Abstract: A system and technique for phased array antenna beam steering for transmitting and receiving without sending the waveform through an actual (physical) time delay when a time varying frequency is used as the waveform. The inventive system is adapted for use with an antenna having an array of radiating elements and includes a plurality of signal sources. Each source is adapted to provide a signal having a predetermined frequency offset signal for an associated radiating element or set of radiating elements. For transmit a plurality of first mixers is provided. Each of the first mixers is coupled to receive an excitation signal as a first input and the output from a respective one of the sources as a second input. The output of each mixer is coupled to a respective subset of the antenna radiating elements. In effect, each of the sources provides a virtual time delay.

Abstract: A system and technique for phased array antenna beam steering for transmitting and receiving without sending the waveform through an actual (physical) time delay when a time varying frequency is used as the waveform. The inventive system is adapted for use with an antenna having an array of radiating elements and includes a plurality of signal sources. Each source is adapted to provide a signal having a predetermined frequency offset signal for an associated radiating element or set of radiating elements. For transmit a plurality of first mixers is provided. Each of the first mixers is coupled to receive an excitation signal as a first input and the output from a respective one of the sources as a second input. The output of each mixer is coupled to a respective subset of the antenna radiating elements. In effect, each of the sources provides a virtual time delay.

Abstract: A phase shifter using digital counters allows extremely accurate phase shifts. In a parallel circuit arrangement of a number of basic phase shift units, which each includes a dual modulus counter and phase control circuitry for controlling the counter modulus, the outputs of several units are combined in parallel. With the divider ratios of all the dividers of the units consisting of roots of pairwise relatively prime numbers, the total number of phase states is equal to the multiplication of its divider ratios.

Abstract: Discrete phase modulation for modulating the transmit and receive radar signal waveforms in order to control distortion. The signal is modulated by discrete phases which change from pulse-to-pulse. A digital frequency division circuit accurately generates the modulation signals, and allows the discrete phases to be generated with precise accuracy. The discrete phase changes can be a quadratic phase progression for target Doppler and range detection.

Abstract: A phase shifter that employs digital circuitry to achieve arbitrarily fine phase control of reference signals at frequencies extending to the Gigahertz region. The phase shifter includes a cascade of identical phase shift units that provide progressively finer phase control resolution over a full 360 degree range. The phase precision is set by the number of stages used.

Abstract: A precision digital phase shift element for achieving precise phase shift of an input pulse train signal. The output is a pulse train at a frequency equal to the input signal frequency divided by N, and having N equally spaced phase states. The relative phase state of the output signal is reliably controlled by selective deletion of pulses from the input signal pulse train. The selective deletion can be achieved by selectively gating the input pulse train, or by use of a dual modulus frequency divider circuit.

Abstract: The frequencies of N oscillators are summed to provide a signal generator output signal. Because the phase noise power spectral densities of the oscillators add as power, the frequency summed output exhibits a noise degradation over a single oscillator of only 10 log(N). The signal generator is implemented to assure independence of the oscillator noise contributions, with phase locking the oscillators to a common frequency for ease of spurious signal control.

Abstract: A digital waveform synthesizer, using a direct digital synthesizer and a digital frequency divider. The direct digital synthesizer provides a digitally synthesized input frequency signal. An upconverter and frequency divider circuit upconverts and divides the synthesized input frequency signal to provide an divided synthesized frequency signal. An output upconverter circuit is coupled to the upconverter and divider circuit for providing an upconverted output frequency signal. A reference frequency generator is coupled to the direct digital synthesizer, to the upconverter and divider circuit, and to the output upconverter, for providing clock and frequency reference signals thereto. The waveform generator is coupled to the direct digital synthesizer for commanding a desired waveform. The frequency divider is used to improve the inherently poor spurious signal performance of the direct digital synthesizer.