Inaccurate measurements of analog sensors caused by electromagnetic interference (EMI) signals threaten the security and reliability of sensor-based systems. This article proposes a self-check method for recognizing and correcting disturbed measurements of analog sensors under EMI signals. The core basis of this method involves the use of a dummy sensing element to make the sensor sensitive only to EMI signals, rather than the measurand. This configuration enables the sensor to switch between normal mode and self-check mode through switching devices. Then the sensor response to EMI signals in normal mode is characterized by that in self-check mode, which is computable. A detailed implementation framework is derived to ensure that the sensor responses to EMI signals in both modes are highly similar, involving the properties of the dummy sensing element, the input voltage of the operational amplifier (opamp), and the power supply rails. Owing to its low demand for additional components and computing resources, the proposed self-check method is cost-effective and convenient to implement. Its effectiveness and robustness are validated on a temperature sensor, an ambient light sensor, a linear variable differential transformer (LVDT) and a wireless temperature sensor node with EMI experiments using different signals parameters, temperatures and light intensities. The experimental results show that this method can enhance the measurement accuracy of analog sensors to help maintain the functioning of sensor-based systems under EMI signals.

The purpose of the electromagnetic compatibility conducted susceptibility test for interconnected cables in the system is to evaluate its ability to operate acceptably when subjected to interference. We propose a novel conducted susceptibility analysis approach: by injecting the Gaussian even pulse signal, we find that the susceptibility threshold of the system shows two different patterns with the change of signal parameters; then we locate the cause of the susceptibility of the device by analyzing the threshold level curves. The effectiveness of the proposed approach is verified by testing with devices containing digital modules such as navigation receivers. The proposed approach facilitates a deeper understanding of the susceptibility mechanism of systems and their appropriate electromagnetic compatibility design.

In this paper, a novel conducted susceptibility (CS) test system is proposed to analyze broadband interference for equipment under test (EUT). This system can quickly locate the susceptibility frequency bands and effectively find the susceptibility thresholds. The system can generate a unipolar or bipolar Gaussian pulse signal with a pulse width of less than 720 ps to perform these functions. In addition, the pulse amplitude can be adjusted from ±50 V to ±1.5 kV under a 50 Ω resistance load. The repetition frequency is adjustable within the range of 1 Hz to 1 kHz. The pulse spacing of the bipolar Gaussian pulse signal can be controlled from 0.25 ns to 12 ns in the step of 0.25 ns. In detail, a CS test on an electric vehicle was performed with the proposed system and an existing CS system. By using the proposed system, three potential problems of electric vehicles were predicted, susceptible frequency bands were located, and susceptibility thresholds were determined. The proposed method has high test efficiency and high reliability.

Polarization multiplexing is one of the key technologies for multi-dimensional information transmission. When constructing a N²-dimensional linear polarization multiplexing network with N input states of distinct polar angle and corresponding N outputs (N > 2), there are inherent couplings for all channels due to polarization decomposition and superposition, exhibiting as information crosstalk among non-orthogonal channels. Also, physical symmetric structure severely limits the full utilization of polarization multiplexing by inducing crosstalk in orthogonal polarization channels. Here by employing polarization diffraction neural network (PDNN) to minimize couplings in a global manner, we establish N² fully-connected independent transmission channels by multiplexing N linear polar angles. Taking chiral-assisted metasurfaces as physical platform, a single-layer PDNN is verified by nine input-output channels (N = 3), ultra-low crosstalk in digital holographic imaging shows the effectiveness of proposed method. We also impose amplitude-feature enhancement of metasurface to further improve transformation efficiency while maintaining channel isolation. Our results exemplify the architecture’s capability for complete polarization multiplexing, with direct applicability to optical linear computing, advanced holography, and high-security optical encryption.