Added MFSKConstants

Author: consuelita

AudioCoder/src/main/java/org/operatorfoundation/audiocoder/mfsk/MFSKConfiguration.kt

@@ -19,7 +19,7 @@ package org.operatorfoundation.audiocoder.mfsk
 data class MFSKConfiguration(
     val mode: MFSKMode,
     val baseFrequencyHz: Double,
-    val sampleRate: Int   = 12_000,
-    val amplitude: Double = 0.5,
-    val timeoutMs: Long   = 60_000L
+    val sampleRate: Int   = MFSKConstants.MFSK_RECOMMENDED_SAMPLE_RATE,
+    val amplitude: Double = MFSKConstants.MFSK_DEFAULT_AMPLITUDE,
+    val timeoutMs: Long   = MFSKConstants.MFSK_DEFAULT_TIMEOUT_MS
 )

AudioCoder/src/main/java/org/operatorfoundation/audiocoder/mfsk/MFSKConstants.kt

@@ -0,0 +1,20 @@
+package org.operatorfoundation.audiocoder.mfsk
+
+object MFSKConstants
+{
+    /**
+     * Recommended audio pipeline sample rate in Hz.
+     *
+     * Divides cleanly into all standard MFSK baud rates with no rounding error.
+     */
+    const val MFSK_RECOMMENDED_SAMPLE_RATE = 12_000
+
+    /** Default transmit output level as a fraction of full scale, in [0.0, 1.0].
+     *  Leaves headroom for signal processing while maintaining adequate output level. */
+    const val MFSK_DEFAULT_AMPLITUDE = 0.5
+
+    /** Default receive timeout in milliseconds.
+     *  At MFSK-16's ~1.95 bytes/second, a 40-byte payload transmits in ~21 seconds.
+     *  60 seconds provides approximately 2.5× margin for timing and signal variation. */
+    const val MFSK_DEFAULT_TIMEOUT_MS = 60_000L
+}