When you compare noise files you need to look at the revision of the noise file and the Standards revision that it applies to. Noise files may have changes when going from one revision to another revision, the changes are recommendations that are voted on by the standards body. Some of the Changes could impact your test in which your data rate may be higher or lower than expected. It is good practice to review the changes in the Standards which applies to the noise file you are using before you start your testing.