#36 NBFM squelch control. Updates NBFM decoder to incorporate squelch control. Squelch is a configuration item and also available to adjust at runtime with new 'Channel' tab in Now Playing window. All decoders were updated to produce continuous channel power (dB) measurements that are displayed in the Channel tab's new Power Meter. (#1100)

Co-authored-by: Dennis Sheirer <dsheirer@github.com>

src/main/java/io/github/dsheirer/dsp/squelch/ISquelchConfiguration.java

@@ -0,0 +1,19 @@
+package io.github.dsheirer.dsp.squelch;
+
+/**
+ * Interface for configurations that support squelch threshold setting.
+ */
+public interface ISquelchConfiguration
+{
+    /**
+     * Sets the squelch threshold
+     * @param threshold (dB)
+     */
+    void setSquelchThreshold(int threshold);
+
+    /**
+     * Squelch threshold
+     * @return threshold (dB)
+     */
+    int getSquelchThreshold();
+}