Simplified scale/refpos approach

main.c

@@ -1704,7 +1704,7 @@ VNA_SHELL_FUNCTION(cmd_trace)
   if (argc == 0) {
     for (t = 0; t < TRACES_MAX; t++) {
       if (trace[t].enabled) {
-        const char *type = get_trace_typename(t);
+        const char *type = unit_string[setting.unit]; // get_trace_typename(t);
         const char *channel = trc_channel_name[trace[t].channel];
         float scale = get_trace_scale(t);
         float refpos = get_trace_refpos(t);

plot.c

@@ -592,13 +592,13 @@ trace_into_index(int t, int i, float array[POINTS_COUNT])
 {
   int y, x;
   float coeff = array[i];
-  float refpos = NGRIDY - get_trace_refpos(t);
-  float v = refpos;
-  float scale = 1 / get_trace_scale(t);
+  float refpos = get_trace_refpos(t);
+  float v;
+  float scale = get_trace_scale(t);
 
   switch (trace[t].type) {
   case TRC_LOGMAG:
-    v-= value(coeff) * scale;
+    v = ( refpos - value(coeff) ) / scale;
     break;
 #ifdef __VNA__
 	case TRC_PHASE:

sa_core.c

@@ -478,13 +478,44 @@ int GetAGC(void)
 
 void set_reflevel(float level)
 {
-  setting.reflevel = (level / setting.scale) * setting.scale;
-  set_trace_refpos(0, NGRIDY - level / get_trace_scale(0));
-  set_trace_refpos(1, NGRIDY - level / get_trace_scale(0));
-  set_trace_refpos(2, NGRIDY - level / get_trace_scale(0));
+  setting.reflevel = level;
+  set_trace_refpos(0, /* NGRIDY - */ level /* / get_trace_scale(0) */);
+  set_trace_refpos(1, /* NGRIDY - */ level /* / get_trace_scale(0) */ );
+  set_trace_refpos(2, /* NGRIDY - */ level /* / get_trace_scale(0) */ );
+
+  if (UNIT_IS_LINEAR(setting.unit)) {   // Never negative bottom
+    float s = setting.scale;
+    if (level - NGRIDY * s < 0) {
+      level = level / NGRIDY;
+      setting.scale = level;
+      set_trace_scale(0, level);
+      set_trace_scale(1, level);
+      set_trace_scale(2, level);
+    }
+  }
   dirty = true;
 }
 
+void set_scale(float s) {
+  setting.scale = s;
+  set_trace_scale(0, s);
+  set_trace_scale(1, s);
+  set_trace_scale(2, s);
+
+  if (UNIT_IS_LINEAR(setting.unit)) {   // Never negative bottom
+    float r = setting.reflevel;
+    s = NGRIDY * s;
+    if (s > r) {
+      setting.reflevel = s;
+      set_trace_refpos(0, s);
+      set_trace_refpos(1, s);
+      set_trace_refpos(2, s);
+    }
+  }
+
+  //  set_reflevel(setting.reflevel);
+}
+
 
 void set_offset(float offset)
 {
@@ -521,17 +552,6 @@ void set_trigger(int trigger)
 //  return (NGRIDY - get_trace_refpos(2)) * get_trace_scale(2);
 //}
 
-void set_scale(float s) {
-  setting.scale = s;
-  if (UNIT_IS_LINEAR(setting.unit)) {   // Bottom always at zero
-    set_reflevel(NGRIDY * s);
-  }
-  set_trace_scale(0, s);
-  set_trace_scale(1, s);
-  set_trace_scale(2, s);
-  set_reflevel(setting.reflevel);
-}
-
 //int GetScale(void) {
 //  return get_trace_refpos(2);
 //}