diff --git a/csdr.c b/csdr.c
index 58edba7..60b1a98 100755
--- a/csdr.c
+++ b/csdr.c
@@ -2592,6 +2592,7 @@ int main(int argc, char *argv[])
         if(argc>=(7+add_q) && !strcmp(argv[6+add_q], "--output_error")) output_error = 1;
         float* timing_error = NULL;
         if(output_error) timing_error = (float*)malloc(sizeof(float)*the_bufsize);
+        errhead(); fprintf(stderr, "--output_error mode\n");
 
         if(argc>=(7+add_q) && !strcmp(argv[6+add_q], "--output_indexes")) output_indexes = 1;
         unsigned* sampled_indexes = NULL;
diff --git a/grc_tests/bpsk31_scurve.m b/grc_tests/bpsk31_scurve.m
index a1cfac2..b17fd24 100755
--- a/grc_tests/bpsk31_scurve.m
+++ b/grc_tests/bpsk31_scurve.m
@@ -46,20 +46,22 @@ function fmtplot(h)
     ylabel('Error value (TED output)');
 end
 
-skips_gardner=0:256
+skips_gardner=0:16:256
 error_values_gardner=mkscurve('GARDNER',skips_gardner);
-skips_earlylate=0:256
+skips_earlylate=0:16:256
 error_values_earlylate=mkscurve('EARLYLATE',skips_earlylate);
 
 %graphics_toolkit("gnuplot")
 h=figure(1);
 
-plot(skips_gardner, error_values_gardner, 'linewidth', 2);
+plot((skips_gardner-128)/256, -error_values_gardner, 'linewidth', 2);
 title('S-curve for Gardner TED');
 fmtplot(h)
+grid on
 pause
 
-plot(skips_earlylate, error_values_earlylate, 'linewidth', 2);
+plot((skips_earlylate-128)/256, error_values_earlylate, 'linewidth', 2);
 title('S-curve for early-late TED');
 fmtplot(h)
+grid on
 pause