Optical quadrupling millimeter wave radio over fiber system adopting 16-quadrature amplitude modulation (QAM) way
A modulation method, millimeter wave technology, applied in multi-carrier systems, electromagnetic wave transmission systems, transmission systems, etc., can solve problems such as waste of useful signal power, and achieve the effect of pure spectrum and low price
Inactive Publication Date: 2011-06-22
DONGHUA UNIV
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Problems solved by technology
Because it is based on harmonics to generate millimeter waves, often after photoelectric conversion in the base station, there are many harmonic components in the photoelectric current, and the modulation signal will modulate each harmonic component, which will lead to a large number of useful signals. power is wasted
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[0013] like figure 1 As shown, a 16QAM modulation optical 4-fold millimeter-wave RoF system provided by the present invention includes a central station 1, a base station 2 and a downlink optical fiber 3, and the central station 1 and the base station 2 are connected through the downlink optical fiber 3. It is characterized in that: the central station 1 includes a laser 1-1, the laser 1-1 is connected to the input end of the first two-electrode Mach-Zehnder optical modulator 1-14 through a polarization-maintaining pigtail, and the first two-electrode Mach-Zehnder light The RF electrode on one arm of the modulator 1-14 is supplied with a cosine microwave signal output by a microwave signal source 1-2, the first bias electrode 1-5 is supplied with a voltage V1, and the RF electrode on the other arm is supplied with a cosine microwave signal output by a microwave signal source 1-2. The microwave signal source 1-2 generates a cosine microwave signal that is phase-shifted by a fir...
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The invention provides an optical quadrupling millimeter wave radio over fiber system adopting a 16-quadrature amplitude modulation (QAM) way, which comprises a central station, a base station and a downlink optical fiber, wherein the central station and the base station are connected by the downlink optical fiber. The system is characterized in that: the central station comprises a laser, wherein the laser is connected with the input end of a first double-electrode Mach-Zehnder optical modulator by a preserving tail optical fiber; a cosine microwave signal and the cosine microwave signal subjected to the phase shifting of a first phi phase shifter are added to the first double-electrode Mach-Zehnder optical modulator; the first double-electrode Mach-Zehnder optical modulator is connected with a second Mach-Zehnder optical modulator by the preserving tail optical fiber; a sine microwave signal subjected to the phase shifting of a phase shifter is added to the second Mach-Zehnder optical modulator, and the sine microwave signal is added to the other arm; and the second Mach-Zehnder optical modulator is connected in series with a light intensity modulator. The system has the advantages of further reducing the number of harmonic waves, achieving lower cost and making purer the frequency spectrums of generated millimeter waves.
Description
technical field [0001] The invention relates to an optical quadruple frequency-multiplied RoF (RoF, Radio over Fiber) system structure, which realizes converting signal modulation of light waves into modulation of millimeter waves while generating millimeter waves from light waves. Background technique [0002] In recent years, wireless communication over optical has become a very attractive solution in the field of broadband wireless access network because of its wide frequency band and high flexibility. In order to meet the requirements of future communication, the radio frequency used in the radio-over-fiber system must be developed towards a higher end, so the radio frequency band selected by most radio-over-fiber systems is generally the millimeter wave band. The millimeter-wave RoF system based on the optical frequency doubling method is a representative type of wireless-over-fiber system. The RoF system based on the optical frequency doubling method proposed in the p...
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IPC IPC(8): H04B10/12H04L27/36H04B10/2575H04B10/556
Inventor 陈翔陈小立
Owner DONGHUA UNIV