介绍了抗干扰通信、雷达系统中采用的频率捷变频技术，并对其关键技术——频率合成技术作了讨论，重点介绍了新型频率合成器——声表面波直接频率合成器。以一种１００点声表面波直接频率合成器为例，该直接频率合成器具有小于３μｓ的频率切换时间（跳频速率达３８０００跳／ｓ），－７０ｄＢｃ的虚假电平抑制，在５００ＭＨｚ偏离载频１ｋＨｚ处相位噪声为－９０ｄＢｃ／Ｈｚ，１００个频率点等多项优异性能。最后分析了声表面波直接频率合成器的应用前景和发展方向 The anti-jamming communication and frequency agile technique used in radar system are introduced. The key technique of synthesizing frequency synthesizer is discussed. A new type of frequency synthesizer, SAW direct frequency synthesizer, is introduced. Taking a 100-point SAW direct frequency synthesizer as an example, the direct frequency synthesizer has a frequency switching time of less than 3 μs (frequency hopping rate up to 38000 hops / s), false-level suppression of -70 dBc, Phase noise at 1kHz at -90dBc / Hz, 100 frequency points and many other excellent performance. Finally, the application prospect and development direction of SAW direct frequency synthesizer are analyzed