Multi-Tuner Crosstalk Reduction via Dynamic Local Oscillator Offset
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Solution Overview
Problem
Multi-tuner receivers experience significant crosstalk issues due to electromagnetic emissions between tuners, particularly when both are tuned to the same local oscillator frequency, leading to reduced demodulation performance for low power signals, and existing methods to mitigate this are complex to implement.
Innovation Solution
A multi-tuner system where the second local oscillator frequency is set to the sum of the first local oscillator frequency and a continually time-variable offset frequency, which varies in a triangular wave form, ensuring that the interference between tuners is minimized without requiring complex frequency offset calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If both tuners are tuned to the same local oscillator frequency, then the device complexity is reduced, but crosstalk increases and demodulation performance deteriorates
Solution Approach 1:
The patent applies dynamics by making the local oscillator frequency variable rather than fixed. The second tuner's local oscillator frequency is continuously varied around a central value, preventing stable interference conditions while maintaining operational simplicity. This dynamic approach resolves the contradiction by allowing both tuners to operate at similar frequencies without fixed crosstalk patterns.
Solution Approach 2:
The patent implements periodic action through continuous frequency variation of the second local oscillator. By periodically changing the frequency around a central value, the system prevents sustained interference conditions that would occur with fixed frequencies, thereby reducing crosstalk while maintaining device simplicity.
2Object-affected harmful factors
If a fixed frequency offset is applied to one of the tuners, then crosstalk is reduced, but the device complexity increases due to frequency offset calculations
Solution Approach 1:
Instead of a fixed offset requiring complex calculations, the patent uses continuous frequency variation. This dynamic approach naturally prevents crosstalk without requiring offset detection or calculation logic, thereby reducing device complexity while maintaining crosstalk suppression.
Solution Approach 2:
The frequency variation mechanism serves multiple functions simultaneously: it prevents crosstalk while requiring no additional control logic or calculations. The system self-regulates interference prevention through the inherent frequency modulation, eliminating the need for complex offset management.
3Object-affected harmful factors
If the second local oscillator frequency is continuously varied, then crosstalk is reduced, but the frequency stability decreases
Solution Approach 1:
The patent resolves this contradiction by implementing controlled dynamics - the frequency varies continuously around a stable central value. This maintains the benefits of frequency variation for crosstalk reduction while preserving frequency stability through the defined central operating point, allowing the demodulator to track the signal correctly.
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 effectively reduces crosstalk between tuners by maintaining the demodulation performance even when both tuners are tuned to similar frequencies, simplifying the implementation process and avoiding interference phenomena.
Implementation Method 1
the first tuner being adapted to translate a frequency of a first received signal into a first translated frequency, the first tuner comprising a first local oscillator operating at a first local oscillator frequency
Implementation Method 2
the second tuner being adapted to translate a frequency of a second received signal into a second translated frequency, the second tuner comprising a second local oscillator operating at a second local oscillator frequency
Implementation Method 3
Electromagnetic emissions exist between the tuners and can create interferences. This phenomenon is known as crosstalk. The problem of crosstalk occurs more specifically when two tuners are tuned onto the same conversion frequency, called LO (Local Oscillator)
Data Source
Figure 1~2
Figure 3a
Figure 3b
AI summary
Multi-tuner reception system comprising at least a first tuner (101) and a second tuner (102), the first tuner (101) being adapted to translate a frequency of a first received signal into a first translated frequency, the first tuner (101) comprising a first local oscillator (1016) operating at a first local oscillator frequency, the second tuner (102) being adapted to translate a frequency of a second received signal into a second translated frequency, the second tuner (102) comprising a second local oscillator (1026) operating at a second local oscillator frequency, the system being characterized in that the second local oscillator frequency is equal to the sum of the first local oscillator frequency and a continually time variable offset frequency, a demodulator being adapted to demodulate a signal from the second tuner (102).