[USRP-users] RFNoC Data Scaling and Representation

Muhammad, Siraj sirajmuhammad at ou.edu
Mon Jul 10 14:27:35 EDT 2017


Hello All,

I have posted several questions previously trying to understand something but it only got me more confused.
So let me put this straight.
1- I am trying to read the output of the Log Power RFNoC block *in dBm*.
2- I want to write a CE that compares these samples against a threshold entered as a user setting register *in dBm*.

I understand that data in FPGA are represented in 16-bit fixed-point. I have another set of questions that I would love to have them answered. But frankly speaking, above two points are my main concern.


1- I understand that the range of numbers I can represent is -1 ~ 0.99997 correct?

2- When numbers out of this range are passed, overflow happens, right? I guess everything is saturated at 0.9997 and -1?

3- Data from host to FPGA are always considered float and mapped to 16-bit fixed-point? Conversely, data from FPGA to host are always mapped back to float? Can I interpret them differently without conversion?

4- What about user registers? I assume they are passed as is and I have to take care of converting them to fixed-point in my CE if ever used with data buses. Correct?

I appreciate your support.

Thanks,
Siraj
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