Abstract: The synthesizer and method provide a relatively wideband swept frequency signal and include generating a first swept frequency signal with a first generator, and successively switching between different frequency signals with a second generator. Such switching creates undesired phase discontinuities in the output swept frequency signal. The first swept frequency signal is combined with the successively switched different frequency signals to produce the relatively wideband swept frequency signal, and the second generator is calibrated to reduce the undesired phase discontinuities during switching based upon the output swept frequency signal.

Abstract: The phase continuous synthesizer and method generate a relatively wideband swept frequency signal with the use of a first generator for generating a first swept frequency signal, and a second generator successively switching between different frequency signals while creating undesired phase discontinuities during switching. A mixer is connected to the first and second generators for mixing the first swept frequency signal and the successively switched different frequency signals to produce the relatively wideband swept frequency signal, and a phase coasting unit is connected downstream of the mixer to reduce the undesired phase discontinuities created during switching in the relatively wideband swept frequency signal.

Abstract: A phased array antenna includes a transmission line network, e.g. optical or coaxial cable network, and a reference signal generator to provide a reference frequency signal to each of the antenna radiating elements. A phase calibrator generates a calibration signal. e.g. a swept frequency signal, on the transmission line network which is also reflected to create a reflected calibration signal. The phase calibrator determines a frequency difference between the calibration signal and the reflected calibration signal at each of a plurality of taps, and outputs a delay measurement signal to the antenna radiating elements, e.g. via an antenna controller, for adjusting a phase of the reference frequency signal.

Abstract: A digitally controlled frequency synthesizer has a first direct digital synthesizer that generates a first phase-coherent, time-varying frequency, and a second direct digital synthesizer that generates an offset frequency waveform. A plurality of cascaded frequency converters successively combine the offset frequency waveform with a reference frequency waveform to produce a plurality of waveforms having respectively different frequencies. A switch switches between the plurality of waveforms produced by the cascaded frequency converters to realize a second waveform. The operation of the second direct digital synthesizer is controlled so as to maintain phase continuity between respective ones of the plurality of waveforms contained in the second waveform as output by the switch. A mixer multiplies the first waveform by the second waveform to produce a time-varying output frequency.

Abstract: A chirp-based method and apparatus measures phase variation through a reference frequency transport cable for a phased array antenna. A chirp is injected into the a signal transport path from a remote transmit/receive portion of the antenna, so that the chirp is conveyed over the signal path, reflected from an upstream bandpass filter at a local transmit/receive portion of the antenna, and returned to a remote transmit portion of the antenna. Energy in the returned chirp is extracted by a downstream bandpass filter and correlated in a delay lock loop with energy in an auxiliary chirp signal, that is delayed relative to the injected chirp. The delay of the auxiliary chirp is adjusted to maximize the correlation output and provide an indication of the delay through the signal path.

Abstract: A chirp-based arrangement derives a measure of phase variation through a reference frequency transport cable of a phased array antenna architecture, such as a spaceborne synthetic aperture radar system. A direct digital synthesized chirp signal is injected in an upstream direction into the transport cable from a downstream end thereof, so that the chirp signal is transmitted in an upstream direction, reflected from an upstream bandpass filter, and returned in a downstream direction. At each of a plurality of nodes that are distributed along the transport cable, the two chirp signals are extracted and frequency domain-processed to derive said measure of transport delay through the cable between the source of the reference frequency signal and each of the nodes.