The Semtec DP1205 RF module is the core of the modem. This module is a Semtec XE1205 transceiver plus an antenna switch and other required discrete components that are not built on the XE1205 chip. The XE1205 is a very generic 900MHz FM module without any built-in protocol logic. It is very similar to the modules produced by Linx Technologies. The module has an SPI interface for changing between transmitter and receiver modes and for setting the RF frequency and the FM frequency deviation. The data connection directly drives the FSM circuity. For this project, the module uses a 100KHz deviation. The transmission power is 15DBm.
A FCC Legal Frequency Hopping Spread Spectrum USB RF Modem – [Link]