초록 ▼

A digital radio frequency memory (DRFM) system for storing and retrieving radio frequency signals in a digital memory. The system includes a digital memory, digital converters at the input and output of the digital memory, and input and output mixers. The RF signal to be stored is applied to the inp

A digital radio frequency memory (DRFM) system for storing and retrieving radio frequency signals in a digital memory. The system includes a digital memory, digital converters at the input and output of the digital memory, and input and output mixers. The RF signal to be stored is applied to the input mixer along with a modulated local oscillator signal to produce an IF signal which is converted into digital values for storage in the digital memory. When the stored digital values are retrieved from the memory to reproduce the RF signal, they are converted back into an analog IF signal which passes through a low-pass filter before being applied to the output mixer. The local oscillator signal, modulated with the same waveform used in storing the digital values, is also applied to the output mixer to provide the reconstructed RF signal. A pseudo random, discrete digital valued waveform is used to phase modulate the local oscillator signal in the preferred embodiment of the invention. This arrangement permits spur free, image free reproduction of RF signals over a large bandwidth.

대표청구항 ▼

A modulated digital radio frequency memory suitable for use as a coherent radio frequency memory in a military electronic countermeasure system, said memory comprising: an RF local oscillator; means for modulating the signal from said local oscillator; a first mixer for converting an RF input signal

A modulated digital radio frequency memory suitable for use as a coherent radio frequency memory in a military electronic countermeasure system, said memory comprising: an RF local oscillator; means for modulating the signal from said local oscillator; a first mixer for converting an RF input signal and the modulated local oscillator signal into an IF signal; an A/D converter for converting said IF signal into digital values; digital memory means for storing said digital values for later retrieval; a D/A converter for converting retrieved digital values into an analog signal; an IF filter for filtering said analog signal; a second mixer for converting the filtered analog signal and said modulated local oscillator signal into an RF output signal; and means for controlling the modulating and memory means such that the modulation on the local oscillator signal which is applied to the second mixer when specific digital values are being retrieved from the digital memory means is identical to the modulation which was on the local oscillator signal applied to said first mixer when said specific digital values were derived and stored in the digital memory means.