The waveform of voltage or current is just like the pulse-beating waveform on ECG, but what about the power pulse and sound pulse we hear now? The original meaning extension of pulse: mechanical forms such as waves emitted in the same time interval. Academically, pulse is defined as a physical quantity that suddenly changes in a short time and then quickly returns to the initial value.
From the definition of pulse, we can't see that pulse has the characteristics of interval, so we can take pulse as a signal. The definition of pulse signal thus produces:
Compared with the continuous signal that appears for a short time in the whole signal period, there is no signal in most signal periods. Just like a person's pulse. Now it generally refers to digital signals, and there is a signal half the time (or even longer) in a cycle. The signal in the computer is a pulse signal, also known as a digital signal.
Specific introduction
Pulse. To be exact, it should be called nerve im-pulse. When a certain part of the nerve is stimulated with sufficient intensity, an action potential is generated in this part and propagates in two directions along the nerve fiber from this point. Impulse and action potential have the same meaning, but impulse is used as a signal propagating along the axon. According to the main position of impulse, it is an organ that acts from the center to the periphery in centrifugal nerve and conducts from the peripheral receptor to the center in centripetal nerve. Its function is to connect the central and peripheral signals. The transmission speed of impulse can vary with the thickness of myelin sheath and nerve fiber. The conduction velocity of myelinated nerve is proportional to the fiber diameter. In mammals, expressed by fiber diameter (micron) × 6m/s, the maximum is 120m/s, and the conduction velocity of unmyelinated nerve is proportional to the square root of the diameter, usually below 2-3m/s. ..
Pulse signal: A voltage or current that changes suddenly and has a very short action time is called a pulse signal. It can be repeated periodically, irregularly or once.
Pulse reactor: a reactor that can reach supercritical state in a short time interval, thus generating high pulse power and strong neutron flux, and can be safely and reliably operated repeatedly. It is divided into thermal neutron pulse reactor and fast neutron pulse reactor. China has built a uranium zirconium hydride pulse reactor, which uses uranium zirconium hydride as fuel. It mainly uses hydrogen as moderator. With the increase of power and temperature, the moderating effect of hydrogen is weakened and the reactivity is immediately reduced. The reactor has a large instantaneous negative temperature coefficient, so it runs in pulse mode. Pulse reactors can be used for training personnel, conducting research and producing short-lived radioisotopes, as well as treating cancer, neutron radiography, activation analysis and irradiating fuels and materials.
Pulse power supply: the user's load needs intermittent power supply, that is, according to a certain time law, the load is powered on for a certain time, and then powered off for a certain time, one at a time, forming a cycle. This repeated execution constitutes a pulse power supply. For example, in the aging process of non-polar electrolytic capacitors, the capacitor needs to be charged forward for a period of time, then discharged, then charged backward for a period of time, and then discharged, thus forming a positive direction → discharge (power off) → reverse direction → discharge → forward direction, and so on.
Pulse width: it is the duration of high level. It is usually used as a sampling signal or trigger signal for components such as thyristors.
Pulse circuit: It is a circuit that generates, shapes and transforms pulse waveforms. The pulse circuit consists of two parts: an inert circuit and a switch. The function of the switch is to destroy the steady state and make the circuit transient.
Pulse dialing: it is a time domain processing method, which uses the number of pulses to represent numbers. Pulse dialing mode has strict requirements on pulse width, size, spacing and shape. If these parameters are changed due to line interference or other reasons, it may lead to wrong number reception. On the other hand, because each pulse takes up a certain time (generally, the time taken up by each pulse is 100ms), this dialing method is slow.
Pulse heating: it is intermittent heating by using pulse current of various waveforms to meet some special process requirements.
Pulse wave: it is a signal waveform generated in the form of impact.