High-frequency signal

The ultrasonic images that we want to process are HF- type, (i.e., huilt from High Frequency signals. Fig. 4). Consequently, the noise is situated in the eentral part of the matrix. In order that we define two thresholds tl and t2. These last will be determined by using one of some measures quoted in the bibliography. 

It is advisable in most of these cases to use accelerometers. Displacement probes will not give the high-frequency signals and velocity probes because their mechanical design is very directional and prone to deterioration. Figure 10-64 shows me signal from the various types of probes. 

In addition to their transporter function, perisynaptic transporters function as buffers to confine the extracellular free glutamate to receptors nearest the postsynaptic release sites. The total concentration of glial transporters in some CNS synaptic regions is estimated to be sufficient to bind the glutamate content of three to five vesicles per synapse [45]. This buffering , which occurs mostly in end-feet of astrocytes, is essential for reliable synaptic transmission of high-frequency signals [46]. 

The phase delay A(nwE) and modulation ratio M(na>E) information of the high-frequency signals is transferred to low-frequency signals by amplitude modulation (cross-correlation) of r.(t) and Iff) with a periodic train of pulses C(f) given by Ref. 29. 

On the other hand, the proposed approach has structure of low pass filter see Eq.(8). Thus, we can expect that the closed-loop response is not sensitive to high frequency signals (as, for example, by noisy measurements or fluctuations in fluids mechanics by agitation). Although Figure 3 depicts the frequency... 

Aliasing Artificial shift of a high frequency signal to a lower... 

Capacitivelv coupled noise. Any two objects form a capacitor ( stray capacitance ) which establishes a path for high frequency signals. Noise which is capacitively coupled into a circuit is basically current noise which is converted to voltage by an impedance between the two objects. 

High-frequency signal (see Table 20). d Low-frequency signal. 

Calculated from high-frequency signals (see Table 24). 305 K. 

Passive filter A kind of usually simple filters composed of elements such as resistors (R), capacitors (C), and inductors (L) that do not depend upon an external power supply. There are different passive filters such as the so-called RC, RL, LC, and RLC varieties. Inductors block high-frequency signals and conduct low-frequency signals, while capacitors do the reverse. Resistors have no frequency-selective properties, but are added to inductors and capacitors to determine the time-constant of the circuit. 

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