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Garmin Mobile PC and eTrex Vista HCx connection issue
eagsc7
Win7 - eTrex Vista HCx v3.2

Whenever the GPS looses its connection with the laptop, and re-gains connection, the GPS looses ALL SATELLITE RECEPTION!

To Re-produce issue:
Start MobilePC, plug in eTrex unit and start driving. Have Passneger unplug and then immediately plug back in the GPS. Watch the GPS as it looses Satellite coverage. To verify, d/l the tracklog and see that it skipps the area in which it was re-acquiring satellites.

Ben

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Win7 - eTrex Vista HCx v3.2

MapSource(v 6.15.3 or 6.16.1) will NOT transfer data to/from MobilePC. This DID work with MobilePC v5.00.60.


Ben
Ken in Regina
Quote:
Originally Posted by eagsc7

Win7 - eTrex Vista HCx v3.2

Whenever the GPS looses its connection with the laptop, and re-gains connection, the GPS looses ALL SATELLITE RECEPTION!

To Re-produce issue:
Start MobilePC, plug in eTrex unit and start driving. Have Passneger unplug and then immediately plug back in the GPS. Watch the GPS as it looses Satellite coverage. To verify, d/l the tracklog and see that it skipps the area in which it was re-acquiring satellites.

Ben
Ben, this would be considered normal behaviour with any version and is a function of the USB driver, not the program and not the GPS receiver. As soon as the USB driver sees the device disappear, it will close down the port and do whatever cleanup is required when a device goes away, including notifying any software connecting to that port. Mobile PC sees that and sits waiting for whatever comes next, e.g. commands from the user or another connection notification.

When the device is plugged back in, the driver starts a new session. This causes the navigation software to begin the satellite acquision process from scratch, starting with a warm start request to the device to make sure it has clean communication with it. For all the navigation software knows, this could be a different device than was previously connected so it must start the communication process fresh to be sure everything is done correctly.

...ken...
eagsc7
I have updated the drivers, and this happens to the GPS! The GPS looses the satellites, just as if you had JUST turned it on!
Ken in Regina
Yes. That's what I said. There is at least one, and possibly two, triggers that are forcing the GPS receiver to re-acquire the satellites when you disconnect the USB connection.

As I said, the navigation program sends a warm start request to the GPS receiver. What looks to you like the GPS receiver losing the satellites is, in fact, the GPS receiver responding to a warm start request from the navigation program. The navigation program is doing that because it is seeing a *new* connection with a GPS receiver.

The second possible trigger, depending on the GPS receiver, is that the GPS receiver may also automatically reset itself when it sees the USB connection disappear and then sees a *new* connection with a computer.

In either case the receiver is going to act exactly as if you had just turned it on.

Neither of these will be changed by changing the USB driver. There is no problem with the USB driver. It's doing what it's supposed to do ... notifying the navigation program when the USB device is disconnected and notifying it again when a *new* connection is seen.

Both the navigation software and the GPS receiver are also behaving exactly as you would expect them to under the circumstances. You break the connection and they respond in an absolutely predictable manner.

This is not the way to simulate a lost or poor GPS signal if you are trying to determine the behaviour of the navigation software under signal loss conditions. You need to actually simulate a lost or degraded signal not some completely different problem as you have done.

Just put your hand above the GPS receiver and move it close enough to degrade the signal if that's what you want to simulate. Or toss a tin plate or metal pot lid over it if you want to simulate complete loss of signal. Wait to see what happens. Then remove the obstruction and see what happens.

...ken...
eagsc7
I have a 'new' issue. 1) Plug in Vista HCx to computer and allow to calculate position 2) Start GMPC(5.0.7) 3) WATCH the Vista HCx 'Re-acquire' satellite connections(and wait another couple minutes) 4) Close GMPC, and WATCH the Vista HCx RE-Re-acquire the satellites.

(once your done... try this same thing from the Passenger seat of a moving vehicle. D/L the Track and see that it truely LOST the connection...

GRRRRRR!!!

I Hate GMPC

Ben
Ken in Regina
Hi Ben,

I'm not sure why you also sent this post to me as a private message. I wish I had seen this first so I wouldn't have to type it all again.

There is no problem with either Mobile PC or your Vista.

When Mobile PC sees your Vista it's sending commands to make it do a warm start and make sure it has the right communication settings to work properly with Mobile PC.

When Mobile PC exits it drops the connection. When the Vista sees the connection go away it does a warm start to be sure it's set to work properly in standalone mode again.

For whatever it's worth, you buy nothing by connecting the Vista and waiting for it to get a lock before starting Mobile PC. You can run Mobile PC immediately after connecting the Vista and Mobile PC will find it just fine. Or you can run Mobile PC and then connect the Vista. Mobile PC will see the Vista as soon as it creates the USB connection with the PC. Waiting for a lock before launching Mobile PC makes no difference because Mobile PC is always going to send commands to the Vista as soon as it sees it, causing it to do a warm start.

...ken...
eagsc7
The ERROR is that Garmin Mobile PC is sending a 'Warm Boot' message, instead of waiting for Coordinates to come thru.

Ben
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