Swept Acquisition for Pulsed Radio Frequency (RF) Phase Lock Loop.
DEPARTMENT OF THE AIR FORCE WASHINGTON DC
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Swept acquisition of reference signals, including pulsed radio frequency radar waveforms, is achieved using sample-and-hold circuitry to track and hold in-phase and quadrature error signals E1 and Eq from a voltage controlled oscillator which is swept by a sweep generator. This presents a constant in-phase error signal to the integrator is the loop so that the phase lock loop may be implemented by conventional means. The quadrature error signal is filtered and compared with a threshold to determine when frequency lock has been obtained when the voltage control oscillator is swept at high speed. Then the voltage controlled oscillator is swept at a lower speed to distinguish the center lobe of the reference signal and attain phase lock. Finally, the voltage controlled oscillator is swept only while sampling the reference signal by gating the sweep rate signal with a sampling signal. This method enables one to acquire a pulsed radio frequency signal with jittered pulse repetition intervals while preventing locking on before or after the center frequency of the main lobe of the reference signal. Patent Applications
- Electrical and Electronic Equipment