A pulse signal is a discrete signal with various shapes. Compared with a normal analog signal (such as a sine wave), the waveform is discontinuous in the time axis (the waveform is clearly spaced from the waveform) but has a certain periodicity. It is its characteristics. The most common pulse wave is a rectangular wave (that is, a square wave). The pulse signal can be used to represent information, and can also be used as a carrier wave, such as pulse code modulation (PCM), pulse width modulation (PWM), etc. in pulse modulation, and can also be used as a clock signal for various digital circuits and high performance chips. . The so-called pulse signal is represented by a curve with infinite number of breakpoints in the plane coordinate. That is to say, there are no limit points in some places in the periodicity, such as sawtooth wave, and the signal 0,1 of the digital circuit used in the computer. The pulse signal, that is, the signal like pulse beat, relative to the DC, intermittent signal, if the water flow is described, the DC is to turn the faucet on the water pulse or the non-stop switch faucet to form a water pulse. The flashlight turns on the light, this is DC, the non-stop switch light is on and off, and a pulse is formed. The speed of the switching speed is the pulse frequency. Pulse signal transmission distance: photoelectric isolation, passive open circuit output, transmission distance less than 500 meters. The pulse signal is divided into a sharp pulse signal and a triangular wave pulse signal, etc., and can be realized by an integral and differential circuit of the first-order transient circuit of Rc. Assume that the periodic rectangular pulse signal f(t) has a pulse width of Ï„, a pulse amplitude of E, and a repetition period of T, as shown in the following figure. The representation of this signal is 1. Find the complex amplitude of f(t) and expand into Fourier series This equation is a triangular Fourier series expansion, thereby making a one-sided spectrum. The above formula is an exponential Fourier expansion, thereby drawing a bilateral spectrum. 2, draw a spectrogram It can be seen from the expression of the complex amplitude Cn that the envelope formed by the line connecting the vertices of the spectral line is a sampling function. 1) Find the point where the harmonic order is zero (that is, the intersection of the envelope and the horizontal axis) If these frequencies happen to be just an integer multiple of the fundamental frequency, then the corresponding harmonic is zero. Therefore, the intersection of the envelope and the horizontal axis should satisfy two conditions: one is the harmonic condition; the other is the condition that the harmonic is zero. 2) Roughly find the amplitude value of each harmonic 3) Determination of phase 3. Analysis of spectrum characteristics Unmanaged POE Industrial Switches
PoE power supply switch refers to a switch that can provide network power supply for remote powered terminals through a network cable. It includes two functions: network switch and PoE power supply. It is a relatively common power supply device in PoE power supply systems.
PoE power supply switch refers to a switch that can provide network power supply to remote powered terminals through a network cable. It includes two functions: network switch and PoE power supply. It is a relatively common power supply device in PoE power supply systems. The port supports an output power of 15.4W, which conforms to According to the IEEE802.3af standard, the port supports an output power of 30W and conforms to the IEEE802.3at standard. It supplies power to standard POE terminal equipment through network cable power supply, eliminating the need for additional power wiring. A POE switch conforming to the IEEE802.3aT standard, the port output power can reach 15-60W. In layman's terms, a POE power supply switch is a switch that supports network cable power supply, which can not only realize the data transmission function of ordinary switches but also supply power to network terminals at the same time .
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POE (Power Over Ethernet) means that without any changes to the existing Ethernet Cat.5 cabling infrastructure, it is used for some IP-based terminals (such as IP phones, wireless LAN access points AP, network Cameras, etc.) can provide DC power supply technology for such devices while transmitting data signals. The POE technology can ensure the normal operation of the existing network while ensuring the safety of the existing structured cabling, minimizing costs. POE is also known as a power supply system based on local area network (POL, Power over LAN) or Active Ethernet (Active Ethernet), sometimes also referred to as Power over Ethernet for short. This is the use of existing standard Ethernet transmission cables to transmit data and data at the same time. The latest standard specification of electric power, and maintains compatibility with existing Ethernet systems and users. The IEEE 802.3af standard is a new standard based on the POE of the Ethernet power supply system. It adds related standards for direct power supply through the network cable on the basis of IEEE 802.3. It is an extension of the existing Ethernet standard and the first international standard for power distribution. standard
Analysis of Periodic Rectangular Pulse Signal
Introduction to pulse signals