When I attempted to use the 433MHz transceivers last week, they did not seem to connect correctly. They both had solid green lights (going to blinking when one was disconnected from power), indicating that they were connected correctly. The Device Manger was throwing an error code (https://technet.microsoft.com/en-us/library/ff710454%28v=ws.10%29.aspx) that refered to Windows Vista. I attempted to uninstall the drivers via the Device Manager, and reconnect the transceiver so that Windows would automatically identify/download the drivers. This did not work. Instead, the drivers had to be found manually online (http://www.ftdichip.com/Drivers/VCP.htm) and installed. They then began to work.
I am hoping that this will allow me to collect live data on the UAV while it is in flight. This should let me better ascertain if the UAV is flying to the waypoints correctly. I have checked the WPNAV_RADIUS parameter, and found it to be set to 200cm. This means that the UAV has to be within 2m of the waypoint for it to be considered successfully navigated to, which seems reasonable. This suggests that this is not the cause of the strange waypoint flight issues.