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Location Sensitivity - Cell Phone GPS
by: Robert Lett

This is basically a system to locate the handheld when making a call to 911. In the mid to late 1990's, many people got cell phones just for the emergency use of being able to call for help almost anywhere. The problem came up when statistics showed that almost 92% of all serious 911 calls, (where the person was just barely able to make the call), they either didn't know where they were or was unable to tell the 911 operator where they were, or they might not have been able to talk at all. This caused a big concern, 911 operators couldn't do anything but listen to the person on their cell phone as they pass away. The Location Sensitivity system still doesn't work if you are in an area that only has an analog signal. (Which is the older cellular system of the mid 1990's and earlier). Most metropolitan areas and all interstate freeways are covered by the newer digital service. It's just when you get out in the middle of no-where, you might end up with an analog signal. Most!

phones will display the letter "A" in the top right or left corner when using this system. Check your phone documentation, some phones don't even have this capability. Which means if you get into one of these areas, you can't make any type of call what-so-ever.

Soon, the Location Sensitivity feature will probably be offered by the cellular companies as part of their pricing plan. Some carriers like Nextel are already taking advantage of this new technology by giving customers a GPS location service along with their calling plan. If you don't have this option with your carrier, and you have a Smartphone you can always purchase one of the SD slot GPS units that works with mapping software. The program I've really enjoyed is Mapopolis, which works great with most of the popular GPS hardware available. And most even have a voice activation that will tell you where to turn, which is directed through the speaker phone portion of the Smartphones. The ability to have GPS information and mapping on your handheld will be a great plus while traveling.

Back to the Location Sensitivity. I'm just wondering how much the cellular companies are going to charge for such a GPS type service!? I'm sure they're all working hard right now on the new pricing plans that we'll have to pay if you don't have the GPS hardware to install on your Smartphone.

When these services become available, they will only be location based. Another words, most GPS's these days will actually give you your current altitude and most have a pretty fast refresh rate. The refresh rate is the time between position updates. An example; If you have a GPS in your hand that refreshed three times per second, this would be a very acturate reading. Even if you are driving at 70 miles per hour, the moving map on the GPS will be able to keep up with your actual location. That's an issue the engineers are dealing with on the Location Sensitivity system. It wasn't designed to have any type of refresh rate at all. Once a position has been found, it never was designed to refresh that position. (I guess if you are hurt, and you called 911, you aren't supposed to be moving. Hmmm, So if you fell off a bridge, and landed in the back of a truck driving down the interestate, I'm not sure if they would be able to locate you. They would know where you were when you!

first dialed 911, but as your location changes, they might not be able to find you). Supposedly, the 911 operator can pull a refresh, this would at least tell them the direction the vehicle is moving. But to locate you while you're moving, might be more difficult than anyone had expected.

Another problem with many of the handheld units, the actual speed of the processors within them. Most cell phones operate on around 1 to 2 MHz processor speed. Most Smartphones operate anywhere between 30 to 500 MHz. (Most new home computers are operating between 2 to 4 GHz processor speed, just to give you an idea). This is where the engineers are running into the biggest problem with creating a GPS refresh rate. The processors in all handhelds will just have to be faster than they are today. And like all of our other technolgies, I'm sure this won't be a problem very much longer for the designers.


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