From 9af7a184adb0235e0e15a0510eea1744efac5b21 Mon Sep 17 00:00:00 2001
From: Denny <denny@denny-desktop>
Date: Fri, 14 Feb 2020 06:11:15 -0500
Subject: [PATCH] Utility for calculating PLL phase lock sync pattern
 derivatives

---
 .../psk/pll/QPSKPhaseInversionCalculator.java | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 src/main/java/io/github/dsheirer/dsp/psk/pll/QPSKPhaseInversionCalculator.java

diff --git a/src/main/java/io/github/dsheirer/dsp/psk/pll/QPSKPhaseInversionCalculator.java b/src/main/java/io/github/dsheirer/dsp/psk/pll/QPSKPhaseInversionCalculator.java
new file mode 100644
index 00000000..faa20b41
--- /dev/null
+++ b/src/main/java/io/github/dsheirer/dsp/psk/pll/QPSKPhaseInversionCalculator.java
@@ -0,0 +1,71 @@
+/*
+ *
+ *  * ******************************************************************************
+ *  * Copyright (C) 2014-2020 Dennis Sheirer
+ *  *
+ *  * This program is free software: you can redistribute it and/or modify
+ *  * it under the terms of the GNU General Public License as published by
+ *  * the Free Software Foundation, either version 3 of the License, or
+ *  * (at your option) any later version.
+ *  *
+ *  * This program is distributed in the hope that it will be useful,
+ *  * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  * GNU General Public License for more details.
+ *  *
+ *  * You should have received a copy of the GNU General Public License
+ *  * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *  * *****************************************************************************
+ *
+ *
+ */
+
+package io.github.dsheirer.dsp.psk.pll;
+
+/**
+ * Utility for calculating phase inverted sync pattern derivatives for QPSK constellations
+ */
+public class QPSKPhaseInversionCalculator
+{
+    public static String[] LOOKUP_MINUS_90 = {"A","8","B","9","2","0","3","1","E","C","F","D","6","4","7","5"};
+    public static String[] LOOKUP_PLUS_90 = {"5","7","4","6","D","F","C","E","1","3","0","2","9","B","8","A"};
+    public static String[] LOOKUP_180 = {"F","E","D","C","B","A","9","8","7","6","5","4","3","2","1","0"};
+
+    public static void main(String[] args)
+    {
+        //DMR sync patterns
+        String[] syncs = {"755FD7DF75F7", "DFF57D75DF5D", "7F7D5DD57DFD", "D5D7F77FD757", "77D55F7DFD77",
+            "5D577F7757FF", "F7FDD5DDFD55", "7DFFD5F55D5F", "D7557F5FF7F5", "DD7FF5D757DD"};
+
+        for(String sync: syncs)
+        {
+            StringBuilder sbNorm = new StringBuilder();
+            StringBuilder sbP90 = new StringBuilder();
+            StringBuilder sbM90 = new StringBuilder();
+            StringBuilder sb180 = new StringBuilder();
+
+            for(char letter: sync.toCharArray())
+            {
+                int value;
+
+                if(Character.isAlphabetic(letter))
+                {
+                    value = letter - 55;
+                }
+                else
+                {
+                    value = letter - 48;
+                }
+                sbNorm.append(letter);
+                sbP90.append(LOOKUP_PLUS_90[value]);
+                sbM90.append(LOOKUP_MINUS_90[value]);
+                sb180.append(LOOKUP_180[value]);
+            }
+
+            System.out.println("NORMAL: " + sync);
+            System.out.println("   +90: " + sbP90.toString());
+            System.out.println("   -90: " + sbM90.toString());
+            System.out.println("   180: " + sb180.toString());
+        }
+    }
+}