Arrangement for generating an angle-modulated carrier signal of constant amplitude in response to data signals
First Claim
1. An arrangement for generating an analog angle modulated carrier signal having a substantially constant amplitude, and a total phase variation produced by data signals of a given symbol frequency 1/T in a period of a first clock frequency of at most π
- radians comprising;
a clock circuit synchronized with the symbol frequency 1/T for producing a first clock signal having a frequency q/T, where q is an integer greater than 1;
a first read-only memory for storing in addressable locations digital numerical values representing a function of the carrier signal phase φ
(t) including magnitude and sign bits;
an addressing circuit controlled by the first clock signal and responsive to a predetermined number of consecutive data symbols for producing addresses at a rate of q/T for reading said digital numerical values from said first read-only memory; and
,a zero-crossing generator connected to receive said digital numerical value comprising;
means for generating a zero-crossing indication signal when the modulated carrier signal changes phase;
means for generating a numerical time setting signal;
a delay circuit controlled by the first clock signal and responsive to said numerical time-setting signal for producing a set pulse having a presettable time delay of at most T/q relative to said first clock signal;
a gate circuit controlled by said first clock signal for passing said set pulse in response to said zero-crossing indication signal;
a bistable pulse generator connected to the gate circuit for producing a two-level signal having a level transition which occurs at the instant set pulses are received from said gate circuit; and
a bandpass filter coupled with the pulse generator and having a center frequency of the carrier frequency of said angle modulated carrier signal.
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Accused Products
Abstract
An arrangement for generating an analog angle-modulated carrier signal of a substantially constant amplitude in response to data signals having a symbol rate 1/T comprises a read-only memory for storing modulation parameters, an addressing circuit responsive to a predetermined number of consecutive data symbols for producing read addresses with a rate q/T, where q is an integer greater than 1, and a signal processor for processing read values to form the analog angle-modulated signal. An arrangement having a predominantly digital structure which does not utilize a DAC circuit as an interface between digital and analog sections of the signal processor is obtained in that the signal processor incorporates a zero-crossing generator comprising a delay circuit responsive to a numerical time-setting signal a set pulse having a presettable time delay of at most T/q, a gate circuit only responsive to a zero-crossing indication signal for transferring the set pulse to a bistable pulse generator, which produces a two-level signal whose level transitions only occur at the instants of the transferred setting pulses, and a bandpass filter having a centre frequency equal to the carrier frequency. These measures result in an arrangement which is capable of processing a wide range of data symbol rates 1/T and which is particularly suitable for monolithic integration.
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Citations
8 Claims
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1. An arrangement for generating an analog angle modulated carrier signal having a substantially constant amplitude, and a total phase variation produced by data signals of a given symbol frequency 1/T in a period of a first clock frequency of at most π
- radians comprising;
a clock circuit synchronized with the symbol frequency 1/T for producing a first clock signal having a frequency q/T, where q is an integer greater than 1; a first read-only memory for storing in addressable locations digital numerical values representing a function of the carrier signal phase φ
(t) including magnitude and sign bits;an addressing circuit controlled by the first clock signal and responsive to a predetermined number of consecutive data symbols for producing addresses at a rate of q/T for reading said digital numerical values from said first read-only memory; and
,a zero-crossing generator connected to receive said digital numerical value comprising; means for generating a zero-crossing indication signal when the modulated carrier signal changes phase; means for generating a numerical time setting signal; a delay circuit controlled by the first clock signal and responsive to said numerical time-setting signal for producing a set pulse having a presettable time delay of at most T/q relative to said first clock signal; a gate circuit controlled by said first clock signal for passing said set pulse in response to said zero-crossing indication signal; a bistable pulse generator connected to the gate circuit for producing a two-level signal having a level transition which occurs at the instant set pulses are received from said gate circuit; and a bandpass filter coupled with the pulse generator and having a center frequency of the carrier frequency of said angle modulated carrier signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- radians comprising;
Specification