[GreenKeys] RTTY Art JAVA Viewer Facelift

[Bob Camp]

Hi

I spent some time thinking about this at work today and looking at an 
ASCII table. I came up with a couple of things:

1) If we straight map the 5 level to 8 level (low bit to low bit) then 
the 5 level all shows up in the first column of ASCII where all the 
control characters are.

2) If you want to put headers on this stuff feeding it into a text 
editor would be a nice thing.

3) If we use another column of ASCII for the map then we have no cr's 
or lf's in the data stream. That's good because lf's won't get added to 
cr's. It's bad because the lines will look like they are way long and 
the editor will puke.

So here's my proposal:

1) Map the 5 level to the column of ASCII that begins with the @ sign 
and contains all the capital letters. Do a straight bit for bit map 
rather than character translations.

2) Break up the translated 5 level with an ASCII cr/lf pair every > 64 
and < 72 characters. Obviously a short line would be fine since the 
picture files will never be an exact number of lines long.

3) Use an ascii # to start any line that does not contain 5 level data

4) Start out the file with #Format 1 cr/lf  in ASCII

5) Finish the file with a #End

To interpret the file you would simply strip out anything that is not 
in the proper ASCII column. You would also throw out any line that 
starts with a #. That's simple enough that you could feed this file 
into a PIC and have it re-transmit it as 5 level while running off of a 
32KHz watch crystal.

I realize this is getting a little complex. It may be more complex than 
necessary. The whole idea is to be able to work on a file with a 
conventional text editor like notepad or nano. That way we can fix 
damaged tapes without a lot of hassle. Writing an editor just to put 
comments on the file sounds like a major hassle.

Any thoughts?

		Bob Camp
		KB8TQ





On Jan 17, 2005, at 9:46 AM, John Foust wrote:

> At 08:38 AM 1/17/2005, Bob Camp wrote:
>> One thing that would be a *very* good idea would be to come up with a 
>> file format for this stuff. The world is more or less an 8 bit 
>> environment these days. We also don't seem to worry much about file 
>> sizes any more. I doubt that my living room full of tape would fill 
>> even a very old hard drive.
>
> Don't sweat the file format, either.  I like the notion of just putting
> the low five bits in a byte.  That means it's not ASCII, but that's OK.
> Make a simple ASCII header that ends in a CR/LF, like "#RTTY tape 
> format v1.0".
> Document the format, including a suggested mapping to ASCII, and 
> you're done.
>
> If you wanted to get fancy, allow any number of comment header
> lines at the start, and don't start the actual data until after
> special comment line like "#START\r\n".  This would allow us
> to put comments inside the file, describing the image and
> where it came from.
>
> - John
>
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