I need some help from anyone who knows their RF stuff. I'm trying to build a Wireless LAN. The speed of the lan does not have to be fast (I would be perfectlly happy with a tx/rx speed of 115.2 Kbs). The only snags are that it can't be line of sight and should be able to transmit over a .5 K radius. Also, I don't have the financial resources to build/buy an expensive system. Is there any one out there that might be able to help me. Oh, and preferable it should transmit on a legal/licenceless freq. I was thinking of just basically transmitting the data that gets sent over a lan cable as all that would require is a 2 channel transciever. Alternatively instead of a lan cable, to send the data on a serial cable. So essentially the transceiver would just be an extension of the cable. Any ideas? Any books I should read? Thanks in advance
Well, RF serial connections are possible, but you specifically said LAN, so do you really need a MAC protocol? I know you said you're on a budget, but 802.11b access points can be had pretty cheaply, and then the problem boils down to selecting/constructing an antenna, which can be pretty cheap. I think the Pringles can trick is perhaps the most widely known.
cheap wlan You say you are on a cheap budget, but how cheap is cheap? You can forget about a .5 kilometer range for a cheap one. You will need several wireless hubs to extend that distance to make the network useable in that range. Several institituions over here in the states whos WLANs I have worked on have a very limited range between hubs, like 20 meter radius. These are places with millions of dollars in their IT budgets.
I have been looking at the 802.11 standard but the problem with it is that it's line of sight (as far as I know). RF Serial... that would be good. I basically want to connect to computers together over a wireless connection. Both PCs would be windows which has direct cable connection so if I could just transcieve the signals that would normally travel along that cable my world would be a better place.
Well, 802.11 isn't really line of sight, it will pass thru walls. But obstructions will attenuate your signal. In spite of what nesbit37 is saying above (welcome to the boards BTW), distance with 802.11 is really a function of antenna gain. You can spend a little money building (or a lot buying) antennas that are more sensitive than the stock ones. Not all cards will allow you to fit a custom antenna, so check for that before you buy. Using the pringles can trick, those guys were getting ranges well over a mile: And there are two other cool things about 802.11b: a) you can operate at a lower bit rate in exchange for more distance, and b) you can operate in 'ad-hoc' mode, with just two cards, no access point required. Unless you have some RF experience, I'm gonna steer you toward the 802.11b alternative.
i know netgear sells a wireless bridge with a 5 mile radius worked with one of them on a project for an instructor at school. no need for LOS but it doesnt hurt to have it. and you can get a narrow feild directional anteena. i dont remember the product nember but try CDW.com as a reseller if they dont have it go to NETGEAR.com
Does it really have to be wireless? CAT-5 Ethernet can do more than 300 metres (A good cable should be able to do 500m) IF you use switches configured at full duplex. If you use hubs (half duplex) then your max cable length is like 100metres. There is another option... RS232 (serial port) can do like 15metres, but, it's big brother, RS485/RS422 can do more than 1km at several megabits using pretty much any twisted pair cable. There are simple RS232<->RS485/RS422 adapters. But if it have to be wireless, then I agree with linear, 802.11 is the way to go.
AmPz, it does have to be wireless cause i'd like the network to span from my friends house to mine. so we really can't use cable. i'm liking the idea of the 802.11, but you still need to buy a card, right? i was thinking of building my own tranciever, etc. i really can afford to buy cards and other expensive computer periperals. i'll have a look into 802.11 and maybe something will come of it.
It's always much more expensive to build stuff than to buy a mass produced product. There are 802.11 PCI cards for less than USD60
