Modulate sine #2
Open
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Correct baud_pll to sine value conversion.
Changed src/modulate.c function send_bit() to ramp down modulation value by RRC before performing a phase reversal. This has the effect of narrowing the bandwidth of the modulated signal and greatly reducing the sidebands. Signed-off-by: David Willmore [email protected]
|
Hold up, I think I found a problem. Investigating. I will update this when I find a resolution. |
|
this is so cool! I'm fine to merge this, if you're OK with me merging it (just your latest note said to hold off on doing that...) |
|
No, it's not ready. I found a large problem and I'm trying to decide if it's easier to recode the whole thing along my way of thinking or to adopt my thinking to the way the code is structured. School is starting for my kids and I've had very few spare brain cycles recently. I'll update this when that changes. |
|
take your time! there's no hurry. just checking in, and thank you again for all the effort. g'luck with the kids! |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
I have changed the way that the BPSK modulation is added to the carrier signal to smooth inversions using a Raised Root Cosine shape. This has the effect of reducing the bandwidth of the signal and greatly reducing the sidebands. Spectral plots are included for before and after.
Note that, instead of smoothing the bit transitions on phase boundries, the inversion was moved to the center of the bit cell. This results in the same signal but shifted one half bit time. Since this is a self clocking signal, that should not make any difference in the decoded data, but the test decoder fails to correctly decode the signal. There seems to be some instability in it which needs to be addressed. It looks like an overflow of some type. This can be seen in the waveform plot in the screenshot attached.
