was out of the
> city.
>
> I just read there is a way to do a hard reset by removing the
> faceplate. Will this help?
>
> Is the unit defective?
Don't go by one happening. See if it happens again, and it the location is the
same.
I've had a 320 for over a year now and it too has exhibited some strange
behavior similar to yours. The map would wonder and the directions would
recalculate. It only happened over a small distance and I didn't recognize
where it thought it was. But always at the same place on the road - just a
few miles from Camp David. I attributed the anomalous behavior to some kind of
GPS jamming with the name of National Security.
--
Mike Vore
http://www.OhMyWoodness.com
http://mike.vorefamily.net/twr
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|
| mike vore wrote:
> romandvoskin@gmail.com wrote:
>
> Don't go by one happening. See if it happens again, and it the location is the
> same.
>
> I've had a 320 for over a year now and it too has exhibited some strange
> behavior similar to yours. The map would wonder and the directions would
> recalculate. It only happened over a small distance and I didn't recognize
> where it thought it was. But always at the same place on the road - just a
> few miles from Camp David. I attributed the anomalous behavior to some kind of
> GPS jamming with the name of National Security.
>
I've had trouble with a 76s that did the same thing. It was caused from
a small transmitter on my motorcycle. The transmitter sent a signal to
an in-helmet LED to notify me when a radar detector picked up something.
Just that small transmitter put out enough interference that it seem
to "sometime" garble a satellite signal. I would regularly have 8
satellites, all with differential data and would loose the lock. Even
had Garmin check out the receiver and found it to work fine.
Have you changed to a different cell phone or other electronic stuff
since this happened?
I have been told some military bases jam GPS signals but never
experienced it.
--
Andy
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| Jack Erbes 2006-12-17, 12:33 pm |
| mike vore wrote:
<snip>
> where it thought it was. But always at the same place on the road - just a
> few miles from Camp David. I attributed the anomalous behavior to some kind of
> GPS jamming with the name of National Security.
I wouldn't be surprised if it wasn't more a case of electromagnetic
interference (EMI) than jamming. When you get in the proximity of
satellite uplinks you will pick up some ground waves or splatter from
satellite uplinks that could cause what you were seeing.
In the purest sense of the word, EMI is incidental and jamming is
intentional. I wouldn't think that localized jamming of GPS signals
from the ground would be an effective defensive measure.
Jack
--
Jack Erbes in Ellsworth, Maine, USA (jackerbes at adelphia dot net)
(also receiving email at jacker at midmaine dot com)
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| mike vore 2006-12-18, 10:33 pm |
| Jack Erbes wrote:
> mike vore wrote:
>
> <snip>
>
> I wouldn't be surprised if it wasn't more a case of electromagnetic
> interference (EMI) than jamming. When you get in the proximity of
> satellite uplinks you will pick up some ground waves or splatter from
> satellite uplinks that could cause what you were seeing.
>
> In the purest sense of the word, EMI is incidental and jamming is
> intentional. I wouldn't think that localized jamming of GPS signals
> from the ground would be an effective defensive measure.
This was about 3 miles from Camp David - the President's retreat. The local
area is rural farming, no industry that I know of. It happened two or three
times at the same point on the road. I think it was at a time when Bush was
there. I agree that local jamming would not do much against a dedicated attack
that got a fix with GPS at some distance then used inertial guidance for the
last few miles - not as accurate as some of our military missals, but ...
There is a Navy base in Southern Md that is known (rumored) to jam GPS over a
wide area, though I've not driven in the area to see for myself.
--
Mike Vore
http://www.OhMyWoodness.com
http://mike.vorefamily.net/twr
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