July 15, 2008

What I’ve been up to lately

Well people will have noticed that I’ve been quiet on IRC, forums, email… and also on most of my usual haunts around the amateur bands (especially HF).

I’ve been out at Laidley for the past few weeks, doing some industrial experience with a small outfit known as Eze Corporation, who trade under their trademark of SmartWheel (warning: Flash-laiden site, not recommended on slow hardware or low-bandwidth links). They’re based about 2km outside the centre of Laidley and specialise in electric vehicles.

At the present time, it’s all research and development.  Rather than having a single engine and transmission system, these vehicles operate similar to the large mining trucks — four individual motors on each wheel, turning independantly.

My role has been primarily the programming of a small driver control console, the Tritium TRI63.  This little beast sports a Texas Instruments MSP430F135 16-bit microcontroller, with a Microchip MCP2515 CAN controller.  A rotary encoder hooks up to the steering column to measure rotation of the steering wheel, while a potentiometer measures the accelerator pedal position.  The role of this controller, is to take these inputs, then figure out the speed and direction for each wheel — and send it out on the CAN bus to the other controllers.

It’s been a fun project thus far.  The development environment I’m using consists of my laptop running Linux (at the moment I’ve moved back to my old PII 300MHz laptop, since my newer one’s screen shat itself last week) which does all the compiling (mspgcc for the win), and a Windows XP desktop that runs IAR Embedded Workbench — which I use for flashing and debugging.  This has been handy experience — since my final year project at uni involves use of CANs on the Atmel AT91SAM7X256 MCU.

Earlier this month I was commuting two and from Laidley… getting up at 4:00AM to catch the 5:10AM bus from The Gap, arriving at Laidley 7:30AM… then catching the 4:38PM bus from Laidley home, arriving back at The Gap around 7:30PM.  This last week however, I’ve spent a few nights out here… makes it a lot easier and it means I can pack the hours in before uni resumes next week.

I’m quite enjoying the lifestyle out at Laidley too … peak hour barely rivals Brisbane’s traffic on a Sunday morning, and it’s all flat, perfect bicycle country.  The only downside is that it’s unpaid work — but hey, I’ve got my foot firmly in the door.  If I could get paid work here at the end of the year, I’d be out of Brisbane like a ball out of a cannon.  Maybe there’s scope for that in the future.  Time will tell. 😉

Portable Whip Antenna Testing

Hi all…

I’ve been busy lately, thus haven’t had a lot of time to post on here… but I’ll save the full details of where I’ve been for another post.  People might recall my earlier attempt at a homebrew 2m/70cm whip antenna for a handheld radio.

At present, I’m out at Laidley (actually about 2km outside… near the Vaux and Lowe street intersection) and tried hitting a number of repeaters on 2m and 70cm.  Depending on where I stand, I seem to be reaching these repeaters in that, I get a response when I hit and release PTT:

  • VK4RGC Mt. Tambourine 146.700MHz (-600kHz offset) — S7, have to stand in a specific spot
  • VK4RDD Toowoomba 146.750MHz (-600kHz offset) — S9
  • VK4RZD Mt. Perseverence 438.050MHz (-5MHz offset) — S2, too difficult for practical use (shame since it’s part of the WICEN/QDG network)

The ones I definitely can reach from here however…

  • VK4RIL Laidley 147.100MHz (-600kHz offset) — S9, no surprises there
  • VK4RAI Ipswich (The Knobby, Glenmorgan Vale) 146.900MHz (-600kHz offset) — S9, have to stand in specific points.

The big surprise however, was this one… VK4RAX.  I can reach it from The Gap no problems with a rooftop antenna and 5W.  Tonight however, I was receiving it S7~S9 (depending on where I stood) and managed to make contact with a few people.  Standing on tiptoe helped — as I haven’t as yet gotten around to building an extension lead that will make the on-hat antenna practical (the coax I’ve got is a little inflexible).

Apparently the signal was quite scratchy, but this is to be expected for a 5W handheld at this distance.  The image below (taken from Google Maps) shows the approximate direct path for the signal and the distance — click for an enlargement.

Signal path between test QTH and VK4RAX

I’m hardly breaking any world records here, but this is by far my personal best on this handheld.