EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: freebil on August 17, 2016, 09:42:06 am
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Hello. Is it possible to see constellation diagram on rigol? I read here (http://cdn.teledynelecroy.com/files/appnotes/lab303b.pdf) that it requires X-Y display, external sampling clock and a persistence display. Does rigol have them?
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Hello. Is it possible to see constellation diagram on rigol? I read here (http://cdn.teledynelecroy.com/files/appnotes/lab303b.pdf) that it requires X-Y display, external sampling clock and a persistence display. Does rigol have them?
Yes, it does have all the features although I haven't tried. You need the I+Q signals separated (which would feed the X-Y display) and one more channel as a trigger. As it has four channels it's not a problem.
I haven't tried but it should work. The X-Y mode has been improved in the latest firmware version, by the way. With the previous versions it wasn's full screen.
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Thanks for the answer. I understand the inputs for the 2 channels but I dont understand what the input must be for the third channel? Thanks.
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Thanks for the answer. I understand the inputs for the 2 channels but I dont understand what the input must be for the third channel?
A clock. What signal are you trying to display?
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I would like to buy a usrp and try digital transmissions..
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I would like to buy a usrp and try digital transmissions..
Nice. And won't you have a word clock available?
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As far as I understand I have to use usrp internal clock or an external clock which I have to connect it on both usrp and oscilloscope?
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As far as I understand I have to use usrp internal clock or an external clock which I have to connect it on both usrp and oscilloscope?
It depends on what you are doing.
If you are doing a transmission yourself and you want to check the results, you will have a symbol clock you can use. It´s the clock that will mark the transmission of each symbol, as its name says.
If you are just receiving a signal someone else is transmitting, you need to derive that clock yourself. Doing a Google search for terms such as QAM QPSK I+Q clock reconstruction should yield some useful answers, there are several lab notebooks from universities available.
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Hello. Is it possible to see constellation diagram on rigol? I read here (http://cdn.teledynelecroy.com/files/appnotes/lab303b.pdf) that it requires X-Y display, external sampling clock and a persistence display. Does rigol have them?
Yes, it does have all the features although I haven't tried. You need the I+Q signals separated (which would feed the X-Y display) and one more channel as a trigger. As it has four channels it's not a problem.
I haven't tried but it should work. The X-Y mode has been improved in the latest firmware version, by the way. With the previous versions it wasn's full screen.
Well... perhaps you _should_ try it. You will find out that you cannot turn on other channels when the X-Y mode is in use, nor is Persistence available, so it _does not_ have all the features required for a constellation display.
Or maybe you could just read what the User Manual says:
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Well... perhaps you _should_ try it. You will find out that you cannot turn on other channels when the X-Y mode is in use, nor is Persistence available, so it _does not_ have all the features required for a constellation display.
Or maybe you could just read what the User Manual says:
Oops I stand corrected. I wrongly assumed that it could trigger on another channel while in X-Y mode, which would make sense.
And, curiously, the manual says "setting persistence" rather than just "persistence". I'll check.
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I am missing something here. Why would a trigger be needed in (any) X/Y mode display? What would it trigger? (Not the start of the horizontal sweep, obviously, so what else?)
Thanks for educating me!
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I am missing something here. Why would a trigger be needed in (any) X/Y mode display? What would it trigger? (Not the start of the horizontal sweep, obviously, so what else?)
It wouldn't. The DS1054Z disables trigger for a reason.
I think the "Constellation diagram" in the original question needs another input to turn the bean on/off or something like that. It's not very clear.