testing if did is sane

src/main/java/com/elphel/imagej/ims/EventLoggerFileInfo.java

@@ -381,6 +381,9 @@ public class EventLoggerFileInfo implements Comparable<EventLoggerFileInfo> {
 					bb_payload.order(ByteOrder.LITTLE_ENDIAN);
 					@SuppressWarnings("rawtypes")
 					Did_ins did_ins = type_ins_2 ? (new Did_ins_2(bb_payload)) : (new Did_ins_1(bb_payload));
+					if (!did_ins.isDidSane()) {
+						continue;
+					}
 //					double full_time = did_ins.getDoubleTime();
 					int [] week_time = did_ins.getWeekTimeMs();
 					if (week_time0 == null) {
@@ -395,12 +398,23 @@ public class EventLoggerFileInfo implements Comparable<EventLoggerFileInfo> {
 					sx2 += ts_master * ts_master;
 					sy +=  ts_gnss;
 					sxy += ts_master * ts_gnss;
-					if (debugLevel > 0) { // -1
+					if (sy>2*sx) { // -1
+						System.out.println (
+								String.format("%6d %10.6f %10.6f", nrec, ts_master, ts_gnss)+" sx="+sx+" sy="+sy);
+						System.out.println(Did_strobe_in_time.getWeekTimeMsDelta(week_time0, week_time));
+					}
+					
+					if ((sy>2*sx) || (debugLevel > 0)) { // -1
 						System.out.println (
-								String.format("%6d %10.6f %10.6f", nrec, ts_master, ts_gnss));
+								String.format("%6d %10.6f %10.6f", nrec, ts_master, ts_gnss)+" sx="+sx+" sy="+sy);
 					}
 				}
 			}
+			if (s0 == 0){
+				System.out.println("calibrateFromDidIns(): no valid records available, aborting.");
+				return false;
+			}
+
 			double d = (s0 * sx2 - sx * sx);
 			double a = (sxy * s0 - sy * sx) / d;
 			double b = (sx2 * sy - sx * sxy) / d;