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[info] detect internet IP
this site can used in other program to detect external IP addr
[wireless]Wireless System overview
Wireless System
Wireless System Overview
Since ancient times, humans have learned to cooperate in order to overcome nature's limitations. There is a growing need to exchange information and services quickly and effortlessly across local, national and now global communities. People want the ability to communicate any time, anywhere in our mobile society.
Wireless technologies make our mobile society possible. Apple's iPod library syncs up with a laptop computer, drivers navigate their cars over uncharted roads, bargain hunters browse online stores, business travelers collaborate 24/7 with associates around the globe. Regardless of the circumstance, people today have an unprecedented level of mobility thanks to any combination of the four common wireless services:
1. WPAN: < 10 m, such as hands-free cell phones
2. WLAN: < 100 m, such as laptop to broadband access
3. WMAN: < xx Kms, such as building-to-building
4. WWAN: cell phones
In general, WLAN provides the most versatile service. WPAN range is too short and still binds the user to the nearest node. WMAN is too bulky and expensive to lug around. And WWMAN suffers speed and service charge constraints.
According to industry consensus, WLAN applications consist of three categories that cover many of our day to day mobility requirements:
1. PC Networking: Desktop Computers, Laptops, Routers, Printers, etc.
2. Consumer Electronics: Video Game consoles, Projectors, DVD players, TVs, Set-top boxes, Digital Cameras, Security Cameras, etc.
3. Handheld Devices: Mobile Phones, PDAs, iPods, Video iPods, etc.
In order to ensure high throughput, good range and universal interoperability, IEEE 802.11x standards govern WLAN operations. WLAN and IEEE 802.11x have become synonymous over the years:
- IEEE 802.11 - The original 1 Mbit/s and 2Mbit/s, 2.4GHz RF and IR standard (1999)
- IEEE 802.11a - 54Mbit/s, 5 GHz standard (1999, shipping products in 2001)
- IEEE 802.11b - Enhancements to 802.11 to support 5.5 and 11 Mbit/s (1999)
- IEEE 802.11c - Bridge operation procedures; included in the IEEE 802.1D standard (2001)
- IEEE 802.11d - International (country-to-country) roaming extensions (2001)
- IEEE 802.11e - Enhancement: QoS, including packet bursting (2005)
- IEEE 802.11f - Inter-Access Point Protocol (2003) Withdrawn February 2006
- IEEE 802.11g - 54 Mbit/s, 2.4 GHz standard (backwards compatible with b) (2003)
- IEEE 802.11h - Spectrum Managed 802.11a (5 GHz) for European compatibility (2004)
- IEEE 802.11i - Enhanced security (2004)
- IEEE 802.11j - Extensions for Japan (2004)
- IEEE 802.11k - Radio resource measurement enhancements
- IEEE 802.11l - (reserved and will not be used)
- IEEE 802.11m - Maintenance of the standard: odds and ends
- IEEE 802.11n - Higher throughput improvements
- IEEE 802.11o - (reserved and will not be used)
- IEEE 802.11p - WAVE - Wireless Access for the Vehicular Environment (such as ambulances and passengers cars)
- IEEE 802.11q - (reserved and will not be used, can be confused with 802.1Q VLAN trunking)
- IEEE 802.11r - Fast roaming
- IEEE 802.11s - ESS Mesh Networking
- IEEE 802.11t - Wireless Performance Prediction (WPP) - test methods and metrics
- IEEE 802.11u - Compatibility with non-802 networks (e.g., cellular)
- IEEE 802.11v - Wireless network management
- IEEE 802.11w - Protected Management Frames
- IEEE 802.11x - (reserved and will not be used)
- IEEE 802.11y - 3650-3700 Operations in USA
Among the physical layers, .11, .11b, .11a, .11g and Draft n offer progressive speeds over the course of development, which are as follows
Standard | Year | Modulation | Peak Rate | Peak Throughput |
.11 | 1999 | DSSS | 2 Mbps | 1 Mbps |
.11b | 1999 | CCK | 11 Mbps | 6 Mbps |
.11a | 1999 | OFDM | 54 Mbps | 25 Mbps |
.11g | 2003 | OFDM | 54 Mbps | 22 Mbps |
Draft n | 2006 | MIMO OFDM | 300 Mbps | 180 Mbps |
Also available are security features vital to wireless protection; QoS support that improves the service quality when service compromise becomes inevitable; radar detection that avoids interference with airport or weather Radar operations.
Users should evaluate application needs carefully and tailor the product appropriately. A sample of video application requirements are listed as follows:
Application | Throughput |
SDTV | 5 Mbps |
Cable Modem | 6 Mbps |
DVD | 9.8 Mbps |
HDTV | 12.9 Mbps |
ADSL2+ | 20 Mbps |
FTTH | 30 Mbps |
HD DVD | 36 Mbps |
Blue-ray DVD | 48 Mbps |
VDSL | 50 Mbps |
[cygwin]Howto make a portable cygwin environment
to make things better in my PC-Architecture course, so I decide to
make a portable cygwin environment.
Because I have no portable devices, such as Flash Disk. I have to
upload the whole environment to internet for further downloading.
Here is WHAT I do to make such a portable cygwin environment.
1. cp the cygwin which is already installed when I used windows to a
work directory named $cygwin.
2. write a script to make a cygwin environment, such as where is the
/, /usr and /bin in windows
use $cygwin/bin/mount to make mount points on which the
$cygwin/bin/bash depends to make a work environment.
/etc/profile will be read when evoke bash with a --login parameter,
namely evoke a login bash shell
[fpga] Storing Quartus II projects under version control
reference at nios2wiki
Storing Quartus II projects under version control
There is no need to backup all files in a Quartus project to be able reproduce it. You have to store source files (so that you can modify the project) and final binary files (so that you can reproduce the system exactly).
NOTE: This is not the final list yet, but it works for most simple projects (the software part is still missing). You should still test a reconstruction of the project from this files.
Quartus II source files:
- project files:
project_name.qpf
Quartus II project fileproject_name.qsf
Quartus constraint file (lists the hardware constraints defined for a project, from the used chip and pinout to timing constraints)project_name.qws
Quartus Window Settings ? (the configuration of the Quartus gui for the project, may be omitted)
- top level source files:
project_name.bdf
Block diagram / Schematic file (top level schematic file, there may be many nested files)project_name.vhd
VHDL file (top level VHDL file)project_name.v
Verilog file (top level Verilog file)
- component source files:
component_name.bsf
Block Symbol file (component symbol file)component_name.vhd
VHDL file (top level VHDL file)component_name.v
Verilog file (top level Verilog file)
- SOPC builder project source files (SOPC builder creates many VHDL or Verilog files, that you do not need to store)
sopc_project_name.ptf
the list and configuration of components selected in the SOPC guisopc_project_name.bsf
Block Symbol file (SOPC component symbol file, especially if you modified it)
- Board Description (if you created your own board, the list is incomplete!)
board_name/class.ptf
- software source files:
- tbd
Quartus II binary files
- hardware binary files
project_name.sof
SRAM Object File
- software binary files
- tbd
Reconstructing a project from a subversion repository
Since the subversion repository contains only the necessary files, a procedure should be followed for reconstructing the full project from the repository.
- Import the selected project from the subversion repository to the local drive.
- Open the project in Quartus II.
- Open the SOPC builder project and build it.
- Build the Quartus II project and program the hardware into the FPGA.
- Import the software part of the project into a NIOS IDE workplace.
References
Archiving SOPC Builder Projects http://www.altera.com/literature/hb/qts/qts_qii54017.pdf[solved] Locking assertion failure. Matlab R2008a.
export LIBXCB_ALLOW_SLOPPY_LOCK=1
[web]Download film directly using Wget
After sniffer some package, I know how to download it
here it is
add a header to http request,
GUID: 00000000-0000-0000-0000-000000000000
and set user agent to
RMA/1.0
use wget to download it
wget -U "RMA/1.0" \
--header="ClientID: WinNT_5.1_6.0.12.1056_RealPlayer_R30CND_zh-CN_686"
URL