Sunday, August 27, 2006
Saturday, August 26, 2006
The requirement, initially, was to get a machine capable of running Fedora Core 5, which would mostly be used as a display station for our radar system. The display software is written in Java (and hence needs a beefy CPU+memory, with lots of L2 cache), and a 19" LCD would be nice to do the display on. Oh, and it has to be cheap!
Being an AMD fanboy, I decided to go with an Opteron CPU. 64-bit Linux is available in all distros now (yes, even Debian!), so the CPU's capabilities are not going to go waste. Most of the radar data processing suite can take advantage of the 64-bit CPU as well. Plus, Xeons are still too expensive, and the AMD64 architecture provides a larger memory bandwidth (which DSP software desperately needs). My choice of CPU is the Opteron 165, a dual-core unit with 1 MB of cache per core. I felt this is important because the Java virtual machine (used by the radar display software) would then mostly fit into the cache and hence run a bit faster. Most Athlon64 CPUs only have 512 kB of L2 cache, but there are exceptions. Opty 165s are capable overclockers, too, should I need the additional horsepower. I also went with the boxed retail version, since it comes with a very beefy heatsink, and the price delta between the retail and OEM+extra heatsink is not very high. Boxed CPUs also have a 3-year warranty.
I did think about the socket-AM2 CPUs, but I also wondered how many times I've actually upgraded the CPU on a comp without changing anything else... zero! So that argument goes down the drain. Also, they (and the motherboards + DDR2 memory) are more expensive than their socket-939 bretheren, which use DDR-400 memory. Linux support for some socket-AM2 mobos is also limited.
The motherboard I picked is the Asus A8N-VM CSM. On a microATX with GeForce 6150 integrated video, this mobo is one of the few that has a DVI socket onboard! It has a gigabit LAN port (supported by the forcedeth driver), which performs well with our network. I've yet to try jumbo frame support, though. A few points to watch out for on this board:
- X seems flaky when using the default video drivers for Linux. It helps to do the first boot in text mode (by adding a "3" to the second line from the boot sequence in grub), download and install the video driver, then do an "init 5" to go back to graphic mode. Installing the video driver in Fedora Core 5 requires three steps: first, at a root prompt, type rpm -ivh http://rpm.livna.org/livna-release-5.rpm and then yum -y install kmod-nvidia . Finally, type nvidia-config-display enable and you should be done.
- The BIOS needs to be updated to something at or above release 1003, this fixes a bunch of problems that otherwise require a ton of kernel boot-time options to fix. Most new boards have the update, so it should be OK.
- Occasionally, the mouse pointer would turn invisible (but the mouse still works), the fix is to, as root, open the X config file /etc/X11/xorg.conf. Locate the "Device" section and add the line Option "HWCursor" "off" This is a bug in the nVidia video driver, and will be fixed in their next release.
- The DVI port only supports digital output, you can't use an adaptor to connect a second analog monitor.
- If you want to use all four memory slots, be sure to buy at least two single-sided sticks (this is a known issue).
- There is a version called the A8N-VM CSM NBP, which currently does not work well with Linux. It doesn't have any additional features except for DRM-chip support (and who wants that, anyway!) Be careful when ordering.
Video is built-in, and is good enough for use as a workstation. Gamers can add an additional video card into the PCI-Express 16-lane slot for better performance.
For the case, I picked the cheap and cheerful Rosewill R604. It has an ambitious toolless optical drive mounting system, but it makes the drives sit too far in, so I removed the plastic brackets and mounted the drives with screws. Given this is on a tight budget, the choice of case is justified. For $40, you can't go wrong (and this includes a 400W power supply!) If you're looking for a better case, though, one that would make several heads turn is the gorgeous Lian Li PC-V800A. <drools>
The hard disk is a Seagate Barracuda ST3250820AS 250GB SATA unit, fairly capable, and with enough disk space for most uses (the radar data currently goes onto a 2 TB RAID). 250GB is the current sweet-spot for GB/$, so unless you want to save about $10, stay with this drive.
I used a BenQ DVD Writer, again, this isn't critical and I picked this because it was on special and came with a free BenQ slim keyboard. Other recommendations include the LG GSA-H10B, which supports DVD-RAM media as well (until recently, NewEgg shipped a free DVD-RAM disk with the drive... the first time you use a DVD-RAM, you'll get hooked!)
I'm very picky about mice, so I chose one I'm comfy with: the Logitech MX-310. X can be configured to take advantage of the extra buttons, which then work as forward/back in Firefox, etc.
The monitor is a Samsung 930B 19" LCD. This may not have been the best buy, since for $10 more, you can get the Samsung 940BX, which features a height adjustable stand (I'm currently using an old phone book... heh!) Anyway, it has a DVI port, and that's what mattered. Cheaper LCDs generally only have an analog input, which is poorer quality than the all-digital DVI system.
Anyway, the system works flawlessly as a radar display and as a general workstation for day-to-day tasks. I was so happy with it that we got another for use at Pawnee and a third one to replace an aging Sun Ultra-10. The latter two have an Athlon64 4000+ CPU instead of the Opty 165, but still perform well. The Asus motherboard, aside from the initial hiccups, works like a charm, highly recommended for Linux users.
Sunday, August 20, 2006
Just great. I believe the British first came up with "divide and conquer". What goes around comes around. I hope those two sue the hell out of the airline and every one of the racists on board.
On a related note, I found an interesting documentary hosted by Richard Dawkins, titled The Root of All Evil? The documentary is available for download here (part 1) and here (part 2).
Saturday, August 19, 2006
You sure you want to be with meA weekend away from work, and all I can do is sit at home and introspect? Ugh, shame on me!
I've nothing to give
Won’t lie and say this lovin's best
Leave us in emotional peace
Take a walk, taste the rest
No, take a rest
Been waiting to try it, so when I got an invite, I thought I'd try Blogger's Beta version. The changeover is pretty painless, despite having a modified template in place. The changes are minimal, the most obvious is post categories (even though I don't see where I can type them in). They've also finally switched to using dynamically generated pages, so there's no more delay when doing a "publish".
Fort Collins is slowly coming back to life, since the university's fall semester starts on Monday. Previously empty streets are now filled with overenthusiastic freshmen, screaming their lungs out. If I don't hear one more "WOO HOO!!!" at 2:30 AM, it'll be too soon :-/ Heck, even as I type this, there's a cop car right outside my window, setting up a pretty lightshow with all them blinkenlights!
Saturday, August 12, 2006
Thursday, August 10, 2006
Having poured in liberal amounts of blood, sweat and tears, we got the radar up and running, complete with calibrations. And mostly moth-free (hmm, now there's a good corporate slogan...)
That's the signal processor after I set it up. From top to bottom, it now holds the test source, high-precision GPS-derived timebase from which radar timings and frequencies are synthesized, antenna position indicator, antenna control, main signal processor, a monitoring console, the digitizer computer and the transmitter control unit. The second pic has a clearer view of my baby, the transmitter control unit... yes, I'm really proud of it :)
Not shown is a gigabit network switch to hook all of this stuff together, and a KVM switch for the signal processor and acquisition node.
Here's some of the data collected by Pawnee today. Ignore the "radar name" field, that's a software bug. The first pic indicates the signal strength (which gives an idea of the rainfall rate), the second indicates the radial velocity, ie, how fast is the rain moving towards/away from the radar. As Murphy's law would predict, we have a working radar but no rain :-/ Most of the weak echo seen is from so-called "clear air" echo: insects, birds and airborne dust. Note the velocity gradient, this means that the wind is blowing in a NE-SW direction. The little white cross indicates a tiny localized storm.
I know, I know, I need a life. I left mine in my other trousers.
Saturday, August 05, 2006
The CSU Pawnee radar is CSU's "other" radar. The flagship (CHILL) is much more capable, and that's where I usually work. The move involves getting some of the new stuff I've been working on, like transmitter waveform shaping, to Pawnee.
Pawnee's up about 40 miles north of Fort Collins, smack in the middle of northeastern Colorado, i.e., nowhere! The first thing that hits you after you step out of your car is the silence. It's like nothing we city folk are used to, all you hear is the hinging in your ears. Then you dare to look around, and there is literally nothing around for miles. Here's a brief idea:
A few miles up to the north is Wyoming. Anyone who's watched Brokeback Mountain will need no further introduction.
To the west is... well, a farmhouse! You can just make out the Rockies behind the clouds. I like the sunlight filtering through the clouds, what Rush referred to as Jacob's Ladder
East of the site is the biggest dose of nothingness, and if you look close, you can even see Tito and Dorothy... but don't worry, click your heels thrice and you'll be back at Pawnee in time for supper.
This is what a part of the inside looks like. The signal processor rack (on the left) is currently being filled in, this is the "before" picture :D I took the picture from where the radar displays are usually located. Behind the processor rack you can make out the archaic MicroVAX that serves as the antenna positioner. Behind the wooden door is the transmitter room, with the same FPS-18 klystron transmitter CHILL has, but running at around 400kW. The processor rack contains (from the top), the calibration signal source, antenna position indicator, antenna positioner, yawning open space :) and a UPS.
Interesting trivia: the site's apparently in the path of a moth migration route, and every year, they come in by the millions, shed their wings, scales, dead relatives... ugh, it's quite a mess! Most trips to the site involve at least one "debugging" session with either a broom or a vacuum. Grace Hopper, you got nothin' on me! Let's hope I don't unleash something as horrific as COBOL on the world!
This is a view of Pawnee's antenna from inside the radome. Unlike the spacious, inflated CHILL variety, Pawnee lives inside a cramped, fixed dome. This makes repairs difficult and taking pictures damn near impossible! The dish is about 7 m across, with a vertically polarized feedhorn at the prime focus. The dome unfortunately leaks quite a bit, and the rainwater leaves quite a mess inside. Luckily, we've been in quite a dry spell this year, so it's not so bad. In it's former life, this antenna used to operate without a radome, which is why it has a mesh structure, unlike CHILL's solid dish. It is, however, generally quite disconcerting to see a big 7-meter dish pointing in your general direction, so we've got a dome. Here's a funny story about the dome: the dome base (see the first photo) is made of wood, and one day during a routine check, Bob (the CHILL tech) found an arrow stuck in it :)
Here's the best part about the site: the road home :)
This one's for, uh, her. The flowers are everywhere! The madness, the torture... ack!