Universal TV Receiver Sampling Shift for Interference Avoidance
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Solution Overview
Problem
Traditional television receivers are limited in their ability to process signals from different television broadcast standards due to the use of expensive SAW filters that cannot be integrated onto a chip, making them incapable of receiving signals from various standards without additional processing.
Innovation Solution
A universal television receiver design that includes an Analog to Digital Converter (ADC) and a digital processing block to digitize signals, adjust sampling rates to frequency shift interferers, and apply resampling ratios, along with an RF processing block for amplification and mixing, allowing the receiver to process signals from multiple broadcast standards without a SAW filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a SAW filter is used to process television signals, then the frequency response is sharp and the passband corresponds to the bandwidth of the television signal, but the component cannot be integrated onto a chip and is relatively expensive
Solution Approach 1:
The patent replaces the mechanical SAW filter with a digital signal processing system consisting of an ADC, digital down-converter, and digital filter. The ADC converts the RF signal to digital form, allowing subsequent digital processing to achieve the frequency selection and filtering functions that were previously accomplished by the SAW filter. This substitution enables integration onto a chip while maintaining the required frequency response characteristics.
Solution Approach 2:
The patent changes the operating parameters of the system by using a sampling rate that is lower than the Nyquist rate for the RF signal frequency. This undersampling technique, combined with digital down-conversion, allows the system to achieve the same effective bandwidth and frequency response as a SAW filter while using integrable digital components instead of discrete analog components.
2Reliability
If a SAW filter is used in traditional television receivers, then the receiver can process signals according to a particular television broadcast standard, but the receiver cannot receive television signals transmitted according to different television broadcast standards without further specialized processing
Solution Approach 1:
The patent implements a universal receiver architecture using digital signal processing that can handle multiple television broadcast standards (NTSC, PAL, SECAM, and digital standards). The ADC samples the RF signal at a rate sufficient to capture all standards, and the digital down-converter and digital filters can be reconfigured via software to process signals according to different standards, eliminating the need for hardware changes or specialized processing for each standard.
Solution Approach 2:
The patent employs dynamic, reconfigurable digital signal processing parameters including variable sampling rates, adjustable down-conversion frequencies, and programmable filter characteristics. These dynamic parameters allow the receiver to adapt to different television broadcast standards by changing the processing configuration rather than requiring fixed hardware designed for a single standard.
3Object-affected harmful factors
If the sampling rate is adjusted to frequency shift the aliased interferer away from the desired television channel, then the interferer is moved away from the channel, but resampling ratios must be applied to compensate for the adjusted sampling rate
Solution Approach 1:
The patent converts the harmful aliasing effect into a beneficial frequency shifting mechanism. By intentionally sampling at a rate that causes aliasing, the system frequency-shifts interferers away from desired channels while simultaneously bringing desired signals into the baseband. The digital down-converter then processes these aliased signals to recover the original information, effectively using aliasing as a tool for interference rejection rather than viewing it purely as a distortion to be avoided.
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
Enables the reception of television signals from various broadcast standards on a single Integrated Circuit (IC), reducing component complexity and sensitivity to environmental variations, while avoiding the need for specialized processing for each standard.
Implementation Method 1
an Analog to Digital Converter (ADC) configured to digitize the first signal at a sampling rate to produce a second signal
Implementation Method 2
an RF processing block configured to amplify and mix the received television signals to generate a multi-channel television signal
Implementation Method 3
the RF processing block comprising a mixing stage having a local oscillator that provides a variable oscillation frequency used for mixing
Implementation Method 4
adjusting the sampling rate to frequency shift the aliased interferer away from the desired television channel
Implementation Method 5
the digital processing block is configured to apply resampling ratios to compensate for the adjusted sampling rate
Data Source
AI summary
Various embodiments are described herein for a universal television receiver that is capable of processing television channel signals broadcast according to a variety of analog and digital broadcast standards. In particular, various embodiments are provided for avoiding interferers in a desired television channel signal and these embodiments generally include changing sampling rate, shifting certain oscillation frequencies or changing sampling rate and shifting certain oscillation frequencies.