Readme file for processing and plotting simrad files
16 sept 2002 scott gallager

The original telegrams from the simrad EK500 for 38, 120, 200 kHz transducers are transmitted to RVDAS via RS232 at 115kb and logged daily with new a file started at 0000 GMT (2000 h local). To process the raw simrad output, the perl script simandmwaythen.pl (written by Karen Fisher) picks up the day.dat file, which must be set by the user, loads and outputs a series of files for each frequency and time. The matlab m file simthenplotter_2.m picks up the output from the perl script, plots and saves mat files. The m file called plotsimrad.m asks you for the matlab filename and plots the output.

All the matlab files for each day of NBP0204 are on this disk in gz zipped format. All the user needs to do is to unzip the mat file of choice, and run plotsimrad.m. You do not need to go back to the raw data if you just wish to plot data for a particular day or time window. The data in the *.mat files are corrected for the offset produced by the noise margin setting on the simrad and calibrated by cross correlation with data from biomaperII when it was in the water at the same time. This is not a true calibration since the accuracy is unknown, but it probably gives correct backscatter intensity within a few db. The range is -100 to -40 and color scaled (thanks to Gareth Lawson) in the plots just as in the output from biomaperII.
 
plotsimrad.m allows you to select the times within a given day to plot so you can "zoom in" on specific activites such as CTD or MOCNES casts. I have included the perl script on this cd if the user wishes to go back to the raw data and re-pprocess for some reason. I also have a script to cross plot backscatter intensity againt temperature gradient data from the CTD and CMIPS during each cast. Let me know if you are interested.