Spectrum Analyzer Digital Sweep Using Cascaded Decimation
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Solution Overview
Problem
Spectrum analyzers face challenges in achieving high-speed performance comparable to FFT spectrum analyzers while maintaining lower resource consumption and cost, particularly in analyzing 5G communication signals, where swept spectrum analyzers are inferior in speed and resource-intensive FFT analyzers are costly.
Innovation Solution
A digital-data-based frequency sweep scheme using a cascaded integrator comb (CIC) filter with a two-stage decimation processing block, combined with an analog-to-digital converter and control unit, allows for efficient digital frequency sweeping and reduced sweep time, enabling performance comparable to FFT spectrum analyzers with lower resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FFT spectrum analyzer is used to achieve high-speed performance, then spectrum analysis speed is improved, but device cost and resource consumption increase
Solution Approach 1:
The patent segments the frequency sweep process into multiple stages using a multi-stage frequency sweep unit. Instead of performing a single comprehensive FFT operation that requires high-performance (and expensive) hardware, the sweep is divided into multiple smaller sweeps across different frequency ranges, each processed separately. This segmentation allows the use of lower-cost processing units while achieving comparable overall analysis speed.
Solution Approach 2:
The patent implements dynamic adjustment of sweep parameters including variable sweep speed, adjustable resolution bandwidth (RBW), and configurable video bandwidth (VBW). The frequency sweep unit dynamically adapts the sweep rate and processing depth based on signal characteristics and measurement requirements, optimizing performance for different scenarios without requiring peak hardware capabilities for all cases.
2Device complexity
If swept spectrum analyzer is used to reduce cost, then device cost is reduced, but spectrum analysis speed deteriorates
Solution Approach 1:
The patent maintains continuous frequency sweeping across the entire frequency range by sequentially executing multiple sweep segments. The frequency sweep unit continuously processes signals across different frequency bands without interruption, ensuring that the useful measurement action continues throughout the expanded frequency range. This continuous operation compensates for the lower speed of individual sweep segments, achieving fast overall analysis.
Solution Approach 2:
The patent performs preliminary frequency range division and pre-plans the multi-stage sweep sequence before actual measurement. The control unit pre-configures the sweep parameters, resolution bandwidth settings, and video bandwidth filters based on expected signal characteristics. This preliminary preparation allows the swept analyzer to execute the measurement sequence efficiently without real-time decision delays, improving overall analysis speed.
3Productivity
If FFT spectrum analyzer processes entire frequency band simultaneously, then spectrum analysis speed is improved, but memory requirements increase
Solution Approach 1:
The patent segments the frequency band processing into multiple smaller frequency ranges, each handled by dedicated processing stages. Instead of loading and processing the entire frequency spectrum simultaneously in memory, the signal is divided into multiple segments that are processed sequentially. This segmentation reduces the amount of data that needs to be held in memory at any one time, lowering memory requirements while maintaining analysis throughput.
4Measurement precision
If swept spectrum analyzer increases sweep time for accurate measurement, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The patent implements dynamic sweep time adjustment where the sweep speed and integration time are adaptively modified based on signal power levels and detected signal characteristics. For weak signals, the system automatically increases integration time and sweep duration to improve detection accuracy. For strong signals, the sweep proceeds faster to maintain throughput. This dynamic adaptation allows the system to achieve high precision measurements when needed while maintaining fast analysis speed for routine measurements.
Data Source
AI summary
A spectrum analyzer having a memory function to adopt a digital-data-based frequency sweep scheme while achieving performance comparable to performance of a high-speed FFT spectrum analyzer, and a method of controlling the spectrum analyzer, in which the spectrum analyzer includes: an ADC for converting a BWP signal, which is at least one analog unit frequency band signal, into a digital data sample at a predetermined sample rate according to a span set by a user; a digital sweep part for sweeping the data sample passed through the ADC while digitally decimating the data sample through a decimation processing block having a two-stage cascaded structure, and processing the swept data sample to increase a frequency sweep speed; and a control unit for controlling the digital sweep part according to various items input, set, and selected by the user to perform spectrum analysis and output a spectrum analysis result.