TV Receiver Digital IF Filtering Without Analog SAW Filters
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Solution Overview
Problem
The high cost of TV receivers is attributed to the need for separate SAW filters for analog and digital TV signals, which are expensive due to their distinct frequency responses and the requirement for separate demodulators to process these signals effectively.
Innovation Solution
Implementing intermediate frequency filtering of analog TV signals in the digital domain using an analog-to-digital converter and a digital filter module, allowing for the removal of the analog TV intermediate frequency SAW filter, thereby reducing the cost of the TV receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate SAW filters are used for analog and digital TV signals, then frequency selectivity and channel separation are improved, but device cost and complexity increase
Solution Approach 1:
The patent merges the separate analog and digital TV signal processing paths into a unified digital domain. The analog TV signal is converted to digital format and processed using the same digital filter and demodulator used for digital TV signals, eliminating the need for separate analog SAW filters and analog demodulator circuits.
Solution Approach 2:
The patent replaces the mechanical/analog SAW filter system with a digital filter implemented in the digital domain. Instead of using physical surface acoustic wave filters for analog signal processing, the invention uses digital signal processing techniques to achieve the same frequency selection and channel separation functions.
2Measurement precision
If separate demodulators are used for analog and digital TV signals, then signal processing accuracy is improved, but device cost increases
Solution Approach 1:
The patent combines the analog and digital demodulation functions into a single digital demodulator. By converting the analog TV signal to digital format first, the same demodulator circuitry can process both analog and digital TV signals, reducing the total number of demodulators from two to one.
Solution Approach 2:
The patent changes the operating domain of the demodulator from separate analog and digital domains to a unified digital domain. The analog signal is transformed into the digital domain through ADC, allowing the demodulator to operate uniformly on digital signals regardless of whether the original source was analog or digital TV.
3Device complexity
If analog TV intermediate frequency SAW filter is removed, then device cost decreases, but filtering capability may be compromised
Solution Approach 1:
The patent substitutes the removed analog SAW filter with a digital filter implemented in the digital domain. The digital filter maintains the frequency selection and channel separation capabilities of the original analog filter while being implemented using digital signal processing, thus preserving filtering capability while reducing hardware complexity.
Data Source
AI summary
The present invention provides a TV receiver and an analog TV signal processing method. The TV receiver includes a tuner, an analog-to-digital converter, and a digital filter module. The tuner is utilized to receive an RF signal and generate a first signal; the analog-to-digital converter is coupled to the tuner for converting the first signal to a digital signal, and the digital filter module is coupled to the analog-to-digital converter for filtering the digital signal in order to filter an analog TV signal contained in the RF signal in digital domain.