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HDMI high-frequency high-frequency measurement parameters measured analysis of the significance of high-frequency measurement n when the operating frequency of the electronic circuit higher and higher, the electrical characteristics of the more difficult to master electronic components. When the component size or the size of the overall circuit and the operating frequency corresponding to the wavelength compared to a ratio of greater than ten, the line inductance and capacitance values, or even parasitic component material characteristics, increases with operating frequency is highlighted. Thus a trace is no longer a simple cable assembly is no longer determined by a simple ideal value; derived from the many to represent the equivalent circuit. At this point you can not get a simple quantity of electricity meter value, and shall be a high-frequency electromagnetic properties or transmission line theory (transmission line theory) to be analyzed. Open & short circuit n Open (Open): refers to the two end points of the circuit is not connected to any component or disconnection occurs, the open ends of the current zero point, the signal can not continue. n short circuit (Short): refers to the direct contact with the two end points of a circuit or path zero resistance value, the potential difference between the two end points of zero short-circuit. Standard load (Load) n standard load (Load): refers to the two end points of the circuit connected to a load, the load and the input of the values ??match, the input is not reflected load transmission via high-frequency signals will not be distorted or deformation. This value represents the VSWR ratio n Another way coaxial transmission line reflections quality, maximum voltage and minimum voltage standing wave ratio is. n is calculated as follows: If the load is equal to the reference voltage, then (Z0 = ZL), VSWR is "1." If the load is open or short circuit, it will be close to VSWR "∞". Attenuation (α, Attenuation) n refers to the output of power (Pout) than the input power (Pin), reducing the number. (And the type expressed in dB) is calculated as follows: n according to American Standard ASTM-D-4566-94, measured at ambient room temperature should be performed 20 ± 2 ℃ in. If you can not measure the temperature, and the amount of change in the other reasonable measure temperature, temperature compensation is required in order to obtain the data measured at 20 ℃ get. Temperature compensation formula is as follows: αT = T ○ C in the amount of time to decay. T = temperature measurement when. α20 = compensation to 20 ○ C attenuation. Velocity ratio (Velocity of Propoagtion) n insulating dielectric material reflects the high-frequency signals transmitted waves hampered the phenomenon of light propagation velocity and percentage (%). Therefore, the propagation velocity is mainly composed of the dielectric constant of the insulating material between the center conductor and the covering (εr) to decide. n vp: phase velocity (%) τd: phase delay (ns) → over LAN cable with length LL: cable length (m) C: light speed 0.3 m / ns propagation delay (VR, Delay) n refers to the fixed frequency signal wave, after the analytes fixed length of time required. n propagation delay time difference (Delay Skew): refers to the different signals reach the receiving end of the time difference. Can be divided into: the differential delay difference (Intra-pair Skew) Internally, the difference between the differential delay (Inter-pair Skew) two kinds. Crosstalk (Cross talk) n interference between the two lines each electromagnetic noise, and increases as the frequency increases. n near-end crosstalk (NEXT) n remote crosstalk (FEXT) n output into the remote crosstalk (IOFEXT) n and other quasi-remote crosstalk (ELFEXT) n power and (Power Sum) rise time of recession or bandwidth (Risetime) n refers to the analyte signal through the waveform rise time of a recession scenario, up longer, more severe recession, high frequency, bandwidth can be used for the smaller range. n 0.35 = rise time of recession (ps) × bandwidth (GHz) attenuation / insertion loss n attenuation / insertion loss: represented by α, is the output voltage Vout compared to the input voltage Vin, the signal loss is much left. Usually used to measure the NA. The amount of the instrument can be directly obtained, and the type expressed in dB. The formula is as follows: α = 10lg (Pout / Pin) = 20lg (Vout / Vin) Consider: How much is the maximum value of α? n 1, Crosstalk: by Xtalk expressed defines mutual electromagnetic interference between the two lines, generally increases as the signal frequency increases. Divided into two categories, NA or TDR can be used to measure, is calculated as follows: Xtalk = 10log (P interference / Pin) = 20log (Vout / Vin) in dB by NA: Xtalk = Vout / Vin in% by TDR n Crosstalk is divided into two categories: NEXT --NEXT = 20log (Vnear / Vin) in dB or Vnear / Vin in% FEXT --FEXT = 20log (Vfar / Vin) in dB or Vfar / Vin in% n Consider: If Xtalk value is closer to 0dB (or nearly 100%), indicating that mutual electromagnetic interference fewer or more serious? N the characteristic impedance of the transmission line structure is affected, when there is a high-frequency signal transmission, the characteristics of each point of voltage and current than the conductor. Its formula is as follows: n the above formulas established conditions are: G ', R' is small, and f >> 0. n transmit signals in different forms depending on the amount of the measured impedance can be divided into the following three: n Single-ended impedance (Single Ended): Zse n differential impedance (Differential Mode): Zdiff n common mode impedance (Common Mode): Zcom according to HDMI specify different selected position, the impedance measurement can be divided into: n (Cable) Differential Impedance-Zdiff (original wire) differential impedance n Connector (Differential) Impedance -Zconn: joint (differential) impedance n Transition area ( Differential) Impedance- transition zone (differential) impedance n impedance mismatch will cause reflection of high-frequency signals, thereby interfering with reception of the signal source, but also cause poor attenuation characteristics. Propagation delay time Propagation delay time n: refers signal transmission line, the input time required to reach the receiver. According to the signal can be divided into: n a single-ended delay (Single Ended Delay) n Second, the differential delay (Differential Mode Delay) n Third, the common-mode delay (Common Mode Delay) Propagation delay time difference n means different signal lines , the signal arrives at the receiving end of the time difference, that is, the difference Delay; common Delay can be divided into two types: n internal delay difference: refers to the input differential signal is the same difference between the two wires within the cable Single-end Delay of value. This parameter measurements can be set Differential signal on TDR, a direct amount, too. Inter delay difference: is the difference between the different lines of Differential Delay between. This parameter is two or more points (depending on the number of pairs may be) measured and then calculated.