Continuous phase frequency shift keying modulation is employed during
wireless transmission from an internal device to an external device to
increase robustness of transmissions. The continuous phase frequency
shift keying processor receives as input an incoming data stream and
includes a timer for toggling its output between a first predetermined
frequency and a second predetermined frequency on a predetermined time
period basis based on the logical state of each bit in the incoming data
stream. For a portion of time while the counter or timer of the CPFSK
processor is counting down the predetermined time period associated with
the detected logic state of a particular bit of the incoming data signal
at least some of the other circuitry, preferably all of the other
circuitry of the processor, is toggled to a sleep mode in which power is
cut off thereby minimizing power consumption by the processor during this
interim state.