Secret data, the government, and you...

Citizensmith wrote in post #2264544
The GPS in most phones is not actual GPS, instead it uses relative strength of nearby cellphone antennas to triangulate. ....

Might still be true for GSM phones as they are a bit sloppy with their tolerances, but any CDMA phone manufactures in the last 2 years contains a real GPS capable of tracking 2 satalites.

Citizensmith wrote in post #2264544
Cell phones on planes are bad because when the phone can't lock a signal it ramps up its transmission strength to try and find one. It has been proved that this can cause inaccuracies in the GPS (the real version) signal the planes uses. However, It has never been in any way linked to any accidents. Other electrical devices are just limited so you are paying attention during take off/landing.

This misconception has been propagated for a very long time. Cell phones are no more likely to interfere with communications than an electric razor which BTW puts out tons of RF noise. For a fun read, check out this link. The jury is not yet in, and wont be until the end of this year, but the FAA has already stated that even if it is found that cell phones do not impact communications, the do not plan to lift the ban. The FCC on the other hand has already ruled to allow the use of personal communications devices.

So it sounds to me as if the cell phone guys say use away, and the airplane guys say NONONO. Use only my phone so that I can charge you an arm and a leg.

By the way, here is a link to the opposing side. Their big reasons to keep the ban is because they are concerned it will be a nuisance to passengers and could be used by terrorists.

gjl711 wrote in post #2267285
Might still be true for GSM phones as they are a bit sloppy with their tolerances, but any CDMA phone manufactures in the last 2 years contains a real GPS capable of tracking 2 satalites

Umm, 2 satellites would be absolutely no use unless you don't mind showing up in two places at once. You need at least 3 to get any kind of position and even then it would be pretty innacurate.

gjl711 wrote in post #2267285
This misconception has been propagated for a very long time. Cell phones are no more likely to interfere with communications than an electric razor which BTW puts out tons of RF noise. For a fun read, check out this link. The jury is not yet in, and wont be until the end of this year, but the FAA has already stated that even if it is found that cell phones do not impact communications, the do not plan to lift the ban. The FCC on the other hand has already ruled to allow the use of personal communications devices.

Carnegie Melon university did a study which that showed that cellphones can have an effect. It was particularly notable when they were scanning at full strength trying to locate a carrier. The same study, which involved carrying a spectrum analyzer onto aircraft (with permission), also had some entertaining info for the average number of phones left on during the flight, and the number of calls made. So basically, its not a misconception.

Here are a couple of links - review - study

Citizensmith wrote in post #2267437
Umm, 2 satellites would be absolutely no use unless you don't mind showing up in two places at once. You need at least 3 to get any kind of position and even then it would be pretty innacurate

Two receivers will work if differential GPS is used. The cell system itself will be the third receiver applying timing correction to the phone on the data channel.

Little tutorial on DGPS here: http://www.trimble.com​/gps/dgps-how.shtml

Note: Previous job we were using 3 satellites and a known GIS surveyed area to lock in high speed "items" to 4cm. By using a known area and differential correction, it was very very accurate. If a "item" lost its GPS we were still able to track for a certain amount of time based upon trajectory and speed. Very high end equipment BTW.

JAZZ D.P.G. wrote in post #2267828
Two receivers will work if differential GPS is used. The cell system itself will be the third receiver applying timing correction to the phone on the data channel.

Ah but thats 3 total, not 2 My point was that 2 satellites gives you 2 intersection locations, differential or not. You need a third something (in this case the cell antennas) to figure out which of those 2 possible locations you are actually near. We were missing some information the first time round.

My apologies, looks as if I am confusing everyone. Anyway, the Motorola MG4100 GPS receiver is capable of position tracking with as few as two satellites, as Jazz points out, however, the chip is capable of tracking 12. Its sensitive down to -150dBm making is good enough for indoor use as well.

Moppie wrote in post #2236850
Your hat isn't working, infact its made the strap appear backwards in your photo, thats a good sign its not working at all.

I think if might be aluminum instead of tin. Aluminium doesn't work as well.

gjl711 wrote in post #2268635
My apologies, looks as if I am confusing everyone. Anyway, the Motorola MG4100 GPS receiver is capable of position tracking with as few as two satellites, as Jazz points out, however, the chip is capable of tracking 12. Its sensitive down to -150dBm making is good enough for indoor use as well.

Sounds like quite a phone. Wonder if it plays mp3s as well.

Does it have some GPS software on it for the owner to use, or is the GPS info just a backend thing? Nextel seem to be advertising their GPS phones like crazy and I'm just wondering if that is one of the phones they are selling.

Citizensmith wrote in post #2272078
Sounds like quite a phone. Wonder if it plays mp3s as well.

Does it have some GPS software on it for the owner to use, or is the GPS info just a backend thing? Nextel seem to be advertising their GPS phones like crazy and I'm just wondering if that is one of the phones they are selling.

It's not a phone, it is a chip. The chip is being integrated into just about any CDMA as well as IDEN phone Moto makes as well as many other manufacturers.

Supposedly there is a way to get out long. and lat. but I have not yet figured out how to do so from my Razr. I'm going over to chat with the mobile guys next week. I'll post instructions when I get them.