Receiver Upsampler Test System Using Step Function Signals
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Solution Overview
Problem
Conventional methods for testing the performance of upsamplers in HD equipment, such as set-top boxes, are limited due to the high integration of these devices, making it difficult to isolate and evaluate the upsampler's performance, especially when displaying SDTV signals on HD displays, which require upscaling to match the higher spatial bandwidth.
Innovation Solution
A test system that generates a modified MPEG-encoded signal with a step function, allowing for the evaluation of the display rate converter's frequency response without the need for a satellite link, using a test signal generator and measurement device to assess the horizontal, vertical, and temporal resolution, enabling performance evaluation of the upsampler and receiver as a whole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If HD equipment is highly integrated to reduce device complexity, then device complexity is reduced, but the ability to isolate and evaluate the upsampler's performance deteriorates
Solution Approach 1:
The patent extracts the upsampler component from the highly integrated HD equipment by providing a dedicated test signal input that isolates the upsampler's function. This allows the upsampler to be evaluated independently without being buried within the integrated receiver architecture, solving the contradiction between integration and measurability.
Solution Approach 2:
The patent introduces a test signal generator as an intermediary device that feeds controlled test signals into the receiver system at a specific point before the upsampler. This intermediary allows measurement of the upsampler's performance without requiring disassembly or isolation of the integrated hardware, resolving the measurement difficulty while maintaining integration.
2Measurement precision
If conventional test signals are used to evaluate upsampler performance, then measurement capability is provided, but the test results are influenced by filtering and prefiltering that prevent accurate isolation of upsampler performance
Solution Approach 1:
The patent applies preliminary action by injecting test signals at a specific point in the signal path before the upsampler processes them. This preliminary injection point is carefully selected to ensure that the test signals are not affected by preceding filtering or prefiltering operations, allowing accurate measurement of the upsampler's inherent performance without contamination from earlier processing stages.
Solution Approach 2:
The patent applies local quality by creating a localized test environment where test signals are introduced at a specific point in the signal path. This localized approach ensures that only the upsampler's performance is being measured at that specific location, while the rest of the system operates normally. The test signal generator provides controlled local conditions that isolate the upsampler from other system influences.
3Adaptability or versatility
If SDTV signals are displayed on HD equipment, then adaptability is improved, but image quality deteriorates due to upsampling requirements
Solution Approach 1:
The patent applies feedback by using measurement devices to monitor the output of the upsampler and comparing it against expected performance criteria. The test system provides feedback about the upsampler's performance in real-time, allowing for identification and correction of image quality issues. This feedback mechanism ensures that while SDTV signals can be adapted to HD displays, the image quality remains within acceptable standards.
Data Source
AI summary
Methods of testing receiver video fidelity are disclosed. One example method includes producing a video test signal; coupling the video test signal into an input of the receiver, wherein the video test signal is configured to cause a decoder to output a step function signal upon processing the video test signal; coupling the step function signal to a display rate converter; and measuring signal characteristics of signals provided at a receiver output.