How to trigger sweep DG1022z and DG1062z - Page 1
Forum section: electronics / testgear

author: stevebeu
author_rank: Newbie
timestamp: August 29, 2018, 03:00:59 am
content: Both my Rigol AWGs output continuously in sweep mode even though the trigger is set to external or manual. Has anyone else had this problem or know a fix?

author: JS
author_rank: Frequent Contributor
timestamp: August 29, 2018, 05:07:43 am
content: Do you have something connected to the trigger input?Do you have them set for single run?Told us a bit more about the setup, how you have the things wired and all that.JS

author: stevebeu
author_rank: Newbie
timestamp: August 29, 2018, 06:15:05 am
content: Thanks for the reply JS. Nothing connected to external trigger input with this application; trigger is issued via usb from LabView code. Modes other than sweep work fine with trigger via usb when mode set to manual, and with external TTL trigger when mode set to external. Not sure what you mean by "set for single run" other than setting appropriate trigger mode. Programming manual indicates that sweep should issue only on receipt of trigger when in external or manual mode; however, both the 1022 and 1062 here output continuously in these modes when set for sweep output. Exchanged a few emails with Rigol a while back but that lapsed on their end with no resolution.

author: stevebeu
author_rank: Newbie
timestamp: August 29, 2018, 07:10:34 pm
content: Initiated another exchange with Rigol and they now explain that that these instruments output continuously at the start frequency of the sweep when set to external or manual trigger! Am really puzzled why Rigol has elected to have output in the absence of a trigger. Does that not defeat the very purpose of triggering!? Is this behavior typical of other arbs and perhaps desirable for some standard test protocol out there? They suggested creating an arb waveform of the desired sweep, which I have done, but this makes changing sweep parameters very laborious.

author: JS
author_rank: Frequent Contributor
timestamp: August 31, 2018, 02:17:27 am
content: I thought it might be an option to select between single and continuous run while external trigger, which would make more sense than only continuous mode as they've done, which doesn't make any. I was thinking it could be with trigger high it will sweep continuously and with trigger low stop or backwards.JS

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: August 31, 2018, 03:33:08 am
content: Are you saying the generator continuously sweeps even though the it has not been triggered, or just that it continuously outputs a non-sweeping (single frequency) signal until its triggered. If its the latter, I'm pretty sure this is normal behavior. As long as the waveform output is turned on, it outputs a signal. Triggering the sweep is just that, starting the actual sweep.

author: stevebeu
author_rank: Newbie
timestamp: August 31, 2018, 06:11:42 pm
content: It continuously outputs the starting frequency until triggered and then sweeps. Am curious why that would be normal behavior for sweep. Is there some standard test protocol out there that requires steady state input prior to chirp? All other AWG modes have no output until triggered. My application requires determining the system response to an isolated chirp event. Am currently doing that with a stored waveform in arb mode; however, that makes changing sweep parameters in response to test results a real pain.

author: JS
author_rank: Frequent Contributor
timestamp: September 01, 2018, 03:19:01 am
content: That makes much more sense. Can't you gate the output, or enable/disable with some other function? Those two functions together will make what you want, only of your frequency is too high for the response of the equipment it could bring some issues, and even then, you could set your start freq a bit lower and enable the output a controlled time later.JS

author: stevebeu
author_rank: Newbie
timestamp: September 01, 2018, 10:51:03 pm
content: Thanks for the suggestion JS; unfortunately, I'm working in the MHz range and the output enable/disable timing via software/USB isn't precise enough to properly "capture" just the desired chirp portion of the output. The application is an impulse/response measurement (of ion cyclotron motion) that requires a known (for spectral selectivity) and reproducible (for response signal averaging) power spectrum of the impulse. Looks like my best bet at this point is just to write a LabView vi to automate the creation and load of desired chirp via arb mode. Thanks again for your thoughts.

author: JS
author_rank: Frequent Contributor
timestamp: September 02, 2018, 12:00:10 am
content: I see.. When you enable the output, the chirp doesn't start over if it was with the trigger up or running continuous?JS