L-band Broadband High-speed Frequency Hopping Frequency Source

Frequency hopping communication is one of the spread spectrum communications, which has the ability of the anti-interference and anti-interception, and the superiority of spectrum efficiency. Therefore, the frequency hopping communication becomes the main method for combating the interference in the modern military wireless communications. It is significant for guarantying the performance of the communication command in the harsh electromagnetic environment. The core parts of the frequency hopping communication systems are frequency hopping sequence generator and the frequency Synthesizer.Wideband frequency hopping radio station requires that the output of the frequency synthesizer has the fast frequency conversion, wide bandwidth, lower spurious, lower phase noise, reduced volume and weight. Based on the discussion of the frequency synthesis techniques and the analysis of the various realization methods, and aiming at the engineering application, this dissertation chooses the direct digital frequency synthesis scheme. The design consideration is to increase the working frequency of the DDS, increase the output bandwidth, and to improve the ability of suppressing the spurious. Meanwhile, the others parameters are not effected.DDS has the characteristics of high frequency resolution and fast frequency conversion. However, the difficulties of DDS are also considerable, such as the limited upper frequency, high power consuming and bad spurious performance. And this dissertation is trying to address the solution of these problems.The proposed scheme adopts the direct connection between the DDS and frequency multiplier. The output frequency and bandwidth could be improved. The following targets are achieved for the proposed scheme in this dissertation. The frequency range is from 1350MHz to 1850MHz. the frequency interval is 1MHz. The frequency conversion time is shorter that 1μs and the hopping rate is 100000Hops/s. the phase noise is below -70dBc/1KHz. In summary, the system satisfies the requirements of the fast frequency hopping radio station on wideband coverage, short conversion time and low phase noise.