The other night, i was driving home, and my navigation map had a mind of its own. It would show that i was on a different street which ran parallel to my street. I turned off the car, turned it back on it was still messed up. I popped the cd out, put it back in, and it went to normal. has this happend to any1? btw, i have the 06 navi

 

happened to me a while back, then the nav drive went up. dealer put in a new drive under warranty. the also left the cd that was in the old drive in my car (i think by accident).

 

It happens every once in a while, especially if the streets are close together. Or if you turn on to a road that doesnt exist on the database and there is a road closeby that runs in the same direction that IS on the database then it will put you on that road. I dont think theres anything wrong with the GPS, its just not military spec accurate.

 

wow i didn't know some people knew that

We have SPS (Standard Positioning Service) and not the military spec PPS (Precise Positioning Service). SPS is accurate within 100m and PPS is accurate within 22m


BTW, if the U.S. is ever at war, they can scramble the satelite's and our GPS navigation won't even work properly

 

I was driving on a newly constructed secondary highway and it kept bouncing me to the old highway that was like 500 meters parallel to the new one.. it was funny watching the icon bounce back and forth the whole time..

 

I have an '04 and I noticed once or twice that the arrow was next to the street instead of on the street, but it did say the correct street underneath as fas as I can remember. And it did jump onto the street shortly after.
Did it actually tell you you are on a different street or was it just the arrow positioned next to the street you were on? As long as the street name was correct I think the arrow would jump to the correct position if you kept driving instead of taking the cd out and shutting off the car. If it is a problem then go to the dealer.

 

no, it said i was on a different street. A street that is a couple of blocks away but runs parallel to my street.

 

The system tries to make up for GPS's inaccuracy by placing you on the closest street. Some areas have roads on the map that are stored differently. Zenrin puts them in for your information, but the system has trouble routing on these roads until Zenrin finalizes them.

 

it's actually a little better that you say:

When it was first deployed, GPS included a feature called Selective Availability (or SA) that introduced intentional errors of up to a hundred meters into the publicly available navigation signals, making it difficult to use for guiding long range missiles to precise targets. Additional accuracy was available in the signal, but in an encrypted form that was only available to the United States military, its allies and a few others, mostly government users.

SA typically added signal errors of up to about 10 m horizontally and 30 m vertically. The inaccuracy of the civilian signal was deliberately encoded so as not to change very quickly, for instance the entire eastern US area might read 30 m off, but 30 m off everywhere and in the same direction. In order to improve the usefulness of GPS for civilian navigation, Differential GPS was used by many civilian GPS receivers to greatly improve accuracy.

During the Gulf War, the shortage of military GPS units and the wide availability of civilian ones among personnel resulted in disabling the Selective Availability. In the 1990s the FAA started pressuring the military to turn off SA permanently. This would save the FAA millions of dollars every year in maintenance of their own radio navigation systems. The military resisted for most of the 1990s, but SA was eventually turned off[16] in 2000 following an announcement by then US President Bill Clinton, allowing users access to an undegraded L1 signal.

The US military has developed the ability to locally deny GPS (and other navigation services) to hostile forces in a specific area of crisis without affecting the rest of the world or its own military systems. Such Navigation Warfare uses techniques such as local jamming to replace the blunt, world-wide degradation of civilian GPS service that SA represented.

Military (and selected civilian) users still enjoy some technical advantages which can give quicker satellite lock and increased accuracy. The increased accuracy comes mostly from being able to use both the L1 and L2 frequencies and thus better compensate for the varying signal delay in the ionosphere (see above).

SA Announcements
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GPS tracking

GPS Navigation using the TomTom softwareMain article: GPS tracking
A GPS tracking system uses GPS to determine the location of a vehicle, person, or pet and to record the position at regular intervals in order to create a track file or log of activities. The recorded data can be stored within the tracking unit, or it may be transmitted to a central location, or internet-connected computer, using a cellular modem, 2-way radio, or satellite. This allows the data to be reported in real-time, using either web browser based tools or customized software.

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GPS jamming
Further information: Selective Availability / Anti-Spoofing Module
Jamming of any radio navigation system, including satellite based navigation, is possible. The U.S. Air Force conducted GPS jamming exercises in 2003 and they also have GPS anti-spoofing capabilities. In 2002, a detailed description of how to build a short range GPS L1 C/A jammer was published in Phrack issue 60[17] by an anonymous author. There has also been at least one well-documented case of unintentional jamming, it traced back to a malfunctioning TV antenna preamplifier.[18] If stronger signals were generated intentionally, they could potentially interfere with aviation GPS receivers within line of sight. According to John Ruley, of AVweb, "IFR pilots should have a fallback plan in case of a GPS malfunction".[19] Receiver Autonomous Integrity Monitoring (RAIM), a feature of some aviation and marine receivers, is designed to provide a warning to the user if jamming or another problem is detected. There are also incidents of unintentional jamming. GPS signals can also be interfered with by natural geomagnetic storms, predominantly at high latitudes.[20]

GPS jammers the size of a cigarette box are allegedly available from Russia, their effectiveness is in question following their use in the Iraq war. The U.S. government believes that such jammers were also used occasionally during the U.S. invasion of Afghanistan. Some officials believe that jammers could be used to attract the precision-guided munitions towards non-combatant infrastructure, other officials believe that the jammers are completely ineffective. In either case, the jammers may be attractive targets for anti-radiation missiles. Low power jammers would have limited military usefulness and high power jammers would be easy to locate and destroy. During the Iraq war, the US military claimed to destroy a GPS jammer with a GPS-guided bomb. [21]

Per wikipedia