Spectrum Analyzer Mixing Lines for Image Frequency Rejection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current spectrum analyzers face challenges in handling high mixing frequencies, leading to practical issues where only mixing frequencies below the center frequency are used, resulting in limitations in image frequency reception.
Innovation Solution
A method involving two mixing lines with different local oscillators, where the input signal is mixed with distinct frequencies, filtered, digitized, and processed to generate auxiliary signals, allowing for the separation of desired and image spectra by shifting and combining these signals, effectively avoiding high mixing frequencies and attenuating image frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high mixing frequencies are used, then the center frequency coverage is improved, but practical problems and image frequency reception issues occur
Solution Approach 1:
The spectrum analysis function is segmented into two separate mixing lines, each handling different frequency ranges. The first mixing line processes signals with a first mixing frequency, while the second mixing line processes with a second mixing frequency. This segmentation allows each line to operate within reliable frequency ranges while collectively covering a broader center frequency spectrum, resolving the contradiction between coverage and reliability.
Solution Approach 2:
A common signal processing unit acts as an intermediary that receives and processes outputs from both mixing lines. This intermediary component coordinates the signals from both paths, enabling the system to achieve high center frequency coverage through the second mixing line while maintaining reliable image frequency rejection through the first mixing line's contribution.
2Reliability
If mixing frequencies below center frequency are used, then practical problems are avoided, but image frequency reception is compromised
Solution Approach 1:
The system segments the frequency processing task into two mixing lines with different mixing frequencies. The first mixing line uses a mixing frequency below the center frequency for reliable practical operation, while the second mixing line uses a higher mixing frequency to extend coverage and improve image frequency reception capability.
Solution Approach 2:
The outputs from both mixing lines are merged in the common signal processing unit. This merging combines the reliable practical operation characteristics of the first mixing line with the extended coverage capabilities of the second mixing line, achieving both goals simultaneously.
3Reliability
If two mixing lines with different frequencies are used, then image frequency attenuation is improved, but device complexity increases
Solution Approach 1:
The common signal processing unit serves multiple functions: it processes outputs from both mixing lines, performs the necessary frequency transformations, and generates the final spectrum analysis results. This multi-functionality reduces the need for separate dedicated processing paths, thereby limiting the increase in device complexity despite having two mixing lines.
Solution Approach 2:
The system changes the frequency parameter of the local oscillators in the two mixing lines to achieve image frequency attenuation. By carefully selecting and adjusting these frequency parameters, the system achieves the desired attenuation effect while keeping the overall structure manageable through parameter optimization rather than structural complexity.
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 enables reliable separation of spectrums, including power spectral densities, by using a common signal processing unit to displace and combine mixed signals, providing a simple and effective method for spectrum analysis while maintaining cost-efficiency.
Implementation Method 1
mixing the input signal at the first mixer with a first mixing signal generated by the first local oscillator having a first frequency to obtain a first mixed signal
Implementation Method 2
mixing the input signal at the second mixer with a second mixing signal generated by the second local oscillator having a second frequency to obtain a second mixed signal
Data Source
AI summary
A method for separating spectrums of an input signal having a first spectrum and a second spectrum by mixing the input signal at a first mixer with a first frequency to obtain a first mixed signal; mixing the input signal at a second mixer with second frequency to obtain a second mixed signal; displacing the first mixed signal and/or the second mixed signal up and down by the difference of the first and second frequency obtaining at least one lower auxiliary signal and at least one upper auxiliary signal, respectively; and extracting the first spectrum and/or the second spectrum using the lower auxiliary signal and/or the upper auxiliary signal as well as the first mixed signal and/or the second mixed signal. Further, measurement devices for separating spectrums are shown.