call_distance_modulation.gnuplot: try to improve the look of xtics labels

Increasing the xtics spacing and decreasing the font size makes the plot
look a little less crowded for long transmissions.

diff --git a/plot/call_distance_modulation.gnuplot b/plot/call_distance_modulation.gnuplot
index 70a171e..a3ea29f 100755 (executable)
--- a/plot/call_distance_modulation.gnuplot
+++ b/plot/call_distance_modulation.gnuplot
@@ -20,7 +20,7 @@ set xlabel "time since the first call (seconds)"
 
 set noytics
 
-set xtics 20 out nomirror rotate by -45
+set xtics 30 out nomirror rotate by -45 font "Georgia,12"
 
 set yrange[0:0.7]
 set size ratio 0.3