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| Siglent SDG1032 as bad as rigol DG812? |
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| Fgrir:
Yeah, I'm not saying it's good or bad to invert about 0V or the Offset voltage, but the instrument behavior does not agree with what the user manual says it should do. |
| 2N3055:
--- Quote from: Fgrir on May 21, 2024, 04:39:40 pm ---Yeah, I'm not saying it's good or bad to invert about 0V or the Offset voltage, but the instrument behavior does not agree with what the user manual says it should do. --- End quote --- User manual is wrong. I will report it. Polarity flip is symmetrical around the 0V. It is multiplying voltage with -1. So signal that goes from 1V to 2V and back becomes signal that goes from -1 to -2. Good catch. |
| nctnico:
--- Quote from: 2N3055 on May 21, 2024, 05:51:03 pm --- --- Quote from: Fgrir on May 21, 2024, 04:39:40 pm ---Yeah, I'm not saying it's good or bad to invert about 0V or the Offset voltage, but the instrument behavior does not agree with what the user manual says it should do. --- End quote --- User manual is wrong. I will report it. Polarity flip is symmetrical around the 0V. It is multiplying voltage with -1. --- End quote --- The device is definitely wrong. There are lots of differential signalling protocols (LVDS, CAN and RS485 for example) which have a DC offset. With the way the SDG1000 is working right now, you can never generate such signals. IOW: the DC offset should be applied to both outputs in the same way, only the AC part of the signal should be inverted. |
| 2N3055:
--- Quote from: nctnico on May 21, 2024, 05:55:53 pm --- --- Quote from: 2N3055 on May 21, 2024, 05:51:03 pm --- --- Quote from: Fgrir on May 21, 2024, 04:39:40 pm ---Yeah, I'm not saying it's good or bad to invert about 0V or the Offset voltage, but the instrument behavior does not agree with what the user manual says it should do. --- End quote --- User manual is wrong. I will report it. Polarity flip is symmetrical around the 0V. It is multiplying voltage with -1. --- End quote --- The device is definitely wrong. There are lots of differential signalling protocols (LVDS, CAN and RS485 for example) which have a DC offset. With the way the SDG1000 is working right now, you can never generate such signals. IOW: the DC offset should be applied to both outputs in the same way, only the AC part of the signal should be inverted. --- End quote --- Don't arbitrarily invent things. AWG is analog device, not digital pulse generator. Inverting analog signal is just that: inverting it, as in put it through unity gain inverting amplifier. We could argue that a request could be made to Siglent to enhance AWGs with adding a choice to cater for digital signals. Adding option Logic NOT, for instance. So you would have "Normal", "Inverted" (both would be same as now) and "Logic NOT" that would invert signal in a logic NOT manner (inverting it but inside current voltage envelope as set). I don't think that is a bad idea. But certainly not a default behavior of an AWG. |
| Fgrir:
I really shouldn't get in the middle of which mode is right or wrong, but I think my preference is to invert about the offset voltage. In a perfect world I think there would be a control to let you do either. A quick check with the function generator on my RTB2004 shows that its invert control works relative to the offset voltage, so there is at least one other example of a function generator that would invert +3.3/0V to 0V/+3.3V. If you think the behavior of the SDG generators are correct, then they would also need to change their GUI representation of the signals when they are inverted. I have to say that this GUI is often times not accurately representing the active settings, but for the invert control the GUI clearly agrees with the user manual. EDIT: Fixed the invert attachment |
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