초록 ▼

Several techniques are disclosed for producing modulation of a carrier signal wherein each transition of the modulated carrier signal includes a midrange level and/or two midrange characteristics, the level and/or ratio of the two midrange characteristics representing data carried by that transition

Several techniques are disclosed for producing modulation of a carrier signal wherein each transition of the modulated carrier signal includes a midrange level and/or two midrange characteristics, the level and/or ratio of the two midrange characteristics representing data carried by that transition. A simplified method over that disclosed in parent application Ser. No. 590,281, filed Mar. 16, 1984 now U.S. Pat. No. 4,613,974 is disclosed herein, and is referred to as a “flipped sine wave”method of producing the modulated carrier signal. Another technique, referred to as a “third harmonic modulation”technique uses the phase relationship between a fundamental and its third harmonic to produce the modulated carrier signal. A technique for storing the modulated carrier on magnetic media and correcting for offset resulting therefrom or from attenuation and advance of the third harmonic relative to the fundamental to permit accurate demodulation is disclosed.

대표청구항 ▼

A circuit for providing a midlevel modulated carrier signal having a plurality of midrange levels in a plurality of respective rising and falling transitions thereof, the circuit comprising: (a) means for providing a first signal having a first frequency and means for providing a second signal which

A circuit for providing a midlevel modulated carrier signal having a plurality of midrange levels in a plurality of respective rising and falling transitions thereof, the circuit comprising: (a) means for providing a first signal having a first frequency and means for providing a second signal which has a fixed phase relationship to the first signal and has a second frequency that is an integral multiple of the first frequency; (b) means for producing a relative shift between the phases of the first and second signals in accordance with the levels of an analog modulation signal; and (c) summing means for summing the first and second signals to produce the midlevel modulated carrier signal with respective midrange levels in each rising transition and falling transition of the modulated carrier signal, each midrange level representing a corresponding valve of the analog modulation signal.