On 03/17/2019 04:46 PM, Stewart Russell via talk wrote: > I can confirm that Baudot is alive and (maybe not quite) well in RTTY > for amateur radio. It's one of the few digital radio modes that's > amenable to massive amplification, so 2 kW+ QRO RTTY rigs are not > uncommon. Listen in around 14.1 MHz and you'll hear RTTY contests > bleating away every weekend. Still around 45 baud, too. Fldigi on > Linux can encode and decode it. >
Actually, 45.4 baud. I used to run RTTY, with both Baudot and ASCII. I wrote the terminal software for my IMSAI 8080 and designed & built the serial port board for it. I designed and wired it for 8 ports, but only had 3 installed. I also built my demodulator, based on a couple of magazine articles, but my Kenwood TS-820s had a built in FSK keyer, so I didn't have to build that half of the system. My serial board used the same 8250 UART as the IBM PC, but in a much more intelligent manner. Instead of each UART having it's own IRQ line, my board shared one among all ports, in the same manner as used on mini-computers, where 8 or 16 port boards were commonly used. When one UART generated an IRQ, my software would read a port to determine which one needed service and write the same value back, to select the appropriate UART. In the process of testing that board, I discovered a bug in the UART, that Western Digital didn't know about. However, there was an easy work around. The software I wrote could convert between Baudot and ASCII, so that I could copy the incoming traffic on my M35 Teletype. It also had a few canned messages and RY or U* generator, to create a continuous reversing bit pattern, to help the other end tune in the signal. I also had unshift on space and several other useful features in that software, such as starting up the tape reader, on the M35, to send tapes, with conversion to Baudot when needed. Back in those days, you knew your computer inside and out, because you did everything from scratch or a kit. --- Talk Mailing List [email protected] https://gtalug.org/mailman/listinfo/talk
