Digital control oscillator, quadrature carrier generation method and quadrature amplitude modulation modulation system

A technology of digitally controlled oscillation and quadrature amplitude modulation, applied in the field of quadrature amplitude modulation modulation system and digitally controlled oscillator, it can solve the problems of difficult band-pass filter filtering, signal distortion, frequency domain image interference, etc., and achieve low cost. , the effect of short switching time and continuous carrier phase

Active Publication Date: 2016-01-20
RIGOL
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Problems solved by technology

The harmonic distortion of the two carriers eventually causes the modulated QAM signal to be distorted, spurious amplitude modulation appears in the time domain, and image interference appears in the frequency domain
Since this distortion is in the same frequency band as the modulated signal, it is difficult to filter out with a bandpass filter

Method used

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  • Digital control oscillator, quadrature carrier generation method and quadrature amplitude modulation modulation system
  • Digital control oscillator, quadrature carrier generation method and quadrature amplitude modulation modulation system
  • Digital control oscillator, quadrature carrier generation method and quadrature amplitude modulation modulation system

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Embodiment Construction

[0035] In order to make the object, technical solution and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Here, the exemplary embodiments and descriptions of the present invention are used to explain the present invention, but not to limit the present invention.

[0036] An embodiment of the present invention provides a numerically controlled oscillator (NCO, NumericalControlledOscillator), such as image 3 As shown, the digitally controlled oscillator includes: a DDS address accumulator 301, a phase register 302, a phase adder 303, a combination switch 304, a wave table memory 305, and a shunt switch 306; wherein,

[0037] The DDS address accumulator 301 accumulates the carrier frequency control word K under the action of the first clock, and sends the accumulated result to the phase register 302 and the phase adder 303;

[0038] The phase register ...

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Abstract

The embodiment of the invention provides a digital control oscillator, a method for generating a quadrature carrier wave and a quadrature amplitude modulation system. The digital control oscillator comprises a DDS (Direct Digital Synthesizer) address accumulator, a phase register, a phase adder, a combining switch, a wavetable memory and a shunt switch. According to the embodiment of the invention, the generated quadrature carrier wave has strict phase orthogonality and amplitude consistency and small gain error; the carrier wave has high frequency resolution and short switching time and continuous phases; in addition, the digital control oscillator has the advantages of simple structure and low cost.

Description

technical field [0001] The invention relates to the technical field of quadrature amplitude modulation, in particular to a digitally controlled oscillator, a method for generating a quadrature carrier and a quadrature amplitude modulation system. Background technique [0002] Quadrature Amplitude Modulation (QAM, QuadratureAmplitudeModulation) is a high-order modulation method that combines amplitude and phase, and has higher frequency band utilization and better power utilization. Therefore, it is widely used in medium and large capacity digital microwave communication systems, high data transmission of cable television networks, satellite communications and other fields. [0003] The so-called quadrature amplitude modulation is to use two independent baseband waveforms to suppress the double sideband modulation of two mutually orthogonal carriers of the same frequency. parallel transmission of digital information. Therefore, the orthogonality (amplitude difference, phase...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03L7/099H04L27/34
Inventor 王悦王铁军李维森
Owner RIGOL
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