ADAU1701- Question of making a adjustable Phase control
Hello everyone,
I have searched the related question in the forum, and I found this topic:
How to use sigmastudio software to realize an external potentiometer to control phase, the phase of the range is 0 ° to 180 °?
Bob gave the answer, but I still have some questions about the "Hilbert Transform" (I can not fine the answer from the wiki, because the page is gone.)
About the Hilbert Transform,
The upside output is 0 degree or 90 degree?
from the Bob's answer, this implement 350 degree adjustable, if I only want to adjust 0 to 180 degree from the ADC, how should I do? change the sine and cosine LUT table? and how to make a step, like 0, 10, 20, ....., 180 degree
Please help me for the question,
Thanks!
Alvis.
Audio Signal Processors
hilbert transform
SigmaDSP Audio Processors
adjustable
adau1701
phase
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Hello Alvis,
Sorry about the lack of documentation. Some time ago I did a little research on the Hilbert block and ran a test -- the results are at: ADAU1446 Hilbert transform response . The Hilbert's upper output is the reference or cosine output, while the lower one (the sine output) has a 90 degree lag compared to the cosine output. Both outputs lag compared to the Hilbert's input -- as you can see from the linked material, this lag is quite frequency dependent.
The easiest way to reduce the phase adjustment range to 180 degrees is to halve the corresponding range into the LUTs as shown below:
Since the reduced input only references half the LUTs, you can shorten them to save parameter memory -- although running out of parameter memory is rather unusual so likely you need not worry about it.
Best regards,
Bob
Hello Bob,
Thanks for your answer!
I will test this in mine EVB.
Thank you!
Alvis.
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