Overlapped Frequency Band Stitching for Spectrum Analysis
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Solution Overview
Problem
Conventional spectrum analyzers face limitations in processing wide frequency spans due to hardware speed and processing constraints, requiring multiple acquisitions and stitching of uniform frequency bands, which is inefficient and suboptimal for non-uniform spans.
Innovation Solution
A test and measurement instrument with non-uniform overlapping frequency bands allows for reduced stitching frequency by processing each band as if the full band were present, using digital down conversion and transform sections with consistent configuration settings across bands, and masking unwanted portions to combine them into a full spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If multiple acquisitions with uniform frequency bands are used to cover wider frequency spans, then the frequency span coverage is improved, but the number of stitching operations increases and processing efficiency deteriorates
Solution Approach 1:
The frequency spectrum is divided into multiple overlapping bands that are processed simultaneously through parallel signal paths. Each band is handled by dedicated filter and mixer components, allowing concurrent processing of multiple frequency portions without sequential stitching operations.
Solution Approach 2:
Multiple frequency bands are combined into a single acquisition process rather than performing separate acquisitions and stitching operations. The overlapping bands are processed together through unified digital down conversion and transformation, eliminating the need for multiple sequential stitching operations.
2Length of stationary object
If multiple acquisitions with different settings are performed to cover wider frequency spans, then the frequency span coverage is improved, but the device complexity and processing time increase
Solution Approach 1:
The signal processing system is configured to handle multiple frequency bands simultaneously using unified processing components. The same digital down converter and transform section process all bands with consistent settings, eliminating the need for multiple specialized processing paths and reducing overall system complexity.
Solution Approach 2:
The system performs preliminary filtering and mixing of multiple frequency bands before the digital transformation stage. By preparing multiple bands in advance through parallel analog processing, the subsequent digital processing operates on pre-conditioned signals, reducing computational complexity and processing time.
3Stability of the object's composition
If uniform frequency bands are used for multiple acquisitions, then the processing settings consistency is improved, but the adaptability to non-uniform frequency spans deteriorates
Solution Approach 1:
The frequency band configuration is made dynamic and adaptable rather than fixed and uniform. The system can configure overlapping bands with varying widths and positions according to the specific frequency span requirements, allowing flexible adaptation to non-uniform spans while maintaining processing consistency through unified digital processing.
Solution Approach 2:
Different portions of the frequency spectrum can be processed with locally optimized parameters while maintaining overall processing consistency. The system allows non-uniform band configurations in different frequency regions based on signal characteristics and span requirements, with each region processed through the same unified digital down conversion and transform section.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes the number of configuration changes, reduces hardware requirements, and allows for more flexible and efficient processing of user-specified frequency spans by combining non-uniform bands, thereby enhancing performance and reducing the need for frequent stitching.
Implementation Method 1
The mixer 130 mixes the bands 2 through N with a local oscillator signal 125
Implementation Method 2
Low pass filter 135 removes local oscillator feed-through and image spectrums that result from the mixing process
Implementation Method 3
The analog-to-digital converter (ADC) 145 receives bands 1 through N from switch 140, and digitizes them
Implementation Method 4
After the ADC, the signal may be further conditioned by a digital down converter (DDC) section 160, which may adjust the center frequency and reduce the sample rate
Implementation Method 5
The bands are then transformed using transform 158, which can be a Fourier transform, among other suitable transform operations
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A test and measurement instrument and associated methods for acquiring and stitching wide overlapped non-uniform frequency bands so that a user specified band can be efficiently displayed and analyzed is disclosed. The test and measurement instrument includes a user interface (298) to receive the user specified frequency span. Acquisition circuitry (203) acquires one or more predefined frequency bands (270)having non-uniform overlapping frequency ranges. A frequency band processing section (290) can decimate (252) the acquired frequency bands, mask (294) the acquired frequency bands, and stitch (296) the masked frequency bands together. A display section (202) displays the user specified frequency span using the stitched frequency bands. Due to the overlap configuration of the wide non-uniform bands, any user specified span between 50 kHz and 6 GHz, or thereabout, can be covered by two bands.