초록 ▼

A modulated single channel (as opposed to a quadrature channel) digital radio frequency memory (DRFM) system retrievably stores incoming radio frequency (RF) signals in a digital memory and replicates the RF signals at the output. The input RF signal to be stored is mixed with a local oscillator (LO

A modulated single channel (as opposed to a quadrature channel) digital radio frequency memory (DRFM) system retrievably stores incoming radio frequency (RF) signals in a digital memory and replicates the RF signals at the output. The input RF signal to be stored is mixed with a local oscillator (LO) signal modulated with a waveform pattern to produce an intermediate frequency (IF) signal which is digitized and retrievably stored in the digital memory. The stored digital values are later retrieved from memory after the programmed delay time, and converted back to an analog IF signal and mixed with the local oscillator to produce the output RF signal. The LO signal is modulated with the same waveform used to produce the input IF signal. A controller for controlling the modulation of the LO signal and the memory includes a ROM for storing a pseudo random string of one bit words and an address counter to drive the ROM beginning at a starting address upon the occurrence of the input RF signal. A latch memorizes the starting address and resets the address counter to the starting address after the programmed delay for the output RF signal. The ROM output is converted to an analog signal and applied to modulate the local oscillator signal with the same waveform so that the output RF signal is a replica of the input RF signal.

대표청구항 ▼

A modulated digital radio frequency memory suitable for use as a coherent radio frequency memory in a military electronic countermeasure system, said memory including an RF local oscillator for producing local oscillator signal; means for modulating a local oscillator signal with a modulating analog

A modulated digital radio frequency memory suitable for use as a coherent radio frequency memory in a military electronic countermeasure system, said memory including an RF local oscillator for producing local oscillator signal; means for modulating a local oscillator signal with a modulating analog waveform and optionally containing discrete digital levels in a pattern for ease of replication; a first mixer for converting an RF input signal and modulated local oscillator signal into an intermediate frequency signal representative of both the RF input and the modulated LO; an analog-to-digital converter for converting the intermediate frequency signal into digital values; digital memory means for storing the digital values in accordance with the occurrence of the RF input signal for later retrieval; digital-to-analog converter means for converting the retrieved digital values into an analog signal; an intermediate frequency filter for filtering the analog signal; a second mixer for converting the filtered analog signal and said modulated local oscillator signal into a demodulated RF output signal; and means for controlling the modulating and memory means such that the pattern of the modulation of the local oscillator signal which is applied to the second mixer when specific digital values are being retrieved and converted from the digital memory means is reproduced identical to the pattern of the modulation which is in the local oscillator signal applied to the first mixer when the specific digital values are converted and stored in the digital memory means so that the output RF signal resembles the input RF signal in form and duration, said means for controlling the modulating and memory means including a waveform generator comprising a digital ROM having stored therein an addressably retrievable string of a pseudo randomly arranged sequence of one bit words, any successive number of such words retrieved from the ROM in a bit pattern, digitally representing the pattern of the modulating analog waveform to be reproduced; a resettable address counter coupled to the ROM for addressably calling the bit pattern beginning at any random starting address chosen in accordance with the occurrence of an input signal pulse, and setting the counter to that random address with a load pulse; the address counter being enabled thereafter to call the bit pattern during a time interval corresponding to the RF input pulse width; said address counter being resettable to the starting address upon the occurrence of a reset pulse occurring after programmed storage length of the converted intermediate frequency signal in the digital memory means; said address counter being enabled to call the bit pattern during a subsequent time interval corresponding to the occurrence of the demodulation of the RF output.