Apple and Radio Waves

Apple has an uncanny ability to develop and market some really slick gadgets that have have changed how folks communicate.

But in its explanation of why iPhones and iPads DO NOT track the location of folks who bought and love them, I think Apple went a wee too far.

The company said iPhones do not log owners' locations; rather, they are "maintaining a database of Wi-Fi hot spots and cell towers around your current location, some of which may be located more than 100 miles away from your iPhone, to help your iPhone rapidly and accurately calculate its location when requested."

This statement defies the laws of radio propagation. Let's take an example we're all familiar with -- FM radio broadcasters.

KENW-FM transmits at a power of 100,000 watts, at a frequency of 89.5, from a 600 foot tower in Portales, N.M., over the relentlessly flat plains of eastern New Mexico and west Texas.

On a good day you can pick up the KENW <=>signal roughly 70 miles to the northwest, in Tucumcari, N.M., and 70 miles southeast, in Levelland, Texas.

Now let's take a look at the radio transmitters that Apple says it can track at distances of up to 100 miles. WiFi, which operates in the 2.5 GHz or 5Ghz frequency range has transmitters whose power is measured in milliwatts and a maximum range of abut 300 feet.

Cellular systems in this country operate in the 800 Mhz, 1300 Mhz, 1800 Mhz and 1900 Mhz frequency bands, which inherently will never have the maximum range of an FM broadcaster like KENW, because higher frequencies mean short range.

The smart folks over at Wikipedia estimate the maximum range of a cellular base station at between 22 and 45 miles.

Handsets, according to the Wiki folks, like WiFi, transmit at a very low power and hence have an even more limited range than a base station. So where did Apple come up with the 100-mile figure, now reported as fact by every news outlet on the planet?