words per minute confusion #2

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SubGuy

Joined Jun 8, 2022
2
This is my first day on this site. I need help reconciling some data in the foregoing comments with my very old memory. The discussion above states in places that in Baudot there are five what I call "intelligence" bits. Then goes on to talk about WPM rates per BAUD. What seems to be missing is accounting for the Start and Stop pulses. Back when I taught AN/UGC-20/25 maintenance there were two basic bits in use. 7.0 and 7.42. 7.0 was a start pulse for synchronization followed by the 5 intel bits, and that was followed by the stop pulse. 7.42 was the same except the stop pulse was .42 times longer. The BAUD rates and WPM rates I recall were 50 BAUD -67+ WPM, 75 BAUD - 100 WPM. Using 7.42 at 75 BAUD came in at about 107 WPM. I should add that even though I told the class we were using BAUDOT code (only through my own ignorance at the time), we really were using ITA2. Any feedback is appreciated. Mike Klein
 

nsaspook

Joined Aug 27, 2009
13,315
Pre-1970 I was feeding five hole paper tape into a teleprinter.
Was this not BAUDOT?
We all called it BAUDOT even if a few chars were mapped differently. The USSR transmitted BAUDOT variation for English text (we received the TASS TTY service from Bakhtar News from Kabul , Afghanistan after the Russian invasion in English and Farsi) was identical to US-TTY.
 
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Thread Starter

SubGuy

Joined Jun 8, 2022
2
This is my first day on this site. I need help reconciling some data in the foregoing comments with my very old memory. The discussion above states in places that in Baudot there are five what I call "intelligence" bits. Then goes on to talk about WPM rates per BAUD. What seems to be missing is accounting for the Start and Stop pulses. Back when I taught AN/UGC-20/25 maintenance there were two basic bits in use. 7.0 and 7.42. 7.0 was a start pulse for synchronization followed by the 5 intel bits, and that was followed by the stop pulse. 7.42 was the same except the stop pulse was .42 times longer. The BAUD rates and WPM rates I recall were 50 BAUD -67+ WPM, 75 BAUD - 100 WPM. Using 7.42 at 75 BAUD came in at about 107 WPM. I should add that even though I told the class we were using BAUDOT code (only through my own ignorance at the time), we really were using ITA2. Any feedback is appreciated. Mike Klein
BAUDOT ? We are going back two centuries now!
When were you teaching this? :eek:
Another test, let's see. Had to be 1971-1973. Also teaching AN/BRR-3 with built in FSK converter. Also AN/UGA-3 Morse to TTY converter.
 

nsaspook

Joined Aug 27, 2009
13,315
Was told the Russians used Siemens TTY gear for the propaganda broadcasts. I don't remember the WPM of broadcasts but it was compatible with our basic TTY gear.

R-390 or R-1051 receiver with a AN/URA-17 FSCK decoder set.
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Papabravo

Joined Feb 24, 2006
21,228
Character encodings like like Baudot, Hollerith, Sixbit, Ascii, BCD, EBCDIC are different from the serial data format used for Asynchronous Serial Data Transmission. Over the years it has been possible to transmit 5, 6, 7, or 8 bit characters, with or without a parity bit, with one START bit and 1, or 1.5 or 2 STOP bits. Converting bits per second into words per minute assumes that the sender is transmitting asynchronous data at the synchronous limit, which many machines of that era had trouble doing as the bit rates kept increasing. Clearly transmitting 8 data bits with only two overhead bits gives you the most bang for the buck at a given bit rate.

Buadrate and bitrate mean the same thing for 2-level or binary signaling. For other signaling methods they will be different.

I believe that the definition of "word" is the same one used by typists of that era which was 5 characters and a space. The best typists of that era could hit 115-130 wpm on an IBM Executive typewriter.
 
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nsaspook

Joined Aug 27, 2009
13,315
I learned to type here on an old teletype machine sweating over 5 letter random code group drills for accuracy. No mistakes for 5 min's copy to pass. If you flunked typing you would become an "artist", painting ships. ;)
https://catalog.archives.gov/id/558536?q=558536

2017-10-16_03-17-41.jpg

Raw TTY was rarely transmitted over the air or on a data-link at 5 or 8 bits in the military. Most text based traffic was encrypted by machines that compressed and removed redundancy in the input bit stream to produce a synchronous secure bit stream for transmission. Start/stop bits were stripped in the encoding machine and then regenerated on the receive encryption device for the needed I/O device that might be a mechanical TTY. BAUDOT was perfectly capable of encoding most messages in a efficient manner when mechanical teletypes were still being used.
 
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Papabravo

Joined Feb 24, 2006
21,228
I learned to type here on an old teletype machine sweating over 5 letter random code group drills for accuracy. No mistakes for 5 min's copy to pass. If you flunked typing you would become an "artist", painting ships. ;)
https://catalog.archives.gov/id/558536?q=558536

View attachment 269057

Raw TTY was rarely transmitted over the air or on a data-link at 5 or 8 bits in the military. Most text based traffic was encrypted by machines that compressed and removed redundancy in the input bit stream to produce a synchronous secure bit stream for transmission. Start/stop bits were stripped in the encoding machine and then regenerated on the receive encryption device for the needed I/O device that might be a mechanical TTY. BAUDOT was perfectly capable of encoding most messages in a efficient manner when mechanical teletypes were still being used.
The Weather Service at FSS stations used RO-28 TTY machines into the 1970's for sequence reports. They even had special symbols for cloud cover, and cool abbreviations like BINOVC (Breaks in the Overcast).
 
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