This causes aliasing and now the digital system will be missing the full picture of the analog signal. The output of the digital signal is not at all close to the original signal as the sampling rate is not high enough to keep up with the analog signal. In this example, you can see where the sampling occurs in the analog input signal. A good example is shown in Figure 2.įigure 2: An example of how aliasing happens. If the sampling rate is slow and the frequency of the signal is high, the ADC will not be able to reconstruct the original analog signal which will cause the system to read incorrect data. Aliasing means that when a digital image/signal is reconstructed, it differs greatly from the original image/signal caused from sampling. It is important to know the sampling rate of the ADC because you will need to know if it will cause aliasing. “What happens when the sampling rate is considerably slower?” you might ask. This is because the frequency of the original signal is a slow 1 Hz, meaning the frequency rate was still good enough to reconstruct a similar signal. The sample rate is very slow, but the signal still came out similar to the original analog signal. T = Period of the sample or the time it takes before sampling againįor example, in Figure 1, it seems f s is 20 S/s (or 20 Hz), while T is 50 ms. One important equation on the sample rate is: The more samples the ADC takes, the higher frequencies it can handle. This simply means how many samples or data points it takes within a second. The sampling rate is measured by using “samples per second”, where the units are in SPS or S/s (or if you’re using sampling frequency, it would be in Hz). The ADC’s sampling rate, also known as sampling frequency, can be tied to the ADC’s speed. Two important aspects of the ADC are its sampling rate and resolution. They first sample the signal, then quantify it to determine the resolution of the signal, and finally set binary values and send it to the system to read the digital signal. This is because microcontrollers can only see “levels” of the voltage, which depends on the resolution of the ADC and the system voltage.ĪDCs follow a sequence when converting analog signals to digital. Microcontrollers can’t read values unless it’s digital data.

(Source: Waqas Akram – Quantization in ADCs) The easiest way to explain this it through a visual! Figure 1 shows a great example of what analog and digital signals look like.įigure 1: A continuous signal (analog) turning into a digital signal. Digital signals are represented by a sequence of discrete values where the signal is broken down into sequences that depend on the time series or sampling rate (more on this later). These types of signals can come from sound, light, temperature and motion. In the real world, analog signals are signals that have a continuous sequence with continuous values (there are some cases where it can be finite).

Multisim 14.0 adc not working