This page covers the basics of downloading and parsing logs for your own use, including building AlogParse under windows.
Downloading log files
Logs are kept in Amazon Web Services's S3 here: http://aws.amazon.com/console/. There is also a google doc with a quick listing of all kayak experimental operations. Email Josh to get access to both AWS and the google doc. Once you sign sign into AWS click on "S3" under the red section titled "Storage & Content Delivery".
Logs are compressed as .tar.gz or .tar.bz2 files. To open them under windows you can use WinRAR available for free at http://www.rarlab.com/download.htm. Download the "Graphic and Command line" version at the very top corresponding to your windows version (32 or 64 bit).
If you have trouble extracting the log files check the file extension. On some computers the files are downloaded with the wrong file extension, such as .gz instead of .tar.gz. Rename the extension to what it says in AWS and WinRAR should open it just fine.
Files you will find
Each time the software on the kayaks is restarted a new folder is created corresponding to the start time. You can expect to find the following extension types in each folder:
.blog - ignore this
.ylog - ignore this too
._moos - a copy of the MOOS configuration file the vehicle was started with.
.alog - the main asynchronous log file.
goby_logX.txt - a log of the communications between iAcommsDriver and the MicroModem
An asynchronous logfile means that when a variable is posted to in the MOOSDB, that posting is logged as a single line with at least its time stamp, source application name, variable name, and value. To import data into matlab we first need to convert our alog to a synchronous logfile.
AlogParse
AlogParse is a simple command line application that will extract the variables you request from an alog and create a text file that can be imported into Matlab. If using Linux just follow the instructions at Software Installation and AlogParse will be built with the other Hovergroup apps. If using windows you can download a pre-built executable here:
You can download the executable wherever, but for the purpose of this example I'm going to create a folder called "alogParse" in my documents folder and put the executable there. To use alogParse follow these instructions:
1) Open up a command prompt go to Start -> Run, type in "cmd" and hit enter. A command prompt should open up in your user directory (e.g. C:\Users\Josh>)
2) Navigate to the directory where you saved alogParse
cd Documents\alogParse
3) Run alogParse
alogParse.exe --help
--help should tell you everything you need to know to use alogParse. It's easiest to pass an alog file to alogParse if you first copy the logfile to the same directory. Then you can run alogParse using a command such as:
alogParse.exe mylog.alog --sync_period=0.2 NAV_X NAV_Y
When dealing with long alog file names, remember that tab auto-completes. Once you start typing a name press tab and the command prompt will automatically try to fill in the rest. Depending on the settings and size of the input file alogParse can take a while to run. A pure back-search (-backsearch) is usually much faster than a partial back-search (-backsearch=X) or full-search.
AlogParse will output a txt file with the same name as the input. This can be imported into Excel or Matlab using their import data functions.