Constellation diagram on rigol ds1054z - Page 1
Forum section: electronics / testgear

author: freebil
author_rank: Regular Contributor
timestamp: August 17, 2016, 09:42:06 am
content: Hello. Is it possible to see constellation diagram on rigol? I readherethat it requires X-Y display, external sampling clock and a persistence display. Does rigol have them?

author: borjam
author_rank: Unknown
timestamp: August 17, 2016, 10:06:52 am
content: Quote from: freebil on August 17, 2016, 09:42:06 amYes, 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.

author: freebil
author_rank: Regular Contributor
timestamp: August 17, 2016, 10:09:05 am
content: 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.

author: borjam
author_rank: Unknown
timestamp: August 17, 2016, 10:11:59 am
content: Quote from: freebil on August 17, 2016, 10:09:05 amA clock. What signal are you trying to display?

author: freebil
author_rank: Regular Contributor
timestamp: August 17, 2016, 10:13:19 am
content: I would like to buy a usrp and try digital transmissions..

author: borjam
author_rank: Unknown
timestamp: August 17, 2016, 10:28:15 am
content: Quote from: freebil on August 17, 2016, 10:13:19 amNice. And won't you have a word clock available?

author: freebil
author_rank: Regular Contributor
timestamp: August 17, 2016, 10:40:52 am
content: 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?

author: borjam
author_rank: Unknown
timestamp: August 17, 2016, 10:45:39 am
content: Quote from: freebil on August 17, 2016, 10:40:52 amIt 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.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: August 17, 2016, 09:10:05 pm
content: Quote from: borjam on August 17, 2016, 10:06:52 amWell... 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:

author: borjam
author_rank: Unknown
timestamp: August 18, 2016, 07:08:27 am
content: Quote from: alsetalokin4017 on August 17, 2016, 09:10:05 pmOops 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.

author: ebastler
author_rank: Super Contributor
timestamp: August 18, 2016, 03:49:31 pm
content: 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!

author: Fungus
author_rank: Super Contributor
timestamp: August 18, 2016, 07:53:08 pm
content: Quote from: ebastler on August 18, 2016, 03:49:31 pmIt 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.