Regional Networks Regional Networks compose the lower level of the overall system. The radius of a "region" varies from dozens to hundreds of kilometers, and mostly depends on environment conditions such as topography and weather. Two kinds of units are included in the network. One is known as "User". Us- ers are the radio-like equipments which are used directly by men to communicate with others. That is, we can talk with or even see each other or tranceive data through such an equipment. To accomplish their jobs Users can establish a dire- ct link with each other, or, when the target User can not be reached, to the o- ther kind of units called "Relay". Relays act very much like postmen. They receive data from the sender, and retransmit it to the recipient. If the recipient is located in the region, data would be delivered directly; if not, the Relay would send the data to the upper level of the system, the Global Network. This operation can also be seen in LAN /WAN architecture of the day. Besides, when the sender wants to "broadcast", a Relay can do the work by retransmitting the message to all reachable Users[3]. To ensure the secrecy of data, spread spectrum modulation was put to use[4] . Since DSSS and FHSS holds their advantage/disadvantage, most of which are co- mplementary, we decided to use the hybrid DSSS/FHSS. In fact, all data flow be- tween Users (and Relays) are DSSS/FHSS modulated; together with other measures to deal with eavesdropping and jamming. References: [3] The Second Raid Episode.3&4 The Communication post set up by Capt. Blueno served as a Relay , while Users are used by task force members such as AS units. All communications during the mission was broadcast. Thus the captain can moniter all communications. Note that the beacons lauched by ASs were repeaters, which would retransmit all valid signals they received. TDD also served as a Relay. [4] The Second Raid Episode.7 Description by Kaname Chidori. =================================以下是翻译==================================== 地区网路 整套系统的低层由地区网路组成。一个「地区」的半径从数十到数百公里不等，主要 受到地形和天候等环境因素影响。 地区网路包含两种单位。其中一种被称为「使用者」，是类似无线电机的装置，供人 相互沟通。也就是说，我们可以透过此一装置和对方交谈甚至使用视讯，以及传收资料。 各「使用者」之间会彼此建立连结以发挥功能；若无法直接和传输的目标连结，则会和另 一种单位「中继站」建立连结。 「中继站」和邮差有相似的作用。他们接收传送端送出的资料，并转达给接收端。当 接收端位在同一区域内时，资料会直接转达；否则「中继站」会将资料上传至高层的全球 网路。这种运作模式类似於今日的LAN/WAN网路架构。此外，当传送端想要「广播」讯息 时，「中继站」会将讯息转达给所有接触到的「使用者」，达成此一功能。[3] 为了确保资料的隐密，使用了展频调变技术。[4] 因为FHSS(跳频展频)和DSSS(直序 展频)各有优缺点—且经常为互补，我们决定使用两者的混合型DSSS/FHSS。事实上，所有 在「使用者」和「中继站」之间传递的资料都以DSSS/FHSS方式调变，配合其他措施来应 付窃听和干扰。 参考来源：[3] The Second Raid 第3&4话 在这两集中，布鲁诺上尉架设的通讯站扮演「中继站」的角色，特别应对 班的派遣队，如AS驾驶员则为「使用者」。该行动中所有的通讯都属於「 广播」，因此上尉能监控所有的通讯。值得注意的是，AS发射的通讯信标 属於「重复器」，一种将全部收到的合法讯号重新发送的装置。 TDD潜舰也扮演「中继站」的角色。 [4] The Second Raid 第7话 千鸟要对「密银」通讯系统的叙述。 --

※ 发信站: 批踢踢实业坊(ptt.cc) ◆ From: 140.113.4.15 ※ 编辑: ComSoc 来自: 140.113.4.15 (08/18 11:53)