Sampling/Triggering externally with DSA cards with even sample spacing in frequency space

Hi there,
Is it possible for the NI DSA cards to trigger on a signal to record at a desired time, at an un-even spacing in the time domain. For my application I need to have the samples evenly spaced in frequency space.
I would set the first channel for acquisition from the source. Would use the external trigger port, or the second channel for the trigger signal?
This is for a optical coherence tomography system.
Thanks!

Hi Anthony,
You may have to excuse some of what I say since I am still a bit uncertain of what you need to accomplish due to my lack of understand of OCT. If you wanted to start your acquisitino at a given time by using an external trigger, most cards have a trigger input which will allow you to do so. However, using an external clock will be much more difficult. While it will be difficult to use an external clock signal with a DSA device, resampling may be a better option. Here is an article which shows some of the resampling functions which, by my understanding, may accomplish what you need to do. Let me know if this puts us in a better direction.
Regards,
Kent
Applications Engineer
Digital Multimeter Home

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External Usb Audio Card Popping and Cracking sound with Satellite L500

Greetings,
My name is Boyan and I am from Bulgaria and about an year ago I've bought a satellite laptop from the l500 series ( i can not state which exactly is the model at the moment because my computer is not currently with me and on my user manual the only thing which is stated is that it is for L500/L505/ L500D / L505D . But by memory I think it was the Satellite L500D-ST5506 which is currently not at my dispossal because I gave it for repair for the same problem which I will state down below)
The problem with my laptop is that when I plug a Usb Audio card in my laptop I have a cracking sound when live sound is played trough the speakers/headphones from the external card. I've tried numerous audio cards and speakers/headpohnes which work perfectly fine with other computer, including laptops but the same problem keeps on showing up in the headphones/speakers of my laptop when I am using an external audio card to connect them to the laptop.
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At first I thought that the problem should be software and I should install new drivers although windows 7 automaticaly recognizes and intalls the drivers for the devices and I have sound in them (but with cracks and popps) so i tried using the official drivers sold to me with the audio cards but with no luck: The problem was still there. I tried finding new drivers of the audio cards on the official distributors websited and i've downloaded them but the problem was still there. Then i tried to delete every audio driver on my computer and just use the external audio card for sound but this dint help eighter. I've updated my drivers for my build-in audio card as well but again - no luck.
After that.the frist thing I did when (2 weeks after i bought the laptop) was to contact the store from which i bought my audio card and they stated that the problem may be eighter latency or high voltage from the laptop so they adviced me to try to lower the latency from the settings or to try and see if the problem remains if my laptop is only running on battery. I've tried both things and they didn't help. The audio cards worked without a problem on every other computer I've tried them on except mine. So they said to me that the problem couldnt possibly be from the audio cards .
What I did next was I gave my laptop to the official distributor of toshiba in my country so they can fix my problem. What they said to me was that the problem is caused from the version of windows which was pre-installed on my laptop and that it wasnt compitable with the audio cards (which was bizzar sounding because I've tried them on the same windows and they've worked, just on other computers). So I got back my laptop and changed my operating sistem from Windows 7 Home Premium 64bit to Windows 7 Ultimate Edition 64bit to Windows 7 Ultimate Edition 32bit and on all of those versions the problem was there: whenever I activate a Usb Audio Card and audio signal passes trough it I heard cracks and popps. I even tried isntalling Windows XP but the laptop wants spesific SATA drivers for the installation of Windows XP which although i did find - they didnt help me install XP and I didn't want to go in to the BIOS of the computer to try to put a new one and so on because I am not so sure about that and I could lose my warranty so I said to the official repair store for Toshiba in my town to put XP on my computer to fix the problem but they can't because they are not liscened to operate with software which doesn't have a recipt for its purchase ( which i didnt because i bought my windows xp long ago and i've lost the recipt)
I gave it for repair for the second time telling them that the change of my operating system did not solve my problem and what they did was they changed the whole motherboard on my computer, stating that the build in realtek audio device on my computer is not good enough to support an usb audio card or it maybe broken and they have to change the whole motherboard because the build in card is glued to it, so they did that but my problem wasn't solved. They told me that although I am using and external usb audio card the signal still passes trough my internal one and I have to disable it so i tried disabling it trough the control panel but this did not solve the problem and i do not have an option from BIOS to disable my build-in audio card. Another thing which I thought maybe causing the problem is that the two audio cards aren't working on the same bit rate and Hertz so I set both cards to 16 bit 48000hz DVD Quality (Also tried other options on the 3 cards i have) but...the same thing happend.
They told me that this is just my luck and that the build in audio card doesn't support this external audio cards and I should had been more careful when choosing my laptop at first.
I couldn't accept this awnser for several reasons:
1) This audio cards work on lower version of windows and are supported by much older models of Realtek and much older computers (one of them was bought 2000!!!!! and my laptop is from 2010!!)
2) The guys who were fixing the problem apperantley didn't go in so deep in to my problem because they didn't know what actually the problem was they just knew that there is a problem with the audio card and the computer interacting with eachother, they didnt know that there is cracking during live play from the external audio card.
3) I can not accept the fact that Toshiba is manufacturing models with chipset audio cards which can not support a simple external Usb Audio Card. This is totally unacceptable for me and I truly hope this is not the case!
4)They didn't try my audiocards on an other laptop from the same series stating that they do not have one at their dispossal at the moment so I will go tomorrow to a local store and try the audio cards by my self on the same computer in the store.
What I did now was I gave back my laptop for repair asking for a statement of the problem in wrtting with all details of the problem so I can go to court or ask for a new laptop but I will be charged with some money because according to them there is no problem in the laptop and the problem is that my external audio cards arent compitable with the build in internal chipset audio card. If I give my laptop for repair and there is no hardware problem I will have to pay some money. I will do this but I am now mad, since this will not solve my problem and I am loosing time and money.
What I am asking here is, if you can not help me solve my problem and advice me what to do to fix it, please provide me the details of the chipset build in audiocard on my motherboard, so i can investigate if it is compitable with my external audio cards and contact the audio card dealers to ask them for their opinion. Or if you can tell me with what it is compitable with and with what not, it would be great. I personally think that this laptop should have no problems at all with running a simple external usb audio card but I am asking you, if you know something more about that.
If the problem is from the build in chipset then Toshiba is manufacturing (or at least selling) audiocards which aren't at a normal standart but sadly I cant do nothing about it except complain to Toshiba and never deal whith such productgs anymore. In the other case if this is not true, then my laptop has a problem which is different and I will have to go to court with the repair mans for not fixing my laptop or not giving a new one when I have warranty which will not be Toshiba's fault and It will in a way solve my problem.
I hope you understand how Important this is for me and I hope I resolve the problem as soon as possible.
P.S
I would like to state that I am well aware of the grammar mistakes I have made in the text below and I would like to ask for your apologies as I am not a native English language speaker.

hi i just like to say i had a similar fault though i would be surprised if it causing yours,but you never know,my fault was my laptop lid, [9 months old] it contains the mic ,and when the lid was in a certain angle crackles could be heard worse when i had my external sound card in, it was a faulty membrane [ lid to body] easily missed by engineer because it was the same angle all the time it happened,good luck, PS you English is very good
Message was edited by: sido1

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Sampling/T​riggering externally with DSA cards with even sample spacing in frequency space

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Sampling/Triggering externally with DSA cards with even sample spacing in frequency space