Because digital oscillograph has weaveform to spark, memory, show, measure, the distinct advantage such as processing of undee data analysis, its are used gain ground increasingly. Because bigger function difference exists between digital oscillograph and imitate oscillograph, if use undeserved, the measurement with meeting larger generation error, affect test job thereby.
Divisional imitate bandwidth and number real time bandwidth
Bandwidth is one of index with the mainest oscillograph. The bandwidth of imitate oscillograph is a fixed cost, and the bandwidth of digital oscillograph has imitate bandwidth and number real time bandwidth two kinds. The number that the highest bandwidth that date of reply of digital oscillograph counterpoise uses ordinal sampling or random sampling technology can achieve is oscillograph real time bandwidth, real time bandwidth and highest digitlization frequency mix the number weaveform rebuilds technical factor K is relevant (number rate of highest digitlization of = of real time bandwidth / K) , do not give out directly as an index commonly. The definition from two kinds of bandwidth can see, imitate bandwidth suits to repeat the measurement of periodic signal only, and real time bandwidth suits the number at the same time heavy reply date and sheet of second signal measure. Manufacturer claims the bandwidth of oscillograph can obtain how many sign, what point to actually is imitate bandwidth, number real time bandwidth is to want to be worth under this. The bandwidth of the TES520B that says TEK company for example is 500MHz, it is to show its imitate bandwidth is 500MHz actually, and real time bandwidth can reach highest number only 400MHz is far under imitate bandwidth. Measuring sheet so when second signal, must consult the number of digital oscillograph real time bandwidth, can give otherwise measure the error that brings expect to be less than.
About sampling rate
Sampling rate also calls digitlization rate, it is to point to unit time inside, input the sampling frequency of signal to imitate, often express with MS/s. Sampling rate is a of digital oscillograph main index.
1. if sampling rate is insufficient, appear easily the phenomenon that mix change
If the signal losing a person of oscillograph is the sine signal of a 100KHz, the signal frequency that oscillograph shows is 50KHz however, is this how to return a responsibility? Because the sampling rate of oscillograph is too slow,this is, arose to mix alternate phenomenon. Mixing change is the undee frequency that shows on screen the actual frequency under signal, or although on oscillograph touch hair indicator light to had shined, and indication weaveform still is not stabilized. If the graph is shown 1 times,mix the generation of alternate. So, to the weaveform of a sealed frequency, the weaveform that how judges place to show has arisen mix change? Can sweep through be being changed slowly fast T/div arrives faster time base archives, the frequency parameter that sees weaveform is changed whether quickly, if be, explain weaveform mixes alternate to had happened; Or the weaveform of rock is stabilized in a certain faster time base archives come down, also explain weaveform mixes alternate to had happened. According to Nai Kui this specific reason, sampling rate at least the 2 times ability of high frequency composition won't produce prep above signal mix change, be like the signal of a 500MHz, need the sampling rate of 1GS/s at least. Be like below a few kinds of methods to prevent OK and simply mix alternate happening:
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