Background:
The US Department of Defense uses modified Consumer Off The Shelf (COTS) wireless LAN products now reprogrammed to operate in military frequency bands with enhanced encryption. Most COTS WLAN products can be easily modified to employ these frequencies because of their modular architecture. Their future versions of modified COTS WLAN products may include frequency agile transceivers that can work in multiple frequency bands via plug-in modules or software selection.
It's a fact that most wireless devices are manufactured for international marketing. The manufacture just makes minor hardware or firmware changes to comply to the intended countries radio rules. These firmware options usually include minor output power and band plan changes. It may be possible and to a hams advantage to shift the center frequency of your device to avoid Part 15 interference or increase the devices output power to overcome Part 15 interference. Also to avoid Part 15 interference a ham may be able to change the country code in the devices firmware to shift frequency operation into foreign band plans that might not be shared with Part 15 here in the US.
Shifting frequency to keep out Part 15 may be a difficult or impractical option, but there are others ways which will have the same desired effect. It might be fairly easy to create a "non-compatible" fork of the source code for hams, that would keep 99.95% of the general public (Part 15) out of ham space.
There are several different chipsets out there such as; Marvell, Atmel, Atheros, Hermes, ADMTek, Infineon, Broadcom, Intersil/Prism, Ralink, Realtek, Texas Instruments, WiDeFi, VIA, Conexant.
The Atheros Chipset
The Atheros chipsets for the IEEE 802.11 standard of wireless networking are used by over 30 different wireless device manufacturers, including Netgear, D-Link and Linksys.
The Ubiquiti Networks frequency freedom technology, seems to lead the way and promise integrated radio technology which uses an advanced RF integration and firmware design to provide a powerful platform capable of operation in any frequency imaginable. Basically Ubiquiti radios are Atheros chipsets with transverters onboard.
StarOS software by Valemount Networks generally supports the additional features of the Atheros Chipset One of these settings is the country code. Changing the country code to that of a country where the Part 15 bands are different than ours may create a convenient incompatible fork. For ham radio use this may keep nosey Part15 users out, and/or provide channels that do not overlap the Part 15 channels in the USA.
All of the below country codes (including XX or ## which have been used for "without regulatory constraints") are part of the driver, or "hardware abstraction layer" (HAL). These are the secrets to unlock all channels supported by the Atheros hardware (2312-2732, 4920-6100 MHz). It is up to the end user to ensure they stay within their region's regulatory channel ranges. (While IEEE has not assigned channels to these upper 2.4 GHz frequencies, however they would equate to 0, -1, -2, etc.)
These two-letter codes can be entered on the Atheros configuration dialog to enable certain bands for that country. Country codes can be used on cards with Regulatory Type (RT): All_Countries as shown in the regulatory information box.
NA - No_Country_Set, AL - Albania, DZ - Algeria, AR - Argentina, AM - Armenia, AU - Australia, AT - Austria, AZ - Azerbaijan, BH - Bahrain, BY - Belarus, BE - Belgium, BZ - Belize, BO - Bolvia, BR - Brazil, BN - Brunei Darussalam, BG - Bulgaria, CA - Canada, CL - Chile, CN - China, CO - Columbia, CR - Costa Rica, HR - Croatia, CY - Cypres, CZ - Czech Republic, DK - Denmark, DO - Dominican Republic, EC - Ecuador, EG - Egypt, SV - El Salvador, EE - Estonia, FI - Finland, FR - France, GE - Georgia, DE - Germany, GR - Greece, GT - Guatemala, JO - Jordan, KZ - Kazakhstan, KP - North Korea, KR - Korea Republic, K2 - Korea Republic2, KW - Kuwait, LV - Latvia, LB - Lebanon, LI - Liechtenstein, LT - Lithuania, LU - Luxembourg, MO - Macau, MK - Macedonia, MY - Malaysia, MX - Mexico, MC - Monaco, MA - Morocco, NL - Nethernlands, NZ - New Zealand, NO - Norway, OM - Oman, PK - Pakistan, PA - Panama, PE - Peru, PH - Philippines, PL - Poland, PT - Portugal, PR - Puerto Rico, QA - Qatar, RO - Romania, RU - Russia, SA - Saudi Arabia, SG - Singapore, SK - Slovak Republic, SI - Slovenia, ZA - South Africa, ES - Spain, SE - Sweden, CH - Switzerland, SY - Syria, TW - Taiwan, TH - Thialand, TT - Trinidad & Tobago, TN - Tunisa, TR - Turkey, UA - Ukraine, AE - United Arab Emirates, GB - United Kingdom, US - United States, UY - Uruguay, UZ - Uzbekistan, VE - Venezuels, VN - Viet Nam, YE - Yemen, ZW - Zimbabwe
Artheros Supported Channels (Center Frequencies) - 2GHz IEEE 802.11b/g channels (frequencies are given in MHz):
2312, 2314, 2317, 2319, 2322, 2324, 2327, 2329, 2332, 2334, 2337, 2339, 2342, 2344, 2347, 2349, 2352, 2354, 2357, 2359, 2362, 2364, 2367, 2369, 2372, 2374, 2377, 2379, 2382, 2384 2387, 2389, 2392, 2394, 2397, 2399, 2402, 2404, 2407, 2409, 2412, 2414, 2417, 2419, 2422, 2424, 2427, 2429, 2432, 2434, 2437, 2439, 2442, 2444, 2447, 2449, 2452, 2454, 2457, 2459, 2462, 2464, 2467, 2469, 2472, 2474, 2477, 2479, 2482, 2484, 2487, 2489, 2492, 2494, 2497, 2499, 2512, 2532, 2552, 2572, 2592, 2612, 2632, 2652, 2672, 2692, 2712, 2732
802.11a channels:
4920, 4925, 4930, 4935, 4940, 4945, 4950, 4955, 4960, 4965, 4970, 4975, 4980, 4985, 4990, 4995, 5000, 5005, 5010, 5015, 5020, 5025, 5030, 5035, 5040, 5045, 5050, 5055, 5060, 5065, 5070, 5075, 5080, 5085, 5090, 5095, 5100, 5105, 5110, 5115, 5120, 5125, 5130, 5135, 5140, 5145, 5150, 5155, 5160, 5165, 5170, 5175, 5180, 5185, 5190, 5195, 5200, 5205, 5210, 5215, 5220, 5225, 5230, 5235, 5240, 5245, 5250, 5255, 5260, 5265, 5270, 5275, 5280, 5285, 5290, 5295, 5300, 5305, 5310, 5315, 5320, 5325, 5330, 5335, 5340, 5345, 5350, 5355, 5360, 5365, 5370, 5375, 5380, 5385, 5390, 5395, 5400, 5405, 5410, 5415, 5420, 5425, 5430, 5435, 5440, 5445, 5450, 5455, 5460, 5465, 5470, 5475, 5480, 5485, 5490, 5495, 5500, 5505, 5510, 5515, 5520, 5525, 5530, 5535, 5540, 5545, 5550, 5555, 5560, 5565, 5570, 5575, 5580, 5585, 5590, 5595, 5600, 5605, 5610, 5615, 5620, 5625, 5630, 5635, 5640, 5645, 5650, 5655, 5660, 5665, 5670, 5675, 5680, 5685, 5690, 5695, 5700, 5705, 5710, 5715, 5720, 5725, 5730, 5735, 5740, 5745, 5750, 5755, 5760, 5765, 5770, 5775, 5780, 5785, 5790, 5795, 5800, 5805, 5810, 5815, 5820, 5825, 5830, 5835, 5840, 5845, 5850, 5855, 5860, 5865, 5870, 5875, 5880, 5885, 5890, 5895, 5900, 5905, 5910, 5915, 5920, 5925, 5930, 5935, 5940, 5945, 5950, 5955, 5960, 5965, 5970, 5975, 5980, 5985, 5990, 5995, 6000, 6005, 6010, 6015, 6020, 6025, 6030, 6035, 6040, 6045, 6050, 6055, 6060, 6065, 6070, 6075, 6080, 6085, 6090, 6095, 6100
You will notice that the channels appear to overlap. But you can lock in rates other than full speed and thusly use less bandwidth. A normal 802.11b channel @ 11Mbps occupies about 20 MHz, the 802.11g equivalent at 54 Mbps will also occupy about 20 MHz. There are a variety of different supported-rates you can lock in; 1Mbps 2Mbps 5.5Mbps 6 Mbps, 9 Mbps, 11Mbps, 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps. Some of these rates are tied to the mode, 802.11b or 802.11g or the supported channels, so you will need to pay attention to that.
As you can see my utilizing different supported-rates, you can take advantage of the different channels with minimal or no overlapping. You may also be able to fit a ham only channel in in band segments not shared with Part 15.
At 802.11b rate 11MBps and 802.11g rate 54 Mbps = 20 MHz bandwidth
At 802.11b rate 5.5Mbps and 802.11g rate 24 Mbps = 10 MHz bandwidth
At 802.11b rate 2 Mbps rate and 802.11g rate 10 Mbps rate = 5 MHz bandwidth
Actually the Atheros chipset doesn't really know about channels; they are determined by the code that's loaded into it at boot time. All of these country codes (including XX or ## which have been used for "without regulatory constraints") are part of the driver, or "hardware abstraction layer" (HAL). Atheros will sell you the tools to build a driver, if you're manufacturing a device and do a licensing agreement with them. There is a partially open source driver for Atheros chips at madwifi.org ... but (per agreement with Atheros) the HAL is a locked-down binary that restricts you to the Part 15 channels. There is another company, Ascom in Switzerland (www.ascom.com), that has written their own Atheros driver (under Atheros license), and will provide various versions of it for a fee. I believe that this is the source of the implementations out there that permit operation out of the ISM/UNII bands such as Mikrotik, StarOS, Ikarus. If pay an extra $10, Mikrotik will give you a code which unlocks the "custom" frequencies in 2.4 and 5 GHz that the Atheros chipset will support. They will ask that you sign a statement that you will comply with the rules of your country.
To use frequencies outside the Part 15 band, Mikrotik just needs a superchannel license.
From the Property Description section of the MikroTik reference manual:
frequency-mode (regulatory-domain | manual-tx-power | superchannel; default: superchannel) - defines which frequency channels to allow
• regulatory-domain - channels in configured country only are allowed, and transmit power is limited to what is allowed in that channel in configured country minus configured antenna-gain.
Also note that in this mode card will never be configured to higher power than allowed by the respective regulatory domain
• manual-tx-power - channels in configured country only are allowed, but transmit power is taken from tx-power setting
• superchannel - only possible with superchannel license. In this mode all hardware supported channels are allowed
/interface wireless set wlan1 frequency=XXXX
The open source madwifi driver isn't quite as developed yet, and presently doesn't allow all the channels:
http://madwifi.org/wiki/UserDocs/802.11a_channels
http://www.bcwireless.net/moin.cgi/AtherosCards
Note:
FCC forbids selling radio devices in which user has total control over radio frequency being used. This is part of the certification process. That's the reason Atheros doesn't open their software. Manufacturers have to be sensitive when it comes to wireless gear. The wireless chipsets are capable of operating outside of their allotted spectrum in many countries and the only thing that stops them from doing so is the lowest level of software/firmware. Their licenses to sell this stuff relies on their being able to stay within their allocated frequency ranges so they are caught between a rock and a hard place. If they allow the hardware to be run without software/firmware/HAL that they wrote, then they can get into trouble. Obviously, company lawyers tend to err on the cautious side, hence the 'hard line' that OSS developers are seeing from some of these companies. They see it as an extreme liability issue, with the capacity to severely harm their company. For more info see "Towards a free Atheros Driver."
Hardware mods:
Prior in older hardware these tweaks were simple hardware changes. Such as in our original work with the Proxim Symphony, it was possible to tweak the card to double its output power.
On the Proxim Symphony it's was possible to change out the dropping resistors that run the RF power amplifer IC and run the IC at 3.6 - 3.9 volts to double the RF power output. The maximum DC voltage for this IC is 4 volts and the maximum RF power output is around +23 dBm (200 mW).
It's also possible to tap the PIN diode bias line to control an external amplifier on most wireless devices.
For more information on this modification see: http://www.qsl.net/n9zia/wireless/cardmap.html
For info on 802.11 hardware mods see: http://www.qsl.net/n9zia/wireless/appendixG.html
Some hams in Germany recrystaling WRTs to go outside of the ISM band:
http://www.rlx.lu/~lx1tb/wrt54gs/
http://db0fhn-i.ampr.org/wrt54gs/
Modified firmware:
In our day we also attempted to see what was possible by modifying and reverse engineering the Proxim Symphony Driver. See: http://www.qsl.net/n9zia/wireless/page03.html
[At the time I also contacted and spoke with several people at Proxim to try and obtain a schematic or block diagram to aide in our project. I even indicated that I might be willing to sign a non-disclosure agreement to obtain this information. The response from a Proxim wireless head official was to the effect of "I'm sorry but our designs are proprietary and we are unable to assist you." We ended up reverse-engineering it all by hand with an oscilloscope and some data books. Interestingly enough a few years later, other companies, namely Linksys, did grasp the open source concept.]
Now days with 802.11 hardware a whole new world of firmware changes are possible. For many old prism cards, the channels (frequencies) were a bitmap in the firmware. Atheros is even easier.
Linksys and other manufactures have been using embedded Linux on their products. Linksys and others have released their source under the GPL. People have been writing alternative 3rd party firmware versions for these devices, adding tons of fixes and great new features. The most popular device to have alternative firmware is the WRT54G (Wireless G router) since this is the device that sort of kick this whole thing in motion.
http://h.vu.wifi-box.net/wrt54g/
For example; this guys Firmware adds tons of new features to the Linksys WRT54G (Linksys Wireless G Router).
Such as using Japan's or the UK's 2.4 GHz bands or increasing the power output of
your antennas. All the wireless devices from Linksys default as 12.5% of the accentual power they can really put out?
This is because in the UK that can use up to 50% of the max, but our firmware restricts it to 12.5%.
People report over 10 times the distance at 100%.
Once can even run telnet access, static DHCP services, VPN servers and clients, OSPF/RIP/RIP2 services, SNMP services, MultiPPTP pass-through, a relay DNS server with an internal cache, an Apache Web Server (great for reverse proxying certain web directories to different machines on your internal LAN or routing a specific domain to a different IP internally).
Another route people are taking the WRT54G is going out and loading NoCatSplash on them. This allows them to have a public access
point, but show a webpage before they can surf (to tell the rules of this AP).
For more info see:
http://www.linksys.com/support/gpl.asp
to get the Linksys source yourself.
http://www.linksysinfo.org/
http://www.sveasoft.com/modules/phpBB2/index.php
http://www.seattlewireless.net/index.cgi/LinksysWrt54g
http://www.seattlewireless.net/index.cgi/WAP54G
http://www.smallnetbuilder.com/Reviews-39-ProdID-WRT54G.php
http://www.seattlewireless.net/index.cgi/Belkin_20F5D7230_2d4
(Yes, Belkin products run Linux too; and so do some Dlink)
http://www.batbox.org/wrt54g.html
http://www.batbox.org/wrt54g-linux.html
http://www.sveasoft.com/forum-cat3.html
These guys released a version of the firmware too.
www.star-os.com check out there starvx software and the WAR bards
http://www.ubnt.com/super_range9.php4
700 mW on 900 MHz - 54 Mbps
Transverters and amplifiers:
RF Linx had some
Bi-directional 2.4 GHz amplifier kits that were really cheap.
http://www.rflinx.com/2.4GHz%20Bi-Directional%20PCB.htm
They look to be based around some WJ ICs.
Transverters:
http://www.teletronics.com/Frequency%20Converters.html
Options like 2.4 to 900 MHz (1 & 4 watts), 2.4 to; 3.4 GHz, 3.5 GHz, 5.8 GHz
http://www.teletronics.com/specialfreq.html
2.4 GHz to 1.2 GHz @ 1 watt
Teletronics Prices
2/2007
1 Watt Outdoor 2.4 GHz 2 pc SmartAmp List Price: $399.99
1 Watt, 2.4GHz Indoor SmartAmp $199.00 US
SmartAmp Bi-directional RF Amplifier 900 MHz Series 4 Watt Price: $900.00
SmartAmp Bi-directional RF Amplifier 900 MHz Series 1 Watt. Price: $800.00
HyperLink Technologies Prices 2/2007:
1 Watt, 900 MHz Indoor model HA901I-APC $350.00
3 Watts, 900 MHz Indoor model HA903I-APC $440.00
1 Watt, 2.4 GHz Indoor model HA2401RTGXI1000 $180.00
2 Watt, 2.4 GHz Indoor model HA2402GXI-NF $350.00
SSB Electronics released at Dayton 2003, "Amateur use only" mast mount biamp for $599 (rumored price) that's up to 4 watts out, 22db Rx amplifier with 1.8 db noise figure.
Fleeman Anderson Bird Corp offers a radio amateur discount, put your callsign in the order comments, 7% will be taken off your order when shipped.
7/08: Ubiquiti has started
shipping its "NanoStation" radios in 2.4 and 5 GHz. With the
appropriate country code selected, the 5 GHz unit will cover the entire amateur
allocation 5660-5925 MHz, not just the ISM/UNII frequencies. 5, 10 and 20 MHz
wide channels, Atheros chipset, 400 mW radio, 802.11a protocols, in a molded
weatherproof case with 13 dBi antenna, dual polarization, plus external SMA
antenna connector, entirely open source firmware available in an all-in-one SDK
for free which you can alter and compile yourself. With power-over- ethernet
injector and 12 volt wall wart, $79 for 2.4 GHz or $89 for 5 GHz.