STVTalk.com

I have a Garmin 3+ and a NavTeq bluetootch gps that I use with an
Axim x30 or Dell 8600. My problem is that both take forever to find
enough satellites to track. Usually, the only way either will find
enough to track is if I pull over and stop. Sometimes, more often
than not, it doesn't seem to make any difference. At first, I
thought it a problem with the many trees in this state. Now, I'm
starting to wonder if it's the Ct sky or tree density or lousey State
coverage. If you've had similar experience I'd be interested. The
Garmin is about 6 years old; could that be a contributor? Thanks,
TL

I have a Garmin 3+ and a NavTeq bluetootch gps that I use with an Axim x30
or Dell 8600. My problem is that both take forever to find enough
satellites to track. Usually, the only way either will find enough to track
is if I pull over and stop. Sometimes, more often than not, it doesn't seem
to make any difference. At first, I thought it a problem with the many
trees in this state. Now, I'm starting to wonder if it's the Ct sky or tree
density or lousey State coverage. If you've had similar experience I'd be
interested. The Garmin is about 6 years old; could that be a contributor?
Thanks,
TL

I have a Garmin 3+ and a NavTeq bluetootch gps that I use with an Axim x30
or Dell 8600. My problem is that both take forever to find enough
satellites to track. Usually, the only way either will find enough to
track is if I pull over and stop. Sometimes, more often than not, it
doesn't seem to make any difference. At first, I thought it a problem with
the many trees in this state. Now, I'm starting to wonder if it's the Ct
sky or tree density or lousey State coverage. If you've had similar
experience I'd be interested. The Garmin is about 6 years old; could that
be a contributor?
Thanks,
TL

"Wayne R." wrote:


To initialize the unit, it needs uninterrupted signal from several
satellites to get the thing initialized. I'm not sure it's a fixed
period or period that's model specific, but moving through trees
during this period constantly resets the buffer (whatever) and
restarts the acquisition process.

Once the initialization is complete, brief interruptions are taken in
stride. (That's one reason why cold start times are longer than warm
start.)


This is the correct answer... In order to lock on to each individual
satellite, the receiver must receive 30 Seconds of PERFECT navigation
data from each satellite... Motion of the receiver is most often the
cause of the long lock times...

The navigation data is repeated every 30 seconds, so with a perfect view
of the sky (depending where you turn the unit on during the 30-second
cycle) it could take 31 to 61 seconds to get a 2D or 3D lock... That's
why Garmin states it as "45 seconds, typical"...

The navigation data is repeated every 30 seconds, so with a perfect view
of the sky (depending where you turn the unit on during the 30-second
cycle) it could take 31 to 61 seconds to get a 2D or 3D lock... That's
why Garmin states it as "45 seconds, typical"...

To initialize the unit, it needs uninterrupted signal from several
satellites to get the thing initialized. I'm not sure it's a fixed
period or period that's model specific, but moving through trees
during this period constantly resets the buffer (whatever) and
restarts the acquisition process.

Once the initialization is complete, brief interruptions are taken in
stride. (That's one reason why cold start times are longer than warm
start.)

I have a Garmin 3+ and a NavTeq bluetootch gps that I use with an Axim
x30 or Dell 8600. My problem is that both take forever to find enough
satellites to track. Usually, the only way either will find enough to
track is if I pull over and stop. Sometimes, more often than not, it
doesn't seem to make any difference. At first, I thought it a problem
with the many trees in this state. Now, I'm starting to wonder if
it's the Ct sky or tree density or lousey State coverage. If you've
had similar experience I'd be interested. The Garmin is about 6 years
old; could that be a contributor? Thanks,
TL

I have a Garmin 3+ and a NavTeq bluetootch gps that I use with an Axim x30
or Dell 8600. My problem is that both take forever to find enough
satellites to track. Usually, the only way either will find enough to track
is if I pull over and stop.

Sometimes, more often than not, it doesn't seem
to make any difference. At first, I thought it a problem with the many
trees in this state. Now, I'm starting to wonder if it's the Ct sky or tree
density or lousey State coverage.

If you've had similar experience I'd be
interested. The Garmin is about 6 years old; could that be a contributor?

Jack wrote:
The navigation data is repeated every 30 seconds, so with a perfect view
of the sky (depending where you turn the unit on during the 30-second
cycle) it could take 31 to 61 seconds to get a 2D or 3D lock... That's
why Garmin states it as "45 seconds, typical"...

What am I missing? Once the receiver locks onto the signal from a
satellite by correlating with the correct spreading code it can start
reading the data link which, as you state, repeats with a 30 second
frame period. So the receiver can store the incoming data until it can
identify the frame structure and therefore properly interpret the data.
Since a frame of the message takes only 30 seconds that amount of data
should be sufficient for the receiver to start its processing and
determine a position fix. I don't see why it would ever take the 61
seconds stated above in the absence of data errors.

Actually only 18 seconds (3 subframes) of the 30 second data message
are required to be received for the unit to use that satellite for a
position fix since the other two subframes have almanac data on the
other satellites (with a superframe of 24 frames providing complete
almanac data every 12.5 minutes). So if we're lucky in our timing of
turning on the receiver we might be able to make do with less than 30
seconds of error-free data, but I don't see why we should ever need
more than the 30 second frame length plus the processing time.

I have a Garmin 3+ and a NavTeq bluetootch gps that I use with an Axim x30
or Dell 8600. My problem is that both take forever to find enough
satellites to track. Usually, the only way either will find enough to track
is if I pull over and stop. Sometimes, more often than not, it doesn't seem
to make any difference. At first, I thought it a problem with the many
trees in this state. Now, I'm starting to wonder if it's the Ct sky or tree
density or lousey State coverage. If you've had similar experience I'd be
interested. The Garmin is about 6 years old; could that be a contributor?
Thanks,
TL

Where do you put the GPS when you drive? It is important they have

Jack wrote:

The navigation data is repeated every 30 seconds, so with a perfect view
of the sky (depending where you turn the unit on during the 30-second
cycle) it could take 31 to 61 seconds to get a 2D or 3D lock... That's
why Garmin states it as "45 seconds, typical"...


What am I missing? Once the receiver locks onto the signal from a
satellite by correlating with the correct spreading code it can start
reading the data link which, as you state, repeats with a 30 second
frame period. So the receiver can store the incoming data until it can
identify the frame structure and therefore properly interpret the data.
Since a frame of the message takes only 30 seconds that amount of data
should be sufficient for the receiver to start its processing and
determine a position fix. I don't see why it would ever take the 61
seconds stated above in the absence of data errors.

Actually only 18 seconds (3 subframes) of the 30 second data message
are required to be received for the unit to use that satellite for a
position fix since the other two subframes have almanac data on the
other satellites (with a superframe of 24 frames providing complete
almanac data every 12.5 minutes). So if we're lucky in our timing of
turning on the receiver we might be able to make do with less than 30
seconds of error-free data, but I don't see why we should ever need
more than the 30 second frame length plus the processing time.

On Sun, 16 Oct 2005 15:26:53 -0400, "TLoewenberg" <termarl@msn.com
wrote:

I have a Garmin 3+ and a NavTeq bluetootch gps that I use with an Axim x30
or Dell 8600. My problem is that both take forever to find enough
satellites to track. Usually, the only way either will find enough to
track
is if I pull over and stop. Sometimes, more often than not, it doesn't
seem
to make any difference. At first, I thought it a problem with the many
trees in this state. Now, I'm starting to wonder if it's the Ct sky or
tree
density or lousey State coverage. If you've had similar experience I'd be
interested. The Garmin is about 6 years old; could that be a contributor?
Thanks,
TL

Where do you put the GPS when you drive? It is important they have
good view of the sky, and are able to watch the same, good sized
portion until they get a lock. Unless you put the GPS all the way
forward up against the windshield, you usually cannot get an initial
lock. I don't think a GPS 3+ supports an external antenna, but on the
models that do, well I have a velcro strip all the way at the front
where the dashboard meets the windshield, and that's where I put
external antennae. Provides a veiw of about 70% of the sky, anything
more than about 65 degrees above the horizon can be seen, regardless
of change of direction.

In addition, the internal battery (on the PCB, not the AA cells that
power the GPS III) may have failed. This causes the unit to fail to
retain current almanac information, and that slows down initial
acquisition not a little, a lot.....

Hmmm, on placement, I try to position the gps as far forward on the dash as
possible. I also have a ram mount that positions the gps further back but
with the antenna still under the windshield. How would I know (or find out)
if the pcb battery has failed? Is it user replaceable? If the battery is
okay, how long does the III+ retain the almanac data? As for the small
bluetooth gps, I place it all the way forward in the center of the
windshield. The bluetooth gps is a Dell, who has agreed to replace it under
warranty. If the new one, acts the same way, I can only assume too many
trees and/or a gps unfriendly windshield.
Thx
TL

Gawd, top postint sux

What am I missing? Once the receiver locks onto the signal from a
satellite by correlating with the correct spreading code it can start
reading the data link which, as you state, repeats with a 30 second
frame period. So the receiver can store the incoming data until it can
identify the frame structure and therefore properly interpret the data.
Since a frame of the message takes only 30 seconds that amount of data
should be sufficient for the receiver to start its processing and
determine a position fix. I don't see why it would ever take the 61
seconds stated above in the absence of data errors.

Actually only 18 seconds (3 subframes) of the 30 second data message
are required to be received for the unit to use that satellite for a
position fix since the other two subframes have almanac data on the
other satellites (with a superframe of 24 frames providing complete
almanac data every 12.5 minutes). So if we're lucky in our timing of
turning on the receiver we might be able to make do with less than 30
seconds of error-free data, but I don't see why we should ever need
more than the 30 second frame length plus the processing time.