FSK synchronizer in PD?

Ojd · Joined: Feb 22, 2008 Posts: 66 Location: Ua Audio files: 1

Is there a way to make FSK tone analyzer in PureData? Basically I need to analyze FSK sync tone from tape and spit midi clock to DAW. FSK clock consists of 2 squarewaves octave apart + Song Position Pointer encoded as binary (? don't know that for sure).

External synchronizers do not cost much today (because they seem totally irrelevand after digital recording), its just I want the most portable rig - 4 track + DAW. If its possible to diy, i'll do it

MusicMan11712 · Posted: Sat May 13, 2017 5:57 am Post subject:

I don't know about MAX/MSP - PD, but a few months ago I did some research to help someone who had some old Casio CZ FSK files. I found some tools that I found quite insightful for the project (and about FSK variants). I seem to recall there were some tools I found that I used.

BTW, I was surprised to see that FSK has advanced way beyond what it was in the 80s.

This has nothing to do with MAX/MSP or PD, but if you think it might be helpful in some way, I can try to see if I have the sites I used bookmarked. Maybe you could convert the methods tp MAX/MSP/PD?

Steve

PS: http://r-massive.cellarseer.com/casio-rz-1-mt-jack/ led me to the tools.

Addendum: The Yamaha MT2X was a 4-track cassette recorder that could be configured to record sync to track 4. There was an optional device (YMC2) that would take the sync (I assume FSK) and convert to midi--not sure if it was clocks and SPP or what. If it helps, the MT2X service manual also has a section at the end for the YMC2. https://elektrotanya.com/yamaha_mt2x_ymc2.pdf/download.html.

Addendum 2: Way back in the old days, I am pretty sure I used the MT2X to sync to something w/o the YMC2. I used the audio sync connectors. I cannot remember what I synced it to, though. Not sure if it was software (midi sequencer) or a drum machine. If it was the latter, it would have been a Korg DDD-5. Maybe the DDD-5 had the ability to sync to track 4 from the cassette. If so, maybe that implies that there was a sync standard. If so, maybe you don't need to analyze the fsk implementation. Anyhow, maybe something here will be useful for your solution.

JovianPyx · Posted: Sat May 13, 2017 5:15 pm Post subject:

FSK decode can be done with a PLL (Phase Locked Loop). a 4046 can easily do it, but there's a bit more to it than just the 4046. FSK is a lot like FM which is why a PLL can do that much of it. You might take a look at old modem schematics for ideas to complete the idea. In the case of MIDI, there is no actual "clock" because MIDI is an asynchronous protocol which is normally fully decoded using a UART. If you're talking about "true" MIDI, it runs at 31250 baud, so the UART will need to be configured for that baud rate for it to be reliable.

No idea if PD or MAX/MSP can do that, since serial asynch communications such as MIDI is not really a "musical" thing, it's a digital serial data thing.

HTH.