5142 rexplore

Question

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
Attachments:
5142_questions.zip ‏270 KB

Answer 1

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