The submarine navy went a step further with the five hole TTY tape in a system called HARE - High (speed?) Radio (emission?) for both speed and security in 1964.
Connected to the Collins URC transmitter, each hole in a character caused a transmission on a different HF frequency, and so there were a dozen receiver sites all around the world listening simultaneously for a signal on all five frequencies (that changed hourly) at 250 words per minute, and the messages were encoded and typically only 30-40 characters long, so the HARE transmission from the submarine was undetectable. We tested south of Greenland and were copied by seven receiver sites on four continents. (And, yes, the HF antenna must be above the water to transmit HF radio signals - a 30 foot vertical on the top of the snorkel mast works great.) Barry Merrill -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Grinsell, Don Sent: Friday, January 13, 2017 4:12 PM To: [email protected] Subject: Re: Paper tape (was Re: Hidden Figures) I remember using paper tape in high school in the mid-70's. Punch cards in college and my first job. I joined the army in 1981. I was eventually assigned to a signal unit in 1984 and lo and behold I had paper tape again in our radio teletype vans. We transcribed the messages onto the tape and then powered up the hf radio for a relatively shorter transmission window. This was during the cold war and the theory was that if you were on air for much longer than 30 seconds at a time our friends on the other side of the iron curtain could triangulate your position and pretty much ruin your day. "The power of accurate observation is often mistaken for cynicism by those who have not got it." -- George Bernard Shaw ________________________________________ ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
