nluckettParticipantnluckett November 6, 2018 at 5:21 pm
When using the latest API version (the 11/06/18 release). I am getting the error “access violation at address 0x0000000000000000” when using the DIRECT_RF or STREAM_IF flags. I am testing these options by modifying the example python code, and the only change that I am making is this flag.
Can I get some guidance as to how to get this working?
AndrewModeratorAndrew November 7, 2018 at 8:34 am
The STREAM_IF flag has been deprecated and the DIRECT_RF flag has been superseded by our IQ streaming functionality. Both flags were from a time when we didn’t have IQ streaming functionality across the full operating frequency of the BB60C. Is IQ streaming adequate for your application? I do not believe we have any examples or documentation on the older two flags right now.
nluckettParticipantnluckett November 7, 2018 at 9:28 am
I figured that was the case. One of our signal processing people wants to implement an algorithm that requires that the phase of the incoming signal be unchanged. Do have any figures or data that I can use to show him that the IQ data is as good or better than the raw RF data would be? Or perhaps a description of the processing that is performed to create the IQ data?
He understands how sampling works with an ADC, but he seems nervous because he doesn’t know what is happening to the data after that.
Justin CrooksModeratorJustin Crooks November 7, 2018 at 9:41 am
The short answer is that the IF to I/Q data transition is a frequency shift to exactly match your requested center frequency, and amplitude corrections to remove ripple in the IF response. The I/Q data is typically easier to work with than the raw IF data, as phase information is a simple atan2 function, and power is simply I*I+Q*Q.
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