On 10/15/23 02:06, tomas@tuxteam.de wrote:
I can beat that Tomas. At one point in the early 90's we had a PDP-11 to run a 7 meter C band dish, The VT 220 died and DEC wanted nearly 2G for a VT-550 but would not guarantee it would work in place of a VT-220. I was then a fan of the TRS-80 color computer and OS9, an aftermarket OS that was a mini UNIX. And a fellow named Brian Marquette had written a VT-100 program that was quite well organized, so well organized that I was able to make a 100% compatible VT-220 out of it in just a few hours.On Sun, Oct 15, 2023 at 09:52:16AM +0700, Max Nikulin wrote: [...]P.S. I believed that most confusing (while still useful) feature of terminals is [Ctrl+s]. It takes some time to realize that it has been hit by mistake, so [Ctrl+q] is required to resume output.Old age gotta have some advantages: I grew up with "real" terms (VT520 and clones, mostly), so this one is "built in" for me. Now don't get me started with CTRL-E, the source of many a prank ;-) Cheers
So my office coco logged into that PDP-11 and updated the satellite schedule daily. But that PDP-11 was not stable, crashing several times daily toward the end. It got to be such a pita, and DEC changed every part in it except the frame rail engraved with the serial number, w/o any effect.
Hugo was the network guy at CBS, so he had DEC trade his test mule serial number for ours, and traded me PDP-11. His Just Worked. But he was not able to fix mine which put him out of business maintaining the rest of the CBS networks machines. 2 months later I show up for work, there's two huge cartons from CBS, he was forced to find a new platform which was an industrial grade IBM PC, with an ARTIC card for the real time stuff, he had to convert the whole CBS networks satellite systems.
Here we get into another problem, when the dish was installed, it came with 4 copies of the site drawings so I had a hole dug, poured the concrete, quite a few yards of it, all according to the drawings, I find 6 weeks later there was a note in just one of the 4 sets of site docs that the base was to be oriented to offset the magnetic north diff at our site, some like 17 degrees, and the sat hardware could not compensate for that much error w/o re drilling the base jacks attachment to the post. A big Roland jack about 12 feet long. They took over the move instructions by a dial up circuit, but because of that base error, my satellite table looked bogus as can be, but it was exact for my site. I finally gave up resetting it because they would helpfully fix it, and disconnected the phone line so I didn't have to screw around for a week re finding the the satellites again and again. Being a non equatorial mount, it was an AZ-EL setup, that is not as simple as equatorial, but more accurate than equatorial. At 40 degrees north, equatorial has an EL error of over a degree over the span of sat positions because of the down angle to get to the equatorial orbit positions. Not easily noted on a 3 meter home dish, but quite important for a 7 meter's much narrower beam width.
Satellites aren't really stationary, the moon pulls on them so they do a figure 8 daily and only expend station keeping fuel when they are in danger of going outside their assigned box, with a 7 meter dishes accuracy, stations on both coasts had to get another bit of software that monitored incoming signal strength and if it got too weak, would go on a half a degree search for a stronger signal. Some satellites moved so far and fast that a station re-broadcasting the signal w/o a good time base corrector, were out of FCC specs for color subcarrier's +- 10 hz requirement due to the doppler effect of the satellites motion. The FCC I suspect looked the other way many times.
Broadcasting can be an interesting business. Cheers, Gene Heskett. -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis