Mike Cattle wrote: > The guess of a week was just that: a guess. More of a hope, > actually. :)
The much hyped SiRFstarIII chip has a power consumption of 75 mW during active tracking, according to the product sheet, http://www.sirf.com/Downloads/Collateral/GSC3(f)_6.20.05.pdf That alone would be 25 mA at 3 VDC, or the equivalent of a 120 ohm resistor across your battery terminals. And then you have to add circuits for processing and storage. Some AA-size rechargable Ni-MH batteries can store 2500 mAh, so a single pair (to reach 3 VDC) would last 100 hours or 4 days. With two pairs in parallel, you could go for a week. But this is a theoretical maximum, so you probably want 3 or 4 pairs. I haven't seen anybody trying to market such a bulky GPS receiver. http://en.wikipedia.org/wiki/Nickel_metal_hydride_battery The older SiRFstarIIe chip uses 60 mW. Apparently, since everybody now praises the new III chip, the increased accuracy is well worth the +15 mW increase in power consumption. Nobody talks much about battery life time. Or to phrase it differently: With the old IIe chip, both accuracy and battery lifetime sucked, but the accuracy was worse. Most units are auto mounted or used for day trips. Hikers can carry extra batteries and replace them when necessary. There is very little market for GPS receivers that can go unattended for a week. -- Lars Aronsson ([EMAIL PROTECTED]) Aronsson Datateknik - http://aronsson.se _______________________________________________ Geowanking mailing list [email protected] http://lists.burri.to/mailman/listinfo/geowanking
