I just wanted to write a bloggish kind of article, to try and record a bit more about how this thing started - at least from my point of view. Tim might want to write something like this of his own... who knows? Hope you enjoy it.
Way back when, Tim and I and several of our mutual friends - most of us who were in concert band together at Lanphier High in Springfield, used to sometimes eat and play video games at the Godfather's Pizza near South Grand and Dirksen Pkwy. I'm happy to say the place is still there! We knew where all the best video games were in Springfield. In my junior year at Lanphier (1981), the school somehow picked up three Apple II+ computers. Long story short I really glommed on to those things and went nuts first learning Applesoft BASIC, then 6502 Assembly and Apple DOS.
Somewhere in there, as on many evenings, Tim and I were putting away one of Godfathers' then-five pound pizzas (back in the day when we could do that and not gain ten pounds!) Out of the blue, Tim started describing to me what I thought was a weird idea of "wiring up" a room with sensors and hooking it to some kind of computer. By this time, Tim knew I was into computers. Although I don't recall him saying it was explicitly so, I had the picture in my head of a dark and scary room. Don't know why. John Blazis says he had something to do with this idea of Tim's but I'm not sure exactly what. John says they discussed it some before Tim mentioned it to me. I believe him. Anyway, that night Tim and I batted the idea around for a little while and I probably said something stupid like "sure, I could build one" - but if so, only Tim would remember. And life went on. Other than that one evening, I don't recall him again mentioning it to me, until:
After high school I signed on for the 10-year B.S. plan, another long story, and finally emerged from the University of Illinois at Champaign-Urbana (UIUC) - mostly unscathed - in 1992, with a B.S.C.S. Tough school back then and probably still is. After being fortunate to land a cool job in Sunnyvale, California with Amdahl doing mainframe hardware design diagnostics, a couple years passed and Tim gave me a call one summer day in 1994. He said "Do you remember that thing we talked about in high school at Godfathers, the wiring up of the room?". I did but wondered why he'd bring it up now. What I didn't expect is for him to next say: "I think we should build it." Which of course, meant he wanted *me* to build it. Without too much arm twisting I agreed to look into how much it would cost, and time it would take. By then I actually had enough EE and CS know-how to have a chance of pulling it off - basically seeing it as a not-too-complicated data acquisition project, which is exactly what it turned out to be.
The tricky part, but what we engineers are trained to do, was to build something on a budget, that works. I already had a "sub-notebook" laptop... a predecessor of what we call "netbook" computers today, and ran Linux or SunOS on all my computers, having fallen in love with Unix while in college. I settled on using that laptop for portability, and building an A/D box and basic set of sensors on the cheap. That month's Popular Electronics happened to have an article on a simple 8-channel A/D project using a serial 8-bit A/D converter with a TTL interface plus a vanilla 8-channel analog mux. Good enough, so I put that together in a project box with BNC jacks for easy connect/disconnect, a set of four resistive pullup selectors to "power" some passive sensors, and gathered up a bunch of surplus coax cabling being thrown away at work to hook it together. Radio Shack and Fry's Electronics were the sources for most of the sensor parts.
Software I wanted to keep simple and so wrote some bare minimum C with inline assembly to control the A/D and mux, with most of the rest being easily modified shell scripts. Displaying the data being recorded or played back was with another small C module using SVGAlib, primarily for speed. All of this was on whatever flavor of Linux was current at the time. Last, needing to call the software tree something I came up with MESA. Surprisingly it's still called that to this day.
What happened after the system was finished and when I don't clearly remember, but I either mailed all the stuff to Tim or flew to Illinois and hand-delivered it. He paid me around a grand for the kit - my cost. I also recall one of the first studies we ran with the new equipment was at the Lincoln Theater in Decatur. That may have even been its maiden voyage. Somewhat surprising to me, everything worked pretty well the first time! Guess that was the intended effect of keeping it simple. In the years that followed, we upgraded laptops - usually surplus I was retiring or was given from someone else, and added sensors. BTW, the picture on the front page shows the first A/D box and the original "386 Subnote" laptop on top, as well as the 2nd laptop we used - a Sharp 486 that worked for a while but its display prematurely died.
One sensor type I found particularly enjoyable to work on was the "FGM" static magnetic field sensors. These little Hall Effect sensors are tremendously sensitive, easily detecting small variations in even the earth's magnetic field. Indeed, the earth's field saturates them, requiring a reset/normalize operation every time after being powered up and secured to the floor. They are not designed to measure absolute magnetic flux, but rather the change in flux over time, up to +/- 10 milligauss or so. Since we have three, they are mounted in a box at right angles to one another so a 3D vector can be derived, if desired. As of this time, we haven't seen any point to drawing a 3D vector, so continue to graph the three sensors separately according to their alignment, e.g. Up, North and East. Perhaps thanks to their great sensitivity, at some survey sites the FGMs do next to nothing, and at others they show fairly wide variations. Why is anyone's guess and one of the questions years of recorded data might eventually help decipher. Tim knows better than I do.
At the Evansville, IN filming of Real Ghosthunters in 1999 we had the camera crew following us around all evening and nothing much happened. Nothing jumped out at anyone, at all. Sure, a few people felt some chills. The MESA team dutifully ran our studies at different spots in WIllard Library, in the methodical way we do. The camera crew and producer seemed pretty disappointed, but hey - they weren't paying us and I was starting to get a bit annoyed with their insistence on us "performing" for them anyway. The bright spot of the evening was close to midnight when we started graphing the recorded sessions, and to all our surprise, for the first time we saw some pretty big magnetic field variations from the FGM sensors. Of course the camera was rolling when I excitedly pointed out how the relatively symmetric spikes meant they were legitimate fluctuations. What I didn't explain is that if the FGM sensor box moves - even a little bit - at least one sensor and its resulting flux vs. time graph will wander off into saturation one way or the other. So, my excitement was mainly that the box hadn't come untaped from the floor!
Before closing, I'll say some really neat people have worked with MESA - primarily with Tim, through the years, and a few have contributed some pretty unique sensors, such as infrasound. I'm still a little skeptical they actually work as intended but being in uncharted territory in this project is par for the course. May we all keep learning and having fun while at it!
