Variable Sampling Clock Digitizer for Adjacent Channel Aliasing
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Solution Overview
Problem
Conventional digitizers face issues with aliasing due to sampling frequencies lower than the Nyquist frequency, leading to poor reception conditions from overlapping unwanted signals, and require additional components to suppress strong adjacent channel interference, increasing costs and power consumption.
Innovation Solution
A digitizer with a variable sampling clock system that dynamically adjusts the sampling frequency based on channel scan results and power levels of adjacent channels, preventing aliasing and reducing power consumption by selecting optimal sampling rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If sampling frequency is reduced below Nyquist frequency to save power and reduce cost, then power consumption and device complexity are reduced, but aliasing occurs causing adjacent channel interference to overlap with desired signal
Solution Approach 1:
The patent implements a variable sampling clock that dynamically adjusts the sampling frequency based on the detected adjacent channel interference conditions. The sampling frequency is changed from a fixed value to a variable parameter that adapts to different channel environments, allowing the system to use lower sampling rates when interference is absent while maintaining higher rates when needed to prevent aliasing.
Solution Approach 2:
The patent changes the sampling frequency parameter based on channel scan results and interference detection. By monitoring the power levels of adjacent channels and adjusting the sampling rate accordingly, the system optimizes the balance between power consumption and interference rejection, using the minimum necessary sampling rate for each channel condition.
2Object-affected harmful factors
If additional components are added to suppress adjacent channel interference, then interference suppression capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces physical filtering components with a digital signal processing approach. Instead of using additional analog filters or hardware components to suppress adjacent channel interference, the system uses variable sampling rate adjustment combined with digital signal processing techniques to achieve interference rejection, thereby reducing device complexity and cost.
Solution Approach 2:
The patent uses parameter adjustment (sampling frequency) as a control mechanism to manage interference rather than adding physical suppression components. By changing the sampling rate parameter dynamically, the system achieves interference mitigation through signal processing rather than through additional hardware filters or components.
3Reliability
If fixed high sampling frequency is used to prevent aliasing, then aliasing prevention is improved, but power consumption increases and dynamic range utilization decreases
Solution Approach 1:
The patent transitions from a fixed sampling frequency to a dynamic, variable sampling frequency that adapts to channel conditions. The sampling rate is adjusted in real-time based on detected interference levels, allowing the system to maintain reliable aliasing prevention when needed while reducing power consumption when interference is absent.
Solution Approach 2:
The patent applies partial sampling rate adjustment rather than consistently using the maximum sampling rate. By using only the necessary sampling rate required for the current channel conditions, the system avoids the excessive power consumption associated with always operating at the highest sampling frequency while still preventing aliasing when required.
Data Source
AI summary
A digitizer includes an analog to digital converter (ADC), a sampling frequency generator, and a controller. The ADC samples an IF signal to generate a digital signal. The sampling frequency generator is connected to the ADC and provides a sampling clock of variable frequency to the ADC. The controller is connected to the sampling frequency generator and determines frequency of the sampling clock.