Old-style altimeters used barometric pressure and are rarely used these days. Phones and GPS units use GPS satellite data, so are not dependent on cell service. My phone altimeter seems to be precise within +/- 30 feet, so should be fine for medical questions.What if you are out in the woods, away from cell towers, and you need to know altitude (medical reasons, yup).
I have used mileposts to check the odometer, and I like to go 50-100 miles to get reasonable precision. I assume that the speedometer will be correct if the odometer is. However, I notice that when there is an electronic sign telling me my speed, it usually indicates about one MPH less than the speedometer (both in the ED and my Honda), so maybe the speedometer does read a smidge high. I may try a check over a flat stretch in AZ or NV in the next week, but it's hard to keep a perfectly constant speed while towing.It should be remembered that the elevation signs on side of highway are not exact. Their close but between surveyor setting stakes, and sign techs installing signs they move. Same with mileposts, if your going to use them to check speedometer need to do over 10 miles so errors average out.
Any GPS will do. They all lock onto the same satellites so theoretically all GPS devices will read exactly the same. However, they all will not lock on to the same number of satellites or in the same order. Thus, their readouts may differ but the difference is very slight. For practical purposes, they will all give the same info.I see people here saying they check distance by GPS. Is that the built-in navigation system, or can that be done with a phone or handheld GPS unit?
I don't know how to get it to measure distance traveled on the phone. I don't think the map apps will do that, so I was wondering if there is a separate app. I use mileposts to check the odometer, but that isn't always convenient.Any GPS will do. They all lock onto the same satellites so theoretically all GPS devices will read exactly the same. However, they all will not lock on to the same number of satellites or in the same order. Thus, their readouts may differ but the difference is very slight. For practical purposes, they will all give the same info.
I trust Merriam-Webster: " ALTITUDE is preferable when referring to vertical distance above the surface of the earth or above sea level; ELEVATION is used especially in reference to vertical height on land. "I’m still laughing over systems that provide “Altitude” vs the correct term “Elevation”. For those who didn’t read my previous rant...
Altitude is the height above ground indicated in MSL (mean sea level) or AGL (Above Ground Level). Elevation is the height OF THE GROUND above sea level. For instance, if you are in Denver (the mile high city) and standing in front of the State Capitol building (actually on the 13th step) you are at 0 (zero) altitude but 5,280 feet MSL elevation. If you climbed up the flag pole (assuming its 100 feet tall) you’d be at 100 feet AGL (Altitude measurement) but 5,380 feet MSL (Altitude measurement). There would be no measurement of elevation up at the top the flagpole.