diff --git a/main.c b/main.c
index 82197709..f6b8255a 100644
--- a/main.c
+++ b/main.c
@@ -2302,6 +2302,7 @@ void get_tlm_fc() {
 //	printf("\nSYMPBLOCK = %d\n", SYMPBLOCK);
 
 	memset(source_bytes, 0x00, sizeof(source_bytes));
+	source_bytes[0] = 0b10000000;
 	source_bytes[10] = (uint8_t) rnd_float(0,255);
 /*
 	printf("\nsource_bytes\n");