Tag Archives: ham radio

My first mobile computing setup

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This Epson notebook, an MFJ TNC and a Yaesu FT209 handheld 2 meter radio set on 145.01 MHz allowed me to have data communications while motoring around the southwest. Back then, hams had assembled a tremendous network of mountaintop digital packet repeaters (digipeaters) that provided amazingly good coverage of California, Utah, Arizona, New Mexico and into Texas.

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I don’t have a picture of it, but I’d built a floor-mounted stand for the Epson in my Rabbit diesel pickup, and a terminal program ran on the Epson talking to the TNC. I could send and receive short messages. The Epson had the tape-drive memory, which made it easy to write my log and store it on the tape.

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The MFJ was pretty cool at the time, and could even do HF packet, though that was especially painful. The Rabbit had a FT757 HF transceiver as well, the antenna (not shown in the above image) was on a ball mount on the left rear side, about midway between the wheel well and the taillight.

It was my first foray into the world of digital, and especially digital mobile communications. From that point on, I always had a computer of some type in my trucks.

Winbook TW700 and Warwalking / Wardriving

This is an amazing little gadget. And an amazing bargain if you play your cards right. The Winbook TW700 has been out for a while, and I learned about it only recently through an APRS reflector post from WA8LMF TW700 Review.

It is a simple Windows 8.1 machine, available only at MicroCenter, and there’s no MicroCenters here in Arizona. However, fortunately I have been traveling to Chicagoland on occasion and there are a couple of MicroCenters there.

Searching the MicroCenter website for pricing on the TW700, it ranges from about $44 to $80, depending on whether it’s new, open box/returned, or bare units without the accessories. And stores only have whatever is available in their store, so you might walk in and find that only new units are available, or they might have a number of open boxes, etc. I was very fortunate to get one at a good price, open box, and I didn’t need the few cables and charger that the new ones come with.

Like I said, these are extremely simple Windows 8.1 tablets, and quite tight on expansion. The one that I picked up had a 32 GB microSD card installed, which has turned out to be quite handy. Also, there’s only 16 GB of permanent storage in the machine, so Windows 8.1 takes up about 6 of that, and there’s about 8 GB in a restore partition. So there’s very little extra storage in the inboard “drive”. There’s also only 1 GB of RAM, and that can be tight unless you have low expectations. The Atom processor is plenty fast, and the screen bright and easily readable. The whole thing can run off its internal battery for hours at a time (maybe 4?).

Through WA8LMF’s and others’ web postings, I was able to increase slightly the available storage on the inboard drive even after the zillions of 8.1 updates that ballooned the size of the base Windows configuration. I have about 2 GB of inboard drive storage available now, which is plenty for my applications.

Speaking of applications, the main reason I got this was that I’m into wardriving using Vistumbler and WiFiDB, excellent tools written and supported by Andrew Calcutt and Phil Ferland. For a while, when working or visiting somewhere without my truck and its built-in Vistumbler wardriving setup, I had to make do with a notebook PC and its built-in dual-band Wi-Fi, and my Garmin GPS jacked in to the PC USB port. Was very bulky, and difficult to observe the results in real-time.

The TW700 changed all that. I also got a $10 USB hub (the TW700 has one regular USB port), a GPS receiver board from Sparkfun, and a very inexpensive TPLink dual-band Wi-Fi USB dongle. Borrowing a better dual-band antenna from the junkbox, I now have a pretty competent pedestrian/mobile warwalking/wardriving setup.

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This is an incredible little warwalking setup. I’ve even rode the bicycle around with this in the backpack, and it is really a nice performer. I taped the TPLink dongle / dual-band antenna to the top of the truck, across from my big Cisco dual-band antenna feeding the truck’s wardriving setup, and got essentially the same results while driving the neighborhood. Excellent sensitivity and lots of access points. The TW700 runs smoothly and supplies enough power to run both the GPS and the Wi-Fi dongle, so I didn’t have to bring along an extra battery to run the hub.

I still have to package the TPLink dongle, GPS and the USB hub together in a single package, so that there’s only the USB cable to the TW700.

You can read more about wardriving, Vistumbler, and the WiFiDB at the techidiots forum.

Getting the NEV Running Again!

What’s an NEV, inquiring minds ask? Why, it’s a Neighborhood Electric Vehicle!

Yes, it looks a lot like a golf cart, and to the uninspired, it smells and feels like one, but to the IRS and the DMV it’s a potentially street-legal electric-powered vehicle. Importantly, here in Arizona it’s a vehicle covered here under Arizona Title 28 Transportation, which describes the street-licensed vehicle parked in my driveway.

This particular one was a boondoggle purchase way back in 2009, due to some extremely generous federal tax credit legislation passed in 2008. Basically, the vehicle was a serious bargain. Runs off 48 VDC (eight 6-volt US Battery 250HC XC batteries), has a speed governor set to 25 MPH max, will easily run miles and miles on a single charge, has a AZ state license plate and registration, and has seat belts, headlights and turn signals.

In our neighborhood, which is gated with private streets, I can run the thing all day. Speed limit in the neighborhood is 20 MPH, with only 4 stop signs and over 2 miles of paved street. If I want to sneak out of the closed neighborhood, according to the statute (noted above) the vehicle is street-legal on roads with speed limits no greater than 35 MPH, and is permitted to cross streets with higher speed limits.

The NEV had been sitting in the boneyard for a few years and the batteries were in pretty poor condition. I know, I should know better on how to manage heavy expensive batteries, but the way the vehicle was built it is a bit challenging to water the batteries and they seem to, from day one, vent copious amounts of sulfuric acid vapor, causing all sorts of corrosion and erosion. Since each battery weighs about 40 kg, pulling all 8 batteries to properly inspect and water is a royal pain. However, I tore the vehicle apart again last month and determined to make all new cables, clean up all the corrosion, and get the thing running again.

For the most part, it’s all back together again and appears to work fine. I purchased 20′ of 2 gauge Excelene welding cable, 25 2-gauge solid copper tinned terminals, and an 8-ton handy-dandy hydraulic crimper tool with a bunch of dies (in case I want to go all hard-core with some 4/0 cables). This wealth of stuff set me back about $80. Add to this some silicone adhesive/sealant, adhesive-backed heat-shrink tubing, and boom! I’ve got new jumper cables to run from the motor controller to the battery bank.

This time I reorganized the batteries so that all the positive posts are completely accessible any time, so that I can more easily clean off the buildups of copper oxide/sulfide/sulfate residues that collect in mere days. This means that some jumpers are a little longer than in the original setup, but since they were using 4-gauge cable before I can stand the slightly greater lengths without sacrificing much at all. The maintenance headache reduction and reduced back strain to me are worth much more.

So, what do I do with this puppy? Well, not much, actually. When I first got it I did take it for some 5 to 10 mile drives, found my way (accidentally, really, truly) on to some golf course roads, went to the grocery store a few miles away (at night, no less), and even took it through the drive-through at Jack in the Box. Beyond that, none of my once-vaunted dreams to add wireless telemetry, GPS, audio, etc., ever transpired. However, I’m feeling the urge to finally get to these projects.

I am currently looking at using an Arduino as my real-time sensor controller, collecting battery voltage, maybe battery temperature, day/night light level, stuff like that. I might use Wi-Fi to form an RF link back to the house, possible as I put a 2.4 GHz Wi-Fi AP at 15′ atop the house on an 8 dBi omni antenna. In the Tahoe (which has a 5-6 dBi omni), I can actually get to one end of the neighborhood on the Wi-Fi link. However, I’m thinking more about using the 2m ham band and amateur packet radio, just in case I want to wander a bit further. I happen to have a little 5 watt 2m transceiver module, and a spare Kantronics KPC3Plus TNC, and a little GPS brick. The whole thing should pull less than 600 mW (50 mA average at 12 vdc), and transmit telemetry and position packets every minute. And, aprs.fi is already set up to display things like this, so there’s no backend work for me to do.

I’ve just started new employment, so this project, while exciting and interesting, will probably not get started for a while. But, while I’m continuing to procrastinate, I will also consider another project that I never got started on for this little NEV, and that was to add about 300 to 400 W of solar panel to the roof, so that I can trickle-charge the batteries at up to about 8 A (sadly, this is maybe C/35, so that’s why it’s a trickle charger). To add the panels I’ll need to find someone to weld up a sturdy bracket, and but at least in theory I could really be grid-free at least for short distances! And I’d be the talk of the neighborhood!!!