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Real Time Data Transfer

Another post....
 
 
I've seen a few posts here in the RF forum regarding real time or near real time data transfer using the NI RF hardware and communications toolkit.
 
This one inquired on how to get two PXI chassis to communicate wirelessly.  NI replied that it had been successful in getting devices on the same chassis to do wireless file transfer, but not two seperate (I'm not sure why this would be any different...maybe someone can shed some light).  Anyway...this post seemed to die.  Was just wondering what the outcome was.
 
This program came from a similar post.  It's an FM SDR implemented with the 5660.  Haven't tried it yet, but looks cool.


Anyway...my question...has anyone (forum browser or NI guru) implemented a real-time or near real-time wireless digital link?  Nothing fancy.  Just a simple PSK/FSK/ASK or something similar.  It appears that it can be done.  Just curious if there are any examples or any experiences to be shared.
 
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Brandon
 
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Hi Brandon,
 
RFSA and RFSG currently do not support the Real-Time operating systems.  You could, however, set up a pretty deterministic wireless link.  The complication is that the front end transient and filter response on the acquisition side may cause you to lose some of your data.  When doing a burst-type transmission, you can trigger the acquistion off the acquired power in the band, but as the front end goes through its transient response, some of the data being acquired could be lost.  Your best bet will be to prepend some bits to your data, so that if they are lost, it does not affect your message signal.  You could also implant a "unique word" or synchronization bit stream within your data, so you know when to start acquiring the message.  The important part is to know when the prepended bits end, so that you can make sure you acquire all of your message bits. 
 
We don't have any examples that are specific to a complete wireless system, but you can use the RFSG examples for your transmitter and the RFSG examples for your receiver to start with.  You can set up the receiver to trigger off the acquired power, and modify the transmitter VI to prepend some bits. 
 
Hope that helps...let us know of your progress and any other questions!
 
Regards,
 
Nicholas B
National Instruments
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