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Bazzer Regular Visitor
Joined: Feb 17, 2005 Posts: 209 Location: Wirral
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Posted: Fri Jul 15, 2005 10:09 am Post subject: Driving Through Tunnels |
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When entering tunnels the signal is quickly lost (as you would expect) and then takes a little while before it reacquires the signal after exiting.
However, I assume that TomTom/TeleAtlas KNOW that the section of road on the route is a tunnel and would take this into consideration when giving voice instructions.
For example, when exiting the Mersey Tunnel (on the Liverpool side), you immediately have to negotiate a roundabout, but as the GPS has not reaquired the signal, it does not know where it is, and so does not give any instruction as to which to turn.
I would have thought (if the programmers are clever enough), that before entering a tunnel, it would give the correct instruction for when you exit, therefore keeping you on the correct route.
Or alternatively, in circumstances when it loses a signal, it automatically gives the command for the next instruction and the distance to it.
I believe that this enhancement should not be too difficult to implement. I think that am email to the TomTom Developers is in order.
Baz _________________ Garmin DriveSmart 61 LMT-D
TomTom Go 50 - Going in the BIN
TomTom Go 730 (RIP)
Garmin Montana 650
Garmin Oregon 45oT
Garmin Edge 1000
Tracklogs Digital Mapping |
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jamiepyoung Regular Visitor
Joined: May 28, 2005 Posts: 65 Location: Warwick
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Posted: Fri Jul 15, 2005 10:11 am Post subject: |
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sounds like a good idea - i had the same last week exiting the m25 for enfield - exit is virtually in the tunnel |
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CJackel492 Regular Visitor
Joined: Mar 15, 2005 Posts: 210
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Posted: Fri Jul 15, 2005 10:24 am Post subject: |
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I thought that when you entered the tunnel and lost signal that TomTom would then estimate your position by using the last speed before the signal loss, So therefore continue to navigate you until it got a signal back?
I'm sure I noticed it a few times that it wold still show me moving through the tunnel?
Might have been TTN3,
Carl, _________________ Phones - Nokia 9500 + a few others
Nokia 9500 running TTM5 |
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Bazzer Regular Visitor
Joined: Feb 17, 2005 Posts: 209 Location: Wirral
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Posted: Fri Jul 15, 2005 10:36 am Post subject: |
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I'm still using TT3 (waiting for upgrade to TT5), and after it has lost the signal, the map screen just hangs stating 'GPS Unreliable' until it finally reacquires the signal upon exit.
Unfortunately, it does not continue to navigate.
Baz _________________ Garmin DriveSmart 61 LMT-D
TomTom Go 50 - Going in the BIN
TomTom Go 730 (RIP)
Garmin Montana 650
Garmin Oregon 45oT
Garmin Edge 1000
Tracklogs Digital Mapping |
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MarkHewitt Frequent Visitor
Joined: Nov 16, 2004 Posts: 1077 Location: Chester-le-Street & York
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Posted: Fri Jul 15, 2005 10:54 am Post subject: |
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CJackel492 wrote: | I thought that when you entered the tunnel and lost signal that TomTom would then estimate your position by using the last speed before the signal loss, So therefore continue to navigate you until it got a signal back?
I'm sure I noticed it a few times that it wold still show me moving through the tunnel?
Might have been TTN3,
Carl, |
It does this for a few seconds, then gives up. |
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chaddow Occasional Visitor
Joined: Jun 07, 2005 Posts: 25
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Posted: Fri Jul 15, 2005 11:54 am Post subject: |
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Having driven through a number of tunnels on a recent trip to Spain with TT5 it would appear that TT5 estimates your position for about a minute after loss of signal and will during this time issue direction messages, e.g. if there is a roundabout or whatever if appropriate.
After the 1 minute TT5 seems to stop estimating poistion or issuing directions until the signal is reaquired. _________________ HP iPaq h5550 ROM 1.10.10 ENG
TomTom Navigator 6.010(7720)/GPS Driver 1.20
TomTom Bluetooth GPS/Wired GPS, Garmin GPSmap 196
Western Europe Map V652.1181/Brodit Car Mount |
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uk89camaro Regular Visitor
Joined: Jul 04, 2005 Posts: 113
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Posted: Fri Jul 15, 2005 7:55 pm Post subject: |
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I believe there are some systems about that have additional sensors attached to the vehicle wheels, that can provide "tunnel support" until a GPS signal is re-acquired.
Tom-Tom is not one of them. _________________ Tom Tom 1005 v2 World, Garmin Dakota 20, IPhone 4S |
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Oldboy Pocket GPS Moderator
Joined: Dec 08, 2004 Posts: 10642 Location: Suffolk, UK
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Posted: Fri Jul 15, 2005 8:44 pm Post subject: |
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uk89camaro wrote: | Tom-Tom is not one of them. |
The TomTomGO does in fact have ASN. It has the necessary items built in. Navigator running on a PDA does not. _________________ Richard
TT 910 V7.903: Europe Map v1045
TT Via 135 App 12.075: Europe Map v1120 |
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Diplo Regular Visitor
Joined: Nov 16, 2004 Posts: 112 Location: Liverpool, UK
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Posted: Fri Jul 15, 2005 9:05 pm Post subject: |
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uk89camaro wrote: | I believe there are some systems about that have additional sensors attached to the vehicle wheels, that can provide "tunnel support" until a GPS signal is re-acquired. |
Yes, they use gyroscopes to do this. _________________ Medion 95000 | TT3.07 | Kingston 512MB SD |
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CJackel492 Regular Visitor
Joined: Mar 15, 2005 Posts: 210
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Posted: Fri Jul 15, 2005 9:46 pm Post subject: |
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And I thought they used accelerometers?
Carl, _________________ Phones - Nokia 9500 + a few others
Nokia 9500 running TTM5 |
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linknet Frequent Visitor
Joined: May 05, 2005 Posts: 872
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Posted: Fri Jul 15, 2005 10:00 pm Post subject: |
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Quote: | The TomTomGO does in fact have ASN. It has the necessary items built in. Navigator running on a PDA does not. |
I believe this is only on the GO 700.
Roger |
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uk89camaro Regular Visitor
Joined: Jul 04, 2005 Posts: 113
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Posted: Fri Jul 15, 2005 10:12 pm Post subject: |
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Oldboy wrote: | uk89camaro wrote: | Tom-Tom is not one of them. |
The TomTomGO does in fact have ASN. It has the necessary items built in. Navigator running on a PDA does not. |
Don't wish to be pedantic, but I believe we're in the Navigator forum, not TT GO. _________________ Tom Tom 1005 v2 World, Garmin Dakota 20, IPhone 4S |
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linknet Frequent Visitor
Joined: May 05, 2005 Posts: 872
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Posted: Fri Jul 15, 2005 10:22 pm Post subject: |
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Quote: | Don't wish to be pedantic, but I believe we're in the Navigator forum, not TT GO. |
Unfortunately there isn't much difference now!
Roger |
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Diplo Regular Visitor
Joined: Nov 16, 2004 Posts: 112 Location: Liverpool, UK
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Posted: Sat Jul 16, 2005 12:38 am Post subject: |
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CJackel492 wrote: | And I thought they used accelerometers? |
Yes, I believe some of the cheaper (I use this term relatively!) units do, but the more expensive ones use a form of gyroscope - eg. Cobra GPSM-3000. _________________ Medion 95000 | TT3.07 | Kingston 512MB SD |
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7andy Regular Visitor
Joined: Jul 02, 2005 Posts: 74
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Posted: Sat Jul 16, 2005 2:30 pm Post subject: |
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GPS units can also be a little clever when they lose signal. My Garmin 12 continues at the last known parameters for up to 15 seconds before giving up, perhaps fooling Navigator into thinking it still has a perfectly good signal!!
Cheers, 7&Y |
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