Hi I would like to chime in here. First let me introduce myself. I work for Applied Ballistics as Support Staff, so if you have any technical questions, or problems your emails come to me, and please feel free to email me with any questions you have at email@example.com
Now to help out some here. Density altitude is what is most important. That is the altitude the bullet feels, basically how the atmosphere feels to the bullet. But this is not the only thing that is going to affect your round. The direction you fire the round (east vs west) will affect the rounds vertical trajectory, this is relative to where you are latitude wise. East is High, West is Low. This has maximum effect at the equator and dies off at the poles. Shooting north or south is also the zero point for this effect. The other thing is closer you move towards the poles the more your round is is effected horizontally. This is basically effected by your latitude but has no effect based on direction of fire. If you fire north or east or whichever this stays the same, its based on your latitude. Then you have gyroscopic drift. Which is another story all together. As well as horizontal and vertical effects from the wind. So when you put all of this together, your weapons characteristics, your location, your atmospheric conditions, as well as other information you get what the Kestrel 4500 AB does for you. Its based on 3DOF + extensions. Basically it takes all of this information together, and gives you a firing solution in a matter of milliseconds.
I see some questions about the Kestrel have popped up. So the different Kestrels will give you loads of different information. In order to break it all down you would need a chart Compare Products | Nielsen-Kellerman
but in short the only ones that will give you density altitude are the 4000 series and up. Secondly I saw some people talking about needing wifi in order to gather information. Their are options for this as well.
AB Tactical (Restricted to Military) is an off the grid program capable of giving you all the information you need. I plan to post about it on this forum in the future. The other AB Programs are capable of reading the instruments or GPS on a phone to give you information as well. But AB Tactical was designed to work off the gird from the ground up. No wifi needed, ever. All the factors that were discussed before are taken in to effect. Another thing to know is the Litz Curves. These are developed in a highly precise full time lab we have, and only available on AB software including the AB Kestrel. Others will say they use the Litz BC, but only AB uses the actualy Litz Curve (G1 or G7 as well if you choose).
Your best solution is of course to get a Bluetooth model. This will input the information for you in to the applications. Battery life is a non issue with a Kestrel, they have outstanding battery life. With a Kestrel that has Density Altitude you no longer need your gps location, or your elevation. It will tell you what the round "Feels" as it travels through the air.
If you have any questions or would like me to answer anything in detail please feel free to ask, or if you would like you can privately email me.