Comments on: TomTom GO 930 http://www.gpsreview.net/tomtom-go-930/ GPS Reviews for Garmin, Magellan, TomTom, and other GPS Systems Sat, 21 Nov 2009 02:27:52 -0500 http://wordpress.org/?v=2.8.6 hourly 1 By: Tim http://www.gpsreview.net/tomtom-go-930/#comment-72518 Tim Tue, 27 Oct 2009 19:04:15 +0000 http://www.gpsreview.net/tomtom-go-930/#comment-72518 If you'd like to read about the modern system for GPS only approaches, see the FAA's TSO C146a standards for GPS WAAS "sole means" navigation. The system can identify when the accuracy isn't sufficient for minimum standards and warn the pilot. In the best case scenario (if I remember correctly) the lowest "minimums" for a GPS approach is 250 feet. (Higher for most runway approaches.) If you’d like to read about the modern system for GPS only approaches, see the FAA’s TSO C146a standards for GPS WAAS “sole means” navigation. The system can identify when the accuracy isn’t sufficient for minimum standards and warn the pilot. In the best case scenario (if I remember correctly) the lowest “minimums” for a GPS approach is 250 feet. (Higher for most runway approaches.)

]]> By: John http://www.gpsreview.net/tomtom-go-930/#comment-72515 John Tue, 27 Oct 2009 18:19:00 +0000 http://www.gpsreview.net/tomtom-go-930/#comment-72515 Granted, I'm not a pilot but I am an Engineer and I do know that the specifications that I've seen in the 80's would have the offsets appear globally and it would be the same offsets at any given time regardless of where you were. I also know that the ALS systems being developed and deployed at the time for ILS were essentially MLS systems based on ground based transmitters with differential frequencies to accurately locate the approach. There would be a lot of technical problems with using a GPS system for final approach and certainly wouldn't have been possible with the civilian specs of the 80's however, as I stated Clinton did open up military GPS for civilian use but I do suspect there would be some strategic reservations that would be periodically employed. Simple physics makes it very difficult for GPS to be sufficiently fine grained and quick for a final approach but may be useful for more general approaches. I certainly would not consider a GPS only final approach to be a safe approach. Modeling the satellite systems like GPS was an assignment in one of our courses. The GPS concept is based on remarkably simple minimal signals and using accurate clocks to infer information which is why multiple satellite locks are required. Granted, I’m not a pilot but I am an Engineer and I do know that the specifications that I’ve seen in the 80’s would have the offsets appear globally and it would be the same offsets at any given time regardless of where you were. I also know that the ALS systems being developed and deployed at the time for ILS were essentially MLS systems based on ground based transmitters with differential frequencies to accurately locate the approach. There would be a lot of technical problems with using a GPS system for final approach and certainly wouldn’t have been possible with the civilian specs of the 80’s however, as I stated Clinton did open up military GPS for civilian use but I do suspect there would be some strategic reservations that would be periodically employed. Simple physics makes it very difficult for GPS to be sufficiently fine grained and quick for a final approach but may be useful for more general approaches. I certainly would not consider a GPS only final approach to be a safe approach. Modeling the satellite systems like GPS was an assignment in one of our courses. The GPS concept is based on remarkably simple minimal signals and using accurate clocks to infer information which is why multiple satellite locks are required.

]]> By: Tim http://www.gpsreview.net/tomtom-go-930/#comment-72514 Tim Tue, 27 Oct 2009 18:00:17 +0000 http://www.gpsreview.net/tomtom-go-930/#comment-72514 John, that isn't true. I'm a pilot. There are about 650 runways (if I recall correctly) in the USA that have GPS approaches. There are about 400 airports that now have GPS approaches that don't have an ILS approach. (Meaning the airport isn't "transmitting" anything.) The WAAS system implemented mostly for the aviation community to make such approaches a reality. John, that isn’t true. I’m a pilot. There are about 650 runways (if I recall correctly) in the USA that have GPS approaches. There are about 400 airports that now have GPS approaches that don’t have an ILS approach. (Meaning the airport isn’t “transmitting” anything.) The WAAS system implemented mostly for the aviation community to make such approaches a reality.

]]> By: John http://www.gpsreview.net/tomtom-go-930/#comment-72511 John Tue, 27 Oct 2009 17:36:09 +0000 http://www.gpsreview.net/tomtom-go-930/#comment-72511 [snip] Air traffic do not use GPS on a runway approach, only for navigation between airports. The airports themselves have transmitters to indicate the approach path to the plane, a GPS system would not be reliable enough to use for a runway approach. Good luck with calling in your TT930 for service, remember to remove any SD cards or the plastic SD blank from your unit before sending it in. The replacement unit will just have a sticker over it's SD port. [snip] Air traffic do not use GPS on a runway approach, only for navigation between airports. The airports themselves have transmitters to indicate the approach path to the plane, a GPS system would not be reliable enough to use for a runway approach.

Good luck with calling in your TT930 for service, remember to remove any SD cards or the plastic SD blank from your unit before sending it in. The replacement unit will just have a sticker over it’s SD port.

]]> By: Charles http://www.gpsreview.net/tomtom-go-930/#comment-72510 Charles Tue, 27 Oct 2009 17:17:35 +0000 http://www.gpsreview.net/tomtom-go-930/#comment-72510 Thanks to both of you for your replies -- this is a great site! I think speed is relatively consistent working/non-working but I will monitor this. Reception could be an issue, but does not seem directly linked to forests of tall buildings. Still, that is more likely than major MilOps in downtown Toronto! I'll keep an eye on the "bars". I update weekly. I do suspect a bug due to the situation disappearing with a power-off/-on. Thanks again! Thanks to both of you for your replies — this is a great site! I think speed is relatively consistent working/non-working but I will monitor this. Reception could be an issue, but does not seem directly linked to forests of tall buildings. Still, that is more likely than major MilOps in downtown Toronto! I’ll keep an eye on the “bars”. I update weekly. I do suspect a bug due to the situation disappearing with a power-off/-on. Thanks again!

]]> By: Tim http://www.gpsreview.net/tomtom-go-930/#comment-72490 Tim Tue, 27 Oct 2009 14:14:04 +0000 http://www.gpsreview.net/tomtom-go-930/#comment-72490 Military operations are extremely unlikely to impact the GPS signal. Don't forget that civilian pilots often rely on GPS for navigation to runways in poor weather, so the integrity of the system is critical. I subscribe to notices of intentional GPS jamming exercises and they are exceptionally rare. Likewise I also get reports of known degradation of the signal. One such notice came in last week and talked of an issue in the Pacific Ocean that lasted only a second or two. There are lots of things that can impact the GPS signal such as a bad bounce from a building (multipath errors), athermic windshield designs, other obstructions, etc. But an error from the system itself or intentional jamming is exceptionally rare. Charles, what you describe sounds more like a bug or signal loss due to the environment. I see it happen from time to time with most GPS devices. If you haven't downloaded any QuickFix updates recently that can sometimes help with that issue as well. Military operations are extremely unlikely to impact the GPS signal. Don’t forget that civilian pilots often rely on GPS for navigation to runways in poor weather, so the integrity of the system is critical. I subscribe to notices of intentional GPS jamming exercises and they are exceptionally rare. Likewise I also get reports of known degradation of the signal. One such notice came in last week and talked of an issue in the Pacific Ocean that lasted only a second or two.

There are lots of things that can impact the GPS signal such as a bad bounce from a building (multipath errors), athermic windshield designs, other obstructions, etc. But an error from the system itself or intentional jamming is exceptionally rare.

Charles, what you describe sounds more like a bug or signal loss due to the environment. I see it happen from time to time with most GPS devices. If you haven’t downloaded any QuickFix updates recently that can sometimes help with that issue as well.

]]> By: John http://www.gpsreview.net/tomtom-go-930/#comment-72488 John Tue, 27 Oct 2009 13:56:08 +0000 http://www.gpsreview.net/tomtom-go-930/#comment-72488 I usually find my TT930 to be pretty good at getting it's location and orientation right although there have been days when it's off by a street or two. Whenever this happens, I'll check the news the next day and find that there was a major military operation during that time so it may just be the military encrypting the GPS and introducing errors into the civilian use of GPS. As to orientation, you have to remember that the TT doesn't actually know which direction your car is pointing, it doesn't even know where it's positioned within the car. It infers the direction you are traveling in from the most recent two locations. This means that at slow speeds, it can be wrong and sometimes quite dramatically whenever one of those military offsets comes in but the orientation improves as you drive faster. If you are having a lot of strange behaviours, don't hesitate to call TomTom's customer support. Unfortunately, the phone lines are only open during the day and they will walk you through some diagnostic steps so expect to spend the entire work day on the problem with your computer, an internet connection and your TomTom handy. I've had to send my TT930 in twice, each time they've replaced it with a refurbished unit. The thought did occur to me that I should've just bought a refurbished unit to begin with as it appears that you'll wind up with a refurbished unit anyways. Initially I was teethering the TomTom with a Nokia 6820b which worked most of the time. Then I had to replace my phone and tried a Samsung Impression, that would only teether for a few minutes after pairing so you had to delete the pairing and repair every time you wanted to use the data connection. I returned the Samsung and exchanged it for a Sony Ericsson W518A and that teethers the TomTom flawlessly, it also teethers my Mac flawlessly. It took a while to get the settings right as the CID string I used for the Nokia didn't work with the Sony but the phone information status screen gives you a hint as to which CID string to use. Naturally, AT&T won't help you with the settings unless you pay them extra for teethering so hit the Internet for the settings. I usually find my TT930 to be pretty good at getting it’s location and orientation right although there have been days when it’s off by a street or two. Whenever this happens, I’ll check the news the next day and find that there was a major military operation during that time so it may just be the military encrypting the GPS and introducing errors into the civilian use of GPS.

As to orientation, you have to remember that the TT doesn’t actually know which direction your car is pointing, it doesn’t even know where it’s positioned within the car. It infers the direction you are traveling in from the most recent two locations. This means that at slow speeds, it can be wrong and sometimes quite dramatically whenever one of those military offsets comes in but the orientation improves as you drive faster. If you are having a lot of strange behaviours, don’t hesitate to call TomTom’s customer support. Unfortunately, the phone lines are only open during the day and they will walk you through some diagnostic steps so expect to spend the entire work day on the problem with your computer, an internet connection and your TomTom handy. I’ve had to send my TT930 in twice, each time they’ve replaced it with a refurbished unit. The thought did occur to me that I should’ve just bought a refurbished unit to begin with as it appears that you’ll wind up with a refurbished unit anyways.

Initially I was teethering the TomTom with a Nokia 6820b which worked most of the time. Then I had to replace my phone and tried a Samsung Impression, that would only teether for a few minutes after pairing so you had to delete the pairing and repair every time you wanted to use the data connection. I returned the Samsung and exchanged it for a Sony Ericsson W518A and that teethers the TomTom flawlessly, it also teethers my Mac flawlessly. It took a while to get the settings right as the CID string I used for the Nokia didn’t work with the Sony but the phone information status screen gives you a hint as to which CID string to use. Naturally, AT&T won’t help you with the settings unless you pay them extra for teethering so hit the Internet for the settings.

]]> By: Charles http://www.gpsreview.net/tomtom-go-930/#comment-72482 Charles Tue, 27 Oct 2009 13:17:12 +0000 http://www.gpsreview.net/tomtom-go-930/#comment-72482 Hi, have TT930 just over a year old, s/w versions listed below. Generally love it, but frustrated with two increasing tendencies of late: 1. TT gets disoriented -- loses precise location & heading. Leads to frequent map re-orientations (compass) even while driving straight and corresponding route re-calculations (est 4/min). Fixed (temporarily) by doing a power-off/-on. 2. TT cannot always connect to Blackberry via BT. Sometimes it does; sometimes not. If not, then doing hard reset (via paper clip) will resolve situation -- until next time. Curious if others have seen these and any suggestions as to cause or solution... Many thanks... TT 930 running v8.351 // TT HOME v2.7.2.1825 // Phone app v15 Hi, have TT930 just over a year old, s/w versions listed below. Generally love it, but frustrated with two increasing tendencies of late:
1. TT gets disoriented — loses precise location & heading. Leads to frequent map re-orientations (compass) even while driving straight and corresponding route re-calculations (est 4/min). Fixed (temporarily) by doing a power-off/-on.
2. TT cannot always connect to Blackberry via BT. Sometimes it does; sometimes not. If not, then doing hard reset (via paper clip) will resolve situation — until next time.

Curious if others have seen these and any suggestions as to cause or solution…

Many thanks…

TT 930 running v8.351 // TT HOME v2.7.2.1825 // Phone app v15

]]> By: John http://www.gpsreview.net/tomtom-go-930/#comment-72453 John Tue, 27 Oct 2009 01:42:51 +0000 http://www.gpsreview.net/tomtom-go-930/#comment-72453 The traffic stopped working with the last map update, the one just before the current one. It says that the subscription has expired even when it hasn't. They've extended my existing subscription by a year while they work on the problem and have stopped offering live traffic to the 930 till they figure out what's wrong. They've told me to just keep downloading updates till it works again. It seems that if I unload the map, and reload it, the traffic feature will work for about five minutes. It takes an awful long time to unload and load the map. Everytime a map or application update happens, something gets broken. TomTom really needs to work on their regression testing. The traffic stopped working with the last map update, the one just before the current one. It says that the subscription has expired even when it hasn’t. They’ve extended my existing subscription by a year while they work on the problem and have stopped offering live traffic to the 930 till they figure out what’s wrong. They’ve told me to just keep downloading updates till it works again. It seems that if I unload the map, and reload it, the traffic feature will work for about five minutes. It takes an awful long time to unload and load the map.

Everytime a map or application update happens, something gets broken. TomTom really needs to work on their regression testing.

]]> By: John http://www.gpsreview.net/tomtom-go-930/#comment-72452 John Tue, 27 Oct 2009 01:36:15 +0000 http://www.gpsreview.net/tomtom-go-930/#comment-72452 There is an earphone connector, a proprietary antenna connector which doubles as an iPod docking cable connector, a mini-usb connector and an SD card slot. I have an 8GB SD card in my SD slot, the mini-usb plugged into the cigarette lighter socket for power, a iPod connector cable in the proprietary connector and one of those tape cartridge adapters in the earphone jack so I can play the mp3's over my car speakers. You can choose whether to put the instructions out over the speaker, the earphone jack, bluetooth, or via the FM transmitter. Likewise with the music. I have my music going to the earphone jack so that it plays over the car speakers and the instructions on the internal speaker. For some reason, the instructions started sounding funny over the car speakers which wasn't the case when I used the FM transmitter to get the music onto the car speakers but I got tired of changing frequencies depending on where I was so I switched to the cassette adapter. There is an earphone connector, a proprietary antenna connector which doubles as an iPod docking cable connector, a mini-usb connector and an SD card slot.

I have an 8GB SD card in my SD slot, the mini-usb plugged into the cigarette lighter socket for power, a iPod connector cable in the proprietary connector and one of those tape cartridge adapters in the earphone jack so I can play the mp3’s over my car speakers.

You can choose whether to put the instructions out over the speaker, the earphone jack, bluetooth, or via the FM transmitter. Likewise with the music. I have my music going to the earphone jack so that it plays over the car speakers and the instructions on the internal speaker. For some reason, the instructions started sounding funny over the car speakers which wasn’t the case when I used the FM transmitter to get the music onto the car speakers but I got tired of changing frequencies depending on where I was so I switched to the cassette adapter.

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