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光纤声光调制器驱动器作为光纤激光器的重要组成部分,其性能参数对激光品质具有重要影响。该文设计了高频、高功率驱动器方案。该方案通过20200kHz脉冲信号控制模拟开关实现脉冲信号和150 MHz载波信号的二进制幅度键控(2ASK)调制,调制信号经功率放大器放大,进行阻抗匹配后输出到声光调制器,驱动声光调制器工作。驱动信号的频率为20200kHz脉冲信号控制模拟开关实现脉冲信号和150 MHz载波信号的二进制幅度键控(2ASK)调制,调制信号经功率放大器放大,进行阻抗匹配后输出到声光调制器,驱动声光调制器工作。驱动信号的频率为20200kHz,功率为3 W。 相似文献
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调制器用于将解调器输出的视音频信号、卫星接收机输出的视音频信号及自办节目的视音频信号调制到电视频道频率上。调制器由中频调制器和上变频器组成。它首先将视音频信号调制到电视中频 ,然后经上变频器 ,把电视中频变换为电视频道信号 ,再送到混合器进行混合 ,最后送入HFC网络。中频调制器是运用在中频处理型邻频前端的一个重要设备 ,它的作用是将视频图像信号调制到电视中频频率 38MHz(或 37MHz)上 ,将音频信号调制到伴音中频 31.5MHz(或 30 .5MHz)上 ,其原理图如图 1所示。由图 1可见 ,伴音中频是由 6 .5MHz伴音载频和38MHz(或 3… 相似文献
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通过分析量子密钥分配系统中相位调制器的工作原理和电路性能要求,设计了相位调制器的驱动电路。该方案基于铌酸锂电光相位调制器而设计,通过现场可编程门阵列(FPGA)提供时钟和控制信号,采用高精度的数模转换器和高速模拟开关,能够产生精度可达纳秒量级的驱动信号。该驱动电路成本低廉,调制精度高,功耗较小,实现了对光信号相位的精确控制。经测试,实验结果完全满足系统要求,验证了该方案的可行性与可靠性。 相似文献
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卫星数据通信往往采用PSK调制方式传输数据信号,本文介绍采用DDS芯片AD7008组成的400MHz卫星通信PSK调制器的电路设计方法,利用集成DDS调制芯片AD7008方便地实现PSK调制,再采用锁相环路把调制信号搬到400MHz载频上,最后给出了该PSK调制器的性能指标。 相似文献
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卫星数据通信PSK信号的调制有多种方法,本文介绍采用专用的DDS调制芯片AD7008完成在2.1~2.3MHz载频上PSK调制,再将2.1~2.3MHz的PSK调制信号用PLL环路把它搬到400MHz载频上,从而实现400MHz PSK调制方法。文中给出了调制器的电路设计方法和性能指标。 相似文献
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中频调制方案:是将电视信号中的视频和音频信号调制在电视的中频上,即图像中频为38MHz,伴音中频为31.5MHz。然后再用变频器将中频信号变为VHF,增补及UHF的标准电视信号上。由于调制载波低(38MHz)残留边带滤波器易采用声表面波滤波器。中频放大及各种必须的处理十分容易,能够达到比较高的质量要求,它适用于大系统和邻频传输前端设备。中频处理调制器实用框图(见图1)。 相似文献
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在原有有线电视系统基础上,利用现有资源,采用频率迁移这一技术手段,进行相应的系统升级改造,安装新型的PBI-2500标准型邻频调制器,将卫星电视信号调制到数字电视信号未占用频段(即790~860MHz之间),有效解决了数字电视信号与我台卫星接收电视调制的频谱重叠这一技术难题。 相似文献
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1 发射机工作原理及维护 1.1 中频调制器 1.1.1 工作原理 中频调制是将来自电视中心的视频、音频信号分别调制在中频图像载频38 MHz和伴音载频31.50 MHz上,输出额定电平的已调图像中频信号和已调伴音中频信号,它们输出的标准电平为图像中频0 dBm,图像与伴音中频输出电平差为10 dB.调制器由6块印制板组成,分别叙述如下. 相似文献
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提出了一种基于偏振调制器(PolM)和Sagnac环级联的多调制格式微波信号的光学产生方案。理论分析了PolM在基带编码信号的驱动下产生偏振键控(PolSK)信号的基本原理,Sagnac环中嵌有两个马赫增德尔调制器(MZM),分别对顺时针和逆时针传输的PolSK信号进行独立调制。通过合理调整两个MZM的驱动信号,实现了幅移键控(ASK)、频移键控(FSK)和相移键控(PSK)微波信号的产生。在仿真实验中,产生了比特率为2 Gbit/s的40 GHz ASK信号、20/40 GHz FSK信号和20 GHz PSK信号,同时验证了比特率和载波频率的宽带可调谐性。Sagnac环结构提升了系统的稳定性,并且针对每种调制格式的微波信号,在不改变链路结构的情况下其比特率和载波频率都可以通过控制基带编码信号和MZM的射频驱动来进行独立且灵活的调谐。 相似文献
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正交振幅调制OAM(Ouadrature Amplitude Modulation)是一种频谱利用率很高的调制方式.文章在介绍OAM调制、解调原理的基础上,深入探讨了OAM的频谱利用率和误码率性能.并在SystemView下对该系统进行了完整仿真.通过仿真观察到调制与解调信号的波形,星座图以及OAM信号功率谱密度曲线,并对仿真结果进行了分析.由分析结果可知,OAM调制系统具有很高的频谱利用率以及较好的误码率性能,因此可增大系统容量,同时也保证了系统的可靠性. 相似文献
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Schiellerup G. Pedersen R.J.S. Olesen H. Tromborg B. 《Photonics Technology Letters, IEEE》1989,1(10):288-290
It is shown experimentally and theoretically that a center frequency shift occurs when an external cavity laser is directly modulated. The shift can be observed even when the frequency deviation is small compared to the roundtrip frequency of the external cavity and can qualitatively be explained by a reduction in the effective feedback level due to modulation. The frequency shift was measured as a function of modulation frequency and current, and frequency shifts up to 350 MHz were observed 相似文献
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Han Shuguang Chi Baoyong Wang Zhihua 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2007,54(6):547-551
A new low-power analog Gaussian frequency-shift keying (GFSK) modulator is proposed and implemented in 0.18-CMOS process based on an analog computer implementation of the FM differential equation. The mixed-loop modulation approach is proposed to achieve high data rate and stable carrier frequency. The core of the GFSK modulator is a tunable harmonic oscillator consisting of two Gm-C integrators, whose center frequency can be adjusted by using the on-chip tunable phase-locked-loop (PLL) technique. A simple nonlinear resistor is used to maintain the constant output amplitude. The modulator operates at the center frequency of 2 MHz with the 0.1-0.55 tunable modulation index at 1-Mbps data rate. The modulator draws about 1.8 mA from the 1.8-V power supply and could achieve 2-Mbps data rate with the total harmonic distortion less than 3%. 相似文献
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Jia Peng Zheng Ruth Wei Li Peng Ren Yi Yang Chien Chun Shao Jun Cheng Wang Ching Long Lin Yu Hua Cheng Yang Yuan Wang 《Analog Integrated Circuits and Signal Processing》2010,65(1):115-121
In this paper, a novel design of spread-spectrum clock generator (SSCG) with a third-order error-feedback delta-sigma modulator
is presented. The proposed SSCG with triangular modulation can generate clocks with center spread ratios of 0.25, 1, 1.75,
2.5, 3.5, 5% and down spread ratios of 0.5, 2, 3.5, 5, 7, 10% over a wide frequency range from 20 to 700 MHz. The SSCG is
implemented on a chip using SMIC 0.13 um CMOS process. Our tests show that 11.31 dB attenuation of the EMI at 80 MHz with
down spread ratio of 10% and 12.98 dB attenuation at 133.3 MHz with center spread ratio of 5% can be achieved which is in
agreement with the theoretic calculation. 相似文献
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正交幅度调制(QAM)是一种频谱利用率较高的调制方式。分析了影响解调性能的主要因素以及解决方法,提出了一种QAM解调器的全数字实现结构。介绍了符号同步环路的构成,在设计中采用FARROW结构立方内插器,内插控制器为内插器提供控制变量,对内插控制器的实现进行了详细介绍,定时误差提取采用Gardner算法。采用结合均衡的载波恢复混合结构,显著提高了载波恢复的性能。所设计的解调器可以应用于通信、侦察接收机中。 相似文献
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Surjadeep Sarkar Basab Chatterjee Ujjwal Maulik Baidyanath Biswas 《International Journal of Communication Systems》2012,25(8):1059-1067
In contrast with the conventional split loop digital phase lock loop, a new loop is presented in this paper that differs from the earlier version principally by design aspects. It incorporates an additional phase modulation input along with its frequency modulation input in the digital controlled oscillator. It is capable of eliminating the deleterious effects of rounding and truncation error with faster signal accusation. Higher loop stability is also achievable using the new split loop digital phase lock loop. Furthermore, radio frequency filtering is done using an In phase and Quadrature phase (IQ) voltage controlled oscillator to avoid interaction between the loop filter and the radio frequency filter. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Hu Jianwei Yang Shaoquan 《电子科学学刊(英文版)》2006,23(4):490-494
The relationship between Haar wavelet decomposition coefficients and modulated signal parameters is discussed. A new modulation classification method is presented. The new method uses the amplitude, frequency and phase information derived from Haar wavelet decomposition as feature vectors to distinguish the modulation types of M-ary Frequency-Shift Keying (MFSK), M-ary Phase-Shift Keying (MPSK) and Quadrature Amplitude Modulation (QAM) modulation types. A parallel combined classifier is designed based on these feature vectors. The overall successful recognition rate of 92.4% can be achieved even at a low Sig- nal-to-Noise Ratio (SNR) of 5dB. 相似文献
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Quadrature amplitude modulation (QAM) is an excellent modulation format for realizing optical communication systems with a high spectral efficiency of much greater than 1bit/s/Hz. We describe QAM coherent optical communication that we achieved by using heterodyne detection with a frequency-stabilized fiber laser and an optical phase-locked loop (OPLL) technique. The phase error variance of the intermediate frequency signal of the OPLL was 6.1times10-3 rad. A 1-Gsymbol/s 64-QAM coherent signal was successfully transmitted over 150km 相似文献