Quote:
Originally Posted by chronster
so is signal strength what causes the battery drain? If not, which one of these radio's uses the least power?
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That's when you have to be more careful with what you mean by "signal strength."
If by "signal strength" you mean the signal-to-noise ratio of your carrier band in a certain area, then greater signal strength actually means less battery consumption. The phone will not have to spend as much power amplifying the signal and separating it from the noise; also, because the signal is clearer, the phone can turn down its output pwoer for the signal it sends back to the tower (the strength of which is regulated by the tower, BTW).
When most people say signal strength, however, they are referring to that below-zero RX value that represents the absolute magnitude of "signal" (be it real signal or just noise within the carrier band) your phone is paying attention to. In this case, greater "signal strength" generally requires more battery power, as your phone is grabbing more signal from the airwaves and will require more power to filter and sort through it to find the actual tower signal.
So basically, it can go both ways: a radio may have algorithms that enable it to zero in on the tower signal more efficiently, essentially giving you better "signal strength" (actually signal-to-noise ratio)
and saving battery power. At the same time, one radio may be more "agressive" than another, running more filtering and amplification to locate a tower signal in more difficult situations; in this case, greater "signal strength" requires more battery power.
The bars you see on your phone are inversely proportional to the amount of amplification the phone is using to locate the tower signal; greater amplification = less bars and less amplification = more bars. Therefore, if you see more bars with a particular radio, that radio is saving you battery power. It may not be as effective as another radio, however, at keeping your calls connected when you drive through tough no-bar or one-bar spots.
At least I think that's how it works.