초록 ▼

A decorrelated spur digital radio frequency memory (DRFM) system stores incoming radio frequency (RF) signals in a digital memory and at some later time replicates these RF signals at the output. The input RF signal to be stored is mixed with a local oscillator (LO) signal, which is coded with a dec

A decorrelated spur digital radio frequency memory (DRFM) system stores incoming radio frequency (RF) signals in a digital memory and at some later time replicates these RF signals at the output. The input RF signal to be stored is mixed with a local oscillator (LO) signal, which is coded with a decorrelation waveform, to produce an intermediate frequency (IF) signal which is next digitized with a multibit analog-to-digital (A/D) converter. This data is stored in a digital memory and is later retrieved from the memory and converted back to an analog IF signal. The IF signal is then mixed with the coded LO to produce a replica of the original RF signal. The code on the LO is the same decorrelation waveform used to produce the input IF signal. The resultant RF output spectrum can be made to be spectrally clean, i.e., containing no spurious harmonic signals arising from the signal\s quantization. This invention has the significant benefit of allowing key design options to be selected, in particular such options include the number of bits per sample, the number of channels, and the decorrelation phase resolution to obtain the most appropriate cost, size, instantaneous bandwidth and spur level combination.

대표청구항 ▼

A multibit decorrelated spur digital radio frequency memory (DRFM) for replicating an analog RF input signal without significant spurious signals (spurs) over a given range of harmonics of said RF signal, said DRFM suitable for use as a coherent RF memory (CRFM) in a military electronic countermeasu

A multibit decorrelated spur digital radio frequency memory (DRFM) for replicating an analog RF input signal without significant spurious signals (spurs) over a given range of harmonics of said RF signal, said DRFM suitable for use as a coherent RF memory (CRFM) in a military electronic countermeasures system comprising: an RF local oscillator (LO) for producing a local oscillator mixing signal; a first mixer for mixing the RF and the LO signals in order to convert the RF input signal into an analog intermediate frequency (IF) signal representative of the RF signal; at least one multibit sampling means for sampling the IF signal at a selected bit rate to thereby convert the analog IF signal into digital values representative of the RF signal; digital memory means for storing the digital values representative of the RF signal for later retrieval therefrom; at least one digital-to-analog (D/A) converter for converting the retrieved digital values into a retrieved analog IF signal; a second mixer for converting the retrieved IF signal into an RF signal which is a replica of the input RF signal; modulating means for modulating the LO signal with a decorrelation waveform when the LO signal is mixed with the RF input signal and when the LO is mixed with the retrieved IF signal; and control means for controlling the modulation means and the number of bits of the sampling means such that over the range of harmonics, spurs are produced only at harmonics corresponding to the selected number of bits of the sampling means and the modulation means is sufficient to decorrelate at least the spurs produced as a result of said selected number of sampling bits.