Improve the AGC key used for GLONASS

christianrowlands · Nov 17, 2023 · 913c900 · 913c900
1 parent c7ca418
commit 913c900
Showing 1 changed file with 13 additions and 10 deletions.
diff --git a/networksurvey/src/main/java/com/craxiom/networksurvey/model/ConstellationFreqKey.java b/networksurvey/src/main/java/com/craxiom/networksurvey/model/ConstellationFreqKey.java
@@ -2,6 +2,9 @@
 
 import android.location.GnssStatus;
 
+import com.craxiom.networksurvey.util.CarrierFreqUtils;
+import com.craxiom.networksurvey.util.MathUtils;
+
 import java.util.Objects;
 
 /**
@@ -10,18 +13,18 @@
 public class ConstellationFreqKey
 {
     private final int constellationType;
-    private final long carrierFrequencyTrimmed;
+    private final String carrierFrequencyNormalized;
     private final int hash;
 
-    public ConstellationFreqKey(int constellationType, long carrierFrequency)
+    public ConstellationFreqKey(int constellationType, long carrierFrequencyHz)
     {
         this.constellationType = constellationType;
         if (constellationType == GnssStatus.CONSTELLATION_GLONASS)
         {
-            // GLONASS frequencies have a pretty wide range, so we trim them down to 10 MHz bins
-            // Even this is not enough, but I am nervous going any farther. For example, here
-            // are the results of GNSS measurement scan, and the AGC class on a Pixel 8 Pro. Notice
-            // that the carier freq ranges from 1598062464 to 1605374976 and they all have the same AGC.
+            // GLONASS frequencies have a pretty wide range, so we use the band label instead.
+            // For example, here are the results of GNSS measurement scan, and the AGC class on a
+            // Pixel 8 Pro. Notice that the carrier freq ranges from 1598062464 to 1605374976 and
+            // they all have the same AGC.
             //
             // GnssMeasurement: Constellation=GLONASS, CarrierFreq=1598062464, AGC=47.18083190917969
             // GnssMeasurement: Constellation=GLONASS, CarrierFreq=1600312448, AGC=47.18083190917969
@@ -34,12 +37,12 @@ public ConstellationFreqKey(int constellationType, long carrierFrequency)
             // GnssMeasurement: Constellation=GLONASS, CarrierFreq=1605374976, AGC=47.18083190917969
             //
             // GnssAutomaticGainControl: Constellation=GLONASS, CarrierFreq=1602000000, AGC=46.839942932128906
-            carrierFrequencyTrimmed = carrierFrequency / 10_000_000;
+            carrierFrequencyNormalized = CarrierFreqUtils.getCarrierFrequencyLabel(GnssType.GLONASS, -1, MathUtils.toMhz(carrierFrequencyHz));
         } else
         {
-            carrierFrequencyTrimmed = carrierFrequency / 1_000;
+            carrierFrequencyNormalized = String.valueOf(carrierFrequencyHz / 1_000);
         }
-        hash = Objects.hash(constellationType, carrierFrequencyTrimmed);
+        hash = Objects.hash(constellationType, carrierFrequencyNormalized);
     }
 
     @Override
@@ -48,7 +51,7 @@ public boolean equals(Object o)
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         ConstellationFreqKey that = (ConstellationFreqKey) o;
-        return carrierFrequencyTrimmed == that.carrierFrequencyTrimmed && constellationType == that.constellationType;
+        return carrierFrequencyNormalized == that.carrierFrequencyNormalized && constellationType == that.constellationType;
     }
 
     @Override