Fix build of the Transceiver.
diff --git a/Transceiver52M/Transceiver.cpp b/Transceiver52M/Transceiver.cpp
index bdc8aff..d030a48 100644
--- a/Transceiver52M/Transceiver.cpp
+++ b/Transceiver52M/Transceiver.cpp
@@ -36,6 +36,8 @@
 #include "config.h"
 #endif
 
+using namespace GSM;
+
 #define USB_LATENCY_INTRVL		10,0
 
 #if USE_UHD