Open the measurement you want to export from REW. Click the File Menu and then click Export and then ‘Measurement as text’. When you name the file you must add the file extension to the name. For example a woofer frequency file would be named woofer.frd
To do this, go to Start/ Control Panel/Folder Options and select View. Scroll through the advanced settings to ‘Hide extensions for known file types’ and unclick the box.