spectrum (Fourier Transform) of the first 4096 points. Rollovers ADC có format ra phù hợp với hệ thống giám sát sẽ khiến cho mọi thứ trở nên đầu will show larger versions of the plots: dễ dàng hơn. The green line in the spectrum is for a fall-off in noise of 1/f, that is, thermal drift. The total noise asymptote, the red line, sums 2.5 counts (RMS) per decade of frequency white noise with the 1/f noise. This is the same as saying that above 1 Hz, the 16 bit converter is operating at 13.5 effective bits (13.5 effective + 2.5 noise = 16), and below 1 Hz, the drift in the overall measurement system results in higher noise. Full scale range What range of signals needs to be recorded? The electrical power grid may carry 60 kV at 120 kA, while a biological cell may have ion currents ~ fA at potential to a few ADC boards typically μV. have full scale ranges no bigger than ±15 V, but may have uni- or bipolar settings and ranges as low as 10 mV. The number of bits one needs interacts with the range. Suppose a measurement is needed with a resolution of 10 To ensure that one can see μV. noise on top of this range, one least significant bit might need to be 1 If one were using a unipolar ADC, at 12 bits full scale μV. would have to be 212 * 1 = 4.096 mV, a most unlikely μV combination. At 16 bits, full scale would be 216 * 1 = 65.54 mV, still smaller than is common, but μV conceivable. But for a 24 bit converter, full scale would be 224 *
spectrum (Fourier Transform) of the first 4096 points. Rollovers will show larger versions of the plots: The green line in the spectrum is for a fall-off in noise of 1/f, that is, thermal drift. The total noise asymptote, the red line, sums 2.5 counts (RMS) per decade of frequency white noise with the 1/f noise. This is the same as saying that above 1 Hz, the 16 bit converter is operating at 13.5 effective bits (13.5 effective + 2.5 noise = 16), and below 1 Hz, the drift in the overall measurement system results in higher noise. Full scale range What range of signals needs to be recorded? The electrical power grid may carry 60 kV at 120 kA, while a biological cell may have ion currents ~ fA at potential to a few μV. ADC boards typically have full scale ranges no bigger than ±15 V, but may have uni- or bipolar settings and ranges as low as 10 mV. The number of bits one needs interacts with the range. Suppose a measurement is needed with a resolution of 10 μV. To ensure that one can see noise on top of this range, one least significant bit might need to be 1 μV. If one were using a unipolar ADC, at 12 bits full scale would have to be 212 * 1 μV = 4.096 mV, a most unlikely combination. At 16 bits, full scale would be 216 * 1 μV = 65.54 mV, still smaller than is common, but conceivable. But for a 24 bit converter, full scale would be 224 * ADC có format đầu ra phù hợp với hệ thống giám sát sẽ khiến cho mọi thứ trở nên dễ dàng hơn.
Analog2Digital_Done.docx