The Ware for September 2009 is shown below. Click on the image for a slightly larger version.
This Ware is again a user-submitted ware. I have a sneaking suspicion that someone out there will guess this one fairly quickly, even though all the naughty bits are obscured in the photo, but I think it’s a neat one because I’ve never seen the insides of one of these before myself.
The Ware for August 2009 is the Viking Lander Command Detector Board (VCLD). The Viking Landers were robotic probes sent to Mars in the 1970’s. The board itself dates from 1970.
The Ware was submitted by Norman Yarvin, and fortunately, the original author of the report on the circuit board, Bob Schuster, was in the loop to explain what it did, and how it was made.
Some notes from Bob Schuster:
The big round thing in the lower right hand corner was an xtal used in the bit timing oscillator. The larger empty rectangular space on the lower left was for a voltage controlled xtal oscillator used in the subcarrier recovery circuits. Most of the components used were already 5 or more years in vintage, there were “better” parts, but we were using only established reliability parts.
A very detailed, and quite interesting, report summary was written by Bob, that explains the design approach behind the board and how it worked. Here’s an excerpt:
This board is one of two boards (primary & redundant) and was part of the Command Control Unit (CCU) a box that also contained power supplies and antenna control electronics-plus other stuff which I forget. It was flown on the Viking mission to Mars and was the first USA landing of a spacecraft on another planet. Its mission was imaging and the search for evidence of life.
NASA’s web site should be visited for more information about Viking.
Since its mission included a search for evidence of life all flight hardware on the Lander had to be sterilized in an oven at 254 degrees F (123deg C) for two days before it could be launched. It still had to function after the sterilization of course.
The board shown in the picture is the first Engineering Test Model (ETM) produced and that is why there are so many cuts and jumpers visible. The dust evident in the pictures (not very sterile) is from sitting around my attic these many years. I should have made it prettier but this was done on the spur of the moment.
The purpose of the board was to recover –- reliably — the digital data being up-linked to the Lander computer from earth. The computer could then be re-programmed as conditions changed or as mission scientist came up with new things to try. The emphasis on reliability was due to the low bit rate viz 4bits/sec and the limited time available each earth day to send reprogramming commands plus the long transit times for the radio signals to reach Mars (maybe about 3 to 4 sun earth transit times or about 4x9min=36 minutes ONE WAY. If the computer data had more than one error it could not correct it, or if the detector declared a poor subcarrier signal or bad bit timing the Lander was programmed to request a retransmission of the data from earth. This event triples the time to get data uploaded to about 1.8 hours! A bit error rate of 1bit in every 100000 bits was selected by systems engineering as an error rate the mission could live with. This would presumably keep code retransmission to a minimum thereby not burning up precious contact time. Given the available transmission power of the Goldstone Tracking station and the vast distances involved the S/N ratio was just sufficient to get to the error rate specified. If the error rate was not achieved then retransmissions episodes would get too numerous and the mission would be compromised. So the VLCD had to make maximium use of the available S/N and not degrade the signal in the data recovery process.
It’s amazing this was done in the early 70’s — years before PCs were introduced — and it’s advanced communications research similar to this that laid the foundations of the mobile phone networks that we take for granted today.
You can read the full summary report here (small — 40 kB). For those interested in the original history, I also have a PDF of some scans of the original pages (large — 3 MB) of the report typed up in 1971.
Oh, and the winner — a bit hard to pick since there were a lot of thoughtful comments; I’ll go with Wang-Lo. Even though I’m not quite sure the coax cables were used as part of a delay line differentiator, he did posit a guess that this was for the Viking spacecraft. Congrats, email me for your prize.
Site has been down for the past few hours because my poor little shared server can’t handle the slashdot traffic that has recently been pointed at my article on H1N1. On the one hand, I don’t have ads on this blog; on the other hand, it means I can’t afford a server strong enough to handle the occasional slashdot DoS.
I have reconfigured the permalinks and caching behavior in an attempt to bring it back up. If you encounter broken links to this site or if you observe strange behavior, I’d appreciate a note here as to what you are seeing. My impression is that this caching plugin causes the pages to look a little bit nasty at first when you load them when the server is under load, and eventually they get a bit prettier with all the images and backgrounds when things lighten up, but I could be wrong.
Thanks for your patience!
Update: post backlog limited to 5 posts and images removed from the latest name that wares to try and keep server load down. Will restore normal reading settings once the slashdot attack is over.
Update #2 (9/3): I thought the traffic would be down by now but my ISP is still recommending I keep the blog in lock-down with “ugly” pages and no images otherwise they might have to pull the plug again. I’m not particularly fond of tinkering around with the mechanics of wordpress, php and mySQL so I’m just going to hunker down and weather the storm for another couple of days.
Update #3 (9/5): Looks like traffic is down, I’m gradually re-enabling features of the blog. Hopefully, now if you see the blog it should look “pretty” i.e., the header is loading properly and the CSS is being served. I will try turning on images on the front page tomorrow if things are still going well. Thanks for your continued patience.
Update #4 (9/8): I think everything is back to normal after the holiday. Hi-res images should be back now. If you do see anything amiss, please do report it. The backlog of posts shown on the front page is trimmed to 5 instead of the usual 10.
This month’s ware is pictured below. Click on the photos for a much larger version.
This month’s ware is a user-submitted ware. This ware doesn’t quite qualify as a “production” ware but it does qualify as a very interesting ware, partially because of its vintage and its relative sophistication. I’d be surprised if anyone out there could exactly identify what this ware is, but I’m thinking someone out there can at least name the general function and origin of this ware…when I name the winner I’ll post some interesting details about the ware!
Well, that last ware was surprisingly easy to guess. I have a couple more blank PCBs I’m going to try in the future, they should be a little more difficult to guess — they don’t have any keyboard lands to help with identifying the design. Still, I’m impressed that people figured it out so quickly. I’m convinced by johnny ^_^’s guess that it’s an HTC Touchpro 2, so he’s the winner! congrats, email me to claim your prize!