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1 数字射频存储器的基本原理数字射频存储器(DRFM)是70年代初期构想出来的,用于储存和复制射频信号。一般的DRFM由5部分组成(图1)。射频输入部分接收要储存的信号。先由其它设备捕获各种发射信号,如搜索雷达的脉冲序列,主动制导导弹的锁定跟踪信号,敌我识别(IFF)询问脉冲,等等,然后输入DRFM。输入信号进行限幅放大处理,再与稳定的本机振荡器输出混频(下变频),然后进行模数转换。数字信号储存在存储器里,可进行研究、校正和修改。在合适的时候,可将捕获到的信号从数字式转换为模拟式,经上变频和放大,然后转发出去。大多数DRFM采用同相和90°相移通道抑制射频镜象信号。
1 Digital Radio Memory Fundamentals Digital radio frequency memory (DRFM) was conceived in the early 1970s to store and copy radio frequency signals. The general DRFM consists of 5 parts (Figure 1). The RF input section receives the signal to be stored. First, other devices capture a variety of transmit signals, such as the pulse sequence of a search radar, a lock-in signal of an active guided missile, an IFF interrogation pulse, etc., and then enter the DRFM. The input signal is amplitude-limited and amplified, mixed with a stable local oscillator output (down-converted), and then converted to analog. Digital signals are stored in memory for research, calibration and modification. When appropriate, the captured signal can be converted from digital to analog, up-converted and amplified, then forwarded. Most DRFMs use in-phase and 90 ° phase-shift paths to reject RF image signals.