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| Gw Instek GDS2204E (200MHz 4 channel DSO) review |
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| nctnico:
--- Quote from: 2N3055 on February 19, 2018, 07:27:24 pm ---For DS1000Z: Offset Range (Probe ratio is 1X) 1 mV/div to 499 mV/div: ±2 V 500 mV/div to 10 V/div: ±100 V As far as I could see, DougM wants to look at part of 40V P-P signal at better than 1V/DIV or less.. No digital scope I know of will have dynamic reserve of 200x of full screen sensitivity... And probably only +-8 to 10 DIVS... --- End quote --- That depends entirely on how the input circuit is designed and it is not 200x but 5x (40V/8V full display range @ 1V/div = 5x). If the oscilloscope allows a large offset then the input circuitry should be designed to handle a signal which swings between the maxima of the offset. It seems the Rigol has a design flaw and thus has overdrive problems. |
| 2N3055:
--- Quote from: nctnico on February 19, 2018, 08:26:57 pm ---That depends entirely on how the input circuit is designed and it is not 200x but 5x (40V/8V full display range @ 1V/div = 5x). If the oscilloscope allows a large offset then the input circuitry should be designed to handle a signal which swings between the maxima of the offset. It seems the Rigol has a design flaw and thus has overdrive problems. --- End quote --- He said that he would want to look at 10mV/DIV if he could... I simply stated that what he expects is unrealistic.. The fact that other scopes might recover a bit better or will allow one more step on a vertical atten before going crazy is not gonna give him what he wants to do... Every overdriven amplifier have overdrive problem. Also I really doubt ANY digital scope will have full 5 screens below and above actual screen of dynamic range.. Maybe a screen but not much more. Like I said, if you know one that has such a great dynamic range I would like to know.. Old CRT scopes had signal path with much higher voltage on power supplies .. That gave them much higher inherent dynamic range.. They were much better in that regard.. On DS1000Z input path is powered by +-5V.. if they used +-15V, followed by limiter to protect A/D converter, it would be much better... I agree. But not much better. Maybe one more step on attenuator.. Don't get me wrong. I'm not defending Rigol. I would be very interested in a test how other scopes would fare in this respect. I suspect not much better. How much quantitatively, needs to be tested.... Regards Sinisa |
| DougM:
--- Quote from: 2N3055 on February 19, 2018, 09:08:59 pm --- --- Quote from: nctnico on February 19, 2018, 08:26:57 pm ---That depends entirely on how the input circuit is designed and it is not 200x but 5x (40V/8V full display range @ 1V/div = 5x). If the oscilloscope allows a large offset then the input circuitry should be designed to handle a signal which swings between the maxima of the offset. It seems the Rigol has a design flaw and thus has overdrive problems. --- End quote --- He said that he would want to look at 10mV/DIV if he could... I simply stated that what he expects is unrealistic.. The fact that other scopes might recover a bit better or will allow one more step on a vertical atten before going crazy is not gonna give him what he wants to do... Every overdriven amplifier have overdrive problem. Also I really doubt ANY digital scope will have full 5 screens below and above actual screen of dynamic range.. Maybe a screen but not much more. Like I said, if you know one that has such a great dynamic range I would like to know.. Old CRT scopes had signal path with much higher voltage on power supplies .. That gave them much higher inherent dynamic range.. They were much better in that regard.. On DS1000Z input path is powered by +-5V.. if they used +-15V, followed by limiter to protect A/D converter, it would be much better... I agree. But not much better. Maybe one more step on attenuator.. Don't get me wrong. I'm not defending Rigol. I would be very interested in a test how other scopes would fare in this respect. I suspect not much better. How much quantitatively, needs to be tested.... Regards Sinisa --- End quote --- No, I don't think I asked for 10mV per box (though that would be excellent!). With a 10x probe the Rigol can only handle 5V/div on a 40V pkpk signal, which is very disappointing. (I will try with the probe at 1x later today and see what I can do). I'd like better than 1V/division for sure, and 100mV would be nice. I'm coming to realize that this may not be a very mainstream use case. Doug |
| 2N3055:
--- Quote from: DougM on February 19, 2018, 10:03:24 pm ---No, I don't think I asked for 10mV per box (though that would be excellent!). --- End quote --- No you didnt, but I kinda figured you would like it :-)) --- Quote from: DougM on February 19, 2018, 10:03:24 pm ---I'm coming to realize that this may not be a very mainstream use case. --- End quote --- No it's not so much. But it would be very useful. On several occasion during years I wish I had a scope that could do that.... Regards, Sinisa |
| tautech:
--- Quote from: nctnico on February 19, 2018, 08:26:57 pm --- --- Quote from: 2N3055 on February 19, 2018, 07:27:24 pm ---For DS1000Z: Offset Range (Probe ratio is 1X) 1 mV/div to 499 mV/div: ±2 V 500 mV/div to 10 V/div: ±100 V As far as I could see, DougM wants to look at part of 40V P-P signal at better than 1V/DIV or less.. No digital scope I know of will have dynamic reserve of 200x of full screen sensitivity... And probably only +-8 to 10 DIVS... --- End quote --- That depends entirely on how the input circuit is designed and it is not 200x but 5x (40V/8V full display range @ 1V/div = 5x). If the oscilloscope allows a large offset then the input circuitry should be designed to handle a signal which swings between the maxima of the offset. It seems the Rigol has a design flaw and thus has overdrive problems. --- End quote --- Yep, the devil is in the detail. For the new Siglent X-E series: Offset ranges 1x input. 500uV~118mV/div: ±2V 120mV~1.18V/div: ±20V 1.2V~10V: ±200V/div 2V/div will give sufficient offset for DougM's needs and using the minor divisions ~250mV resolution. |
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