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[info] ASCII Table


[info] detect internet IP

http://ipid.shat.net/iponly/

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 YearModulationPeak Rate Peak Throughput
.11 1999DSSS2 Mbps 1 Mbps
.11b1999CCK 11 Mbps 6 Mbps
.11a1999OFDM54 Mbps 25 Mbps
.11g2003OFDM54 Mbps 22 Mbps
Draft n 2006MIMO 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
SDTV5 Mbps
Cable Modem 6 Mbps
DVD 9.8 Mbps
HDTV12.9 Mbps
ADSL2+20 Mbps
FTTH 30 Mbps
HD DVD 36 Mbps
Blue-ray DVD 48 Mbps
VDSL50 Mbps

Video streaming is very demanding in frame errors, e.g., FER < 10-4 or tighter, so the peak throughput of a specific WLAN device is recommended to scale down to one-third of its original value for budgetary purposes. For example, a peak throughput of 15 Mbps is necessary for satisfactory SDTV streaming at 5 Mbps in general.

[cygwin]Howto make a portable cygwin environment

I, have thoroughly emigrated to Linux, need a Linux-Like 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 file
    • project_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 gui
    • sopc_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.

  1. Import the selected project from the subversion repository to the local drive.
  2. Open the project in Quartus II.
  3. Open the SOPC builder project and build it.
  4. Build the Quartus II project and program the hardware into the FPGA.
  5. 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

[udev]Check cable status of LAN

To check carrier status

cat /sys/class/net/eth0/carrier

[info]rsync

Delta-transfer algorithm, which only transfers difference


[web]Download film directly using Wget

Ah oh,  my univ. has a VOD server, but we cannot download the movies that storage on it directly.

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