Frequency-Locked Carrier Feedback for False-Lock-Free Wireless Tuning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems, particularly those using phase locked loops (PLLs), face issues such as unintentional locking onto harmonics, susceptibility to phase-noise and jitter, and inability to align with frequency valleys, leading to instability and increased chances of false locks.
Innovation Solution
A frequency locked feedback loop system that employs dither modulation, bandpass filtering, and vector cross product calculations to determine and adjust the wireless carrier frequency, allowing for stable locking onto target frequencies, including non-peak values and frequency valleys, using a multicore device with independently configurable frequency locked feedback loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a phase locked loop (PLL) is used for frequency tuning, then phase alignment between target signal and adjustable signal is achieved, but the system becomes susceptible to phase-noise, jitter, and skew
Solution Approach 1:
The patent replaces the traditional PLL feedback mechanism with a frequency-locked loop that uses frequency error detection instead of phase error detection. This substitution eliminates the system's susceptibility to phase-noise, jitter, and skew while maintaining frequency alignment capability. The frequency error detector compares the frequency of the adjustable signal with the target frequency directly, bypassing the phase detection stage that is vulnerable to these disturbances.
Solution Approach 2:
The invention changes the fundamental parameter being controlled from phase difference to frequency difference. By detecting frequency error rather than phase error, the system achieves frequency locking without the instability issues that plague PLLs. This parameter change transforms the feedback mechanism to be inherently more robust against phase-related disturbances while maintaining effective frequency tuning.
2Measurement precision
If a PLL attempts to drive phase-error to zero, then phase alignment is achieved, but the chance of false lock increases and continuous reference clock is required
Solution Approach 1:
The patent replaces the phase-error-driven feedback mechanism with a frequency-error-driven mechanism. The frequency error detector directly compares frequencies without requiring phase alignment, eliminating the false lock problem inherent in PLLs. This substitution removes the need for continuous reference clocks while maintaining accurate frequency control, as the system locks on frequency matching rather than phase nulling.
3Measurement precision
If frequency tuning functions tune to a single frequency to match a single filter peak, then frequency alignment is achieved, but alignment with frequency valleys between peaks is not possible
Solution Approach 1:
The patent implements a dynamic frequency-locking system that can adapt to any target frequency within the filter's passband, not just peak frequencies. The frequency error detector continuously monitors and adjusts the adjustable frequency to match any desired target frequency, enabling the system to lock onto frequency valleys between peaks as well as peaks themselves. This dynamic capability provides versatile frequency tuning across the entire operational range.
4Power
If a PLL is used for frequency tuning, then frequency control is achieved, but the system cannot be used to align with valleys between two filter peaks
Solution Approach 1:
The invention changes the control parameter from phase difference to frequency difference, enabling the system to achieve frequency locking at any desired frequency point including valleys between filter peaks. The frequency error detector directly measures frequency deviation from the target, allowing the system to converge to any target frequency within the passband regardless of whether it corresponds to a filter peak or valley, thus providing complete frequency tuning versatility.
Data Source
AI summary
A method and systems for a frequency locked feedback loop for wireless communications are provided. The method includes applying dither modulation from a harmonic modulator to modulated data at a transmit source, and mixing the dither modulation at a dither modulation frequency with the modulated data at a wireless carrier frequency to produce a modulated signal. The method also includes filtering and splitting the modulated signal using a bandpass filter to produce a wireless output signal and a feedback signal. The method further includes determining a frequency error in the feedback signal as a function of alignment of the wireless carrier frequency to a target frequency in a frequency response of the bandpass filter. The method additionally includes adjusting the wireless carrier frequency in response to the frequency error to establish a frequency lock between the wireless carrier frequency and the target frequency.