Tuner Local Oscillator Frequency Shifting for Spurious Signal Placement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional RF tuners face challenges in achieving wideband capture bandwidths of 64 MHz to 96 MHz due to the introduction of LO-related spurious signals, which degrade signal quality and fail to meet DOCSIS 3.0 standards.
Innovation Solution
The solution involves shifting local oscillator frequencies to place spurious signals within a predetermined spur placement window between traffic channels, rather than adjusting frequencies to exclude them, thereby maximizing capture bandwidth while maintaining signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If local oscillator frequencies are adjusted to exclude spurious signals from the capture bandwidth, then signal quality is improved, but capture bandwidth is reduced
Solution Approach 1:
Instead of adjusting LO frequencies to exclude spurious signals from the capture bandwidth (traditional approach), the invention inverts the approach by deliberately placing spurious signals within the capture bandwidth but positioning them in null regions between traffic channels. This allows the capture bandwidth to remain wide (64-96 MHz) while spurious signals do not interfere with actual data channels, thus resolving the contradiction between signal quality and capture bandwidth.
Solution Approach 2:
The invention converts the harmful effect of spurious signals into a beneficial outcome by strategically positioning them in the null regions between traffic channels. The spurious signals that would normally degrade signal quality are instead placed in frequency regions where they have no adverse effect, effectively turning a harmful factor into a non-interfering element that allows wideband operation.
2Adaptability or versatility
If wideband capture bandwidth of 64 MHz to 96 MHz is achieved, then channel selection capability is improved, but LO-related spurious signals fall within the capture bandwidth and degrade signal quality
Solution Approach 1:
The invention moves the spurious signals from the traditional frequency domain conflict into a spatial arrangement dimension by utilizing the frequency spectrum's structure. Instead of trying to eliminate spurious signals in the traditional sense, the solution arranges them in the frequency landscape between channels, using the dimensional structure of the spectrum to separate useful signals (data channels) from harmful signals (spurious components).
Solution Approach 2:
The null regions between traffic channels serve as intermediary zones that accommodate spurious signals. These intermediate frequency regions act as buffers where LO-related spurious signals can exist without directly interfering with the traffic channels, thus mediating between the wideband capture requirement and spurious signal elimination requirement.
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 allows for wideband tuner configurations that meet DOCSIS 3.0 standards by effectively mitigating the impact of spurious signals, ensuring high signal quality and compliance with performance specifications.
Implementation Method 1
In operation of a RF tuner, an incoming signal at frequency fIN is mixed with a signal at frequency fLO1 from a local oscillator (LO) to produce a signal at a first intermediate frequency fIF1. In a dual conversion tuner configuration, this signal may then mixed with a signal at frequency fLO2 from a second local oscillator signal to produce a second intermediate frequency fIF2
Data Source
AI summary
Systems and methods which place a spurious signal within a capture bandwidth of a tuner. Placement of the spur is preferably controlled to dispose the spur within a spur placement window, such as may be defined between traffic channels of an input signal. A tuner system operating in accordance with embodiments may be controlled to select a particular input frequency band comprising a plurality of traffic channels for frequency conversion and to determine local oscillator frequencies which result in most relevant spurs being placed outside of the tuner capture bandwidth. The local oscillator frequencies may be shifted to place a relevant spur remaining within the capture bandwidth of the tuner between traffic channels of the plurality of traffic channels. Embodiments operate to determine frequency offset between a transmitter and a tuner to determine the midpoint between channels.