Post by thread:[EE] hardware modulation, software demodulation

Hi All, I'm struggling with finding any info googling, so I'm hoping someone on here has some links or info... I need to store digital data on an audio soundtrack. Source data rate is not higher than 4800 bps, bandwidth of audio soundtrack is 32 KHz. The store solution needs to be hardware based, and lowish cost... ideally PIC, or PIC+modulation circuitry. The decode needs to happen on a PC, so the modulation parameters need to be published and understandable. Anyone got any ideas? Jon

> I need to store digital data on an audio soundtrack. Source data rate > is not higher than 4800 bps, bandwidth of audio soundtrack is 32 KHz. You have ample 'room' between the baudrate and the audio bandwidth, so a simple FSK modulation should do. IIRC 1200 baud tape (casette) recording used to be common, scale the frequencies up by a factor 4 and try that. Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: http://www.voti.nl/hvu

You could try Googling "Kansas City Standard" IIRC it was 1200 baud onto cassette tape but is likely to be scalable with a higherf bandwidth media, RP On 20/01/07, Wouter van Ooijen <spam_OUTwouterTakeThisOuTvoti.nl> wrote: {Quote hidden}> > I need to store digital data on an audio soundtrack. Source data rate > > is not higher than 4800 bps, bandwidth of audio soundtrack is 32 KHz. > > You have ample 'room' between the baudrate and the audio bandwidth, so a > simple FSK modulation should do. IIRC 1200 baud tape (casette) recording > used to be common, scale the frequencies up by a factor 4 and try that. > > Wouter van Ooijen > > -- ------------------------------------------- > Van Ooijen Technische Informatica: http://www.voti.nl > consultancy, development, PICmicro products > docent Hogeschool van Utrecht: http://www.voti.nl/hvu > > > -

Look at: http://www.cmlmicro.com/products/WData/FX469.htm That will give you some ideas. On 21 Jan 2007 at 14:20, Richard Prosser wrote: {Quote hidden}> You could try Googling "Kansas City Standard" IIRC it was 1200 baud > onto cassette tape but is likely to be scalable with a higherf > bandwidth media, > > RP > > On 20/01/07, Wouter van Ooijen <.....wouterKILLspam@spam@voti.nl> wrote: > > > I need to store digital data on an audio soundtrack. Source data rate > > > is not higher than 4800 bps, bandwidth of audio soundtrack is 32 KHz. > > > > You have ample 'room' between the baudrate and the audio bandwidth, so a > > simple FSK modulation should do. IIRC 1200 baud tape (casette) recording > > used to be common, scale the frequencies up by a factor 4 and try that. > > > > Wouter van Ooijen > > > > -- ------------------------------------------- > > Van Ooijen Technische Informatica: http://www.voti.nl > > consultancy, development, PICmicro products > > docent Hogeschool van Utrecht: http://www.voti.nl/hvu > > > > > > --

Thanks guys, some good ideas there. I'd been thinking of modem chips, and not having much luck - but 80's computer game sqwauks is a good lead! thanks jon On 21/01/07, enkitecKILLspamgmail.com <.....enkitecKILLspam.....gmail.com> wrote: {Quote hidden}> > Look at: > > http://www.cmlmicro.com/products/WData/FX469.htm > > That will give you some ideas. > > > On 21 Jan 2007 at 14:20, Richard Prosser wrote: > > > You could try Googling "Kansas City Standard" IIRC it was 1200 baud > > onto cassette tape but is likely to be scalable with a higherf > > bandwidth media, > > > > RP > > > > On 20/01/07, Wouter van Ooijen <EraseMEwouterspam_OUTTakeThisOuTvoti.nl> wrote: > > > > I need to store digital data on an audio soundtrack. Source data rate > > > > is not higher than 4800 bps, bandwidth of audio soundtrack is 32 KHz. > > > > > > You have ample 'room' between the baudrate and the audio bandwidth, so a > > > simple FSK modulation should do. IIRC 1200 baud tape (casette) recording > > > used to be common, scale the frequencies up by a factor 4 and try that. > > > > > > Wouter van Ooijen > > > > > > -- ------------------------------------------- > > > Van Ooijen Technische Informatica: http://www.voti.nl > > > consultancy, development, PICmicro products > > > docent Hogeschool van Utrecht: http://www.voti.nl/hvu > > > > > > > > > -- >