共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
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
3.
基于逆向调制反射器(MRR)的空间光通信系统因其结构紧凑、可免去链路一端的捕跟(APT)系统、功耗低等优点,是空间光通信系统研究热点之一。提出采用双波长激光发射实现全双工逆向调制回复空间光通信结构,并基于该结构对强度调制解调模式,通信距离为300 km,通信速率为1 GHz下的地面站对近地小卫星全双工通信链路进行了链路计算及通信误码率的分析。当MRR端口径为0.1 m时,通信链路余量大于5 dB,通信误码率优于10-15,满足通信链路的要求。并进一步分析了仿真结果存在的缺陷。结果表明所提出的空间光通信结构在小卫星对地面站全双工激光通信是可行的,是未来空间光通信系统发展趋势之一。 相似文献
4.
单光源全双工逆向调制的光通信技术研究 总被引:1,自引:1,他引:0
逆向调制光通信是自由空间光通信的一种特殊形式 ,它的系统包括两个不对称的终端:询问端和逆向调制端,询问端由光发送机和光接收机组成 ,逆向调制端由逆向调制装置组成。逆向调制光通信可实现逆向调制端对询问端的单向通信 ,它具有视场角大、功耗低、体积小等优点,适合于小平台工作环境。与 传统自由空间光(FSO)通信相比,逆向调制光通信系统无需复杂的跟瞄系统,但通常只能 完成逆向调制端对询 问端的单向通信。如果要实现逆向调制光通信的全双工通信,可以考虑从调制方式和系统设 计上进行研究。 本文从调制方式出发提出了一种单光源全双工逆向调制光通信方案,仿真分析了方案的信 号传输过程,实现了室内近距离逆向调制单光源全双工光通信实验,验证了方案的可行性 。 相似文献
5.
6.
7.
8.
9.
本文首先介绍了CO_2激光窄脉冲调制与移频在CO_2相干接收技术中的意义及调制与移频的方法,简要分析了声光调制器的工作原理,并利用声光调制器进行了CO_2激光的窄脉冲调制和100MHz的移频,最后给出了实验结果和结论. 相似文献
10.
11.
针对传统反馈环路补偿速度无法跟上目前混合跳扩频通信系统误差变化速度导致同步失败的问题,提出一种基于坐标旋转数字算法(Coordinate Rotation Digital Computer,CORDIC)的跟踪同步方法.该方法将系统载波同步误差和定时同步误差映射到相位上,利用二维旋转的方式对误差进行补偿,并根据二进制相移键控(Binary Phase Shift Keying,BPSK)调制的性质,确定最佳旋转位和补偿误差,实现系统同步.实验证明,此方法成功让具有跳频速率20000 hop/s、跳频带宽327.52 MHz的混合跳扩频通信系统实现了稳定同步,补偿性能相比于传统补偿技术具有明显优势. 相似文献
12.
13.
密集波分复用激光光源的声光偏频无调制频率锁定 总被引:1,自引:0,他引:1
利用声光调制器(AOM)的偏频特性,以CH4分子吸收线R9支一条强吸收线(λ=1.6378μm)作为参考频率,实现了对外腔式半导体激光器的无调制频率锁定。实验中在100 s内典型的频率起伏小于5.6 MHz,较激光器自由运转时的频率起伏34 MHz有了显著的改善,而误差信号的阿仑(Allan)方差平方根(即稳定度)在平均积分时间为16 s时达到最小值5.75×10-10。该方法实现了基于气体分子吸收线的半导体激光器无调制锁频,并且CH4分子在1.6~1.7μm处有丰富的振转光谱,满足光纤通信中对激光器输出波长的要求,可应用于光纤通信中激光光源的频率锁定。 相似文献
14.
In order to alleviate the influence of atmospheric turbulence on the performance of satellite-to-ground laser communication system,based on the M-distribution atmospheric channel model,a multi-carrier coherent orthogonal frequency division multiplexing (OFDM) modulation system was proposed for uplink and downlink in the satellite-to-ground laser communication.The closed-form expression of bit error rate (BER) of coherent OFDM modulation system was derived.The relationship between the zenith angle,receiving aperture,signal-to-noise ratio (SNR),optimal beam divergence angle,and optimal transmission radius and the BER were studied under weak,and strong atmosphere turbulence,and compared with binary coherent differential phase shift keying (DPSK) modulation.Both the theory and the simulation results show that compared with coherent DPSK modulation,the bit error performance of the coherent OFDM modulation system in the satellite-to-ground laser communication system is better. 相似文献
15.
Santi P. Maity Malay K. Kundu 《AEUE-International Journal of Electronics and Communications》2013,67(5):438-447
The proliferation of the digitized media (audio, image and video) introduces a challenging problem for data transmission in the network environment. In this paper, a novel, simple and low cost algorithm that serves the purpose of distortion free covert image-in-image communication is proposed. Its very large scale integration (VLSI) implementation using field programmable gate array (FPGA) is also developed. A binary equivalent message signal is developed first from the combination of the auxiliary gray scale image information and the carrier gray scale image (original) using channel coding and spatial bi-phase modulation scheme. The auxiliary image information is then decoded from the distorted/distortion free version of the original image using binary message under certain noise constraint. Implementation of the proposed low cost algorithm can be speeded up significantly by hardware realization. The developed hardware design allows data transmission at the rate of 4.706 Mbits/s at 80 MHz clock frequency. 相似文献
16.
介绍了自由空间光通信中的相干通信系统,通过对相干光通信中振幅键控(ASK),频移键控(FSK),相移键控(PSK),差分相移键控(DPSK)四种光载波相干调制方式性能的分析和比较,仿真结果得出PSK调制误码性能更好,提出了一种光载波外差差分相移键控(DPSK)系统. 相似文献
17.
在信号调制过程中,为了缩短载波生成的捷变时间,分析了影响捷变时间的因素。提出了单频信号的并行合成结构,解决了载波频率受现场可编程逻辑门阵列( FPGA)时钟限制的问题。为了解决调制过程中采样频率受时钟约束的问题,给出了矢量信号的正交并行调制结构。通过在FPGA上编写Verilog代码实现了时钟频率为160 MHz、采样率为1.92 Gsample/s的并行矢量信号调制,载波频率为200~300 MHz可变,捷变时间小于35 ns。结果表明,并行载波生成和并行调制的方法在克服系统时钟约束方面有较强的实用性。 相似文献
18.
《Microwave Theory and Techniques》1982,30(4):428-441
Direct frequency modulation characteristics in three different AlGaAs lasers - a channeled-substrate planar (CSP) laser, a buried-heterostructure (BH) laser, and a transverse-junction-stripe (TJS) laser- are studied theoretically and experimentally. Experimental FM responses are measured by using the Fabry-Perot interferometer and birefringent optical filters in the 0-5.2 GHz modulation frequency region. Experimental FM response dependence on modulation frequency, dc bias level, and stripe structure are successfully explained by the theoretical analyses considering both the carrier density modulation effect and the temperature change effect. FM response in the low modulation frequency region from 0 to 10 MHz, gradually decreasing with the modulation frequency, stems from the thermal effect. FM response in the high modulation frequency region from 10 MHz to 5.2 GHz is caused by the carrier effect. A flat FM response of several hundred MHz per 1 mA is observed in the CSP and TJS lasers, but a V-shaped FM response is obtained in the BH laser. Resonance peak due to relaxation oscillation and cutoff characteristics are observed in several gigahertz regions. Weak lateral mode confinement, strong vertical mode confinement, carrier injection outside the effective core region, and p-side down mounts are effective ways to achieve a flat and efficient FM response with a small spurious intensity modulation. 相似文献
19.
Kwang Seon Kim Bong‐Su Kim Min‐Soo Kang Woo‐Jin Byun Hyung Chul Park 《ETRI Journal》2014,36(2):206-213
This paper presents a novel 90 GHz band 16‐quadrature amplitude modulation (16‐QAM) orthogonal frequency‐division multiplexing (OFDM) communication system. The system can deliver 6 Gbps through six channels with a bandwidth of 3 GHz. Each channel occupies 500 MHz and delivers 1 Gbps using 16‐QAM OFDM. To implement the system, a low‐noise amplifier and an RF up/down conversion fourth‐harmonically pumped mixer are implemented using a 0.1‐μm gallium arsenide pseudomorphic high‐electron‐mobility transistor process. A polarization‐division duplex architecture is used for full‐duplex communication. In a digital modem, OFDM with 256‐point fast Fourier transform and (255, 239) Reed‐Solomon forward error correction codecs are used. The modem can compensate for a carrier‐frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of 10–5 at a signal‐to‐noise ratio of about 19.8 dB. 相似文献
20.
为了实现中心波长为1064nm的单频光纤激光器的稳频,采用相位调制光外差(PDH)激光稳频技术,搭建稳频系统光路。分析了相位调制光外差稳频信号以及误差信号特征;设计基于现场可编程门阵列(FPGA)的数字式解调和反馈控制电路,在FPGA中实现对相位调制光外差稳频信号的数字解调,再经数模转换器输出获得误差信号。结果表明,在FPGA中能成功实现对相位调制光外差信号的解调,经Allan方差计算,频率漂移的方差值可达10-11,即所设计的数字系统实现了较高的稳频精度。 相似文献