diff --git a/CalP25.cpp b/CalP25.cpp
index 9fff731..b1b9b6d 100644
--- a/CalP25.cpp
+++ b/CalP25.cpp
@@ -20,6 +20,8 @@
 #include "Globals.h"
 #include "CalP25.h"
 
+// Recommended 1011 Hz test pattern for P25 Phase 1 (ANSI/TIA-102.CAAA)
+// NAC: 0x293, srcID: 1, dstID: TG1
 unsigned char LDU1_1K[] = {0x00,
                            0x55, 0x75, 0xF5, 0xFF, 0x77, 0xFF, 0x29, 0x35, 0x54, 0x7B, 0xCB, 0x19, 0x4D, 0x0D, 0xCE, 0x24, 0xA1, 0x24,
                            0x0D, 0x43, 0x3C, 0x0B, 0xE1, 0xB9, 0x18, 0x44, 0xFC, 0xC1, 0x62, 0x96, 0x27, 0x60, 0xE4, 0xE2, 0x4A, 0x10,