-
公开(公告)号：US5023947A
公开(公告)日：1991-06-11
申请号：US430041
申请日：1989-11-01
CPC分类号： G02B6/4215 , H04B10/25133 , G02B6/29358 , G02B6/29394
摘要： An optical equalization receiver for countering the effects of delay distortion is realized by utilizing dynamically controllable Fabry-Perot etalon structures. By dynamically adjusting the frequency response of an etalon that is in a feedback loop configuration, the associated delay characteristic of the etalon may be used to counter the effects of delay distortion, thereby allowing higher transmission rates and transmission distances to be achieved. In one exemplary embodiment, an optical receiver comprising a reflective Fabry-Perot etalon and a piezoelectric transducer is used in a feedback loop configuration wherein a feedback control circuit monitors an output signal from the etalon for generating a control signal representing the amount of delay needed to compensate for distortion in an optical signal incident on the etalon. Specifically, the control signal causes a change in the optical path length of the etalon that results in a shift in its frequency response for producing a delay substantially equal and opposite to the associated delay distortion.
-
公开(公告)号：US5008958A
公开(公告)日：1991-04-16
申请号：US308697
申请日：1989-02-08
IPC分类号： H04B10/135
CPC分类号： H04B10/532
摘要： To exploit the potential advantages of coherent optical communications systems, the polarization states of the received optical signal and the local oscillator waves must be matched. A mismatch may severely degrade detection performance. These mismatches occur because the received signal state of polarization changes with time and along the fiber. We first review several existing techniques for handling this problem, such as polarization-maintaining fibers, polarization-state controllers and polarization-diversity receivers. The insensitive technique reduces the problem of polarization mismatch by forcing the polarization state of either the transmitted signal or local oscillator to vary with time in a non-adaptive manner so that polarization-insensitive performance is obtained. The proposed scheme adopts a completely new approach which uses high-birefringence single-mode fibers to implement polarization switching. These techniques require only a single photodetector and give a fixed level of detection performance, with a power penalty relative to ideal of 3 dB. A specific technique is presented in which polarization-insensitive heterodyne detection is achieved through data-induced polarization switching. The polarization switching is brought about by inserting a passive, birefringent optical device in the path of the transmitted FSK signal.
摘要翻译： 为了利用相干光通信系统的潜在优势，必须匹配接收的光信号和本地振荡器波的极化状态。 不匹配可能严重降低检测性能。 发生这些不匹配是因为接收到的信号状态的偏振随时间和光纤而变化。 我们首先回顾了现有的几种处理这个问题的技术，例如偏振维持光纤，极化状态控制器和极化分集接收器。 不灵敏技术通过强制发射信号或本地振荡器的偏振状态以非自适应方式随时间变化来减少偏振失配的问题，从而获得极化不敏感的性能。 该方案采用高双折射单模光纤实现偏振切换的全新方法。 这些技术仅需要一个光电检测器，并提供固定的检测性能水平，相对于理想的3dB的功率损失。 提出了通过数据激励极化切换实现极化不敏感外差检测的具体技术。 通过在被发送的FSK信号的路径中插入无源双折射光学器件来实现偏振切换。
-
公开(公告)号：US5930267A
公开(公告)日：1999-07-27
申请号：US649552
申请日：1996-05-17
CPC分类号： H04L7/0083 , H04L7/041
摘要： A method for transmission of a digital information packet. A synch word of a packet header of the packet is transmitted from a transmitter to a receiver over a distorting channel. During transmission of the synch word, transmission is interrupted by at least one bit time of quiescence of the transmitter. The synch word is received at the receiver. Based on a channel distortion characteristic determined for the received synch word, a preferred sampling point is determined for succeeding bits of the packet.
摘要翻译： 一种用于传输数字信息包的方法。 分组的分组报头的同步字通过失真信道从发射机发送到接收机。 在同步字的发送过程中，发送器的静止至少一个比特时间中断发送。 在接收器处接收同步字。 基于为接收到的同步字确定的信道失真特性，确定分组的后续比特的优选采样点。
-
公开(公告)号：US5276730A
公开(公告)日：1994-01-04
申请号：US876554
申请日：1992-04-30
摘要： A method of providing local autonomous control of channel allocation of a cellular telecommunications network. In one prior art method, which can be identified as the timid method, a channel is selected for use by an incoming user if it is not being used by any of the cells which surround it. Otherwise, another channel is selected according to the same rule. The channels are tested in random order and a call is blocked if all of the channels are in use. For heavy loading, because of the vagaries of the way the demand for channels occurs, this method can result in inefficient channel deployment. In another method, which can be identified as the aggressive method, a channel is selected for use by an incoming user even if that channel is currently being used in the surrounding cells. If the channel is in use, the incoming user "bumps" the current user off the channel in the timid mode. The "bumped" user is then forced to find and use another channel. With this method, an unreasonable number of reconfigurations and an unreasonable number of dropped calls can result, especially when the system is heavily loaded. This invention integrates the aggressive and timid methods to obtain the best of both: the former's improved performance and the latter's stability. Initially, the timid mode is used to look for a channel with acceptable interference. However, if the timid mode fails to obtain a channel, the call is not necessarily blocked. Instead, the mode of operation becomes more aggressive and the first channel tested that has only modest interference is taken. The "bumped" user on that channel then attempts to locate another channel. If the "bumped" user is unsuccessful, the incoming user must then retreat and is blocked.
摘要翻译： 一种提供蜂窝电信网络的信道分配的本地自主控制的方法。 在可以被识别为胆小的方法的一种现有技术方法中，如果入口用户没有被其周围的任何小区使用，则选择频道用于使用。 否则，根据相同的规则选择另一个频道。 频道按照随机顺序进行测试，如果所有频道都在使用中，通话将被阻止。 对于繁重的负荷，由于频道需求的变化，这种方式可能导致信道部署效率低下。 在可以被识别为侵略性方法的另一种方法中，选择频道以供入局用户使用，即使该频道当前正在周围小区中使用。 如果频道正在使用中，进入的用户将以当前用户的“嘀嗒”模式将“当前用户”从“通道”中消失。 然后，“碰撞”用户被迫找到并使用另一个频道。 使用这种方法，可能导致不合理的数量的重新配置和不合理的掉话数量，特别是当系统负载过重时。 本发明整合了积极和胆小的方法，以获得最佳的两者：前者的改进性能和后者的稳定性。 最初，胆小的模式用于寻找具有可接受干扰的信道。 但是，如果没有获得通道，则呼叫不一定被阻止。 相反，操作模式变得更加积极，并且仅采用适度干扰的第一通道测试。 该通道上的“碰撞”用户尝试找到另一个频道。 如果“碰撞”用户不成功，则进入的用户必须撤退并被阻止。
-
公开(公告)号：US5091916A
公开(公告)日：1992-02-25
申请号：US590201
申请日：1990-09-28
IPC分类号： H01S3/07 , H01S3/067 , H01S3/08 , H01S5/00 , H01S5/026 , H01S5/0625 , H01S5/12 , H01S5/125 , H01S5/14
CPC分类号： H01S5/125 , H01S3/067 , H01S5/06256 , H01S5/0654 , H01S5/1206 , H01S5/1212 , H01S5/1215 , H01S5/146
摘要： Improved side mode suppression with significantly reduced side mode suppression ratio fluctuation during laser tuning is realized in a distributed Bragg reflector laser structure by incorporating at least one reflector element which exhibits an asymmetric reflection characteristic versus wavelength over a band of wavelengths wide enough to include at least two longitudinal modes of the laser. That is, the asymmetric characteristic is wider than the mode separation for adjacent longitudinal modes of the laser. In one embodiment, a distributed Bragg reflector laser is shown wherein the Bragg reflector includes a corrugated waveguides with corrugations having a period which varies nonlinearly from .LAMBDA..sub.O at one end of the reflector to .LAMBDA.hd L at the opposite end of the reflector, where .LAMBDA..sub.O is greater than .LAMBDA..sub.L. Integrated and extended cavity or hybrid structures are described in both semiconductor and fiber laser structures.
摘要翻译： 通过在分布式布拉格反射器激光器结构中实现改进的侧面模式抑制，在分布式布拉格反射器激光器结构中实现了具有非对称反射特性对波长的至少一个反射器元件的侧面模式抑制，波长宽度足以至少包括 激光的两种纵向模式。 也就是说，不对称特性比激光的相邻纵向模式的模式分离宽。 在一个实施例中，示出了分布布拉格反射器激光器，其中布拉格反射器包括具有波纹的波纹波导，波纹具有在反射器的一端处的LAMBDA O非线性地变化到在反射器的相对端处的LAMBDA hd L的周期，其中LAMBDA O大于LAMBDA L.在半导体和光纤激光器结构中都描述了集成和扩展腔或混合结构。
-
-
-
-
搜索结果
5 条记录 (耗时 0.019 秒)