5142 rexplore

[madd]

Hello

 

I want to acquire real data only using 5142 I have mention the path through  which options I want to acquire the real data (attachment) include Real acq, real_frequency translation. What should be the options I have to set for this.  The vi’s I attached here are

For real acquisition. But If u look at these they don’t set the acquisition type to real. Only complex data is acquired either I set it to complex or real.the Vi in which (Complex_bydefult) I do not set the data processing Mode or DDC option but it acquires same complex data as I acquired using (Real_Socalled). This means that either I set the data processing mode to real or not it(Real _Socalled) is acquiring complex data. Am I not setting the options correctly what I am missing. How do I set this complex interleaving or it is active by default when I acquire complex data only.

 

Someone respond to my 5142 channel queries about two channel acq saying

 Technically you can do downconversion from ch 0 and ch 1 at the same time.  However, you will only get real data (and not complex data) for each channel (I is ch 0 and Q is channel 1).  Also, both channels will have to frequency translate from the same IF/center frequency.  If you want to do this, then start from the baseband example and enable frequency translation (and set the center frequency).  You will probably want to set the I and Q phase appropriately. 

2 channel real I have attached will work how if channel 0, channel1 are acquiring both complex data also. I think if this is the case then there is something wrong……what will de the data flow in this case. active channelQ 1

Regards

Madd

[John_P1]

Hi Madd,

The 5142 is capable of being used as a regular digitizer to acquire real data.  You can also use the OSP in the following 4 ways:

1. Send one IF signal to CH 0 and perform quadrature downconversion on the signal (complex data is returned).
2. Send I and Q baseband signals to CH 0 and CH 1 and perform alias-protected decimation (complex data is returned).
3. Send a signal to CH 0 and perform alias-protected decimation (real data is returned)
4. Send a signal to CH 0 and perform real downconversion on the signal (real data is returned)

Which of the above do you wish to implement?  It is not completely clear to me from your post, but if you want to do real downconversion (#4), then you should start with the niScope EX OSP Downconversion.vi example found in example finder under Hardware Input and Output >> Modular Instruments >> NI-SCOPE >> Features.

-John

[madd]

Hello

1- U r certainly true about option 4.The example u have mentioned i have checked it .The confusion i  have is that i  this example both DDC and Frequency translation are true.When we say frequency translation true does it mean that both I(phase) and Q(phase) are generating signals.if so doesn't it make signal complex. also this fetch VI is acquring real data out of complex one coming(using only real value). or .

2 - in real acqusition mode when we eanble frequency translation only I(phase) generate signal multiply it with comming signal.then DDC and then on bord memory comes in this case i think real acqusition is going on.

why i am asking thes question . if i am acquiring real pure data then my complete On bord memory is available to samples i am acquiring(say 256Mb). but with complex mode half the memory is acquired by complex(128) and i am having only half availabe for my real acqusition(128) ist this the case.

Regards

Madd

[Chris_W.]

Hello,

I was hoping to clarify what is actually going on with your application, you wouldn't mind posting some information about what exactly your application involves.What is the signal or signals, that you are going to be acquiring? What is the application? and what is your end goal? What do you expect out of the 5142? And last, why are you so concerned with the way that the DDC block on the OSP works for this real signal? I think it would help to get a better idea of exactly what you're doing and why so that we could come up with the best solution. 

Chris

[Chris_W.]

Hello Madd,

Because your question on this post is the same as on other threads, we would like to consolidate your posts to one thread so that everyone who is interested can follow the progress of your issue. All further activity on this issue will continue on thread linked HERE. Thanks.

Chris W