Monday Jan 09, 2006

First Galileo bird operational

New Scientist is reporting that the first satellite in the Galileo constellation is now communicating with its ground station and appears nominial, following its December 28th launch. Galileo is a European system similar to the USA's GPS, but will be dedicated to civilian use.

Thursday Oct 27, 2005

Fixing my Sony

This evening's fun and excitement was fixing my Sony Z1 notebook. I had to put a new hard drive in, as the old one just upped and died. In my experience, Sony notebooks are stylish to look at, but hard to work on. There were several hairy moments during the disassembly and reassembly, and I would never have got it done without ombrenoire.com's help. I'm not hugely fluent in French, although I seemed to make a better job of it than Babelfish. But the pictures are 90% of the battle here.

I'm currently reinstalling system software, so I'm not completely sure that everything is working. But at least it sees the new hard drive and the mouse and keyboard, so it hasn't been turned into a paperweight.

Monday Sep 19, 2005

Computer-aided music

Today I hooked up the MIDI output of my Yamaha digital piano to a USB MIDI interface attached to my Windows XP computer. My first baby steps towards integrating computers and music. I tried playing some of the soft synths that came free with Cakewalk Sonar. However, they seemed to have an extreme amount of latency between me pressing the key and the sound starting. Since the computer is a dual-core Athlon running at 2.4 GHz and has two gigs of RAM, I suspect that the computation is not the bottle-neck. There are plenty of places the latency could be coming from - the keyboard generates a MIDI note-on message, which propogates over a 30' cable, which gets read in by the USB device, sent down the USB stack, read by the program, a waveform is generated, and sent out the sound card, which propogates up a short cable to my speakers, and finally the sound travels back across the room from the computer to the keyboard. The only parts of this I can quantify the latency for are the electrical propogation of the MIDI message, which should be well under a microsecond, and the propogation of the sound waves back across the room, which should be about 15 ms. No doubt having the speakers closer to the keyboard would help, but I feel like the delay is hundreds of milliseconds total.

From the brief research I've done online, it seems like making sure I have the latest drivers for the USB chipset on the motherboard and the Yamamaha USB interface would be a good first step. The USB stack is quite often found to be the culprit in these situations. I shall investigate further tomorrow.

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Friday Sep 16, 2005

Thank you Garmin tech support

As I mentioned before, the heart rate stopped working on my Forerunner 301. This morning, my replacement strap arrived, as promised by tech support. I just tried it, and it works fine. Result! Of course, it would have been better if it hadn't taken a month to get the replacement, but you can't have everything.

Now I have a broken transmitter I can cut open to see what's inside. Stay tuned...

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Friday Sep 02, 2005

Garmin listens!

Some time ago, I talked about how I really like my Garmin Forerunner 301, but wish it had a barometric altitude sensor. Well, this just went to the head of my seasonal holiday gift list. It is a similar device to the Forerunner, but tweaked more for cyclists than runners. And it comes with baro! Cool...

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Wednesday Aug 17, 2005

My forerunner broke.

The heart rate stopped working on my Garmin Forerunner 301. I changed the battery and cleaned the electrodes, no help. I called Garmin today, and they are shipping me a new transmitter strap, basically no questions asked. According to their site, the strap is $60 if you buy it. The person I spoke to said to call back if the new strap didn't fix the problem, since it is is possible the receive part of the equation is the culprit. I'm not thrilled it stopped working, but the support experience was quite pleasant. Hopefully I'll be back in business with the heart rate in a few days. In the mean time I have my Polar if I'm desperate to know heart rate, but of course the data won't integrate into the Garmin software or upload to MotionBased.

Monday Aug 15, 2005

Cell phone usability

I thought I understood what clam-shell cellphones were about. You fold it up so that the buttons and the display are protected when not in use. I like that idea, I would buy one of those for sure. So why oh why (yes Motorola, I'm looking at you) would a designer take a clam-shell phone and stud the outside with buttons! I can't put my phone in my pocket without my keys setting it to speaker mode, or my sunglasses changing my selected ring tone. I know I could use software to lock out button presses, but why should that be necessary when the basic design of the phone should have taken care of this? Grrr...

Okay, rant over, sorry...

Monday Aug 01, 2005

Shiny new toy

This weekend, I went into my local hobby store, looking for a simple "toy" helicopter, similar to the one I mentioned previously. They didn't have one, but they had a number of "real" model helicopters. The distinction I'm making here is that a "toy" helicopter doesn't have cyclic pitch control, and a "real" one does. So after a short discussion with the sales guy, I ended up with an Eflite Blade CP. In my enthusiasm to grab the shiny new toy and take it home, I made a tactical error. The package comes complete with it's own transmitter, and of course since this is the USA, it is set up Mode 2. But I fly Mode 1. D'oh! I haven't yet decided whether to attempt the surgery to swich modes on the transmitter, or just to learn to fly Mode 2. Helicopters are a whole other ballgame compared to fixed-wing anyway...

The Blade CP comes fully-assembled. All I had to do was charge the battery and attach it with the provided hook-and-loop fastener tape. Speaking of charging, the provided "wall-wart" charger is pretty pathetic. The instructions say it should fully charge the battery in about 3 hours. But this didn't seem to be the case. Fortunately, I have a peak-detecting fast charger I can use. So far, that's my only complaint about the product.

I spent a couple of hours "skating" the helicopter around the living room floor. There's a slight Catch-22 with helicopters, which is that they are harder to fly when they are close to the ground, but if you get too high, you can't just chop the throttle if you get disorientated. For now, I'm staying low. I'll probably blog some more about learning to fly this thing, especially any Aha! moments that may occur.

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Sunday Jul 24, 2005

A cool toy

While I was on vacation, I got a chance to play with one of these cool indoor radio control helicopters. I've always wanted a radio control helicopter, but I've never quite gotten past the whole "expensive, hard to fly, easy to break" thing. I can say from experience that the Blade Runner is the opposite on all points. I had a fun time playing with this, and it was pretty easy to control (I already know how to fly fixed-wing radio control airplanes). I also crashed it a number of times without damage. However, it did break at one point — one of the two gearboxes failed. I opened up the moulded plastic fuselage and fixed it. The shaft had just popped out of its press-fit hole, so I squeezed it back in with some pliers. Embarassing to break someone else's toy though...

The only thing I don't like about this toy is that the controls are set up on the "wrong" sticks to give you practice for flying a more complex chopper. It doesn't have any cyclic control, so you have throttle for climb rate, a horizontal tail rotor to control pitch (and hence forward/backward flight), and differential speed between the contra-rotating rotors to control yaw. No roll control is provided. The stick assignment on the transmitter is

stickup/down axisleft/right axis
leftthrottlenone
rightpitchyaw

It seems that in the USA, most people fly Mode 2, which has pitch and roll on the right stick, and throttle and yaw on the left stick. However, I learned Mode 1, which is more common in the UK, where we have roll and throttle on the right and yaw and pitch on the left. So for me, it might be possible to swap the two stick assemblies and have the controls correct for a Mode 1 helo, which would be cool, since I might go for a Piccolo at a later date.

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Tuesday Jul 12, 2005

Thinking about 10 GHz

I'm a licensed amateur radio operator (ham). I've hardly been on the air at all in the last few years, but I think I'm getting the urge again. For me, ham radio isn't about talking to people. I've got a telephone for that. Rather it is that the FCC has given me a license to experiment with radio technology, over a quite large range of parameters. Hams are allowed to build their own equipment, and operate it without it needing to be certified by the FCC. We can invent our own modulation methods and data encodings — currently, low bandwidth digital modes are in vogue, and many new ones have been invented recently. We are allowed to use much higher power than typical consumer equipment, too.

So the thing that's got me interested again is discovering that there are several microwave clubs in Southern California, and that I live about mid-way between two of them. Furthermore, these clubs operate beacons on microwave frequencies. I was thinking I could get a 10 GHz transverter kit from DEM (more likely to succeed than home-brewing my first ever piece of microwave equipment), and use an all-mode 2m radio I already have as the IF. I could then listen for some of the "local" beacons. Unfortunately, I don't think I'd get anything from home, because the mountains either side of the valley obscure line-of-sight to all the beacons. But certainly from either the top of the tram or from Joshua Tree national park, I should be able to get something. From Joshu Tree, I might be able to work both the San Bernardino crowd and the San Diego folks.

Was that a bit geeky? Oh well...

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Friday May 20, 2005

GPS fun

I love GPS. It's even better than ever, since they turned off S.A. a few years ago. Our new car has a GPS nav system built in, which is very useful. But for me, the "killer app" of GPS is not to get me where I'm going, but to tell me where I've been.

I'm a licensed amateur radio operator (ham), and I used to do a lot with APRS. I had trackers on two motor vehicles and one bicycle. But these days, I mainly track myself with a Garmin Forerunner. This unit combines a GPS with a heart-rate monitor, and provides a display typical of a regular bicycle speedometer. I can put it on any bike, and it never needs to be calibrated for wheel size. And when I get back from my ride, I can download the tracklog to my computer and see not only how far and fast I rode, but also where. Unfortunately there doesn't seem to be any cross-platform support for accessing the 301 track data, but I believe people are working on it.

I also subscribe to a web service called MotionBased where my data is aggregated, and I can (for instance) compare rides on the same route on different days. These guys are working with J2EE and SVG and other good stuff. Unfortunately, the browser support situation for SVG at the moment means they don't fully work on all platforms. The more advanced functionality which requires the SVG and the web page to work together are currently targetted at Internet Explorer on Windows. Still, they are committed to making it work with other browsers, and in a platform-independent way.

I find the 301 a useful addition to my gadget collection. I've found it to be very reliable and functional. I have only two suggestions for hardware improvements. First, the heart rate transmitter eats batteries at an alarming rate, and when the battery gets low, the heart rate data becomes very suspect. So a new transmitter chest strap that worked better would be good. Second, the device uses GPS to determine altitude. Due to the geometry of GPS, this is not very reliable. I would willingly pay $50 extra to have a barometric alititude sensor built in to the device. Garmin already sell GPSs with baro, so they know how to do it. Even taking into account these comments, I think I'd give my new toy 4.5 stars out of 5.

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terryh

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