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Analog Output signal conditioning
chrisj247
Member
12-19-2007 06:58 AM
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Hi,
1) I am using a PXI6723 analogue output card with the PXI-1033 controller. Since the output of the card is sample and hold based leaving the output "blocking" in morphology, is there a way to interpolate samples and output this from the card to give them a more smoother output and thus reduce the harmonic content of the signals. In other words are there any analogue or digital filters on the card or is there a way to produce this in a labview VI?
2) The card itself is a 13-bit device. Is there a way to ensure this resolution is being used, perhaps there is a setting in MAX to get the 13bit range from the card. I think i may have come across a post where it was mentioned that to get the full amount of bits from the card there was a process that had to be followed in software, in steps of 8 bits. In otherwards if I had a 24-bit card I would have to manually program the sampling of the card in 3 * 8-bit chunks. I dont know where I saw this post so thats why I am checking again. Is the resolution of the card affected by the max-min values specified in software for the card? Similarly I have a 24-bit AI card, PXI4462, and perhaps this has to be catered for also?
1) I am using a PXI6723 analogue output card with the PXI-1033 controller. Since the output of the card is sample and hold based leaving the output "blocking" in morphology, is there a way to interpolate samples and output this from the card to give them a more smoother output and thus reduce the harmonic content of the signals. In other words are there any analogue or digital filters on the card or is there a way to produce this in a labview VI?
2) The card itself is a 13-bit device. Is there a way to ensure this resolution is being used, perhaps there is a setting in MAX to get the 13bit range from the card. I think i may have come across a post where it was mentioned that to get the full amount of bits from the card there was a process that had to be followed in software, in steps of 8 bits. In otherwards if I had a 24-bit card I would have to manually program the sampling of the card in 3 * 8-bit chunks. I dont know where I saw this post so thats why I am checking again. Is the resolution of the card affected by the max-min values specified in software for the card? Similarly I have a 24-bit AI card, PXI4462, and perhaps this has to be catered for also?
JonBowers
NI Employee (retired)
12-20-2007 06:56 AM
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Hi Chris,
There are no filters that reduce this effect on the output of this card. You could apply your own filters to the signal but they would invariably induce some kind of phase delay.
As for the resolution this particular card only has one output range of +-10V. With a resolution of 13 bits this gives you 8192 possible values that the DAC can output, which gives you a code width of about 2.4mV. The way to get the most out of this resolution is for all the signals you output to be between +-10.
The 4462 has configurable gain settings so the value you specify for maximum and minimum will determine which input range and gain the card will use.
Regards
Jon B
Applications Engineer
NI UK & Ireland
There are no filters that reduce this effect on the output of this card. You could apply your own filters to the signal but they would invariably induce some kind of phase delay.
As for the resolution this particular card only has one output range of +-10V. With a resolution of 13 bits this gives you 8192 possible values that the DAC can output, which gives you a code width of about 2.4mV. The way to get the most out of this resolution is for all the signals you output to be between +-10.
The 4462 has configurable gain settings so the value you specify for maximum and minimum will determine which input range and gain the card will use.
Regards
Jon B
Applications Engineer
NI UK & Ireland
