diff --git a/demod/mod/mXXmod.c b/demod/mod/mXXmod.c
index 072a7eb..2bd2b24 100644
--- a/demod/mod/mXXmod.c
+++ b/demod/mod/mXXmod.c
@@ -77,6 +77,7 @@ dduudduudduudduu duduudduuduudduu  ddududuudduduudd uduuddududududud uudduduuddu
                                                     //"0111011010011111"; // M10: 76 9F , w/ aux-data
                                                     //"0110010001001001"; // M10-dop: 64 49 09
                                                     //"0110010010101111"; // M10+: 64 AF w/ gtop-GPS
+                                                    //"0100010100100000"; // M20: 45 20 (baud=9600)
 static char rawheader[] = "10011001100110010100110010011001";
 
 #define FRAME_LEN       (100+1)   // 0x64+1
@@ -618,7 +619,9 @@ static float get_Temp(gpx_t *gpx) {
     x = (4095.0-ADC_RT)/ADC_RT;  // (Vcc-Vout)/Vout = Vcc/Vout - 1
     R =  Rs[scT] /( x - Rs[scT]/Rp[scT] );
 
-    if (R > 0)  T = 1/( p0 + p1*log(R) + p2*log(R)*log(R) + p3*log(R)*log(R)*log(R) );
+    if (R > 0)  T = 1.0/( p0 + p1*log(R) + p2*log(R)*log(R) + p3*log(R)*log(R)*log(R) );
+
+    if (T > 333.15) T = 0; // T > 60C invalid
 
     return  T - 273.15; // Celsius
 }
@@ -641,7 +644,7 @@ static float get_Tntc2(gpx_t *gpx) {
     ADC_ntc0  = (gpx->frame_bytes[0x07] << 8) | gpx->frame_bytes[0x06]; // M10: 0x40,0x3F
     x = (4095.0 - ADC_ntc0)/ADC_ntc0;  // (Vcc-Vout)/Vout
     R = Rs / x;
-    if (R > 0)  T = 1/(1/T25 + 1/b * log(R/R25));
+    if (R > 0)  T = 1.0/(1.0/T25 + 1.0/b * log(R/R25));
     //if (R > 0)  T =  1/( p0 + p1*log(R) + p2*log(R)*log(R) + p3*log(R)*log(R)*log(R) );
 
     return T - 273.15;
@@ -730,8 +733,8 @@ static int print_pos(gpx_t *gpx, int bcOK, int csOK) {
         get_SN(gpx);
 
         if (gpx->option.ptu && csOK) {
-            gpx->T   = get_Temp(gpx);  // temperature
-            gpx->TH  = get_Tntc2(gpx); // rel. humidity sensor temperature
+            gpx->T  = get_Temp(gpx);   // temperature
+            gpx->TH = get_Tntc2(gpx);  // rel. humidity sensor temperature
             gpx->RH = get_RH(gpx);     // relative humidity
             gpx->P  = get_P(gpx);      // (optional) pressure
         }
@@ -945,7 +948,7 @@ static int print_frame(gpx_t *gpx, int pos, int b2B) {
             }
             fprintf(stdout, "\n");
         }
-        if (gpx->option.slt /*&& gpx->option.jsn*/) {
+        if (gpx->option.slt /*&& gpx->option.jsn && gpx->frame_bytes[1] != 0x49*/) {
             print_pos(gpx, bc, cs1 == cs2);
         }
     }
@@ -956,6 +959,7 @@ static int print_frame(gpx_t *gpx, int pos, int b2B) {
                 byte = gpx->frame_bytes[i];
                 fprintf(stdout, "%02x", byte);
             }
+            if (cs1 == cs2) fprintf(stdout, " [OK]"); else fprintf(stdout, " [NO]");
             fprintf(stdout, "\n");
         }
     }
diff --git a/demod/multi/m20base.c b/demod/multi/m20base.c
index 52f7d7f..9a4100d 100644
--- a/demod/multi/m20base.c
+++ b/demod/multi/m20base.c
@@ -601,7 +601,9 @@ static float get_Temp(gpx_t *gpx) {
     x = (4095.0-ADC_RT)/ADC_RT;  // (Vcc-Vout)/Vout = Vcc/Vout - 1
     R =  Rs[scT] /( x - Rs[scT]/Rp[scT] );
 
-    if (R > 0)  T = 1/( p0 + p1*log(R) + p2*log(R)*log(R) + p3*log(R)*log(R)*log(R) );
+    if (R > 0)  T = 1.0/( p0 + p1*log(R) + p2*log(R)*log(R) + p3*log(R)*log(R)*log(R) );
+
+    if (T > 333.15) T = 0; // T > 60C invalid
 
     return  T - 273.15; // Celsius
 }
@@ -624,7 +626,7 @@ static float get_Tntc2(gpx_t *gpx) {
     ADC_ntc0  = (gpx->frame_bytes[0x07] << 8) | gpx->frame_bytes[0x06]; // M10: 0x40,0x3F
     x = (4095.0 - ADC_ntc0)/ADC_ntc0;  // (Vcc-Vout)/Vout
     R = Rs / x;
-    if (R > 0)  T = 1/(1/T25 + 1/b * log(R/R25));
+    if (R > 0)  T = 1.0/(1.0/T25 + 1.0/b * log(R/R25));
     //if (R > 0)  T =  1/( p0 + p1*log(R) + p2*log(R)*log(R) + p3*log(R)*log(R)*log(R) );
 
     return T - 273.15;
@@ -713,8 +715,8 @@ static int print_pos(gpx_t *gpx, int bcOK, int csOK) {
         get_SN(gpx);
 
         if (gpx->option.ptu && csOK) {
-            gpx->T   = get_Temp(gpx);  // temperature
-            gpx->TH  = get_Tntc2(gpx); // rel. humidity sensor temperature
+            gpx->T  = get_Temp(gpx);   // temperature
+            gpx->TH = get_Tntc2(gpx);  // rel. humidity sensor temperature
             gpx->RH = get_RH(gpx);     // relative humidity
             gpx->P  = get_P(gpx);      // (optional) pressure
         }