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| Siglent SDG1032 as bad as rigol DG812? |
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| 2N3055:
--- Quote from: Fgrir on May 21, 2024, 06:22:20 pm ---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 --- End quote --- I'm not arguing that sometimes to someone because of work they do some options seems more logical. Full name of that function is "Invert polarity". Which explains it. Like I said, if you are doing analog work, inverting polarity will accomplish same thing as adding inverting unity gain buffer in signal chain. You set one channel to track another and then invert one and you have fully differential signals. RTB does what it does because it's dynamic range is already very low so they did that... I reported documentation error to Siglent. I also asked to consider enhancing this with more user control. More user control is good. GUI representation is more symbolic. It shows the shape but not offset. We will see what they think. In meantime, documentation needs to follow the reality. |
| nctnico:
--- Quote from: 2N3055 on May 21, 2024, 06:04:07 pm --- --- 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. --- End quote --- Hint: digital signals do not exist in the real world! If you want to generate any of the signalling protocols I listed before (especially for introducing analog domain errors), an AWG is the tool for that purpose. |
| Fgrir:
--- Quote from: 2N3055 on May 21, 2024, 06:37:00 pm ---GUI representation is more symbolic. It shows the shape but not offset. --- End quote --- Except the GUI does show the offset, and it disagrees with what is coming out of the output. But I agree that the main important thing is that documentation, GUI and output all agree. |
| 2N3055:
--- Quote from: nctnico on May 21, 2024, 06:42:33 pm --- --- Quote from: 2N3055 on May 21, 2024, 06:04:07 pm --- --- 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. --- End quote --- Hint: digital signals do not exist in the real world! If you want to generate any of the signalling protocols I listed before (especially for introducing analog domain errors), an AWG is the tool for that purpose. --- End quote --- You are changing a subject by introducing truisms. Of course that digital signals are analog signals. We are calling signals digital when we are referring to signals as used in various digital circuits, where that implies some sort of logic signals that have two defined voltages for LO/HIGH states and transitions between the two are made fast. Some kind of square wave ish signals that have defined low and high voltages. General purpose AWG is not specialized generator for generating LVDS, CAN and RS485 or that sort of data. Especially inexpensive one that costs same as cheap analog function generators few years ago. With little care you can create them but AWG are not specialized for that. Digital pattern and pulse generators are made for that. Some AWG are made to do that too. SDG7000A has differential outputs and does the stuff you are saying. But it is expensive. |
| 2N3055:
--- Quote from: Fgrir on May 21, 2024, 06:48:43 pm --- --- Quote from: 2N3055 on May 21, 2024, 06:37:00 pm ---GUI representation is more symbolic. It shows the shape but not offset. --- End quote --- Except the GUI does show the offset, and it disagrees with what is coming out of the output. But I agree that the main important thing is that documentation, GUI and output all agree. --- End quote --- You are correct it show something, but it was not how I expected it so I didn't even realize. Thank you for that. Yes, it should show and document what it does. |
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