Feeds
|
Location:
Sun, 02 Apr 2006I had to go without my mobile for a little over a week. Thankfully the Linksys Community Network provided adaquate roaming coverage for my WiFi phone for this not to really be a problem. It is also interesting to note the amount of WEP encrypted access points vs. open access points within London. Nearly all access points are encrypted, with the exception of a very small few. This is entirely opposite in the Seattle area, where just about anything is wide open without any sort of measure of deterence.
Sat, 15 Oct 2005
No Free Hotel WiFi? Now there is...Whoops..
I am in Boston this week for work. While the hotel I am staying at offers high speed internet access, it is only available on a 3 foot ethernet cable, and is over $10 a day for service. Well, after plugging in TrainNode, paying the lousy $10 service fee, and making a few modifications, I accidently lit up the entire wing of my hotel with free high speed wireless internet -- whoops. And i'm sure that an SSID of "FreeBroadbandInternetAccess" is a dead giveaway of the nifty new offering.
Wed, 20 Jul 2005I just got yet ANOTHER antenna from someone, a good 24dBi parabolic grid (galvenized steel). If anyone has a need or project coming up where they need 3 24dBi parabolics, array of omis, sectors, coax, radio cards, soekrises, etc. just give me a call :) Wed, 04 May 2005As much as I do not like to admit, Bluetooth is pretty neat. Its painfully slow FHSS physical layer is shadowed by its nearly universal vendor support, object exchange, serial cable replacement and digital voice capability. While Bluetooth was great for GPRS, and perhaps 1xRTT and EDGE, its turning into a bottleneck. Currently, WCDMA/UMTS and EVDO speeds far exceed the maximum symmetrical serial rate Bluetooth can deliver. What does this mean? Break out your USB cables again folks! Bluetooth is now useless. But why did the Bluetooth SIG let an aging physical layer linger for so long? Especially when standards-based technologies like 802.11/WiFi have seen profound increases in physical layer speeds. While there are many political reasons, the adoption of a non-standards based unscalable FHSS technology did not help the issue. What was the Bluetooth SIG thinking? The Bluetooth vision was an application, not a set of physical and electrical specifications. Yet, development went in to create a completely proprietary radio interface and protocol that barely plays friendly with other spectrum users. This likely reminds readers of the HomeRF days, yet another proprietary wireless LAN protocol competing with an open standards based specification. HomeRF is dead; Bluetooth is dying. But wait a minute, Bluetooth is useful! What about the cool headsets, ease of swapping contact information, and multiplayer java games? Why can't we take Bluetooth to the higher OSI layers, like any other real application, and use a mass produced, well supported, nearly universal physical and MAC layer like 802.11/WiFi? Blueooth over WiFi?? Now guys, I'm not on drugs. I am talking about the Bluetooth application suite on top of WiFi instead of its old FHSS counterpart. Some advocates say Bluetooth's advantages are in footprint, cost, and power consumption; I believe that this can be changed. Specific on-chip integration of a bluetooth-like stack, mass production, and reduced power output can all mitigate these factors. While it would be great to see Bluetooth riding on IP/UDP, making it routable, it may not be very possible. Issues such as IP addressing, security, and implementation complexity will arise. I could see Bluetooth existing as its own lightweight layer 3 protocol. Both peer-to-peer and infrastructure modes are well supported in 802.11. Concepts such as piconets and pairing could be implemented with ease. Devices could easily attach to WiFi networks and packetized voice services would operate nicely. Bluetooth would not rely on functions such as WEP, as better encryption facilities could be built into the higher layers. As WiFi advances, Bluetooth over WiFi could advance. Much like the original 802.11 DSSS cards operating in concert with 802.11g radios. It will be a long time before even the 802.11b MAC becomes too slow to be usable. Will we ever see Bluetooth over WiFi? Most likely not. I suspect the Bluetooth SIG has the same amount of intellectual property interest in the MAC as they do the actual bluetooth application. Besides, if you could do it over WiFi, you really wouldn't need a Bluetooth chip anymore. And that means less property control and royalties. Will we see Bluetooth Turbo? Wireless USB? UWB? The Bluetooth SIG can sit on this topic forever. The wireless industry will not. Micro WiFi access points are already being considered to correct the bottleneck in next generation EVDO/UMTS phones. If somebody invents a Bluetooth-like application protocol, the party is over for old 10th century Danish King Harald Blatand; old Bluetooth himself. Fri, 06 Aug 2004
Stop! before you steal that laptop...
I am very excited over a growing trend among laptop manufacturers: Built-in WiFi. These typically consist of internal MiniPCI WiFi adapters and antennas built into laptop screens. That means I can use the PCMCIA slot for something else, in my case, a nifty CDMA data card. But I have also noticed that as a side effect, there is no quick way to remove WiFi functionality. After all, who in their right mind would want to disable such a wonderful technology on their computer? If you didn't think wireless was cool, you probably wouldn't be reading this article. Most people are completely unaware of how WiFi works -- even if you are not connected to a network. And thanks more to a WiFi card's premicious nature, constantly hunting for an Access Point, even if you only have "LINKSYS" or "MYCOMANYAP" assigned. Thats right, depending on the WiFi client, your laptop may search for a signal several times a minute. My WiFi card on Windows XP seems to send out almost 30 requests a minute. And on each transmission WiFi makes, a unique fingerprint is encoded into the packet, more commonly known as a MAC address. MAC addresses are unique, and no two MACs are alike. Format the machine? Re-install windows? Unless the MAC is purposely changed, it will never go away. Using trivial software (ie: passive 802.11 frame sniffer), we can look for scanning messages (more technically, probe management frames) and hunt for a specific MAC address. So what happens if a dishonest neighbor or employee lifts a laptop? They better disable that WiFi card, because in combination with available evidence and usual cirumstances, it is the final nail in the coffin. That laptop will be shouting out, in the dark, with a bright flashlight saying "Im here! Im here!" for about 500-1000 feet, depending on equipment. This technique may sound far-fetched, but its amazing how effective it is. Tue, 27 Jul 2004
Matt has a great
Fri, 04 Jun 2004
IBSS "Infections"
But what happens if that is an IBSS association? Well, it looks like it just stays in it indefinitely, until further user action is made (ie: force new association, profile change, etc). By walking around with an IBSS radio, you can make a whole bunch of IBSS nodes with the same SSID. They never bother to change their names. Its a bit annoying because it made a peer-to-peer session act erratically when one third party associated to my IBSS at random with one particular default -- requiring a WEP key. My second peer did not want to associate without WEP (obviously because the third party wanted WEP), and it destroyed my IBSS. Thu, 08 Apr 2004
ELF Band
You can see the Earth's frequency at 7.8Hz, as well as peaks on 14, 20, 26, 33, 39, and 45Hz. Here is a picture of the sensor:
This site also has a cool writeup and spectrum plot of the band:
as well as a cool writeup and spectrum plot of the even weirder Less than 2Hz "Pc 1-2 IPDP band":
Thu, 05 Feb 2004I saw something on the PTP regarding some sort of IEEE seminar about this topic. While the question is like being concerned Oranges will drive Apples out of my local supermarket, it is a very good question. WiFi, or any future wireless LAN technology, will always have its place. A WAN will never replace the LAN. But hotspot carriers beware, EV-DO and EV-DV are very fast, and my $80 EV-DV plan with Sprint in two years will be like high speed DSL in my pocket. Why would I pay starbucks $40 for 5 coffee shops in seattle? For past blog entries, check out the archive on the side or click here. |
Make some extra cash with your blog too: |
