From 2f20d6b10812ba26b1d2fb89fe26f0444ac02e3e Mon Sep 17 00:00:00 2001
From: fros4943 <fros4943>
Date: Mon, 15 Mar 2010 19:22:03 +0000
Subject: [PATCH] fixed cc2420's received signal strength indicator to be an
 average of the last 8 symbols (192us)

---
 .../mspmote/interfaces/SkyByteRadio.java      | 46 ++++++++++++++++---
 1 file changed, 39 insertions(+), 7 deletions(-)

diff --git a/tools/cooja/apps/mspsim/src/se/sics/cooja/mspmote/interfaces/SkyByteRadio.java b/tools/cooja/apps/mspsim/src/se/sics/cooja/mspmote/interfaces/SkyByteRadio.java
index 89bdd2f86..338c2db89 100755
--- a/tools/cooja/apps/mspsim/src/se/sics/cooja/mspmote/interfaces/SkyByteRadio.java
+++ b/tools/cooja/apps/mspsim/src/se/sics/cooja/mspmote/interfaces/SkyByteRadio.java
@@ -26,7 +26,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: SkyByteRadio.java,v 1.24 2010/03/10 10:11:36 fros4943 Exp $
+ * $Id: SkyByteRadio.java,v 1.25 2010/03/15 19:22:03 fros4943 Exp $
  */
 
 package se.sics.cooja.mspmote.interfaces;
@@ -325,19 +325,51 @@ public class SkyByteRadio extends Radio implements CustomDataRadio {
     return 31;
   }
 
+  /**
+   * Current received signal strength.
+   * May differ from CC2420's internal value which is an average of the last 8 symbols.
+   */
   double currentSignalStrength = 0;
+
+  /**
+   * Last 8 received signal strengths
+   */
+  private double[] rssiLast = new double[8];
+  private int rssiLastCounter = 0;
+
   public double getCurrentSignalStrength() {
     return currentSignalStrength;
   }
 
   public void setCurrentSignalStrength(final double signalStrength) {
+    if (signalStrength == currentSignalStrength) {
+      return; /* ignored */
+    }
     currentSignalStrength = signalStrength;
-    getMote().getSimulation().scheduleEvent(new MspMoteTimeEvent(mote, 0) {
-      public void execute(long t) {
-        super.execute(t);
-        cc2420.setRSSI((int) signalStrength);
-      }        
-    }, mote.getSimulation().getSimulationTime());
+    if (rssiLastCounter == 0) {
+      getMote().getSimulation().scheduleEvent(new MspMoteTimeEvent(mote, 0) {
+        public void execute(long t) {
+          super.execute(t);
+
+          /* Update average */
+          System.arraycopy(rssiLast, 1, rssiLast, 0, 7);
+          rssiLast[7] = currentSignalStrength;
+          double avg = 0;
+          for (double v: rssiLast) {
+            avg += v;
+          }
+          avg /= rssiLast.length;
+
+          cc2420.setRSSI((int) avg);
+          
+          rssiLastCounter--;
+          if (rssiLastCounter > 0) {
+            mote.getSimulation().scheduleEvent(this, t+DELAY_BETWEEN_BYTES/2);
+          }
+        }        
+      }, mote.getSimulation().getSimulationTime());
+    }
+    rssiLastCounter = 8;
   }
 
   public JPanel getInterfaceVisualizer() {