Help needed archiving Griffinsoft tapes

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flaxcottage
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Re: Help needed archiving Griffinsoft tapes

Post by flaxcottage »

Brilliant, thanks. =D>
- John

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vanekp
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Re: Help needed archiving Griffinsoft tapes

Post by vanekp »

lurkio wrote:
Sat Jun 12, 2021 10:21 pm
vanekp wrote:
Sat Jun 12, 2021 8:11 pm
I a curious how you created the csw files?
I used the Windows GUI app “CSW Viewer”, which I believe calls out to the DOS program CSW.EXE:


0320D1D4-A779-4BA8-9435-73868E142C78.jpegA7C663CD-2229-4137-9F6B-74C632A3EC05.jpeg0D93BE57-7A15-423C-8590-913B76B48988.jpegCFC7DCA1-8F05-45B1-BB50-BED1E2031FA6.jpeg
thanks for the info I just found it odd you got a working CSW and it was not for me, also see its the slightly older version of csw viewer and guess you must be running it on old hardware as csw.exe will not run on 64bit OS, I normally only use csw but run it in a DOSBox pity these applications don't get brought up to date to run on modern operating systems.
Regards Peter.
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Diminished
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Re: Help needed archiving Griffinsoft tapes

Post by Diminished »

I've done a great deal of messing about with DSP over the past week or so. Much of that time has been spent trying to get a software PLL to lock on to the 2400 Hz carrier reliably, which has proved harder than I expected. I think it works now, though.

So, using a PLL to sync with the incoming signal, and then either the DFT or Goetzel to identify bits, looks like it might be a credible alternative to walking the waveform in the time domain. Of course I may have to eat those words when I try to implement it properly.
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scarybeasts
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Re: Help needed archiving Griffinsoft tapes

Post by scarybeasts »

Diminished wrote:
Tue Jun 15, 2021 12:00 am
So, using a PLL to sync with the incoming signal, and then either the DFT or Goetzel to identify bits, looks like it might be a credible alternative to walking the waveform in the time domain. Of course I may have to eat those words when I try to implement it properly.
Best of luck! Latest beebjit master has a CSW loader that may be useful to you for testing. It logs a warning if the signal goes from "in data" to "silence" without transitioning to "carrier". It gives a few false positives in quiet sections of tape, i.e. where the carrier drops out slowly, but has generally worked for me to indicate where a WAV -> CSW failed. There also the option -opt tape:check-csw-bits that'll try and keep an eye on whether the stop bits in the serial stream are correct -- only works for 8N1 chunks at this time.
I'd be happy to enhance any of these widgets if it'd help.


Cheers
Chris
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Diminished
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Re: Help needed archiving Griffinsoft tapes

Post by Diminished »

scarybeasts wrote:
Tue Jun 15, 2021 12:16 am
Best of luck! Latest beebjit master has a CSW loader that may be useful to you for testing. It logs a warning if the signal goes from "in data" to "silence" without transitioning to "carrier". It gives a few false positives in quiet sections of tape, i.e. where the carrier drops out slowly, but has generally worked for me to indicate where a WAV -> CSW failed. There also the option -opt tape:check-csw-bits that'll try and keep an eye on whether the stop bits in the serial stream are correct -- only works for 8N1 chunks at this time.
I'd be happy to enhance any of these widgets if it'd help.
Thanks, I'll keep that in mind.

First indications are not awful, but whether "not awful" equates to "good enough" remains to be seen:
bitstream1.png
(By the way, flaxcottage, your tape machine was running at 94.7% of the nominal speed. :mrgreen: )
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flaxcottage
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Re: Help needed archiving Griffinsoft tapes

Post by flaxcottage »

Diminished wrote:
Tue Jun 15, 2021 7:47 pm
(By the way, flaxcottage, your tape machine was running at 94.7% of the nominal speed. :mrgreen: )
That is good to know, thanks. How I shall make use of that knowledge is another matter. :? :lol:
- John

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Diminished
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Re: Help needed archiving Griffinsoft tapes

Post by Diminished »

Made a thread for my DSP experiments.
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