#2518 P25P1 LSM Decoder enhancements. (#2523)

* Uses same shared architecture and symbol processor pattern as other C4FM decoders.
* Adds soft symbol processing and sync detection.
* Removes RRC filter and replaces with improved channel filter.
* Viterbi soft symbol decoding with demodulator reliability weighting
* Improved sync reacquisition in low SNR
* Improved handling for phase wrapping and interpolation
* NAC Tracker updated to track by NAC count
* Native buffers returning partial buffers
* Message processor uses only valid LDU1 words
* Reduced phantom TDU messages
* Tuner/Channe frequency error corrections don't reset the symbol trackers and fix possible divide by zero error
* LSM timing error detector now updates per symbol block size instead of sample buffer size - faster convergence
* New unit tests
* Resolves several issues, including a lagging sync detect offset issue in the recently updated P25P1 C4FM decoder.
* Consolidate filter designers for each protocol back into the FilterFactory class.
* DMR, P25 Phase 1 C4FM and LSM, and P25 Phase 2 decoders design the baseband filter once and share the taps across the I and Q filters.

Co-authored-by: denny <dennis.sheirer@gmail.com>

src/test/java/io/github/dsheirer/source/tuner/frequency/ChannelFrequencyErrorManagerTest.java

@@ -0,0 +1,104 @@
+/*
+ * *****************************************************************************
+ * Copyright (C) 2014-2026 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.source.tuner.frequency;
+
+import io.github.dsheirer.sample.Listener;
+import io.github.dsheirer.sample.complex.ComplexSamples;
+import io.github.dsheirer.source.tuner.channel.TunerChannel;
+import io.github.dsheirer.source.tuner.channel.TunerChannelSource;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * JUnit tests for the channel frequency error manager.
+ */
+public class ChannelFrequencyErrorManagerTest
+{
+    /**
+     * Test: a tuner PPM change is removed from the channel's applied frequency correction, and the updated correction
+     * is applied to the channel source.
+     */
+    @Test
+    void testTunerPPMChange()
+    {
+        TestChannelSource source = new TestChannelSource();
+        ChannelFrequencyErrorManager manager = new ChannelFrequencyErrorManager(source, null);
+
+        manager.receive(-10);
+        assertEquals(10, manager.getFrequencyError(), "Applied correction");
+        assertEquals(10, source.mFrequencyCorrection, "Channel source correction");
+
+        manager.receive(25);
+        assertEquals(-15, manager.getFrequencyError(), "Applied correction");
+        assertEquals(-15, source.mFrequencyCorrection, "Channel source correction");
+    }
+
+    /**
+     * Channel source that records the applied frequency correction.
+     */
+    private static class TestChannelSource extends TunerChannelSource
+    {
+        private long mFrequencyCorrection = Long.MIN_VALUE;
+
+        public TestChannelSource()
+        {
+            super(null, new TunerChannel(460_000_000L, 12_500), "test", null);
+        }
+
+        @Override
+        public void setFrequencyCorrection(long correction)
+        {
+            mFrequencyCorrection = correction;
+        }
+
+        @Override
+        public void setFrequency(long frequency)
+        {
+        }
+
+        @Override
+        protected void setSampleRate(double sampleRate)
+        {
+        }
+
+        @Override
+        public void setListener(Listener<ComplexSamples> complexSamplesListener)
+        {
+        }
+
+        @Override
+        public double getSampleRate()
+        {
+            return 50_000.0;
+        }
+
+        @Override
+        public long getFrequency()
+        {
+            return 460_000_000L;
+        }
+
+        @Override
+        public void reset()
+        {
+        }
+    }
+}