Spectral Shaping Circuit for In-Band Emission Control on UTP Cables
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Solution Overview
Problem
Unwanted electromagnetic emissions from automotive vehicles, particularly in the frequency ranges used by Digital Audio Broadcasting (DAB) and Frequency Modulated (FM) radio systems, pose interference risks to electronic devices within and outside the vehicle, especially when using Unshielded Twisted Pair (UTP) cables, which lack the electromagnetic shielding of Shielded Twisted Pair (STP) cables.
Innovation Solution
A transmitter device with a digital filter circuit and a switching unit that selectively shapes the spectral density of RF signals, allowing precise attenuation of unwanted frequencies, particularly below 200 MHz, using a Finite Impulse Response (FIR) filter and a digital-to-analog converter, enabling efficient transmission over UTP cables without significant interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If UTP cables are used for tethered communication signals, then weight and aging are reduced compared to STP cables, but unwanted electromagnetic emissions increase in frequency ranges used by DAB and FM radio systems
Solution Approach 1:
The patent extracts and removes the harmful frequency components from the transmitted signal by implementing a filter circuit that specifically targets and eliminates emissions in the DAB (174-239 MHz) and FM (65-108 MHz) radio frequency ranges. This allows UTP cables to be used without their shielding, achieving weight reduction while preventing electromagnetic interference through selective frequency removal at the transmitter output.
Solution Approach 2:
The patent changes the spectral parameters of the transmitted signal by applying spectral shaping through filtering. The filter circuit modifies the power spectral density of the Ethernet signal, attenuating specific frequency bands to comply with electromagnetic emission regulations while maintaining signal integrity for data transmission.
2Object-affected harmful factors
If spectral shaping is applied to reduce electromagnetic emissions, then interference with DAB and FM radio systems is reduced, but device complexity increases due to additional filter circuitry
Solution Approach 1:
The filter circuit is designed to perform multiple functions simultaneously: it shapes the spectrum to reduce electromagnetic emissions, maintains signal integrity for Ethernet communication, and ensures compliance with regulatory standards. This multi-functionality reduces the need for separate circuits for each purpose, thereby limiting the increase in overall device complexity.
3Object-generated harmful factors
If filter circuit is always active for spectral shaping, then electromagnetic emissions are consistently controlled, but energy consumption increases
Solution Approach 1:
The filter circuit is implemented as a dynamically controllable component that can be activated or deactivated based on operational requirements. The control terminal receives switching signals that enable the filter only when electromagnetic emission control is necessary, such as during normal data transmission, while allowing the filter to be bypassed when full transmission power is needed, thereby optimizing energy consumption.
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
The solution provides effective electromagnetic interference reduction, allowing interference-free reception of FM and DAB signals, reduces electromagnetic pollution, and optimizes energy consumption through operational state reconfiguration, making it suitable for automotive applications with UTP cables.
Implementation Method 1
a filter circuit for (filtering and) spectrally shaping the generated digital transmit signal and for outputting a filtered digital transmit signal
Implementation Method 2
using a Finite Impulse Response (FIR) filter
Implementation Method 3
a digital to analog converter (DAC) unit for receiving the digital transmit output signal and for converting the received digital transmit output signal to the analog signal (to be transmitted)
Implementation Method 4
a switching unit (MUX) comprising (c1) a first input terminal for receiving the filtered digital transmit signal, (c2) a second input terminal for receiving another digital transmit signal, and (c3) an output terminal for outputting a digital transmit output signal
Data Source
AI summary
It is described a transmitter device (100) and a method for transmitting an analog signal (251, 261) via an electric cable (192). The transmitter device (100) comprises (a) a signal generation circuit (210) for generating a digital transmit signal (211) comprising a sequence of transmit symbols; (b) a filter circuit (230) for spectrally shaping the generated digital transmit signal (211, 221) and for outputting a filtered digital transmit signal (231); (c) a switching unit (240) comprising (c1) a first input terminal (242) for receiving the filtered digital transmit signal (231), (c2) a second input terminal (244) for receiving another digital transmit signal (297), (c3) an output terminal (246) for outputting a digital transmit output signal (241), wherein the digital transmit output signal (241) is based on, depending on a switching state of the switching unit (240), the filtered digital transmit signal (231) or the another digital transmit signal (297), and (c4) a control terminal (248) for receiving a control signal (285) from a control circuit (280), the control signal (285) being indicative for the switching state. The transmitter device (100) further comprises the control circuit (280); and a digital to analog converter (250) for receiving the digital transmit output signal (241) and for converting the received digital transmit output signal (241) to the analog signal (251, 261).