Interesting technical questions

[skybirds]

I often wonder where my hotmail yahoo
Files are stored. I can go anywhere in the
world and dig up the same emails. Is there
a physical place a data bank(s) where this
is stored?
Another question is about cell phone range.
How far can a signal go? I know the signal is
High frequency line of sight. I also know TV
and FM broadcast signals can travel great
distances under the right conditions such as
a skip caused by humid atmospherics.

[wb.john]

I often wonder where my hotmail yahoo
Files are stored. I can go anywhere in the
world and dig up the same emails. Is there
a physical place a data bank(s) where this
is stored?
Another question is about cell phone range.
How far can a signal go? I know the signal is
High frequency line of sight. I also know TV
and FM broadcast signals can travel great
distances under the right conditions such as
a skip caused by humid atmospherics.

Here's some interesting reading for your first question.

[dcan]

Not only is your data stored in a data center, but in all likelihood in multiple data centers mirrored around the world. Also on all of the daily, weekly, and monthly backups that are done at each data center.

Yes, it does raise interesting privacy concerns. And yes, they probably automatically read for keywords every document you save and use it to build a more detailed profile of who you are for marketing purposes. That's what Google does, and the others do it too.

[blu2blu]

Cell phones actually operate in the UHF (Ultra High Frequency Range). Basically a cell phone is a fancy two way radio. You mentioned High Frequency which is defined as 3mhz-30mhz. These frequencies are not high at all, they are actually very low. There are historical reasons for why they are called "high frequency."

You may hear stories about how very old cell phones would get better reception than their newer counterparts. This is sometimes true. Currently cellphones are limited by the FCC to an output of .5 watts (half a watt). Old phones did not have this restriction so they were able to "talk" further. There is no way to easily pin down how far a signal can travel. You hit the nail on the head with line of sight. The more obstancles between your phone and the tower it is talking to the more interference and less distance you will get. On the flip side of that coin if you were in a place where there was nothing between you and the tower you could talk much further.