| 摘要 |
<p>An information bearing signal (the object signal) for use in radar or radar-like circuitry is generated in a digital circuit and then converted through a bandpass matching filter into a corresponding analog signal. The object signal is then first combined in a NAND gate with a blanking control signal. In one embodiment, the selectively blanked object signal is frequency doubled by combining the blanked object signal and its quarter wave length shifted version in an EXCLUSIVE-OR gate. Thereafter, the frequency doubled version of the blanked object signal is combined in a second EXCLUSIVE-OR gate with a biphase modulation control signal which selectively inverts or noninverts the frequency doubled object signal. The output of the biphase modulated frequency doubled signal is then gated through a blanking NAND gate and coupled to the bandpass matching filter. In a second embodiment the blanked object signal is first combined in an EXCLUSIVE-OR gate with the biphase modulated control signal and thereafter provided as an input to a second EXCLUSIVE-OR gate wherein it is combined with a quarter wave length version of the blanked object signal. The phase modulated frequency doubled signal is then coupled to a blanking NAND gate and bandpass matching filter as before. According to the values asserted for the biphase modulation control signal and blanking signal, the object signal is digitally frequency doubled, blanked and phase modulated as desired prior to conversion into analog form.</p> |
