www.bewet.fora.pl

loczytzn

Oscilloscope should pay attention to the problems with

Reliable measurement results. Oscilloscope should be noted that the use of many places, the author many years of use and scope of the process of testing some of my feelings, introduce some scope to use some of the issues worth noting when, for your reference. (1) CRT oscilloscope preheating before use, should scan the baseline brightness is turned darker or trigger mode selection does not appear as a normal scan lines; such emission electron gun in a CRT electron beam bombardment on the screen fluorescent substance to a lesser extent, help protect the CRT to extend the life of CRT. First,[link widoczny dla zalogowanych], in measuring the level of adjustment to the baseline scan lines parallel to the scale, not too light to transfer the waveform,[link widoczny dla zalogowanych], which will help protect the user's eyes. (2) the process of measuring the amplitude of the signal if we find the regulation as a distinct change in brightness, the so-called \Should be used to continue normal maintenance. (3) measuring the signal amplitude, the wave height should be as close to the oscilloscope face 60% to 80%, the wave height is too small measurement errors. The period or frequency measurement, the whole screen should be 1 to 2 complete waveform; this resolution measurement of the visual impact of errors on the measurement results relative decreases, the measurement results more accurate. (4) with fine-tuning the control of mechanical measuring devices should pay attention to fine-tune the position and should be made in the \Oscilloscope vertical deflection and horizontal deflection factor coefficient with a fine-tuning devices are usually, sometimes fine-tuning than to 2.5:1. If it is not calibrated position, fine tune and can not be accurately than we know at this time of the measurement value is not accurate. (5) Similarly, for the extension of the knob with the measurement process should pay attention to the expansion of the state. For example, the display of the waveform amplitude measurement height 5div, the vertical deflection factor position 1V/div; not expand the actual wave amplitude when the lV / div × 5div = 5V. If the \. As can be seen from this example, if not pay attention to the expansion of the state extension knob, the measurement results will have a huge impact. (6) When the frequency of the signal is low, the vertical oscilloscope input coupling should be placed in \If you are in \get the correct measurements. (7),[link widoczny dla zalogowanych], the higher the frequency range of the measured signal measurements, the bandwidth of the oscilloscope should pay attention to the impact on the measurement results. When the frequency of the signal close to or above the upper limit of the oscilloscope bandwidth, this time on the oscilloscope measured magnitude smaller than the actual rate. For example, with a maximum bandwidth of 20MHz measurement of the frequency range of 20MHz to 1V sine wave signal, the oscilloscope display rate dropped to 0.707V or so. This is the vertical oscilloscope amplitude frequency characteristics of the system caused by the upper limit of the bandwidth it will drop a 3dB, which dropped to 0.707 times the original range. If the frequency of the signal exceeds the maximum bandwidth of the oscilloscope, the oscilloscope shows the rate to fall by more, or even trigger the synchronization is not good and so on. Usually the upper limit of the oscilloscope bandwidth than the signal frequency of at least 3 to 5 times higher, the bandwidth of the oscilloscope measurement of the amplitude can be ignored. ( Cool

,[link widoczny dla zalogowanych], the rising edge of the waveform rise time measurement, pay attention to the oscilloscope rise time of its impact on the measurement results. Waveform displayed on the oscilloscope rise time t, not the actual rise time measured waveform, but the actual rise time of pulse wave t, and the oscilloscope rise time t, its synthesis; that t = √ trl + tr2, then t, 1 = ~ / tr2 a tr2. When using a oscilloscope rise time IOns measuring a rise time similar to IOns pulse waveform, the waveform displayed on the oscilloscope rise time of 14ns or so. Only when t, 1 more than 3 times greater than when tr2, t a tr2; oscilloscope rise time itself can be ignored. About the author: Li Baowen. Male,[link widoczny dla zalogowanych], engineer. Company: Anhui Institute of Measurement and Testing. Address: 230022 Range Road 15, Hefei, Anhui Province. Received :2006-04-14

相关的主题文章：

[link widoczny dla zalogowanych]

[link widoczny dla zalogowanych]

[link widoczny dla zalogowanych]