■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
▼
Signal Connection to External Devices
DS1104 Hardware Installation and Configuration March 2004
153
▲
■■■■■■■■■■
I
▲
■
■■■■■■■■■■■■■■
ADC Performance of dSPACE Boards
We are frequently contacted because of the “poor” performance of
the A/D sections of our boards. This is usually derived from looking at
the noisy signal traced in ControlDesk when sampling an unconnected
A/D input or an A/D input shorted to ground. However, this has
nothing to do with the definition of the SNR (signal-to-noise-ratio) we
publish in the data sheets of our boards.
A common misunderstanding is that theoretical maximum values of
ideal ADCs are expected from real-world components in real-world
board designs, even inside PC environments. This is impossible. A
16-bit ADC, for example, never has an effective number of bits equal
to 16.
The A/D section of every dSPACE board is FFT (Fast Fourier Transform)
tested during production so that we can guarantee the published data
sheet values for every board. For 16-bit ADCs we typically achieve an
SNR of 78 … 82 dB depending on the board type. This corresponds to
an effective number of bits of about 12.5 … 13. This is the best that
can be achieved in typical PC environments.
For background information, refer to:
■
Definition of SNR
on page 154
■
Measuring Noise
on page 155
■
“Noise Reduction Techniques in Electronic Systems” by Henry W.
Ott, John Wiley & Sons, Inc.
Содержание CLP1104
Страница 6: ...Contents DS1104 Hardware Installation and Configuration March 2004 I 6 ...
Страница 20: ...Safety Precautions DS1104 Hardware Installation and Configuration March 2004 I 20 ...
Страница 70: ...Implementing and Handling Applications DS1104 Hardware Installation and Configuration March 2004 I 70 ...
Страница 118: ...Mapping of I O Signals DS1104 Hardware Installation and Configuration March 2004 I 118 ...
Страница 156: ...Signal Connection to External Devices DS1104 Hardware Installation and Configuration March 2004 I 156 ...
Страница 162: ...Data Sheets DS1104 Hardware Installation and Configuration March 2004 I 162 ...