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2. Before you start

2.1 Useful stuff to have

Familiarity with Linux: You need to have a working Linux box to make major modifications to the default LRP disks. Familiarity with core Unix networking concepts is required.

Compass: Line of sight (LOS) does not mean that a human being can see that far. It is useful to have a compass to take bearings.

Telescope: Pick out landmarks and obstructions between endpoints.

Soldiering Iron: Some facility with one of these is required to build your cables.

Map: Once you figure out where you are, a map helps you tour around the streets.

Greg comments: As far as maps go, I'd have to recomend (to our readers) that they get a good high-quality topographic map, rather than attempting to use street maps. Street maps are meant for people following streets, whereas topo maps are for outdoorsy type folks who rely on their compasses (as do antenna aligners). These maps will accurately orient north with a compass, and will document the magnetic declination for a given area (Most of the bay area is 17' east of true). It'll also prove helpfull for those in hilly areas (to judge where your LOS is blocked). Here's a brief guide to orienteering for those geeks that don't get out in the woods much.

2.2 Useful stuff to know

Magnetic declination: A standard compass can vary off of true north by 17 degrees or more. If you know the typical magnetic variance for your area you can compensate for it. A good topo map usually has this clearly marked.

2.3 Useful background material

2.4 Hardware Required

It's apparently impossible to get all the stuff you need from a single vendor. The FCC is not fond of unlicensed wireless technology, although this is changing with the release of some new bandwidth in th 5.725Ghz band. The guys that do this sort of stuff generally want you to buy the install from them too. Since this is a DIY sort of project we didn't exactly get all the support we needed from any one vendor. You can see our list of vendors below under suppliers.

2.5 Software Required

2.6 Using the LRP code

Read everything you can from the linux router project. Then you can pull down the wireless starter disks and pretty much forget about most of what's on the lrp site. We've got a quickstart guide on how to use these floppies.

2.7 First, figure out where you are

The wonderful mapping facilities of mapquest and yahoo are a great aid to figuring out your latitude and longitude. However, neither service explicitly tells you what your latitude and longitude are. You can figure it out from the url you get back from the sites.

What these tools are not good at is figuring out your height above ground or if there is a building in the way. There is a tool that can figure out LOS over and around obstructions, but I can't find the url for it.

Here's where a telescope comes in handy. Even with a high quality telescope it's hard to see your end points at extreme ranges (+10 miles). A good high powered colored light at your downstream site helps a lot.

2.8 Find a suitable downstream site

In our case only a very narrow slice of the of the valley was viewable from the house. Neither of our primary sites worked out (that 17 degree magnetic declination bit us) and we spun our wheels for a while.

Ultimately we posted to the ba.internet newsgroup and the svlug mailing list and found a bunch of hackers willing to share their bandwidth, which was really heartwarming. However their grip on technology was better than their grip on geography and none of our 5+ volunteers was within LOS.

A few commercial ISPs did email us with offers to connect to us. Netcom,, and a few others all claimed to offer wireless service, but all of them got real nervous when we told them about our hardware. All of them wanted us to use their hardware and pay fees in the 250-450 month range for 384K access.

After another posting we finally ran into a very clueful ham radio dude smack dab in the middle of our LOS. We got a good connection on the the very first try. We were in business! The trouble was, he didn't have an internet connection yet. But that's another story.

The point of this is that the community spirit of the internet is not dead, and it is certainly possible to find someone who can connect you to the internet who is within your line of sight, if you look in the right places.

2.9 Notes on Cabling

Greg notes: The most custom part of this setup is that the arlan cards use a very special (hard to get) type connector, a Reverse-Polarity TNC (RP-TNC). This is probably where most people will run into trouble. The connector is so rare, that there are no adapters; the user must make an adapter. They need the connector, a N-Type(Fem).to.RJ58 connector, and about 6 or so inches of RJ58 cable (the shorter the better). They then use the cable to connect the two connectors together (therefore making an adapter (or as we call it 'the tail')). T-type fem's are easy to find, RJ58 cable is easy to find. To connect it together the'll prolly need a coax stripper, crimper and a solder gun. As far as constructing the tail, beats me, I faked it and it seems to work. They can then connect their router to their antenna using an easy to find N-Type(male) cable of the required length.

The RP-TNC can be obtained through any Amphenol dealer, its part number is '31-5677'. The connectors are roughly $5 each, however the dealer may require a minimum order (say $50).

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