Can telegrams be sent over the PSTN? [closed]

Question

I am wondering how one would go about sending telegrams in a wired fashion nowadays. Obviously, telegrams can be sent wirelessly using spark transmitters and antennas. But the legality of doing so is questionable and getting a ham license seems cumbersome,

I am assuming sending telegrams using wires would be legal since there would be no spamming of the electromagnetic spectrum. It would also be safer since the operators wouldn't be exposed to huge doses of radiation. Since wireless telegraph came about after wired telegraph, I know such a system exists.

Is there an inherent difference between telephone wires and telegraph wires? Can telegraph signals be sent over telephone wires, and vice versa? I ask because they seem very similar in design and we already have a nationwide system in place connecting every home that could be used for many purposes (i.e. today, the PSTN is used for DSL, telephone, fax, etc...)

Back in the day, was there a switching system for telegrams, or was a dedicated wire needed between every single node you wanted to communicate with, and only one message could be sent at a time?

If equipment existed to do this, could wired telegraphy be re-integrated into the PSTN using RJ11 (telephone) cables? For example, say I have a modern telegraph with an apparatus to pulse dial a number; any number can be dialed, but we obviously want to dial a telegraph, much like how fax machines dial fax machines. Once the other telegraph picks up (automatic), the Morse code can flow over the wire (it can either be manually keyed or sent by a computer somehow) and the receiving telegraph will both audibly spit out Morse code and also print out the message in case nobody is there at the moment. This sounds like a neat idea to me, but I'm sure nothing like this exists. I just don't see any reason why such contraptions could not be. The infrastructure is great and already exists; a connection could be established to any household at will (that has a telegraph).

Post Script: Comments below seem to indicate that telegraph and telephone cables are largely the same. Does that mean that if there were both telegram and telephone wires on a pole, one would be unable to distinguish the two without tracing them?

And would there even be both telephone and telegraph lines on a pole? The telegraph came first - so I think it's fair to say that when telephone wires starting going up, telegram wires were already strung up in many places. Did they repurpose some of these wires (obviously they could no longer be used for telegraph) or string along new wires?

Answer 1

operators wouldn't be exposed to huge doses of radiation

Only if your antenna is set up very badly, or you have the operator sitting in a beam between two dishes.

Back in the day, was there a switching system for telegrams, or did you actually need a dedicated wire between every single node you wanted to communicate with, and only one message could be sent at a time?

No switching. One message at a time per link. Usually single-duplex links. No automatic relaying between links either. Encoding done by humans. Decoding gradually automated. Last-mile services were done by sending typed pieces of paper by couriers. No wonder the whole thing was spectacularly expensive compared to modern telecoms.

Is there an inherent difference between telephone wires and telegraph wires? Can telegraph signals be sent over telephone wires, and vice versa?

In theory they're both just long copper wires driven at moderate voltage and current, but ...

I ask because they seem very similar in design and we already have a nationwide system in place connecting every home that could be used for many purposes (i.e. today, the PSTN is used for DSL, telephone, fax, etc...)

... in practice the PSTN has been digitised. Your legacy copper wire runs as far as the nearest exchange, or possibly only as far as the nearest street cabinet. At that point all the signals are digitised and fed into a core network. Not necessarily IP, ATM or X25 networking have also been used. This means that signals which don't sound like speech or modems will probably be discarded as noise.

You can build a wired telegraph across your garden if you like, it's a spectacularly simple piece of equipment and much better than the tin-cans-and-string system.

Edit: we can look at the original 1840 patent by Samuel Morse. It's not particularly clear, but his system involved a kind of recording galvanometer.

You can use almost any insulated wire for this. People have run telegraph over fence wire, although I can't find a nice reference for this. It can even be uninsulated if you're hanging it up and keeping the pair apart. The basic operation is a current loop. You have a power source and a switch ("key") on one end to type with, and a detector on the other - lamp, LED, buzzer, galvanometer, multimeter, whatever. You just need to inject enough voltage into one end for it to read out on the other, and batteries will suffice for anything under a kilometer of wire.

Use of the PSTN network: I suppose you could emulate a telegraph by ringing up someone and playing morse tones at them. Rather like those DTMF phone menus. But this seems neither really historical-reenactment enough nor practical. It's a lot slower than just using a modem and still uses the telephone network and gets billed accordingly.

Building a V21 fax system from scratch is an interesting little project, maybe suitable for final year EE students.

Edit 2 in response to comment:

Because copper is superior to IP networks, which are not secure and do not work in a power outage

Well, technically your telegraph won't work in a power outage either. And it's hilariously insecure - anyone can tap it at any point. Encrypted IP is your most practical form of secure comms.

It doesn't seem to be superior in any way that people actually value, or we'd still be using it.

Answer 2

The simple answer to your title question is: "In modern America, you can't do it." There simply aren't any households which are directly connected to each other by copper wire. Every household is connected to a local exchange, where the signals are converted to or from a digital format, and all connections are made using these digital signals.

As to your second question, the answer is, "Yes". Telegraphs did not have electrical/mechanical switching networks. All communication was between two dedicated operators. For long distances a series of relay stations was used. (Thomas Edison started out as a telegraph operator). There were signal hubs to connect separate lines, but the transfer of information from one line to another was performed by passing slips of paper with the text printed out.

Back awhile, there did exist "party line" systems, which had several households on a given line which were connected to an exchange (with a real, live operator who would connect different circuits together). Each household would (theoretically) respond to a different ring combination - so many shorts and longs. Of course, there was nothing to prevent one's neighbors from listening in on your conversation.

Answer 3

You really need to get over your obsession with old telegrams or telegraphs. Even hams in most of the civilized world these days no longer have to do Morse code. The shift is to more complex digital modes.

There is a scientific principle which governs this. It is called Shannon's law and basically it says that the better the quality of your link, wired or wireless the more data you can transfer. Today most of these links are very good so why would you go back to ancient low bandwidth methods to transmit data.

Having said that in low signal to noise ratio environments, combined with the processing capability of the human brain Morse can still do pretty well.