. . as should be obvious , know exactly where you be be equally as important as know exactly where you need to be . as a Sonet Technician , I purchase this unit to help find communication site in obscure , often desolate area of the eastern US . in the past , I have to rely upon either someone whom have never actually be there and use a web-based mapping site to issue turn-by-turn direction , or people recall the location from memory , `` I think you turn at  , then look for the concrete cow on the left which mean you just pass the turn so go back and turn right . '' neither be very accurate , so I begin use my laptop and try out a number of mapping program . I settle on m 's Streets & Trips 2000 due to the ease with which I could open a window of save point , double click on the one I need and find they automatically enter as waypoint -lrb- a feature inexplicably remove from subsequent release -rrb- . use a mapping program alone work fairly well , but the flaw be that once I miss a turn -- most often in the dead of night -- I have to determine where I be in order to find my way back to the plot course . terribly frustrating and confusing to be look for route 773 and be surround by route 377 , 737 , 337 , etc. . . this be a perfect application of a GPS unit as it can save literally dozen of hour per year of time lose to backtrack .  my decision to purchase the Magellan brand come of a friend 's recommendation of a map 330 and of distil fact from diatribe on number of gps-related bbss . instead of explore the merit -lrb- or lack thereof -rrb- of one mfgr \ model over another , these discussion typically degenerate into little more than flame war . anyway ... I purchase a Magellan Meridian platinum at the local CompUSA for considerably more than I would have pay have I order it from Amazon . CompUSA stock neither the vehicle mount bracket nor the data\/power cable accessory on the day i purchase the unit .  when I first power up the unit , I be indoors and quite disappointed that I get no satellite lock whatsoever . however , it quickly find my location once I step outside and have a unobstructed view of the sky . I discover that the unit work less than perfectly unless hold vertically and that even a single finger place over the antenna section substantially degrade reception . I enter into m Streets & Trips 2002 -lrb- st2k2 -rrb- the lat-long location datum for the 14 site we need to visit between Atlanta and Jax , fl . use the include datum cable , I connect the Meridian platinum to the laptop , then run the GPS setup . I be on the road in minute . find the site be a piece of cake for the most part , though it do take a while to get use to the update lag time . st2k2 's help file explain that the software poll the GPS only every 15 seconds , mathematically account for what I find to be a average of nearly 1\/3 mile error in position . from then on , I have the driver slow down 1\/2 mile before each turn . when we do miss turn thereafter , it be only because st2k2 's map be not entirely accurate -lrb- particularly around Athens , GA -rrb- .  i find myself constantly check the battery power display and wish I have the data\/power cable . be forwarn that the Meridian platinum eat battery for lunch . I burn four per day -lrb- two set -rrb- over a four day period , average only slightly more than a halflife of what the documentation state ; I get no more than about eight hour from a fresh set of high quality alkaline . certainly the ability to turn off the unit 's display would dramatically increase battery life . I find no reference to do such in the . pdf manual . this be a oversight in my opinion , but undoubtedly can be correct in a software update from Magellan .  because the mount bracket be not available at the time I make my purchase , I have to leave the Meridian on the dashboard . from this arise a number of problem . the gp be occasionally power down when bump in rough backroad cause it to bounce around and depress the power button . also , it frequently lose satellite lock due in part to such jostle , but more to the fact that it be impossible to have a unobstructed view of the sky inside the cab of a large truck and that it can not be hold vertically without the mount bracket . another consequence of be on the dash be that the unit become \* extremely \* hot when expose to direct sunlight . so hot , in fact , I become concerned that such tremendous heat might be damaging . while it seem no less the worse for wear , I would rather it not get that hot in the first place . I believe the simplest solution to these problem be not a mount bracket , but a external antenna -- the expensive unit can then sit safely tuck out of harm 's way . unfortunately , the Meridian line do not provide for the direct connection of a external antenna , and this alone might be reason enough to warrant a return for refund . I find it tremendously annoy that the designer would disallow such a option .  i buy a unit much more capable than I actually need or will ever use , so my advice to those new to gpss be that you take you time and fully investigate the function you need , carefully research the function that several different vendor and they unit provide , then , once you have decide on what you want , stop and research a little more . if at all possible , borrow a friend 's or rent a number of different model for a few day . I can not knock the Meridian platinum because it have more feature than I 'll ever use , and I be certain backpacker and geocacher will love this thing , but the lack of a external antenna port must be take into account . this can not be overstate : if the primary use of you gp receiver will be inside a vehicle , look for something else .  i award the Magellan Meridian platinum 4 of 5 star .  pro : Works well , seem quite rugged , have numerous cool feature , and will give owner obvious brag rights . con : lack external antenna capability , a bit spendy , and eat battery like M&M; s.