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The Project:
Photos:
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Technical
On this page I'll describe in more detail which hard & software I use
and how it's usually all set up together. If you want to convert your car to
a moving ISP you'll possibly find some hints here :>
Hardware
The car:
Actually, almost any car will do :> It should have a
12V plug somewhere reachable to get power from and you should look up
the maximum amps for the connector in the manual. I did this after
I had smoke in the car, but luckily it wasn't the car's limit
but a too cheap Y-cable on which the plug got too hot, melting the
plastic around it's fuse. Must have been a very lazy fuse :> Also
you should make sure to have good batteries if you want to use the
car as a mobile internet access point without having the engine running,
the car I use has two 65Ah batteries in the trunk so I can run quite a
while without getting into trouble.
The power converter:
This is a quite discussable part of the setup. Converting 12V DC current
to 220V AC just to convert it back to a low DC voltage isn't a very
nice solution, but as I simply had too many different devices needing
too many different voltages I chose this way.
There are many different types of converters available, I use a
Sundox Power Inverter (bought at conrad electronics) which can provide
220W permanently and 450W peak, having an efficiency of >90%. There are
two points to consider when buying such a device: first of all it
should not need more power that your car's power outlet can provide.
There are such devices for 1000W and more, but if your cars provides
for example only about 180W (12V@15A, like the Mercedes E I used to
drive to the HAL2001) you'll kill the fuse or yourself :> The second
point is that the cheap Inverters provide 220V AC, but not a smooth
sine wave like but a very ugly rectangle. This might be dangerous for
your devices, I haven't killed anything with mine so far but you never
know, generally mobile devices accepting anything from 100-240V usually
have better tolerances than for example a desktop PC.
There are better converters available which provide sine-like or real sine waveforms,
but these are much more expensive und usually also bigger. Oh, speaking
of size, you should be able to place the converter in your car in a
way it doesn't overheat, so don't cover the ventilation openings...
The PCs:
I use notebooks, older ones which aren't too valuable (so I won't be
ruined if one dies, OK, the T41 isn't that cheap any more) usually are enough to manage ne available
bandwidth in a car :> If you really want a permanent installation
in your car you possibly should look for a low-power PC, best would
be one which's CPU can be cooled passively, and get a power supply for
it which can directly connect to 12V. Today several such PCs are readily
available, but as I'm always just playing around I stay with a bunch of
notebooks.
The next thing to consider are the interfaces, it should have at least
one PCMCIA and one RS232 port, even if most things today can be done
using USB or bluetooth I often prefer the more simple setups.
I ordered a Argosy quad-RS232 card here some time ago, a really cool card as my T41 doesn't have a
single RS232 and I often need more than one.
The Network:
You don't have to use wavelan :> Some people are afraid of the electro
smog in the car, others simply think it's too expensive. The ultra
cheap way is to simply use 10base2 as I did 1999, but as we have
220V power in the car we now could also use a normal 10baseT hub
or even switch.
I decided to use WaveLan as I had the cards and basestation
anyway and to be able to build a cross-car LAN. You don't need a
basestation for this, just the cards in "ad-hoc" mode will of course
also work OK, but a basestation has several advantages. For one,
when running in ad-hoc mode all stations must be able to see each other,
otherwise performance will get bad due to collissions. In a multi-car
setup this will be the case quite certainly. Second, using a
basestation you can use power-save mode on the clients. And third,
you can put two cards in some basestations (like the Lucent WavePoiny II
I use) and then connect multiple antennas to these to get better
coverage :>> Also note that not all stations/card have the
possibility to connect external antennas.
This passage was written years ago, today you'll probably just want
WaveLAN.
The Phones:
If you're new to mobile data prepare to do some research on what's the
right phone and network provider for you, this is much too complex to
discuss here, at least for the moment :) Generally most modern middle-class
phones offer mobile data over Bluetooth with AT commands UMTS might look
attractive and I really like it, but beware, it won't be there on most parts
of the german Autobahn in the moment.
The GPS:
Finally the GPS. The two big ones in the consumer market today
are Garmin and Magellan, and almost all receivers today provide a
rs232 serial data port, some USB and Bluetooth. On this port position data is sent using the NMEA standard, so the software used here will work with most
GPSs without modifications. But you won't want to use the GPS just
for your gigacar, and for edition waypoints and downloading tracklogs
and such things there's no standard protocol. Currently for the
garmin protocol there are more and better unix tools available, but
I also like my Magellan 315. Ask friends, read the web, search google,
it's mainly a question of what else you want to do with it and how much
you're willing to spend... Oh, and when you're thinking about one of
the more expensive models with map functionality: you currently
need Windows to upload the map :/ Possibly a Mac will do, too, but AFAIK
there are no Unix tools available for any of the available models...
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