This is a concern when using Linx transparent radio modules with OOK modulation in the 260 to 470MHz band.
Part 15 Section 231 governs operation in the 260 – 470MHz band. In these frequencies the FCC has decided to restrict the type and duration of data that can be transmitted but has allowed for exceptions as well. Keyed carrier signals such as those produced by Linx OOK products can be averaged over a 100ms time, allowing a significantly higher potential output power. The high-bit-to-low-bit ratio of the data will thus have a direct impact on allowed power and thus range.
In the case of the 902 – 928MHz band, the FCC has only specified the output power and harmonic levels. There are no restrictions on the type or duration of data that can be sent. This gives the design engineer a great deal of freedom in the possible applications, but also results in the band being more crowded. Additionally, the band legally allows for the operation of high power spread spectrum devices. This means that a good protocol and a more robust modulation method, such as FM/FSK, is needed to try and ensure data integrity.
For more information, review the FCC Resource Document. A hard copy of FCC Title 47 can be obtained from your local government bookstore or from the Government Printing Office in Washington.