A collection of note-to-self's
When studying for my Cisco ISCW exam, I wanted to get somewhat more in-depth information on the different DSL-techniques.
First of all, there are different DSL techniques, ranging from IDSL (providing 144/144kbps) over the popular ADSL (somewhere around 1/10Mbps up/down) up to the newer VDSL variants (around 50Mbps). Within each technique, there are different modulation schemes.
I decided to explore what my Alcatel SpeedTouch modem (now Thomson) had to tell me; here is the report.
When experimenting with Cisco routers, it’s very nice to have a (small) lab environment to test things. Unfortunately, Cisco routers tend to be fairly expensive and noisy, especially if you need 5 or more of them. So I was looking for a cheaper and more flexible solution.
Dynamips is a Cisco router emulator which loads an official Cisco IOS-image and runs it on emulated hardware. It started out as an emulation of 7200 routers only, but now supports 3600 and 2600 series as well.
When you want more than a single router, you’ll need dynagen as well. Dynagen connects to a running dynamips instance and does some magic to get the (emulated) ethernet-ports connected to wherever you specify. The network-topology is created using plain text files. While this seems scary at first, the excellent tutorial covers every frequently used scenario.
Both tools are Open Source software and run on Linux and Windows (although it needs cygwin and doesn’t run as stable). The only catch is that you need real Cisco IOS images. The cisco.com site provides downloads only to selected users. Another way to get them is to copy them from a real router.
As reported in my previous post, I needed to re-balance the rotor-blades. Again… Also, the glowplug needed a checkup.
The glowplug was easily fixed: some oil got between the alligator clip and the glow plug which caused some bad contact. After cleaning both the clip and the plug the glow heater was able to pump 4A through the circuit.
Rebalancing the blades was a bit more work…
When it came to tuning my nitro engine, most guides referred to subjective measurements: “enough smoke”, “accelerates swiftly”, “sounds good”, … I, as a nitro-engine newbie, did not know what an engine should sound like and how much smoke it should produce.
I finally found some objective criteria to figure out whether the engine is too rich or lean: the temperature. This PDF by Tony Chaveiro reviews a CarbSmart needle controller, which uses the head-temperature as a feedback mechanism.
Apparently, 100°C is a nice head temperature to aim for. Leaning the mixture will increase the temperature, giving more fuel will cool it down.
I don’t know how I’ll use this knowledge to tune my engine, but at least I have an objective way judge the mixture.
I just came across some very weird behavior on a family members Apple MacBook. For whatever reason, Finder does NOT show all files in a folder. The folder is located on an SMB share, but I’m not sure if this has anything to do with it. The machine is fully patched with all software updates available on the day of this post.
Here is a screenshot illustrating the behaviour (some text blurred intentionally to protect privacy):
As you can see, the Terminal DOES show all files (e.g. the “untitled folder”).
Until here, this seems strange, but is probably some weird setting somewhere. But it gets a lot weirder.
Continue reading ‘Weird MacOS X Leopard behaviour: Finder hides files’ »
I keep a logbook of every flight I make with my Raptor. Here is the entry for today. I’ll probably do some history-posts to get my complete logbook in the same database.
Place: Halle
Tanks flown: 2.5
Time flown: 1h20 (cumulative model timer: 20h38)
Rx battery recharged with: 1861 mAh
Tx battery recharged with: 773 mAh
Glow heater battery recharged with: 763 mAh
Starter battery recharged with: 1416 mAh
Comment:
A lot of wind at the field; it was difficult to keep him in a stable “hoover” (read: sideways flight into the wind).
Tried some figure-8’s with nose pointing in the right direction (i.e. forward). I learned the hard way that turning from downwind to upwind requires a lot more power than the other way around. That, combined with a pilot error, left we with my heli falling down much faster that anticipated. I don’t recall what happened next, but some scary moments later I found my heli coming to a stop at 1m altitude, fighting gravity at full power…
I convinced myself to fly another tank; to overcome the fear. Hoovering in front of me, I noticed some vibration in the rotor, along with a strange sound. I couldn’t see the tracking very clear, but it seemed to be fairly good. I landed and verified all links on the rotorhead; none of them felt loose. When trying to restart the engine, the glow-heater wasn’t able produce much current. I’ll have to check my glow extender and plug.
When I finally got the engine running again, the first few minutes where fairly normal flight. Next, the strange sound reappeared. Also, my RPM was somewhat lower than usual. The sound came and went, but it was definitely the rotor producing it. After landing the heli I found the source:
I guess I’ll have to re-balance the rotor again…
One of the things I like about Vim is its support for syntax highlighting and folding. Especially when reviewing or editing config-files, the coloring is a true relieve. (Yes, I am aware that emacs can do this much better, nicer, easier and with a lot more Meta-Control sequences.)
Googling for a syntax file which would color the Cisco configuration files for me didn’t get me very far. So I decided to run my own. Here is the result:
(Public IPs in the screenshot are masked by 0’s)
Continue reading ‘Cisco config syntax highlighting in Gvim’ »
As a follow-up on my previous post on the Futaba FF9 trainer interface, I’m reporting the measurements of my E-Sky “0404” remote.
The E-Sky uses a much more popular 4-pin miniDIN connector:
Pin numbering is left-to-right, bottom-to-top: left-bottom is 1; right-bottom is 2; left-top is 3; right-top is 4; shield is all around.
Using the described pin-numbering, I measured the following signals:
When configuring a bunch of devices (switches, routers or even computers), most of the configuration will be identical. The Konsole program of KDE has a nice feature which sends the keyboard input to all open tabs. By simply telnet-ing or ssh-ing into the devices and activating this feature, I can quickly configure them all at once.
At work, using my Windows laptop, I have been looking for a feature like this. After some googling I found PuttyCS. It’s a standalone application which emulates this behaviour: It sends emulated keypresses to all (or a subset of) open putty sessions.
Configuring 8 blade-switches with PuttyCS is a breeze: just open all the putty sessions and start typing in PuttyCS!
When learning to fly a remote controlled model, getting a good teacher is worth a lot. But if all the teacher can do is watch the plane crash, he/she is of not much use…
Most transmitters have a “trainer” connection. This allows two remotes to be connected together. One is preforming the master-role and is actually controlling the model. The other remote is the slave and sends signals to the master. The teacher can program his master-transmitter to copy some of the slave’s signals, thereby letting the student control the plane. A simple toggle of the switch returns the control to the teacher.
Obviously, each brand of transmitters has its own “standard” of doing things. Some use a DIN6 contact, others use a mono- or stereo 3.5mm jack and there is the obligatory “proprietary connector”. Here are my notes of the expedition into the trainer-cable jungle.
This work by
http://blog.dest-unreach.be/ is licensed under a
Creative Commons Attribution-Noncommercial-Share Alike 2.0 Belgium License.