SATELLITE TECHNOLOGY

In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavor.Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon.

There are three basic categories of non-military satellite services:

1.Fixed Satellite Service
Fixed satellite services handle hundreds of billions of voice, data, and video transmission tasks across all countries and continents between certain points on the earth’s surface
2.Mobile Satellite Systems
Mobile satellite systems help connect remote regions, vehicles, ships and aircraft to other parts of the world and/or other mobile or stationary communications units, in addition to serving as navigation systems

3.Scientific Research Satellite (commercial and noncommercial)
Scientific research satellites provide us with meteorological information, land survey data (e.g., remote sensing), and other different scientific research applications such as earth science, marine science, and atmospheric research.

There are many different types of satellites
Astronomical satellites
Biosatellites
Communications satellites
Miniaturized satellites
Navigational satellites
Reconnaissance satellites
Earth observation satellites
Space stations
Tether satellites
Weather satellites

SATELLITE

What about satellite
In the last few years satellite began to be applied in Internet networking, mainly by medium-big ISPs and we have seen it diffused between users. Sat connections are a very different kind of networking than terrestrial ones, with different timing such as higher RTT (round trip time), but also with different bandwidth value, up to 2 Mbps or more.

How does it work
We can imagine a path like this:


So first we make the request (1) (using our Internet connection) to the Sat-Server, after it will retrieve out info from Internet (2) and it will send it to Satellite (3); in the end we would receive data from the it (4) to our home using a parabolic antenna and a Sat Card.

Typically exist 2 kinds of request :

* Http
* Ftp

Both of them have a little request data and a much bigger answer size, so satellite works very well with it, but with a big time of answer, this is the biggest problem of satellite connection (consider a typical Sat distance, like 36.000 km, so you would have a time access of [ 36000 km / 300.000 km/s = 0.120 s = ] 120 ms you have to add (2 times, cause first ISPs server send it to, then you download it from) to classical Internet time access.

Recently ISP allows their clients to use also other kind of service, like
* Chat
* Email
* News
and many others.

There exist also services called "one-way", which consist in mail service , download on-demand (where you make a file reservation to be scheduled at some time) and site download: these services are offline, so you can access to them without modem (or other kind of) connection.

Working with the Windows Prefetcher

What is the Prefetcher? It is a very nifty component of Windows XP that can seemingly read your mind and will start loading your program seconds before you actually start it to boost the startup of the application.

Although the Prefetcher keeps track of the applications that you run, creates optimized copies of them, and stores them in a special cache on your computer, this special cache is simply a location on your hard disk that has no, or very few, file fragments and stores application setting files. The next time you start your program,Windows will load it out of the Prefetcher cache, which is what causes the application to start up quicker.

If you really want to investigate this matter further, take a look at the Prefetcher cache. It is located in the Windows directory inside the Prefetcher folder. You will notice that the cache does not have an exact copy of each application because the files are a fraction of the size of the actual application executable file. Rather, it just has fragments of applications that are used to boost the performance of the startup.
The Prefetcher constantly monitors what applications you are running, even during parts of the bootup. That information is then passed on to help the disk defragmenter optimize the boot files.

The Prefetcher is a very complex component. The majority of the settings can be changed by hacking the registry; however, due to a lack of documentation on these settings, changing them without any guidance would be very risky. Thankfully, a few tips have surfaced in the vast documentation buried at Microsoft’s site and revealed in Microsoft’s applications.

Do you know to disable the system boot screen?

So, are you enjoying the fun blue bars moving across your screen when your system starts up? Not? Are you finding that you can live without the daily reminder that you are running Windows XP? If so, then you might want to consider removing the boot screen. One added advantage to doing so: You will be getting a boost of performance in return.

Disabling the boot screen might only save you a fraction of a second off your boot time. But keep in mind, every fraction of a second counts.

This performance improvement works on a very simple principle. It takes time for the computer to do anything.Taking away some work that it has to do, such as loading the boot screen, will free time that it can spend loading your system files instead.

The process for disabling the system boot screen is similar to the process for modifying the default operating system in the boot file. If you do not have any other operating systems installed on your system, then you will have to create your own boot.ini file to place in your drive root (that is, the c:\ drive). I am going to show how to create a file first, and will then show how to modify the boot.ini file if you already have one in your drive root or have multiple operating systems installed.

Creating boot.ini file

This section will show you how to create a boot.ini file for your computer if you have just one operating system installed and you do not already have a boot.ini file in your drive root. To get started, let’s go over what the boot.ini file looks like.

The boot.ini file that disables the boot screen looks like the following:

[boot loader]
timeout=0
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]multi(0)disk(0)rdisk(0)partition(1)\WINDOWS=
"Microsoft Windows XP Professional" /fastdetect /noguiboot

The above boot.ini file is pretty standard except for the addition of the /noguiboot to the last line of the file. That is the parameter that tells Windows to start up without using the graphical user interface boot screen. To get started, open up a copy of Notepad, found in the Accessories menu of the All Programs entry, in the Start Menu and follow these
steps:

1. On the first line of the file, type in [boot loader].

2. On line 2 of the file, key in timeout=0 so Windows does not show the boot selection screen at all. You don’t want this anyways because you only have one operating system installed on your computer.

3. On line 3 of the file, type in defaultmulti(0)disk(0)rdisk(0)partition(1)\WINDOWS
so that Windows knows where to look on your hard drive to start the operating system.

4. On line 4, type in [operating systems].

5. On line 5, type in multi(0)disk(0)rdisk(0)partition(1)\WINDOWS=”Microsoft
Windows XP Professional” /fastdetect /noguiboot to start up Windows with the
/noguiboot parameter to disable the boot screen.

6. Click the File menu bar item and select Save As.

7. Type Boot.ini in the File name box and change the Save as type to All Files.

8. Then, change the Save in directory to your drive root, which is usually Local Disk (C:).

9. Click the Save button and you are now finished.

You can now close Notepad. The next time you reboot your computer, you will not see the boot screen.

Hacking Techniques

All about autorun ini files

Extending the functionality of Autorun.inf

There are also some extensions to the autorun.inf file you can use that will put shortcutson the right-click menu of CD's icon. For example, add this to your autorun.inf (below the icon= line):

shell\read\command=notepad.exe readme.txt
shell\read=Read M&e First

The CD icon right-click menu will have a new item, “Read Me First” (with E as a hotkey)that launches Notepad with the readme.txt from the CD loaded. The ampersand (&)character in the second line denotes the hotkey letter, which is underlined in the menu. So Rea&d Me First would make ‘D’ the hotkey, and the menu item would appear as “Read Me First”. If you use hot keys (you don’t have to), do ensure that the letter you wish to use isn’t already assigned to a standard Windows context menu choice, such as Copy, Properties and Rename. The first listed menu entry for any hotkey gets executed. As for the open command, you can give a path to the file you wish to open (note as for the‘open=’ and ‘icon=’ lines, no leading backslash is used):

shell\read\command=notepad.exe mydocs\readme.txt

You can add more than one such context menu shortcut by tweaking the ‘read’ verb:

shell\read1\command=notepad.exe readme.txt
shell\read1=Read M&e First
shell\read2\command=notepad.exe EULA.txt
shell\read2=Read My E&ULA

This adds “Read Me First” and “Read My EULA” items to the CD’s right-click context menu. Items are added in the order they are in the autorun.inf. For more use ‘read3’, ‘read4’ etc. You may be aware that as from version 4.x, Adobe Reader can also be run from CD. This means that you can provide the user with a way of opening the Browser's "Quick Start guide" which is provided in PDF format - without assuming the user has Acrobat installed.

shell\read1\command=notepad.exe readme.txt
shell\read1=Read M&e First
shell\readit2\command=acrobat\reader\acrord32.exe
portbrws\qsg.pdf
shell\readit2=Read Quick Start Guide (PDF)

Note: the shell\readit2\command line is typed all as one line with a space between the 2 paths.

Hacking Techniques