802.11b Wireless Networking with Linux
(Using the Belkin F5D6050 USB or D-Link DWL-650 card)
This is my wireless networking page. There is little information around on setting up a Wireless LAN using Linux at the moment. Most drivers are either flaky or non-existant, especially for some of the cards I ended up purchasing. Whilst most people seem to search out Lucent style Orinoco cards or similar devices - I had to try the hardest way. Under windows this isn't a problem - but for some serious networking, linux is the go and my devices need to be configured differently. I currently have the D-Link card below talking to the Belkin adapter both using linux.
D-Link DWL-650 PCMCIA wireless card. (was RRP $199.00 Harvey Norman - now $99 in some other stores)
Here are a couple of pictures I cropped from the net... mine is just the same inside. A bit hard to pull apart though. The D-Link DWL650 is a "CardBUS" (32 bit) type card, not a standard PCMCIA (16bit). so the old 486 Toshiba laptops would not support it. The Compaq Armada series laptops work well though as they have a CardBUS slot. The DWL-650 card uses a PRISM2 chipset by Intersil and a HFA3841 MAC controller.
D-Link DWL650 top view
D-Link DWL650 bottom view
So what driver do you use with the D-Link?
So far I know that a 2.2.17 linux kernel, pcmcia_cs-3.1.22 with swld11_cs-1.20.tar.gz will work.
I have also got a 2.2.17 linux kernel, pcmcia_cs-3.2.0 with swld11_cs-1.20.tar.gz to work.
I am trying to get the Samsung driver will working with kernel 2.2.20, pcmcia_cs-3.2.2 and swld11_cs-1.22.tar.gz.... different combinations give very different results.
I am currently running wireless_tools.23.tar.gz to configure everything on this card.
The standard wvlan_cs and prism2_cs have been tried with limited success, although the card will load with wvlan_cs and appear backward compatible with some commands. wlan-ng works okay, but does not support standard linux wireless extensions (in the versions I tried). I like iwconfig to configure things too. I have so far found the Samsung driver to be the best. A HOWTO will be made up shortly for this card.
Also I found a program called "Wavemon" on the Internet - It's a bit like a text mode version of 'netstumbler' but I have not got it to work properly with the D-link. It seems to be a nice console based application, but the '650 did not seem to report it's signal strength correctly to this program using the Samsung driver.
Belkin F5D6050 USB wireless adapter. (was RRP $229.00 Harvey Norman, now selling for a lot less!)
Here are some pictures once you dismantle this unit by pulling out the rubber feet and four screws.
|The AMTEL Wireless controller IC on the bottom of PCB||
The Wireless side of the PCB and antenna's.
The bottom view of the PCB
The USB interface side of the PCB
Where the antenna coax's are soldered on (easy to put a plug on!)
From reading the pictures, the Belkin USB adapter has a AMTEL AT76C503A MAC controller. The radio appears to be a RFMD type similar to a PRISM2 Chipset by Intersil. You could even unsolder one of the coax's and install a proper RF antenna connector on this unit. Remember that 2 antenna's are only used for diversity reception and let's face it, if the signal is point to point with a reasonable S/N then diversity is not really required, you can in fact probably use a dummy on the diversity antenna input without a problem. If I was adventurous I would find the diversity switch IC on the main PCB and bridge it out... but why bother, manufacturers like D-Link don't do it.
So what driver do you use?
I'm still working on it - this is what I am using:
A Pentium or above class machine ( I am using a Pentium 100 with 96Mb RAM)
A USB controller (I have an Opti 82C861 chipset special 2 port unit from PLE computers)
A Linux system (e.g. RedHat 7.3 install. I tried the 2.4.18-3 kernel and it wouldn't work properly, try using the 2.4.19 kernel which requires a complete recompile)
and the Belkin card (box!)..... and suitable USB cable. Other users reckon that 3x 5m length USB extensions can be coupled together and the whole thing works but this remains to be seen here. However USB rather than LMR series coax would be alot easier for RF. My antenna is just about ready for this device and pictures will be added to this site soon. A word of warning - I tried making a LONG usb lead and it failed miserably. The group delay is horrible on the data cable I used and the reflections caused by the two joints I made in the cable muck up the 12Mbit/s usb data considerably - it's now in the bin. Next trick is to try a commercial 5m extension lead first.
UPDATE: The 5m extension lead works okay, for a 10m lead - Jaycar sell a 5m 'active' USB lead for AU$50.. so this would probably also work. However I found the data errors created on the USB cable by joining a 3m extension and a 5m extension just made the whole thing fail.
Further information is now available at the "belkin-howto" page HERE to get it all working under linux.
Here is the latest modification for a Belkin USB adapter. 5m of USB cable is working okay, but still no good results yet. (It's horizontally polarized in the picture!)
And here's my latest access point antenna.... click here!
To calculate coax RF attenuation - try this excellent webpage : COAX LOSS CALCULATION