A feedback loop corrects timing errors by reducing deviations from a constant radar sweep rate. Errors are detected and fed back to a phase corrector in a high gain feedback system. A precision radar rangefinder can be implemented with a direct digital synthesizer (DDS) that includes feedback error correction for reducing range errors by, for example, 100 times, or to 0.1 mm. An error-corrected DDS swept timing system can enable a new generation of highly flexible, repeatable and accurate radar, laser and guided wave rangefinders.

Phase angle measurement system

Error corrector for radar timing systems

A VHF omnidirectional range converter wherein digital logic replaces the analog circuitry heretofore used in the phase shifter and related portions of the converter.

Omni-converter with digital phase shifter

The system described is a closed loop analog system which determines its bearing to a Tacan beacon. The beacon transmits a complex signal including pulse pairs amplitude modulated by fundamental and harmonic waves and spaced main and auxiliary reference pulse groups. The bearing is determined by phase locking two voltage controlled oscillators to the main reference pulse group to provide two reference signals, one having a frequency equal to the frequency of the fundamental wave and the other having a frequency equal to the frequency of the harmonic wave. These reference signals are then correlated with the fundamental and harmonic waves of the complex signal with the resultant phase error signals controlling a motor which is mechanically coupled to phase shift elements to control the phase of the reference signals. A synchro is also coupled mechanically to the motor to provide the bearing when the phase error signals are reduced to zero.

Phase angle measurement system

Citations

Error corrector for radar timing systems

Omni-converter with digital phase shifter

Analog bearing measuring system

References

Device for measuring phase angles between oscillations

Digital phase measuring apparatus utilizing a counter as a delay means

Bearing computer for use in electronic navigation systems, such as tacan

Digital bearing measuring system

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