Paul Creekmore wrote:
Context: I'm adding new
quantization (sample width) options to the USRP FPGA configuration.
(Long time in coming; yes, I know.)
Question: I'm seeing that in 8-bit mode, the USRP outputs samples from
its internal channels in the following sequence (an 8-bit, 8-channel
example):
1, 0, 3, 2, 5, 4, 7, 6, 1,0, 3,2, ...
where each grouping of two channels makes one 16-bit word.
----> What is the rationale behind this convention?
As I'm deciding how to output 4, 2, and 1-bit samples, it makes much
more sense to me to use a sequential order, like this (4-bit, 8-channel
example):
0, 1, 2, 3, 4, 5, 6, 7, 0, 1, 2, 3, ...
This way if the user writes the data directly to a file, one word after
another, everything is in sequential order for whatever post-processing
later.
----> Will the GNU Radio world fall apart if use a sequential
channel ordering for my output and submit this development for
inclusion in a future release?
Thanks,
Paul
Amendment:
I see now why the sequence is as it is. As a real-time program reads
one word at a time and picks off samples from LSB to MSB, the ordering
makes sense. I may just include a setting to reverse the sample order
for more efficient data recording. If the powers that be have any
other thoughts, please let me know.
--Paul
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