What different about Trace OSD II and III

Trace II to III is only the GPS module (10Hz) and smaller current sensor. The OSD board is the same. If you upgrade the firmware, it will say III. If you are using the software on a Windows 7 computer, run it in administrator mode. Windows 7 does not work well with unsigned USB to Serial drivers. If that doesn't help, try on a Windows XP computer. The GPS locks even inside my aparment. Outside lock is within 20 seconds.