GPS for Dummies.pdf - Engineering Surveyor

Chapter 5: Selecting and Getting Started with a GPS Receiver91Based on a number of years of search and rescue experience, I can list numerousoccasions when hunters and hikers thought that their GPS receiver wassome kind of magic talisman that would prevent them from getting lost. Andquite often when the search teams finally found them, they had no clue whatsoeverhow to properly use their GPS receiver. If you’re going to rely on a GPSreceiver for navigating outside of urban areas, take the time to find out howto use it so the friendly, local search-and-rescue people don’t have to comelooking for you. I’ll step off my soapbox now, thank you.Powering Your GPS ReceiverBefore you can start using your GPS receiver, you obviously need to give itsome power. For portable GPS receivers, that usually means AA or AAA batteries.Manufacturers all give estimated battery lifetimes for their GPS receivers,but the actual number of hours a GPS receiver will run depends on how it’sbeing used. For example, with the backlight on, battery life goes down becausemore power is consumed. In addition, what type of batteries you’re using canalso make a difference.You can really get geeky with batteries andpowering your GPS unit. If you get a charge outof electricity, here are some links to nitty-grittyinformation sources that cover voltage, milliamperes,and GPS drainage rates: Battery drain for selected GPS receivers:www.gpsinformation.net/main/bat-5.txt. This site offers the lowdown onjust how much juice different GPS receivermodels consume. The Great Battery Shootout!: www.imaging-resource.com/ACCS/BATTS/BATTS.HTM. This site is more orientated todigital cameras (not GPS receiver-specific),Battery Tech 101but you’ll find some good data on howdifferent types of batteries perform. Newsgroups: sci.geo.satellite-nav.Do a Google Groups search in this USENETnewsgroup for batteries and be prepared tospend a couple of hours reading througheducational (and sometimes controversial)posts.When you check these sources, you’ll run intomAh, which means milliampere-hours. Mostrechargeable batteries like NiMH have the mAhrating printed on their label. This rating is thebattery capacity. Typically, the higher the mAhnumber, the longer the battery will last.