>
> Yikes,
>
> I haven't seen a cassette tape interface since my Altair S100 bus days!
>
> There were actually standards for this, try "Kansas City Standard".
>
> Bob Ammerman
> RAm Systems
> (contract development of high performance, high function, low-level
> software)
>

> I haven't seen a cassette tape interface since my Altair S100 bus days!
>
> There were actually standards for this, try "Kansas City Standard".

> > Can anyone point me to information on building or probably purchasing a
> > QPSK Modulator/Demodulator. I'll be using a 16C874 to collect data and
> > then dump it to a standard tape recorder. I was considering FSK but QPSK
> > offers better data density.
> >
> > Yes, I know, it can all be done with solid state memories, but consider
> > this , the data interface is RS232C, the proposed data format is TAR
> > (uncompressed) and the quantity of data is small. Tapes are very cheap
> > and tape recorders can be purchased for < $50.00 (AUS). The QPSK
> > interface will hopefully be very cheap to put together. This permits
> > connection to any PC, Laptop, PDA, UNIX, LINUX, Ultrix, SunOS, IRIX, you
> > name it work station and OS.
> > Nino.

> Seems that this may be a challenging project ;-)
>
> Bob Ammerman wrote:
> >
> > Yeah, I knew Kansas City was FSK. I was just fondly remembering
> the good old
> > days.
>
> Such simplicity is lacking these days...
>
> >
> > You should be able to find an old modem chip that will do the job
> (if you
> > can actually source the chip).
> >
> > Alternatively, you might be able to generate the QPSK with a PIC's
> PWM
> > output , but reading it back might be rather challenging.
>
> Decoding it may be too much of a challenge. Bit rate is undecided at
> the
> moment but we're looking at 14.4k as a minimum.
>
> >
> > What bit rate do you hope to achieve?
> >
> > Bob Ammerman
> > RAm Systems
> > (contract development of high performance, high function,
> low-level
> > software)
> >
>
> Nino.
> --
> ------------------------------------------------------
> | Antonio (Nino) L. Benci                            |
> | Professional Officer, Electronic Services          |
> | School of Physics & Materials Engineering          |
> | Monash University                                  |
> | email: RemoveMEnino.benciTakeThisOuTspme.monash.edu                  |
> | T: 61 3 9905 3649. F: 61 3 9905 3637               |
> | M: 0414 924 833                                    |
> ------------------------------------------------------

>
>
> I doubt you will achieve this on an audio cassette with acceptable error rates.
> My memories of trying to use audio cassettes with KCS interface was that the
> error rate was nothing fantastic, and that was at 300 baud. One had to have
> really high quality tapes to achieve reliable recording/playback error rates.
>
> You are trying to do what modems do over clean phone lines, and the wow and
> flutter of an audio cassette is going to play absolute havoc with the playback.
>

>
> QPSK and most other phase encoded data formats do not pass audio tape, and
> just barely pass FM channels, on account of the induced phase noise etc.
> F.ex. recording modems on audio tape over 4800 Bauds is very difficult
> even on high end audio tape recorders.
>
> Peter
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.

>
>
> The cons from someone who works repairing
> tape decks??
>
> * Head wear (<1 year depends on use)
> * belt rubber goes gummy (1-2 years depends on time and heat)
> * tape deck motors internal speed control circuits
> often failwith high use, giving +/- 5% speed error.
> * buildup of crud on heads greatly reduces high freq recording
> * tapes stick and bind together
> * pinch roller wear pulls tape to side and loses signal
>
> Being construcive now, try to avoid high freqs.
> (stay under 1kHz if possible.)
> Use lots of error checking, checksums,
> repeated data, redundancy.
> Software tape speed checking.
> Use a good tape deck.
> Lots of regular cleaning, lubing and tape replacement.
> Only use good 60 min tapes. 90 and 120 use thinner
> less reliable tape.
> Use a good gloss tape for less head wear.
>
> For this much work, why not try hacking a
> 3.5" floppy drive, it has two stepper motors,
> one for spin and one for head translate.
> Not too hard!
>
> If you are making the hardware yourself
> this gets you past belts and tape speed and
> pinch roller problems. You only want low data
> rates so you can make it many times more reliable
> than a normal floppy, which is already 100x more
> reliable than a tape system...
>
> Just a thought?? :o)
> -Roman
>

>Can anyone point me to information on building or probably purchasing a
>QPSK Modulator/Demodulator. I'll be using a 16C874 to collect data and
>then dump it to a standard tape recorder. I was considering FSK but QPSK
>offers better data density.
>
>Yes, I know, it can all be done with solid state memories, but consider
>this , the data interface is RS232C, the proposed data format is TAR
>(uncompressed) and the quantity of data is small. Tapes are very cheap
>and tape recorders can be purchased for < $50.00 (AUS). The QPSK
>interface will hopefully be very cheap to put together. This permits
>connection to any PC, Laptop, PDA, UNIX, LINUX, Ultrix, SunOS, IRIX, you
>name it work station and OS.
>
>I welcome all pro's and cons.
>
>Nino.
>--
>------------------------------------------------------
>| Antonio (Nino) L. Benci                            |
>| Professional Officer, Electronic Services          |
>| School of Physics & Materials Engineering          |
>| Monash University                                  |
>| email: EraseMEnino.benci@spam@spme.monash.edu                  |
>| T: 61 3 9905 3649. F: 61 3 9905 3637               |
>| M: 0414 924 833                                    |
>------------------------------------------------------
>
>Attachment Converted: "c:\eudora\attach\Nino.Benci16.vcf"
>