Hi Clive,
To get the GPRMC messages being sent firstly you need to download a track file from PilotAware.
This can then be opened in Excel (select all file types), in the text input wizard highlight Delimited,next, select Tab and Comma, next, select text and Finish. This should populate the spread sheet. Now you need to filter the data. Select data, filter, and tthen select only the GPRMC message type in column A.
BTW there may be a much easier way to achieve this I'm self taught and complete amateur with Excel.
Once you have the messages you can see column B time stamp , position, speed and heading, date.