Radio frequency interference effects

Electromagnetic interference (EMI) refers to the interaction between electric and magnetic helds and sensitive electronic circuits and devices. EMI is predominantly a high-frequency phenomenon. The mechanism of coupling EMI to sensitive devices is different from that for power frequency disturbances and electrical transients. The mitigation of the effects of EMI requires special techniques, as will be seen later. Radio frequency interference (RFT) is the interaction between conducted or radiated radio frequency helds and sensitive data and communication equipment. It is convenient to include RFI in the category of EMI, but the two phenomena are distinct. 

Figure 14. The effect of radio frequency interference (periodicpattern noise) on the S/ N performance of the SPD when inadequate RFshielding was used. The emission signal of Zn 213.8 nm at 2.0 pg/mL happened to be located at the node in this particular case. Signal integration time was 16 s. Spectra background subtraction was performed.

On a practical level, while designing the PCB (printed circuit board), we have to be cautious in not putting too much copper at the switching node. Otherwise it becomes an effective electric-field antenna, spewing radiated radio frequency interference all around. 

The original design of the plant did not consider the effects of electromagnetic interference/radio frequency interference, heavy load switching transients and transients generated in the electrical and control systems due to external causes. 

The Class 1 electrical equipment, identified in Table 2.5.2-1 of Reference 4.4, has electrical surge withstand capability and can withstand electromagnetic interference, radio frequency interference and electrostatic discharge conditions that would exist before, during and after a Design Basis accident without loss of safety function for the time required to perform the safety function. SSCs required to perform the plant safety functions (reactivity control, core heat removal control, exposure to radioactive material, release of radioactive material) that could be vulnerable to these effects are classified as Class 1. 

In the case of a radio operating in the FM wavelength band, or indeed any wavelength band, the aerial receives a signal which contains all the transmitted frequencies. What the radio does is, effectively, to Fourier transform the signal so that we can tune in to any of the frequencies without interference from any others. 

In shielding for radio-frequency and electromagnetic interference an electroplated coating may -not be necessary. Highly effective performance can be obtained with deposits of thickness as low as 2 to 3 /on and these can be applied economically by electroless processes, which give very uniform thicknesses of deposits even in recessed areas. 

Nonthermal effects may result from the possible interactions between RF fields and the various components of the biological material. Established effects include (1) The interference of radio frequencies with cardiac pacemakers is possible, however, new models of pacemakers are currently equipped with electronic filters making them immune to fields from... 

It was mentioned in sub-section 13.5.2 that the cut-off frequency for effective screening is in the range of 0.5 kHz to 2.0 kHz for external interference. At frequencies higher than about 1 MHz it is useful to consider the coupling between the screen and the core as an impedance that relates the screen current to the core open-circuit voltage. In such a case it is not specified how the current appears in the screen. It could be by mutual induction from nearby cables, but more often by radio waves received from local radio transmitters, radio telephones, or a radar antenna. The impedance is called the shield transfer impedance Zj and it can be measured by a relatively simple test procedure. The expression for the impedance Zj is -... 

Introduction Types of Distortion The Wireless Radio Channel Effects of Phase and Frequency Errors in Coherent Demodulation of AM Signals Effects of Linear and Nonlinear Distortion in Demodulation of Angle Modulated Waves Interference as a Radio Frequency Distortion Mechanism... 

Radio frequency signals are processed in the transmitter, prior to transmission, and in the receiver, prior to demodulation, by electronic circuits. Such processing can be regarded in a generalized way as filtering. Distortion introduced by nonideal filters and the atmospheric radio channel will be discussed. Following this, the effects on demodulation outputs of frequency and phase distortion and interference on radio frequency signals will be discussed. 

The ICP (Berth, 1970) is an argon plasma maintained by the interaction of an radio frequency (RF) field and ionized argon gas. The ICP is reported to reach temperatures as high as 10,000 K, with the sample experiencing useful temperatures between 5500-8000 K. These temperatures allow complete atomization of elements, minimizing chemical interference effects. 

Next we proceed to develop the theory o resonance fluorescence experiments using the ensemble density matrix to describe the system of atoms. The important concepts of optical and radio-frequency coherence and of the interference of atomic states are discussed in detail. As an illustration of this theory general expressions describing the Hanle effect experiments are obtained. These are evaluated in detail for the frequently employed example of atoms whose angular momentum quantum numbers in the ground and excited levels are J =0 and Jg=l respectively. Finally resonance fluorescence experiments using pulsed or modulated excitation are described. 

Other effects (frequency, conductivity, specific heat capacity, etc.) are discussed by Schiffmann (1995), but are less relevant because the range of available frequencies (which do not interfere with radio transmissions) is small (2.45 GHz, 910 MHz). Lower frequencies lead... 

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