Data communications over telegraph circuits 1895

Jim Haynes

I presume the image was 'digitized' somehow in that a pulse was sent for dark areas and no pulse sent for light areas. The stylus was activated to make a mark on dark areas. I doubt they could handle gray areas or had high resolution.

I'm guessing, but I don't think they needed a voice grade line for this. I presume a voice grade line would yield faster transmission speed, but that's it, regardless of the fax process. A telegraph grade line would simply transmit the image more slowly, but it would still get transmitted.

The Tech Review suggests that they did have a fair amount of voice grade lines which they used to carry multiple telegraph messages (I think at least four). The DeskFax seems to have come along at the same time they introduced widespread system improvements.

Good point. In an old train station I saw a Western Union pay phone to send telegrams--it was a direct line to Western Union.

I do recall reading references that said IBM didn't want to alienate AT&T. My impression is the the early data networks were on private lines, perhaps because there were few modems to work on the switched network.

The data networks of the late 1950s appear to be more batch oriented than real-time. Branch offices would send information to the central HQ. Perhaps HQ would send summarized reports to the branches.

I think SABRE was a major pioneer on-line network, but I don't know how that communicated between remote sites and central computers.

Oslin says the FCC blocked them from doing so. Also, the networks did want Western Union to handle transmissions, but would not formally commit to a link and WU wouldn't build the facilities without a firm commitment. AT&T had the advtg of using its channels for growing voice traffic.

Oslin tells of several FCC decisions adverse to Western Union.

The WU Tech Rev suggests WU was looking into voice service beginning around 1961. They were researching transmission, subscriber sets, etc. I don't know what became of that effort. The Tech Review masthead changed from merely "Record Communications" to "Voice and Record".

You make a good point. In addition, AT&T owned the company that made the teleprinter units.

I am getting the impression that AT&T could've easily--if it so chose--to put Western Union out of business by expanding telegraph services. I suspect they let WU survive out of the appearance of having compebreastion in the industry. IBM could've end off its small compebreastors in the punched card field but chose to let them exist so the image was presented. The govt didn't buy either story and went after both IBM and AT&T.

I did find some numbers--apparently a day letter telegram cost about a $1.00 in the postwar era. That's roughly equivalent to a long distance for a few hundred miles; toll calls to a greater distance or longer conversation could get extremely expensive. I suspect the cost of a telegram could only go up as salaries went up while the cost of a telephone call went down as microwave went in.

There's a library not too far that has Business Week and the NYT on microfilm with indexes. I must admit I appreciate computer-based searches and sources a lot more after working with microfilm--finding a specific article is slow sequential searching through the roll squinting at a fuzzy image. Some articles are informative, but often it's only a two sentence brief mention that isn't very meaningful. Further, a company will publicize new services, but be more discrete about cutbacks and shutdowns.