AFSK generator?

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Re: AFSK generator?

Permanent link to this post Posted by Robert J. H. » Mon Oct 17, 2016 6:05 pm

weldo5 wrote:I already knew that this wasn't even valid anyways. You both provided the coding, which I wanted to reject right away because I was afraid both of your coding would not work. Sorry to be a bit argu, but don't start to play games on me because of the coding I copied from the both of you (no longer in the file, but in this discussion) and rob. Ask Robert H, because this is his coding, (from the messaging encoding on below on to the gauss), and the frequency sets...(although being deleted due to further discussion on something can't remember on the top of my head


We are not playing games.
The text has been corrupted in a odd way, as if the code went through OCR.
For instance, the "%\" after "(format" should be read as "nil".
I'm sorting it out, be patient.
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Re: AFSK generator?

Permanent link to this post Posted by weldo5 » Mon Oct 17, 2016 6:08 pm

I'm also trying to sort this darn thing out. I just think this plugin was a great idea, it just seems "harder" than other plugins. Im being patient, don't worry
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Re: AFSK generator?

Permanent link to this post Posted by weldo5 » Sat Nov 26, 2016 12:41 am

well its been over a month and I STILL have no idea how this modulator is going to turn out......... Since I seemed to have posted at the wrong time through which I still dont know the basics of lisp, of which it seems very simple... i dont know if im going to call it quits or not.....
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Re: AFSK generator?

Permanent link to this post Posted by weldo5 » Fri Dec 02, 2016 4:20 am

Hey robert,
it will be a lot easier to generate a sequence of waveforms (of course from the binary). Instead of a pulse train. Pulse trains will of course need to have much more code.

Once again im trying not to be annoying. It seems no one will respond to this, (of course because this topic I made is so disorganized and disexplanatory, especially by me.)

I actually should have said "sequence of tones", back in that post where you converted the message stream to binary.
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Re: AFSK generator?

Permanent link to this post Posted by steve » Mon Dec 05, 2016 11:33 pm

weldo5 wrote:I still dont know the basics of lisp, of which it seems very simple...

LISP is not "very simple". It's a powerful computer language, but it IS relatively easy to start working with LISP if you invest a little time and effort into learning how to use it.

The top part of this code makes up the "header" for the plug-in.
You can read about Nyquist plug-in headers here: http://wiki.audacityteam.org/wiki/Nyqui ... _Reference

To understand the rest of the code, try working through it by looking up each of the commands in the manual: http://www.cs.cmu.edu/~rbd/doc/nyquist/
The XLISP manual has additional information, including examples, for all of the standard XLISP functions: http://www.audacity-forum.de/download/e ... -index.htm

I would particularly recommend this free book as an introduction to LISP programming: http://www.cs.cmu.edu/~dst/LispBook/index.html

Note that this plug-in is intended to help you get started. The code should be reasonably robust, but contains no error checking, so the usual GIGO rule applies.

afsk.ny
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Re: AFSK generator?

Permanent link to this post Posted by weldo5 » Sat Dec 10, 2016 1:29 am

I already knew how to do the header in the first place. The only thing that's an issue is the info. I think Rob fixed that already.

Me and rob are working on this via email, which was the actual reason why i wanted this topic locked.

Look, i know you all provided great info and all, but this seems way to challenging, now that i look at it. Me and rob are currently working on it together, and were actually making great progress so far. Heck ive even tested a beta version of it, it sounds exact.

Plus im not even sure if this will be added to the plugin list on audacitys main site. Many tests need to happen first. Think of it as like a small program (which in this case is not even a program). If i get my internet back on my L-top ill see if everything goes okay with it or if I add it to the list.

I also wanted to apologize for my inefficiency with no knowledge with this stuff.
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Re: AFSK generator?

Permanent link to this post Posted by steve » Sat Dec 10, 2016 1:39 pm

If you read my previous post you will see that I've written and posted an AFSK generator plug-in for you: download/file.php?id=16645
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Re: AFSK generator?

Permanent link to this post Posted by weldo5 » Sat Dec 10, 2016 7:28 pm

I can't download it because my L-top is not cooperating with internet at the moment. Therefore I can't download at the moment. Just let me and Rob work on ours. I'll test yours later. K?

I don't want to cause anymore arguments.
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Re: AFSK generator?

Permanent link to this post Posted by Robert J. H. » Sun Dec 11, 2016 7:04 am

steve wrote:If you read my previous post you will see that I've written and posted an AFSK generator plug-in for you: download/file.php?id=16645


Thanks Steve.
I've not seen your code until lately.
Although my version an yours do essentially the same, they are very different nonetheless.

You have one input (+ some hidden ones), I have seven (hopefully reducible).
- you: input binary as digits 0/1
- me: input as plain text (ASCII/ANSI) with escape sequences for:
-De Bruijn Sequence (32 byte in succession that hold all possible 256 values, if shifted one position at the time and
changing one bit only, e.g. 0011= 00 01 11 10 [wrapped around])
- Grey codes, same as before but one byte at the time, thus the second bit stream from above 00011110.
- alternating 0101...
- binary input

- individual length for marks and spaces in samples (yours are defined as *sound-srate*/ baud). This ensures a pure square wave with only two values but the resulting baud rate might not be accurate if the sample rate doesn't fit-->resampling.
It is difficult to handle this properly since we are actually doing an analogue thing digitally. All the sample rate is good for is how much we are oversampling, e.g. at 1200 baud at 48 kHz, the factor is 40. .

I've chosen a Gaussian FIR filter instead of an IIR.
It's purpose is to reshape the pulses before the actual modulation and it should thus be symmetric with the lowest possible group delay (=Gaussian).

In contrast, your filter is at the output stage. I'm not sure if a low pass filter is appropriate here:
- The pulse train is at base band--> low pass with (half-) bandwidth frequency deviation (min 500 Hz for 1200 Baud).
- After modulation the signal is shifted and we need a bandpass with (full) bandwidth 1200 Hz min at 1700 Hz, since the modulated signal is double-sided.

It is important to me that the plug-in returns the sound at any desired stage.
- text as binary
- pulse train
- pulse train filtered
- modulated signal
- modulated signal with pre-filtering applied.

Currently, my output creation is floored since I use 'seqrep'.
It seems to me that Nyquist has some memory leak there. I had a stack-overflow error once. The only way to get rid of it was to restart Audacity since applying any kind of code produced the same error.
I will probably try your PWL approach.

Robert
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Re: AFSK generator?

Permanent link to this post Posted by steve » Sun Dec 11, 2016 2:10 pm

Robert J. H. wrote:I've chosen a Gaussian FIR filter instead of an IIR.

Yes, I'm cutting corners with the IIR filter (pun intended), but in terms of reducing sideband power it is pretty effective, and it's very simple code (because Nyquist has Butterworth filters built in http://www.cs.cmu.edu/~rbd/doc/nyquist/ ... l#index473)
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