What is the bandwidth and sample rate of an oscilloscope?

What is the bandwidth and sample rate of an oscilloscope?

What is bandwidth? In general terms, the bandwidth of an oscilloscope is defined as the maximum input signal amplitude that attenuates the input signal by 3db.

What is sample rate? How many points can be acquired per second. The faster the speed, the lower the error, generally the sampling rate should be 4 times the oscilloscope bandwidth (amplifier type is Gaussian response).

For digital oscilloscopes there are at least two parts: the Y-channel of the signal under test and the sampling part.

The Y-channel is to amplify (or attenuate) the signal under test, and the bandwidth is for the Y-channel. If the Y-channel can amplify all sinusoidal signals in the range of 0 to 10 MHz uniformly and without distortion, its bandwidth is 10 MHz. since complex waveforms consist of sinusoidal signals with various harmonics, and these harmonics constitute a potentially very wide bandwidth, the larger the bandwidth of your Y-channel, the better, in order to ensure true amplification of complex signals.

It is not enough to have a Y-channel with enough bandwidth. In order to capture the waveform, you have to sample the signal amplified by the Y-channel! The speed of this sampling is the sampling rate. The faster the sampling rate, the more points per unit of time to capture the complex waveform, the final assembly of the waveform displayed closer to the real complex signal.

Therefore, although bandwidth and sampling rate are two different parameters, they are both very important for the true restoration of the measured waveform.

Why the larger the bandwidth, the less distorted the signal?

Complex signals can be broken down into countless high-frequency sinusoidal harmonics, and these high-frequency harmonics make up the details of the original signal. If your bandwidth is not wide enough (mainly because the high end is not high enough), the higher harmonic signals cannot be effectively amplified and passed through (they are blocked or attenuated). As a result, the signal you get at the end of the Y-channel will be distorted (lose the detail of the complex signal).

Therefore, it is important to increase the Y-channel bandwidth as much as possible in order to restore the signal details (without distortion).

Bandwidth is to reflect the signal frequency through the ability, the larger the bandwidth, the signal in the various frequency components (especially high-frequency components) can be accurately and efficiently amplified and display, is also more accurate, if the bandwidth is not enough, it will lose a lot of high-frequency components, the signal naturally display inaccurate, a large error. The sampling rate is the analogue to digital conversion of the signal conversion frequency (i.e., the number of acquisitions per second), the higher the frequency, the higher the acquisition of the signal per unit of time, the more the signal is retained in the signal information, the more information is lost, less information, the conversion of digital quantities will be able to accurately reflect the value of the signal, and then by the LCD display will be able to display a more accurate and complete display of the signal waveform, the more sampling points, the more display points, the clearer it will be. The more sampling points, the more points will be displayed and the clearer it will be.

Simply put, the bandwidth reflects the frequency range of the signal that can be displayed, while the sampling rate reflects the details of the signal waveform.

Why is it that the larger the bandwidth, the more accurately and efficiently the various frequency components (especially high frequency components) in the signal can be amplified and displayed?

For example, if the bandwidth of an audio amplifier is relatively small, such as the bandwidth of 50Hz~15KHz, then signals above 15KHz can not be effectively amplified, the output will be very small or even none, and you can't hear the sound above 15KHz. If the amplifier bandwidth is wider, such as 10Hz~20KHz, then all the audio can be amplified and output, it can output the complete audio sound. Oscilloscopes show the same thing.