一、导言短波无线电在将来相当长的时间内仍将是长距离通信的重要手段.由于电离层的不稳定性,短波通信的可靠度或畅通率问题一直是通信技术中的一项重大课题.除了传播的影响的问题外,干扰和大气噪声的问题也很严重.目前全世界短波呼频不下20余万个,其中50%是近十年来新增的.平均每年约增加一万个,这些呼频虽然使用时间和工作方向不尽相同,但频段 I. Introduction Shortwave radios will remain an important means of long-range communications for a long time to come and due to the instability of the ionosphere, the reliability or smoothness of shortwave communications has always been a major issue in communications technology. In addition to the issue of the impact of transmission, the problems of disturbance and atmospheric noise are also serious.Now there are more than 200,000 short-wave calls worldwide, of which 50% have been added in the recent decade, with an average increase of about 10,000 per year Although the use of call frequency and work in different directions, but the band