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General => General Technical Chat => Topic started by: Homer J Simpson on November 12, 2023, 12:48:04 pm
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Video on the design and laying of the first trans Atlantic cables.
Get past the 2 minute Dr Strangelove intro and it goes in the history and design of the early cables.
https://www.youtube.com/watch?v=MDwf2k4ivaA (https://www.youtube.com/watch?v=MDwf2k4ivaA)
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About a century before TAT-1 there were transatlantic telegraph cables. The first one failed soon after laying, but the second cable lasted nearly a century.
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I am fairly sure a neighbor had a bit of the first cable Atlantic cable. I wonder what happened to it, when his wife died the children (one of them) got a company in to clear the house to within a couple of weeks of her death. Lots of stuff just chucked out.
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I had some of the last transatlantic coax (TAT-7) in the lab. I'm still kicking myself for not liberating 1cm before I left.
This topic is well covered by Arthur C Clarke's "Voice Across th Sea", and in an abridged form in his "How the World Was One".
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Porthcurno in Cornwall is still a major landfall hub for transatlantic cables. This dates back to the earliest telegraph cables to the US and the world in general. It's an unassuming little cornish beach for such an important role.
The telegraph cables are still terminated in the famous cable hut just above the beach... https://duckduckgo.com/?q=porthcurno+cable+hut&atb=v328-1&iax=images&ia=images (https://duckduckgo.com/?q=porthcurno+cable+hut&atb=v328-1&iax=images&ia=images) This has cables running to the US, Gibraltar, India, the Azores etc.
The Porthcurno museum is housed in the (by WWII standards) bomb proof relay station build further back in the cliff (irrc). It has a lovely collection of old submarine telegraph equipment including a working display of the, all electromechanical, sensitive high speed galvanometer relays etc, receiving gear. Theres also a very elaborate configurable LCR long cable simulator. Well worth an engineer's family holiday day out on a cloudy day... https://pkporthcurno.com/ (https://pkporthcurno.com/)
The Lizard (just a bit further south) was also the base for Marconi's transatlantic wireless experiments, first from a hut and eventually wireless station at Poldhu... https://blogs.mhs.ox.ac.uk/innovatingincombat/tag/poldhu/ (https://blogs.mhs.ox.ac.uk/innovatingincombat/tag/poldhu/)
I've attached a couple of photos of two of the very earliest experemental submaring cables winding their way up the cliff in a cove down towards the tip of the Lizard. I can't find a reference at the moment, but they're mentioned in the booklet from the Marconi wireless hut (now a tiny museum) on the cost path. Irrc they went to Ireland, but I can't find the right search term at the moment. The technology of bringing them ashore has improved somewhat over the years!
If you go to the Open Infrastructure Map https://openinframap.org/ (https://openinframap.org/) and turn on the Telecoms layer, you can see the absolute web of current subsea communications cables, with a considerable number of the UK ones still running into Porthcurno. It's easy to see why protecting them all from those of evil intent and a fleet of submarines is such a challenge.
Chris (a bit of a cable spotter)
P.S.
About a century before TAT-1 there were transatlantic telegraph cables. The first one failed soon after laying, but the second cable lasted nearly a century.
Yes, that was when they first learned the valuable lesson that if you have a cable with dodgy insulation (I think it was water ingress in that case), don't keep turning the voltage up! I have seen the log somewhere (either on the web or in one of my books) documenting how they increased voltage (in terms of number of cells) over a couple of days until it ultimately failed.