Thread: Wireless connection with 2 mile range? Radio Modem?

Originally Posted by eastcoastbumps

*snip*
Someone on another forum mentioned radio modems but didn't have any more info to contribute. I found old Motorola RS232 RF modems out of police cruisers on eBay that are cheap. Would this work? I'm not sure what else I'd need. It would be great if I could find one that does voice and data.

http://cgi.ebay.com/Motorola-VRM600-...#ht_4107wt_907

It´s likely they were programmed to communicate with a base on differing frequencies, and you´d need the software set-up for them in addition to the motorola knowledge/equipment to program them over again.

I know packet radio has been used by other HAM radio operators for a long while, but it never really got super-popular, or very fast. I´m also unfamiliar with the FCC regs in this matter, I know they tend to have panties bunched when there isn´t voice communication involved for private/business use. So long as that doesn´t concern you much your probably on the right track. Just with some rather unknown caveats.

It is likely however it´d be less costly and less of a headache to just slap good antenna´s down with 1-2watt amps on them. If your in the pit, you can probably put up a good one that´ll get line of site, no? Something like this with an amp comes to mind for the pit, on a good length pole with ties. Then of course a decent one on the car itself. Any method you decide on will require a good antenna with good placement, so my first inclination would be to go this route unless there´s something major that would truly hinder it.

Unfortunately there isn't line of sight around most of the tracks I race at. They're not your typical NASCAR ovals with the pits right in the middle. Virginia International Raceway is probably the biggest track I go to. Its a little under 2 miles from the pits to the far end. Mosport in Canada has part of the track on the far side of a hill thats covered with trees. I also do hillclimbs, racing from the bottom of a mountain up to the top on the paved access road.

I need this to be a reliable connection. It would be a real PITA to be connected for 90% of a lap and then loose data for the other 10%.

Originally Posted by eastcoastbumps

Unfortunately there is no line of sight for most of the tracks I race at. They're not your typical NASCAR ovals with the pits right in the middle. Virginia International Raceway is probably the biggest track I go to. Its a little under 2 miles from the pits to the far end. Mosport in Canada has part of the track on the far side of a hill thats covered with trees.

I need this to be a reliable connection. It would be a real PITA to be connected for 90% of a lap and then loose data for the other 10%.

So long as it´s level I´m still leaning towards amped strong antenna(s) as the best bet. With the base one being put up >25ft.

Perhaps some of the forums for the more wireless troublesome racing might offer some better options? Only ones I´ve heard of remotely are these from data-linc.

And I don´t think your going to be fond of the overall cost to buy/implement in comparison to the relatively cheaper option of using your existing wi-fi. Many of their lower-cost products in fact are doing in essence what I mention, just using the 2.4g band with around .5watts of juice behind it. Obviously with better results as they´re not using the same exact section that your 802.11g US(1-10) would use, and using spread spectrum with other improvements I´m sure, but still. You can usually set the cards/routers easily enough to use the 11-14 g-channels that are out of band here in the US.

Any of these will be line-of-site dependant, meaning if you´ve got part of a mountain blocking you from the pit going up on the one you mention, nothing aside from satellite, or a repeater based set-up will stop it from cutting out on you.

WiFi is very useful in situations where things are moving around, and the distances are short, and they are great for long distances (up to 30 miles) with fixed antennas. But there is no way you're going to get two omni directional antennas to connect to each other at a mile away when you don't have line of sight (there are trees and buildings in the way). Sorry, but it just isn't happening. You can have a 11dBi omni on a mast 25 feet in the air, and another on the car, and 2 watt transmitters, and you're still not going to have a reliable connection at 2 miles away.

If I were you, I would do an analysis of how much data you need. You said you don't want to lose 10% of your data for a lap... no problem - keep the data buffered and then at the end of each lap when you're near the pits, you use your wifi connection and transfer a big 10MB dump of data for the lap.

If you -really- need to have an always on connection, I would suggest looking at something in the 900Mhz spectrum. It is an unlicensed spectrum (like 2.4Ghz and 5.8Ghz), but has much better performance through trees and walls. Take a look at the Ubiquiti Rocket M9. In order to clear the fresnel zone, you're going to have to have the base unit up as high as possible.

Another suggestion is that you can try to use more than one base unit. If you can setup 4 or 5 base units around the track, and each of them has another radio with a directional link back to a 'master' base station, then you can setup your wifi network to allow your client (car) to roam and automatically transfer between them.

Let me be clear... This is going to take a lot of work, and it is going to be expensive.

A friend of mine has set up solutions just like this for people doing baja style races out in the desert. Like CyberBill suggested, if you can get 4-5 radios set up around the track, except you don't need a second radio to go back to a "master" base station, you just need a mesh setup. I can get you a quote if you want to PM me some more details of exactly what kind of bandwidth you're looking for. The radios aren't that expensive, they range from around $150 to $2000 depending on your needs.