OPPORTUNISTIC MODEM

An opportunistic modem (OM) system receives user data at an input port and transmits a modem output signal at an output port. In one aspect the data is initially transmitted over a first carrier in the modem output signal having a first frequency and bandwidth. Subsequently a second carrier having a second frequency and bandwidth is established, initially used to transmit pilot data, and then the user data is divided between the first and second carriers in the modem output signal. In another aspect the data is initially transmitted over a first and a second carrier in the modem output signal having respective first and second frequencies and bandwidths. Subsequently the second carrier is used to transmit pilot data for a period time. After the period of time the second carrier is de-established. In another aspect establishment and de-establishment of carriers is performed in response to detected interference.