Importance

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Abstract

A carrier wave is frequency modulated to one of M different output frequencies that deviate from the carrier wave frequency by .+-.k.sub.1, .+-.k.sub.2 . . . .+-.k.sub.q. The carrier is modulated in response to a clocked digital signal having n data bits forming a data word, where M=2.sup.n. In response to the digital signal an n bit control signal is derived. M/2 clock frequencies synchronized with the clock data signal are simultaneously derived. An up-down counter responds to the control signal so that one bit of the control signal controls the counting direction of the counter and (n-1) of the bits control which one of the M/2 frequencies is applied to a clock input of the counter. In response to the count in the counter, orthogonal sinusoidal like waves at one of the frequencies k.sub.1, k.sub.2 . . . k.sub.q are derived. The M/2 clock frequencies are equal to k.sub.1 2.sup.P, k.sub.2 2.sup.P . . . k.sub.q 2.sup.P, where P is the number of clock frequency bits in the counter. The orthogonal sinusoidal like waves at the selected frequency are vectorially combined with the carrier wave to derive a constant amplitude wave that deviates from the carrier frequency by the selected frequency k.sub.1, k.sub.2 . . . k.sub.q in a direction controlled by the value of the one bit.

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First Claim