set polar
set angle degree
set size ratio 1
set tmargin 3
set bmargin 3
set title "Microphone Polar Diversity Response : Mic Spacing 0.1 (meters)"
set key out vert nobox
set style line 1 lc rgb 'gray80' lt -1
set grid polar ls 1
unset border
unset xtics
unset ytics
f_maxGain=0. # Maximum gain - MUST BE FLOATING POINT
minGain=-80 # Minimum gain - MUST BE INTEGER
tickstep = 10 # Ticks every 10 dB
numticks = 8 # numticks = r / tickstep :: Don't use divide because numticks is used in for loop and doesn't work
f_numticks = 8. # Floating point numticks
set rrange [minGain:0]
set rtics tickstep format '' scale 0
set label '0°' center at first 0, first -minGain*1.05
set label '90°' right at first -minGain*1.05, 0
set label '180°' center at first 0, first minGain*1.05
set label '270°' left at first minGain*1.05, 0
set for [i=.1:numticks] label at first minGain*0.001, first minGain*((i/f_numticks) + 0.007) sprintf("%d dB", minGain+(i*10))
unset raxis
plot "250.dat" u (-$1+90.):($2-f_maxGain) t "250 Hz" w lines lc rgb "magenta", \
"500.dat" u (-$1+90.):($2-f_maxGain) t "500 Hz" w lines lc rgb "red", \
"1000.dat" u (-$1+90.):($2-f_maxGain) t "1000 Hz" w lines lc rgb "blue", \
"2000.dat" u (-$1+90.):($2-f_maxGain) t "2000 Hz" w lines lc rgb "cyan", \
"4000.dat" u (-$1+90.):($2-f_maxGain) t "4000 Hz" w lines lc rgb "orange"
print "Hit <CR> to continue ..."
pause -1
The data was generated in a C program and written to the .dat files, then I just used gnuplot on the command line to execute the script and plot the results.
The data files look like this (i.e. two columns : angle and gain) :
# Antenna Beam Pattern
# Angle Gain
-9.00e+01 -1.17e+00
-8.90e+01 -1.17e+00
-8.80e+01 -1.17e+00
.
.
Here is the plot for 100 mm mic spacing :
The gnuplot script allows the min and max gain values to be changed.
If you have found this solution useful then please do hit the Google (+1) button so that others may be able to find it as well.
Numerix-DSP Libraries : http://www.numerix-dsp.com/eval/
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ReplyDeleteThank you for the script.
ReplyDeleteWith small changes I'm using it for antenna pattern.
Pascal