For the installation, please have a look at :
Off all the methods, the one I would recommend is PIP install
As far as the viewer is concerned, I am experiencing troubles with the latest versions, see my report (
d-ronin/dRonin#2239 ), so I would suggest to use the wired sources (which are the ones you normally download through the PIP install). You also need a live internet connection in order for the old log viewer to work with the latest logs ! I presume it collects the latest XUAV schema online.
Once you've got it installed, and have the logs recorded on the SD card, you just have to launch the Logviewer, open the file, that will be displayed by default with a few graphs. On the right panel, additional graphs are available depending on what is in the log. If you select one of the item in the drop down list and hit the "Add time series plot" an additional graph will pop-up.
Note that If you click on the "enable context menu" check box, you've got quite a few options in order to customize the graphs. If you click on the margins of the graphs and slide on the right or left with right or left mouse buttons, a few zoom / move features are activated. Once you get used to it, it works great.
Regarding the log themselves (i.e what is recorded by the FC), you can either use basic / fullbore / custom (GCS Module menu). Basic should be OK with openlog, fullbore log does require openlAger as openlog is slow. Custom logging, allows you to selectively enable UAV objects. It does require to navigate through the UAV objects (system tab in the GCS) and define which items are supposed to be recorded (a 0ms recording means not recorded). In order to access theses logging settings, you have to click on the "eye" on the toolbar and enable "view metadata".
Maybe you should log the flight statistics, as every 5 seconds it record what was the max amp draw, lowest voltage and a few other Min/max values. This is a small set of data that can be easily recorded even on the flash memory.
See my thread on LQG tuning (https://forum.dronin.org/forum/d/607-tuning-the-lqg-flight-mode-bis) in order to get an idea of what the graphs do look like.
Hope this helps