| 1. | Principle and application of direct sequence spread spectrum asic
直序扩频芯片的原理与应用 |
| 2. | The theory of direct sequence and cck is described . the mechanism of tdm is established . then , a method to maintain the synchronization of the tdm is proposed
在介绍了ieee802 . 11协议的物理层用到的直序扩频技术和补码键控技术后，对系统的时分双工工作机制的建立与维护进行了详细的分析。 |
| 3. | The results of the testing prove that the system compare with dsss takes great advantages over others on the aspects of the rate of transmitting data , its stabilization and its possibility of expanding
测试结果表明，与直序扩频系统相比， ofdm系统在数据传输速率、稳定性和可扩展性等方面具有十分明显的优势。 |
| 4. | The paper firstly analyses the fundamental principles of the direct sequence spread spectrum technique , the arithmetic in the frequency - domain by using the technology of the spectrum correlation adaptive filter
本文首先就设计中选择采用的直接序列扩频技术、以及在频域中实现直序扩频信号中多窄带干扰抑制的自适应算法的基本原理做了分析。 |
| 5. | For dsss signals , we proposed two algorithms , one is a hypothesis test algorithm that can be used to detect if there are dsss signals , the other is a symbol period estimation algorithm using the cycle - stationary feature of dsss signals
对直序扩频( dsss )信号，本文提出了一种假设检验算法检测其存在性；利用dsss信号的循环平稳特性，提出了估计dsss信号符号周期的方法。 |
| 6. | Cck , dqpsk are concluded as the best spread spectrum / modulation techniques in wireless image communication systems . 1 imbps and 300 meter range can be obtained using orinoco wireless network card based on eee802 . 11b wlans , which specifies cck , dbpsk , dqpsk techniques
这种网卡采用直序扩频和cck 、 dbpsk 、 dqpsk调制方式，工作在2 . 4ghz频段，数据传输速率为11mbps ，传输距离最远达300米。 |
| 7. | We analyzed the anti - jam and band inside anti - interfere performance of the system , and the low probability intercept ( lpi ) of the traditional direct sequence spread spectrum ( dsss ) modulations in the uav platform ' s applications . so a new modulation technique using a multi - level pseudo noise ( pn ) code has been presented . the new multi - level pn code is built from a high speed pn code through a low passed filter ( lpf )
分析了系统抗阻塞式干扰和抗带内频带干扰的性能，以及常规bpsk qpsk - dsss调制在无人机通信中存在的安全隐患，提出了一种用多电平pn码进行扩频调制的方法：采用高速pn码，经过低通滤波器，产生多电平pn码进行直序扩频调制，能在低信噪比情况下有效抵抗平方率检测器对系统载波的检测。 |
| 8. | The selection of the pn sequence is very important because it influences the quality of the channel measurement directly . so it is discussed in this paper . because this system is a set of software radio , that is to say that the system is based on the pc platform and all other function is implemented by programming , so the selection of correlation fast algorithm , which is used in receiver frequently , is also very important
本文对直序扩频技术进行了系统地研究，对其中伪随机码的选择直接影响到信道测量的质量的问题进行了讨论，因为本系统是一套软件无线电，即以pc机为平台，其他的功能都由软件编程完成，所以对信号接收中大量使用的相关的快速算法的选择也至关重要。 |
| 9. | In addition , hybrid spread - spectrum communication system is propitious to enhance anti - jamming performance of the system that is make up of direct sequence ( ds ) and frequency hopping ( fh ) , and it can satisfy the require of anti - jamming of systems . it concentrate their virtue and overcome shortage in single spread spectrum style . this paper discusses the aspect in detail
另外，将扩频技术中应用最广泛的两项技术直序扩频( ds )和跳频( fh )结合在一起，构成混合扩频通信系统，有利于提高系统的抗干扰性能，更能满足系统抗干扰的要求，而且将跳频系统和直扩系统的优点集中起来，克服了单一扩频方式的不足。 |
