Wifi-mobile

[Frogon]

I've recently gotten really interested in Wifi, and I've seen people do crazy stuff involving their car. That gave me an idea: Put a wireless AP in my car, a 1989 Oldsmobile Regency 98.

I'm still planning things out, and I've got a few questions about how to rig it all up. First, I was thinking of using a linksys WRT54G because they're fairly cheap, and because they've got 4 wired connections on the back and I'd put that in the trunk. Then I'd get CAT5 cables running from the router, to inside the car's seats so you can have a laptop, and plug into a LAN. However, this is when I run into problems.

First, I want to have the wireless router use the car's antenna, I dont think that this would be too hard to do. But, it'd also be nice if the people connected by the wired connections could access the internet, or connect to other AP's. Sure they could do that normally, but they're inside a car, and I'm guessing you dont get near as high dB inside of a car. So after a few ideas, I thought why not put my spare computer in the trunk, put in a wireless card and hang the antenna outside the car. Since the WRT54G has a CAT5 input for internet, I thought maybe I could have the spare computer act another router for internet. (not sure at all about that)

I know there's gonna be a problem with power, so I'm planning on getting a 2nd battery just powering the computer (but hooked up to the alternator, and I'll probably need to get a bigger alternator).

So all my questions in a really nice list:

1. How to connect a wireless router's antennas up to a car's radio antenna
2. Can a computer act as another router?
3. How much power does a car battery give off?
4. How much larger of an alternator would I need?

[crenn]

Putting wireless into a car will be a very interesting task.

1.The car's radio antennae might not be sufficent at operating at high frequencies. I'm unsure about this but I can also point out another reason why not to. Unless you don't listen to the radio much, then this might be fine, but if you do, then you might be some interferance. EMI is going to be an enemy at this stage, you will need to plan to avoid it.
2. Yes, a computer act as a router but you come across one problem, all of the laptop based router's I've heard of (they use a router distro of linux) aren't able to act as wireless access points. I'm not sure if this has changed since I last researched this information. But according to your idea, even if you do have a laptop acting as a router, you will still need a switch, I would recommend getting a wireless router and get a regulated cigerette lighter plug for that router's voltage and amperage need. This might involve you having to design your own, I would hope not but the problem might occur.
3. I'll put it very simply. A LOT. The battery is used to power the starter motor which uses a lot of current to start the engine. Also the cigarette lighter socket in most cars (can't comfirm this) is able to supply 12v with a maximum of 20Amps, or a total of 240W. Enough to power a small computer for gaming.
4. As for this question, you need to work out how much power the car needs, how much power the alternator provides and how much more power you are adding onto the car. In most cases, the alternator you already have will still do it's job. Again, I can't confirm this as I'm not a mechanic, but I know quite a bit of electronics.

[Frogon]

Ok, sweet : P

1. I dont listen to the radio much (woot). But, I assume that means I should have an alternate antenna for the wireless router.
2. Ok, this was more of an extra thing I wanted to see if it worked, and I had my doubts. I really just wanted to know if it was like, quick and simple, otherwise I wont do it : P
3. I calculated my P3 requires 100watts : ) I was also thinking of maybe expanding stuff later (GPS, speakers, ect) so I wanted to make sure I'd have enough power in the future. And by using a 2nd battery for like, the "extras" I figured I could have pretty much as much power as I would ever need. I didnt know the cigarette lighter thing that much power! I could just use that for now..
4. Ok, I wasnt sure, because a friend of mine put a huge sub in his trunk (it's huge and takes up the whole trunk) and it drained his battery slowly. And I dont know how to measure how much extra power I have, but I'll ask around about this.

Thanks! : )

[crenn]

1. I would recommend an alternate antenna for the best preformance.
2. If you have a notebook or something like that, you could have a mini file server (using a 100GB 2.5" drive) and wireless connect to it. Because your design includes a 2nd battery you should be able to leave it on without worrying about flattening your main battery.
3. I would use that just for now as if I remember correctly, that socket will turn off when the engine is turned off.
4. The main reason a sub would drain the battery if the engine was off was because the person who fixed and wired it into place didn't wire it to the correct fuse. There are some fuses which remain on even when the engine is off. If you plan to put a computer into your car, I would recommend getting a Mini-ITX, even if it's a fairly crappy one, it has very very very low power consumption. There is also a book on the correct way of putting a computer into a car. If you want I'll dig up the link again.

[crazybillybob]

Here's a Link Mini-box Wireless access point (http://www.mini-box.com/s.nl/sc.8/category.19/.f) It's a mini-itx board developed for use in wireless networks (they have 1-3 lan ports and 1-2 mini PCi ports for wireless nics). Also on this page is high gain antnnas and Nics. Just giving you more Ideas!!! This stuff runs on 12Vdc!


Crazybillybob

[crenn]

Good find CBB, this would be great for car use as long as you regulate the voltage coming from the car's battery. I wouldn't call it a mini-ITX board, but it's very close to it.
This give me more ideas for my future car project. Having 3 computers in the seats with 'xbox 360' controllers available for gaming (for something like Halo ;)). But this project will be quite expensive XD, and this one will need it's one battery to run as It's 3 Pentium Ms!!

[OvRiDe]

Soekris (http://www.soekris.com/) makes a board very similar to the WRAP boards, I don't know if I would call them Mini-ITX since they have no video output or keyboard input capabilities, they are completly "headless". But I think we all know what CBB was getting at. There are several router distros specifically designed for these boards that are REALLY nice. The one I prefer is called m0n0wall (http://m0n0.ch/wall/). I have had pretty good luck with it. It has a nice web interface for configuration and lots of features. Another benefit is its Open Source and free! Their site is pretty comprehensive and has screenshots (http://m0n0.ch/wall/screenshots.php) and a gallery (http://m0n0.ch/wall/gallery.php) of how the users have implimented it. They also have a generic CDROM version that will run on a regular PC (aslong as you have supported hardware) in which you can use a PC and a CDROM drive. No HDD is necessary.

[crazybillybob]

Good find CBB, this would be great for car use as long as you regulate the voltage coming from the car's battery. I wouldn't call it a mini-ITX board, but it's very close to it.


Look around on that site, The sell some very nice power supplies for all these products that are made for in your car. They have battery monitors (so they shutoff if the batt gets to low...so you can still start your ride!), they filter the noise and high/low voltage fluctuations out (think starting your car...the lights dim) and can be set to remotely start audio amps (via the amps remote terminal). I think the one I'm talking about is MX100A (or 1A.... Can't remeber for sure).

and your Right there not full mini-itx...but there based on the same CPU line and very small.

Crazybillybob