Pb let2num.m

function [station_num]=pb_let2num(sletter)

  if sletter == 'A' | sletter =='a' station_num=7;
    elseif sletter == 'B' | sletter == 'b' station_num=6;
    elseif sletter == 'C' | sletter == 'c' station_num=5;
    elseif sletter == 'D' | sletter == 'd' station_num=4;
    elseif sletter == 'E' | sletter == 'e'  station_num=3;
    elseif sletter == 'F' | sletter == 'f' station_num=2;
    elseif sletter == 'G' | sletter == 'g' station_num=1;
  else
    station_num=-999;
  end

pb_let2num