Pete_WirelessWales
01-15-2005, 01:21 PM
One of our members has been rather busy of late, building a system that can be run in the field.... literally
This is just stage one of the write-up - keep an eye on it at http://www.wirelesswales.net/articles/rentanode/
Please note, this is copied as-is from his report, so the wording and/or target audience may not match for this forum....
Any references to strangely sounding placenames, or bad weather, are due to the fact we are based in Wales, UK.
RentaNode - A Portable Wireless Node
Andrew Cornish, December 2004
The idea of deploying a wireless node anywhere, especially to locations without mains power, is certainly not new and several examples have been documented elsewhere. However, the combination of the PC-WRAP board and STAR-OS has for some time looked an attractive option to me, and recently I had saved just enough pennies to go mad. So, in November 2004 I decided to take the plunge and build a node to extend from my AP at home in Whitehill, Pembrokeshire.
The object was to construct a node which could itself act as an AP, but be capable of taking a wireless “backhaul” from another node. It should also be battery operated, using a solar panel to keep the battery charged. The WRAP-2C board from PC-Engines (www.pcengines.ch) provides for two mini-PCI slots and a single Ethernet connection. The board has 64MB of RAM and takes a Compact Flash (CF) card in lieu of hard drive. The CF card can be loaded with an OS such as STAR-OS, from a PC using, say, a USB adaptor.
The WRAP board is ideally suited for battery power, as it requires 12V and this can be supplied through both a two-pin 12V 2.1mm power socket, or through the Ethernet cable using Power over Ethernet (PoE). The board is shown below.
http://www.wirelesswales.net/articles/rentanode/fig1.jpghttp://www.wirelesswales.net/articles/rentanode/fig2.jpg
I bought mine direct from PC-Engines in Switzerland as the postage and packing is very reasonable (15 EUR for two boards and two CF cards), although the current state of the US Dollar makes buying from North America very attractive (in particular Valemount, the developers of STAR-OS (www.star-os.com), can supply virtually everything needed, including CF cards with STAR-OS loaded).
I liked the look of the Gewiss range of outdoor plastic boxes, because of the solid construction, ability to hinge the lid by only partially unscrewing two of the four plastic securing screws, and the ability to attach mounting plates on the bottom without going through the casing! I bought one from Maplin (www.maplin.co.uk) for £14.99, because it was there and so was I...
Of course, the internal mountings don’t match the mounting holes of the WRAP board, so I constructed a platform to screw onto the inside of the box and provide mountings for the board. I used a spare piece of transparent acrylic of the type you can buy from the likes of B&Q. I drilled four 4mm holes for screwing into the box, then drilled four more 3.2mm holes for the board. Four PC mounting spacers were then pushed onto the platform and secured using superglue (the spacers have screw mountings, but these go through the holes nicely to make for a good bond).
Next, three holes were drilled in the side of the box, two for the RP-SMA connectors on the pig-tails for connecting the antennae, and one for the gland through which the Ethernet cable would pass. The connectors were then mounted and the platform was screwed into the box (see below). Some might prefer to use pigtails with N-connectors, and these are available from Valemount (not, at the time of writing, from PC-Engines).
http://www.wirelesswales.net/articles/rentanode/fig3.jpg
The board was fitted with the mini-PCI cards and CF card, powered up from a 12V battery, and a cross-over cable connected from my laptop to the Ethernet port. The Ethernet port defaults to an address of 192.168.1.1 and so I set up the laptop to use a static IP of 192.168.1.2 and used PuTTY to talk to the board, checking that the wireless cards were recognised and everything running OK.
http://www.wirelesswales.net/articles/rentanode/fig4.jpg
Disconnecting the power, the pigtails were carefully connected to the board, which could then be pushed onto the PC mountings (above). I then made up 5m of Ethernet cable after threading it through the cable gland (remembering not to crimp the second connector until AFTER threading it!) Although it is perfectly OK to make up much longer cable, I wanted to keep voltage loss through the cable quite low, and I don’t anticipate the need to remote the battery too far (that is, after all, one of the reasons for using a battery!)
A simple PoE injector was constructed using a dual-socket Ethernet box, with a hole drilled at the rear to take a 12V 2.1 mm power socket. The sockets were wired so that a standard Ethernet cable could be run from the node supplying power and a cross-over cable from a laptop can then be plugged into the other socket (or indeed any wired network if it is desired to operate the node in that way). The final build, ready for taking into the field, is shown here:
http://www.wirelesswales.net/articles/rentanode/fig5.jpghttp://www.wirelesswales.net/articles/rentanode/fig6.jpg
PC-Engines advertise PoE injectors at what seems to me to be an incredibly reasonable price (3.50 EUR!) However, they were out of stock at the time I ordered, hence the DIY approach.
I’m using an Atheros CM-9 card for the link, with an Agere Ruby card for the AP. Both of these were obtained from SolWise (www.solwise.co.uk) The CM-9 can operate over both 2.4 and 5GHz in 802.11b, 11g and 11a modes. The Ruby is restricted to 2.4GHz 802.11b only, but it’s a good deal cheaper! I also believe that 802.11b is perfectly fine for operating over a wide area – most folk would fail to achieve much above 11Mb/s with 11g, and 11a is effectively restricted to fixed point-point links anyway through OFCOM’s light licensing regulations.
Although I have a solar panel and have tested it, there is some work (practical testing!) to do before I can be sure that it will be an effective solution for running this node over a long period. However, this now provides a useful prototype extension node to demonstrate coverage over a village or for a local event.
This is just stage one of the write-up - keep an eye on it at http://www.wirelesswales.net/articles/rentanode/
Please note, this is copied as-is from his report, so the wording and/or target audience may not match for this forum....
Any references to strangely sounding placenames, or bad weather, are due to the fact we are based in Wales, UK.
RentaNode - A Portable Wireless Node
Andrew Cornish, December 2004
The idea of deploying a wireless node anywhere, especially to locations without mains power, is certainly not new and several examples have been documented elsewhere. However, the combination of the PC-WRAP board and STAR-OS has for some time looked an attractive option to me, and recently I had saved just enough pennies to go mad. So, in November 2004 I decided to take the plunge and build a node to extend from my AP at home in Whitehill, Pembrokeshire.
The object was to construct a node which could itself act as an AP, but be capable of taking a wireless “backhaul” from another node. It should also be battery operated, using a solar panel to keep the battery charged. The WRAP-2C board from PC-Engines (www.pcengines.ch) provides for two mini-PCI slots and a single Ethernet connection. The board has 64MB of RAM and takes a Compact Flash (CF) card in lieu of hard drive. The CF card can be loaded with an OS such as STAR-OS, from a PC using, say, a USB adaptor.
The WRAP board is ideally suited for battery power, as it requires 12V and this can be supplied through both a two-pin 12V 2.1mm power socket, or through the Ethernet cable using Power over Ethernet (PoE). The board is shown below.
http://www.wirelesswales.net/articles/rentanode/fig1.jpghttp://www.wirelesswales.net/articles/rentanode/fig2.jpg
I bought mine direct from PC-Engines in Switzerland as the postage and packing is very reasonable (15 EUR for two boards and two CF cards), although the current state of the US Dollar makes buying from North America very attractive (in particular Valemount, the developers of STAR-OS (www.star-os.com), can supply virtually everything needed, including CF cards with STAR-OS loaded).
I liked the look of the Gewiss range of outdoor plastic boxes, because of the solid construction, ability to hinge the lid by only partially unscrewing two of the four plastic securing screws, and the ability to attach mounting plates on the bottom without going through the casing! I bought one from Maplin (www.maplin.co.uk) for £14.99, because it was there and so was I...
Of course, the internal mountings don’t match the mounting holes of the WRAP board, so I constructed a platform to screw onto the inside of the box and provide mountings for the board. I used a spare piece of transparent acrylic of the type you can buy from the likes of B&Q. I drilled four 4mm holes for screwing into the box, then drilled four more 3.2mm holes for the board. Four PC mounting spacers were then pushed onto the platform and secured using superglue (the spacers have screw mountings, but these go through the holes nicely to make for a good bond).
Next, three holes were drilled in the side of the box, two for the RP-SMA connectors on the pig-tails for connecting the antennae, and one for the gland through which the Ethernet cable would pass. The connectors were then mounted and the platform was screwed into the box (see below). Some might prefer to use pigtails with N-connectors, and these are available from Valemount (not, at the time of writing, from PC-Engines).
http://www.wirelesswales.net/articles/rentanode/fig3.jpg
The board was fitted with the mini-PCI cards and CF card, powered up from a 12V battery, and a cross-over cable connected from my laptop to the Ethernet port. The Ethernet port defaults to an address of 192.168.1.1 and so I set up the laptop to use a static IP of 192.168.1.2 and used PuTTY to talk to the board, checking that the wireless cards were recognised and everything running OK.
http://www.wirelesswales.net/articles/rentanode/fig4.jpg
Disconnecting the power, the pigtails were carefully connected to the board, which could then be pushed onto the PC mountings (above). I then made up 5m of Ethernet cable after threading it through the cable gland (remembering not to crimp the second connector until AFTER threading it!) Although it is perfectly OK to make up much longer cable, I wanted to keep voltage loss through the cable quite low, and I don’t anticipate the need to remote the battery too far (that is, after all, one of the reasons for using a battery!)
A simple PoE injector was constructed using a dual-socket Ethernet box, with a hole drilled at the rear to take a 12V 2.1 mm power socket. The sockets were wired so that a standard Ethernet cable could be run from the node supplying power and a cross-over cable from a laptop can then be plugged into the other socket (or indeed any wired network if it is desired to operate the node in that way). The final build, ready for taking into the field, is shown here:
http://www.wirelesswales.net/articles/rentanode/fig5.jpghttp://www.wirelesswales.net/articles/rentanode/fig6.jpg
PC-Engines advertise PoE injectors at what seems to me to be an incredibly reasonable price (3.50 EUR!) However, they were out of stock at the time I ordered, hence the DIY approach.
I’m using an Atheros CM-9 card for the link, with an Agere Ruby card for the AP. Both of these were obtained from SolWise (www.solwise.co.uk) The CM-9 can operate over both 2.4 and 5GHz in 802.11b, 11g and 11a modes. The Ruby is restricted to 2.4GHz 802.11b only, but it’s a good deal cheaper! I also believe that 802.11b is perfectly fine for operating over a wide area – most folk would fail to achieve much above 11Mb/s with 11g, and 11a is effectively restricted to fixed point-point links anyway through OFCOM’s light licensing regulations.
Although I have a solar panel and have tested it, there is some work (practical testing!) to do before I can be sure that it will be an effective solution for running this node over a long period. However, this now provides a useful prototype extension node to demonstrate coverage over a village or for a local event.