GPS-PPS Frequency Control with Adaptive Gate Time Correction
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Solution Overview
Problem
Existing radio devices face challenges in accurately correcting frequency errors in high-frequency reference signals due to errors in pulse per second (PPS) signals from GPS, leading to prolonged correction times and inaccuracies, especially at frequencies above 10 GHz.
Innovation Solution
A frequency control assist device that includes a counter to count pulses, an averaging circuit to calculate average values, and a deviation detection circuit to adjust the correction process by dynamically changing the target value and gate time based on detected deviations, allowing for faster and more accurate frequency correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long gate time (150 seconds) is used to reduce PPS signal error to 1 ppb, then measurement precision is improved, but time for frequency correction increases significantly
Solution Approach 1:
The gate time is changed from a fixed 150 seconds to a dynamic value that adapts based on the detected frequency deviation. When deviation is large, a shorter gate time is used for faster initial correction. As deviation decreases, the gate time extends to improve precision, ultimately achieving both speed and accuracy.
Solution Approach 2:
The system performs preliminary frequency correction using a shorter gate time before the final precision correction phase. This preliminary action reduces the initial large deviation quickly, making the subsequent long gate time correction more efficient and reducing total correction time.
2Manufacturing precision
If multiple feedback control iterations are performed to achieve frequency accuracy within allowable range, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The number of feedback control iterations is dynamically adjusted based on the frequency deviation magnitude. For large deviations, fewer iterations are performed initially, and the gate time is adjusted to compensate, reducing total processing time while maintaining final accuracy.
3Ease of operation
If a fixed target value is used for frequency correction, then ease of operation is improved, but adaptability to different error magnitudes decreases
Solution Approach 1:
The target value transitions from a fixed parameter to a dynamic one that changes based on the detected deviation magnitude. The system automatically adjusts the target value to be more aggressive when deviation is large and more conservative when deviation is small, optimizing correction efficiency for all error magnitudes.
Data Source
AI summary
A frequency control assist device is configured to: calculate an average value of pulse numbers each of which is a pulse number of a reference signal generated by an oscillator in one cycle of a PPS signal generated based on a GPS signal, from a total of the pulse numbers counted for a time period whose length is a predetermined number times the one cycle, the average value being an average value of the pulse numbers each for the one cycle; and every time a deviation between a specified value of a reference frequency of the reference signal and the average value falls below a target value, reduce the target value from the current value and increase, from the current value, the predetermined number that specifies the time period for obtaining the total of the pulse numbers from which the average value is to be calculated by an averaging circuit.