On Thursday, December 12, 2019 at 3:09:55 AM UTC-5, Trevor Wilson wrote:
On 12/12/2019 1:50 pm, Michael Terrell wrote:
The first one that I saw was Non Linear Systems, in the late '60s. It had just been purchased by the local steel mill for their research center. One of their engineers brought it to our high school Electronics class to show it to us. It used an electro mechanical display that was slow to update. I wasn't impressed.
https://stevenjohnson.com/nls/index.htm is an example.
**Cool. I learned my craft as a trainee with an Aussie quasi-government
agency called The Overseas Telecomunications Commission. They were
responsible for all communications in and out of Australia. That
included satellite, cable and, HF radio They had so many cool toys,
including:
* An entire floor dedicated to a large mainframe. Which included a 2
Metre long computer drum drive.
* The very first ink jet printer I had ever seen (1972-ish). As I
recall, the ink was accelerated to the paper via a 2.5kV potential
difference. The printer was VERY slow and the print quality was
appalling. Cost over 2.5 Grand, if I recall.
* Huge page printers, churning out print at quite respectable speeds.
* A thing called T.A.S.I. Time Allocation, Speech Interpolation.
Multiple racks of tubed equipment, which examined the incoming and
outgoing voice comms and shuffled bits of voice into quiet parts of
different conversations. Bandwidth of the cable was doubled. Astonishing
technology.
* A HUGE 2.5kV power supply for the tube cable repeaters between Sydney
and New Zealand. VERY reliable tubes were chosen (obviously, as repair
was expensive).
* A massive (600mm X 600mm X 600mm frequency counter, using tubes and
NIXIE tubes as readouts. Something like 10 digits.
* A huge battery room, full of Pyrex„¢ glass lead/acid batteries. The
room also had four, 2 Metre high CO2 cylinders and a 2 Tonne fire door.
We were told that, if there was a fire, run like Hell and, if the door
closed, climb onto the Diesel generator (about 2 Metres high) and hope
the CO2 doesn't suffocate us. Prolly and urban myth to scare trainees.
I used the 'White Alice Network', back in the early '70s. It was built during WW-II as the first, Over the Horizon, Microwave telephone system to connect the various military bases in Alaska. It used huge dishes, and the refraction of mountain peaks to get their signals over the various mountains.. The audio was remarkably clear, for telephone service, considering it was almost 30 years old. Our telephone, teletype and radio network feeds were delivered by this system. A lot of people died, building it but it made more sense than trying to build thousands of miles of lead covered aerial cable, or even worse, burying it in a region that varied from below -40F, to +80F during the year. The last traces of the old sites are mostly gone now, but there are websites dedicated to its history. It took dedicated and rugged engineers and technicians to build and maintain a huge system, like this.
I used it from what had been 'Delta Field' in WW-II. It was one of the major transfer sites for the Lend-Lease program, where Russian pilots picked American built aircraft and weapons to fight Germany from the Russian Front. The building I worked at had been the pilot's mess hall, barracks and the original boiler plant for the airfield. Considering the age and severe weather conditions, I don't recall a time that it ever gave us problems, other that high audio loss on dedicated audio feeds. It was never designed to handle a Network radio feed, and it was around -20dB depending on the time of year. That wasn't unexpected, on 30 year old Arial lead cable. I had a spare mag phone preamp on hand, so I added it to the feed, to bring it up to the required level. The station was AM, and played mostly Rock, so no one complained about the bad equalization.
Prior to that modification, it was a sight to watch the DJ switch from Network to local feed. The levels had to be reset at three points, in just a couple seconds, and they were all on different racks. They loved just flipping a switch, instead.