Modulators – Amplitude modulator – Nonlinear device controlled by modulating signal
Patent
1981-07-02
1984-11-06
Grimm, Siegfried H.
Modulators
Amplitude modulator
Nonlinear device controlled by modulating signal
331 23, 332 30V, 375 65, 375120, 455102, 455113, 455126, H03C 309, H04L 2712
Patent
active
044814895
ABSTRACT:
A frequency modulator for radio frequency (RF) signals is described that symmetrically modulates the RF signal with either binary signals or voice signals without distorting the amplitude of the binary signal near bit edges. The inventive frequency modulator includes a reference signal generator, a phase comparator for comparing the reference signal and a feedback signal to provide an error signal, a filter for filtering the error signal, a voltage-controlled oscillator (VCO) responsive to the filtered error signal for generating an output signal, a divider for dividing the VCO output signal by a predetermined number to provide the feedback signal, circuitry coupled to the VCO for modulating the VCO output signal with the binary signal, and circuitry coupled to the divider for varying the predetermined number of the divider between a first predetermined number and a second predetermined number in response to the binary signal. Since both the VCO and the divider are modulated by the binary signals, the filtered error signal applied to the VCO remains essentially constant, while the frequency of the VCO is symmetrically varied.
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UH Syntor Synthesizer, Manual #68P81043E45, Motorola, Inc., 1980.
Parallel Input PLL Frequency Synthesizer, MC145152, Motorola, Inc., 1980.
Binary Counter, MC10178, Motorola, Inc., 1974.
4-Bit Data Bus Input PLL Frequency Synthesizer, MC145146, Motorola, Inc., 1980.
Dual 3-Input 3-Output NOR Gate, MC10211, Motorola, Inc., 1974.
Semiconductor Update, vol. 5, No. 11, Mar./Apr., Motorola, Inc., 1981, p. 5.
Gillman James W.
Grimm Siegfried H.
Hackbart Rolland R.
Motorola Inc.
Roney Edward M.
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