Posts Tagged ‘System’

WAAS-Enabled GPS System

Jeff Sanders
Garmin GPS Navigation Systems
www.GpsFrontier.com
04/05/09

WAAS-Enabled GPS System

WAAS (Wide Area Augmentation System) was developed by the Federal Aviation Administration to augment the Global Positioning System to improve its accuracy, integrity, and availability. WAAS was originally intended to enable aircraft to rely on GPS for all phases of flight, including the precision approach to airport’s within its coverage area. The WAAS system typically provides better than 1.0 meters laterally and 1.5 meters vertically throughout most of the contiguous United States and large parts of Canada and Alaska. This accuracy is capable of provideing aircraft with the precision needed for safe approaches and inflight navigation for all weather conditions. Integrity of the WAAS information is no more than 3 seconds of bad data per year allowing the system to be considerd safe by the FAA for instrument flight rules.

Although orignally developed for aviation, WAAS is not just limited to the aviation industry, any GPS receiver that is capable of receiving the WAAS signal will be able to benefit from it’s correction data, making the GPS positioning more accurate. In fact a WAAS-enabled GPS receiver can even give you directions right down to the lane your car is traveling in (as long as the maping program supports “lane assist” directions). Because the Wide Area Augmentation System is quickly becoming standard in the GPS industry, most new GPS receivers today are WAAS-enabled. Just like with the conventinal GPS, the WAAS system doesn’t come with any extra cost or fees to use. All that is required is that the GPS receiver be WAAS-enabled so it can receive and decode the data then be able to apply corrections to it’s position. Currently the WAAS service is limited to the U.S.A., Canada, Alaska and Hawaii. Although independant from WAAS, Europe and Asia are working on their own supplemental GPS correction systems. Europe has the “Euro Geostationary Navigation Overlay Service” (EGNOS) and Japan is working on their “Multi-Functional Satellite Augmentation System” (MSAS) .

How The WAAS System Works

WAAS uses a network of approximately 25 ground based Wide-area Reference Stations (WRS) in North America and Hawaii, to measure small variations in GPS satellite signals in the western hemisphere. These precisely surveyed ground stations monitor and collect information on the GPS signals and send their data to the three Wide-area Master Stations (WMS). The WMS’s generate two different sets of corrections: fast and slow. The fast corrections are for errors that are changing rapidly and are a primary concern to the GPS satellites instantaneous positions and clock errors. These corrections are user position independent, which means they can be applied instantly by any receiver in the WAAS broadcasting area. The slow corrections are for long-term ephemeric and clock error estimates and ionospheric delay information.

Once these corrections are generated, the Master Stations sends them to two pairs of Ground Uplink Stations (GUS) that transmit the correction messages to a series of geostationary satellites that broadcast their correction data back to earth. Then WAAS-enabled GPS receivers use this information to make corrections to the original GPS signial, giving WAAS-enabled GPS receiver a more accurate position. GPS receiver’s use the information broadcast from each GPS satellite to determine their location and the current time. Depending on the GPS device, a GPS receiver only needs to receive a signal from 3-4 satellites (out of the 31 satellites currently transmiting a signal for civilan users) to be able to calculate it’s position. In addition to the GPS signal, a WAAS-enabled GPS receiver can also receive the geostationary WAAS satellite signal.

The two different types of correction messages from the WAAS system (fast and slow) are used by the GPS receiver in different ways. The fast type of correction data includes the corrected satellite position and clock data to determine its current location using normal GPS calculations. Once an approximate position fix is obtained the GPS receiver begins to use the slow corrections to improve its accuracy. Slow correction data Includes the ionospheric delay. When the GPS signal travels from the satellite to the receiver, it passes through the ionosphere. The receiver calculates the location where the signal pierced the ionosphere and, if it has received an ionospheric delay value for that location, it corrects for the error that the ionosphere created. Unlike the fast data, the slow data doesn’t need to be updated frequently because the ionosphere conditions don’t change rapidly. While the slow data can be updated every minute if necessary, they are only updated every two minutes and are considered valid for up to six minutes.

Limitations of the WAAS System

(1) The WAAS system is currently only available to United States and large parts of Canada and Alaska but there plans to expand the system to other countries and continents. (2) Because the WAAS broadcasting satellites are geostationary causes them to be less than 10° above the horizon for locations north of 71.4° latitude. This means aircraft in areas of Alaska or northern Canada may have difficulty maintaining a lock on the WAAS signal. (3) In order to calculate an ionospheric grid point’s delay, that point must be located between a satellite and a reference station. The low number of satellites and ground stations limit the number of points which can be calculated. (4) Aircraft conducting WAAS approaches must possess certified GPS receivers.

Jeff Sanders
Garmin GPS Navigation Systems
www.GpsFrontier.com
04/05/09

GPS Tracking Solutions: What are the Main Components of a GPS Tracking System? Part 2

In the first part of this series of 10 articles I explained the differences between GPS Navigation Systems and GPS Tracking Systems, and how they are two completely different of implementations of Location Based Services. In this second article I will develop some additional concepts related to the elements that constitute a GPS Tracking System. There are 3 main parts to a GPS Tracking System:

- A GPS device or GPS Tracker, which receives the location information and then delivers it to a software application.

- A data transmission system, which takes the information provided by the GPS Tracker, and delivers it to the software application.

- A Software Application, which presents to its users the data recollected by the GPS Tracker in several formats including maps and reports.

This article will present the main components of a GPS Tracking Solution, and will start expanding on the first component: GPS Trackers. It will take me this article and the next one to go in detail over GPS devices.

GPS Devices

==========

In this section I will define what a GPS Device, and how they work; after that I will present the types of GPS Trackers, including most of the features that these devices offer, and my opinion in regards to each type.

At its simplest definition, the GPS device, or better the GPS tracker, is the component in charge of receiving the information about the location of the vehicle, and providing this data to the GPS Tracking Application through the Data Transmission System (which will be explained in coming articles). GPS Trackers are usually small boxes (metal or plastic) that can be the size of a man’s wallet, or a little bigger. All of them need at least one antenna (GPS antenna), and most of them need an additional antenna to enable the data transmission module. So this leads to a first classification of GPS Trackers:

-Full satellite trackers. This type of trackers will use satellites to receive and transmit data.

-Hybrid trackers. This type of trackers will use satellites to acquire location (we will see some variations here later in this article), and another method to transmit the data (a data modem, a data port to download the data, etc).

On the next article I will expand on these concepts.

So, the main task of a GPS Tracker is to provide information of the location of a vehicle or an asset, or a person. The location of the units is usually acquired from the GPS satellites, but there is another method based on triangulation with cell towers to calculate locations. Getting the location from satellites is the most accurate mechanism, providing a minimal margin of error most of the times (from 2 up to 50 feet). GPS location can be acquired anywhere in the world. The only down side for this location technology is that the GPS antenna has to have a view to the sky. For example, if the vehicle gets into a garage, most probably there will not be GPS locations available.

Getting the location based on a triangulation with the cell towers (those that are also used by our cell phones to transmit voice and data) has a bigger margin of error (up to a few hundred feet), making it a not very accurate location mechanism. This type of location also requires the presence of the named cell towers to work. The upside of this mechanism is that it will perfectly work within buildings, which is not the case for GPS satellite location. Some GPS Trackers are designed to work with both location mechanisms, creating a new concept called Assisted GPS (AGPS).

There are mainly three types of GPS Trackers: Passive Trackers, PING Trackers, and Live Trackers. Also, there are some GPS Trackers that have more features than other – not just a location of the vehicle.

In this article I have dissected a GPS Tracking solution into three main components: a GPS Tracker, a data transmission system, and a GPS Tracking application. I have also started exposing the details of GPS Trackers, specifically the two main ways to locate a vehicle. Finally, I introduced two more elements to consider in GPS Trackers: types of trackers and advanced features of a GPS device.

“Couldn’t mount…” Error Message while mounting Linux Operating System

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Superblock is the most significant component of a Linux volume that restrains critical information about files and folders in file systems as ext2, ext3 and more. It enables us to mount and access the file systems. Superblock corruption primarily occurs due to metadata structure damage, file system corruption, unexpected system shutdown, malicious software like virus and more.

In most cases of superblock corruption, the volume becomes unmountable and the data becomes inaccessible. In such situations, you can restore the lost data using an updated backup. However, if you have not maintained any backup or it is not up-to-date, then you need to recover your data by using advanced Linux Data Recovery tools.

Consider a practical scenario, when you attempt to boot your Linux system, you encounter the below error message:

â??Wrong fs type, bad option, bad superblock on /dev/hda8, missing codepage or helper program, or other error. In some cases useful info is found in syslog – try dmesg | tail or soâ?

After running dmesg tail, you encounter the below error message:

â??Couldn’t mount because of unsupported optional features (2000200)â?

After the above error message appears, the system becomes unmountable and data stored on the hard drive volume becomes inaccessible. Additionally, you encounter the same error message each time you attempt to boot your system.

Cause:

The main reason behind occurrence of the above error message is superblock corruption.

Resolution:

To resolve the problem and access all inaccessible data, you need to follow these steps:

1. Boot your system by using an alternate block by running the below command:

e2fsck -b 98304 /dev/hdb8

2. Once the file system gets restored to the point at which it can be mounted, you need to fix it by using this command:

e2fsck -c /dev/hda8

-c parameter checks for the bad blocks

However, if the above steps are not able to resolve the issue, you should consider reinstalling Linux. A clean Linux reinstall will erase all existing data from the selected volume. For complete recovery of lost data, you should use efficient Linux Data Recovery software.

Linux Recovery tools incorporate effective scanning algorithms to recover all your lost data. These recovery tools provide highly graphical user interface that makes them easily understandable without prior technical knowledge. These tools recover data post situations like superblock corruption, group descriptor faults, inode table damage and more.

Stellar Phoenix Linux Data Recovery is the foremost Linux Recovery tool. It supports recovery from Ext2, Ext3 and ReiserFS file system based Linux volumes. This Data Recovery Linux tool gets installed on Windows (Vista, XP, 2003 and 2000) and the affected Linux drive is connected as slave.

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“Couldn’t mount…” Error Message while mounting Linux Operating System

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Superblock is the most significant component of a Linux volume that restrains critical information about files and folders in file systems as ext2, ext3 and more. It enables us to mount and access the file systems. Superblock corruption primarily occurs due to metadata structure damage, file system corruption, unexpected system shutdown, malicious software like virus and more.

In most cases of superblock corruption, the volume becomes unmountable and the data becomes inaccessible. In such situations, you can restore the lost data using an updated backup. However, if you have not maintained any backup or it is not up-to-date, then you need to recover your data by using advanced Linux Data Recovery tools.

Consider a practical scenario, when you attempt to boot your Linux system, you encounter the below error message:

â??Wrong fs type, bad option, bad superblock on /dev/hda8, missing codepage or helper program, or other error. In some cases useful info is found in syslog – try dmesg | tail or soâ?

After running dmesg tail, you encounter the below error message:

â??Couldn’t mount because of unsupported optional features (2000200)â?

After the above error message appears, the system becomes unmountable and data stored on the hard drive volume becomes inaccessible. Additionally, you encounter the same error message each time you attempt to boot your system.

Cause:

The main reason behind occurrence of the above error message is superblock corruption.

Resolution:

To resolve the problem and access all inaccessible data, you need to follow these steps:

1. Boot your system by using an alternate block by running the below command:

e2fsck -b 98304 /dev/hdb8

2. Once the file system gets restored to the point at which it can be mounted, you need to fix it by using this command:

e2fsck -c /dev/hda8

-c parameter checks for the bad blocks

However, if the above steps are not able to resolve the issue, you should consider reinstalling Linux. A clean Linux reinstall will erase all existing data from the selected volume. For complete recovery of lost data, you should use efficient Linux Data Recovery software.

Such Linux Recovery tools incorporate effective scanning algorithms to recover all your lost data. These recovery tools provide highly graphical user interface that makes them easily understandable without prior technical knowledge. These tools recover data post situations like superblock corruption, group descriptor faults, inode table damage and more.

Stellar Phoenix Linux Data Recovery is the foremost Linux Recovery tool. It supports recovery from Ext2, Ext3 and ReiserFS file system based Linux volumes. This Data Recovery Linux tool gets installed on Windows (Vista, XP, 2003 and 2000) and the affected Linux drive is connected as slave.

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Nikon Digital & Film SLR System Case Gadget Bag for D3, D3x, D700, D300, D200, D90, D80, D60, D5000, D40x, D40, D3000 & D300s Cameras

• Interior Dimensions: 10.5″L x 6″W x 6.5″H Exterior Dimensions: 11.5″L x 7.5″W x 7.5″H
• Holds & Protects Your 35mm or Digital SLR Camera With Zoom Lens Attached, Plus 2 to 3 Extra Lenses & Flash
• Adjustable Padded Dividers For Easy Customization plus Multiple Pockets With Easy Access
• Constructed of Durable Wear-Resistant Nylon
• Nikon 5 Year USA Warranty

Product Description
Protect your valuable camera investment with this Nikon brand camera carrying case. Made from durable Cordura Nylon, and outfitted with a reinforced handle, this compartment case will easily hold your camera, lenses, flash, and accessories. Travel is made even easier and safer with the slip-resistant shoulder strap. The many zippered pockets hold all your supplies. A small pocket on the outside of the top flap allows easy access to film, memory cards or batteries. L… More >>

Nikon Digital & Film SLR System Case Gadget Bag for D3, D3x, D700, D300, D200, D90, D80, D60, D5000, D40x, D40, D3000 & D300s Cameras

Nikon Digital & Film SLR System Case Gadget Bag for D3, D3x, D700, D300, D200, D90, D80, D60, D5000, D40x, D40, D3000 & D300s Cameras

• Interior Dimensions: 10.5″L x 6″W x 6.5″H Exterior Dimensions: 11.5″L x 7.5″W x 7.5″H
• Holds & Protects Your 35mm or Digital SLR Camera With Zoom Lens Attached, Plus 2 to 3 Extra Lenses & Flash
• Adjustable Padded Dividers For Easy Customization plus Multiple Pockets With Easy Access
• Constructed of Durable Wear-Resistant Nylon
• Nikon 5 Year USA Warranty

Product Description
Protect your valuable camera investment with this Nikon brand camera carrying case. Made from durable Cordura Nylon, and outfitted with a reinforced handle, this compartment case will easily hold your camera, lenses, flash, and accessories. Travel is made even easier and safer with the slip-resistant shoulder strap. The many zippered pockets hold all your supplies. A small pocket on the outside of the top flap allows easy access to film, memory cards or batteries. L… More >>

Nikon Digital & Film SLR System Case Gadget Bag for D3, D3x, D700, D300, D200, D90, D80, D60, D5000, D40x, D40, D3000 & D300s Cameras

Group Descriptors Corrupted in Linux Operating System

The EXT3 file system in Linux is divided into various block groups. Each block group further contains a data structure called ?group descriptors? that contains critical information about the block. Corruption in group descriptors primarily occurs due to operating system malfunctioning, file system damage, malicious software like virus and more. Two major outcomes of corrupted group descriptors are unbootable system and inaccessible data. To successfully recover the lost data, restore it from the latest backup. In case, no recent backup is available or is invalid, you need to go for advanced? Linux Recovery software.

Consider a practical scenario, where you encounter the below error message when you attempt to boot your system:

?Uncompressing Linux:…Ok booting kernel

audit(xxx.x….x..:0) : initialized

EXT3-fs error (device hda3):ext3_check_descriptors:Block bitmap for grade 38 not int grade ( block 34799616)

EXt3-fs:roup descriptors corrupted.

Mount: error 22 mounting ext3

pivot root ivot_root (/sysroot, /sysroot/initrd) failed: 2

unmount/initrd/proc_failed:2

kernel panic: No init found: Try passing init=0 to kernel?

You encounter the same error message each time you attempt to boot your system. As a result of the above error, all your critical data becomes inaccessible.

Cause:

The above error message is encountered when group descriptors are corrupted.

Resolution:

To resolve the above issue and access the data, you need to use FSCK command. This command is mainly used to repair the EXT3 file system. But, if the file system has been badly corrupted, then this command fails to repair. In such circumstances, you need to recreate the file system again by formatting and reinstalling Linux. A clean reinstall of Linux will completely erase all data from the selected Linux volume. For complete and orderly recovery of data after reinstalling Linux, you will need to se powerful Linux Recovery software.

These Linux Data Recovery applications ensure comprehensive scanning of formatted Linux volumes by using powerful scanning algorithms. These recovery tools can recover and restore data after problems like group descriptors faults, Inode table damage and superblock corruption. They are built with highly graphical and interactive user interface that makes them easily understandable without prior technical skills.

Stellar Phoenix? Linux Data Recovery is the most efficient and trust worthy Linux Recovery tool. It supports Ext2, Ext3 and ReiserFS file systems based Linux volumes. This read only Data Recovery Linux application gets installed on Windows (Vista, XP, 2003 and 2000) and the affected Linux drive should be connected as slave.

Use Windows Xp Registry Cleaner for Xp Operating System

If you are using Windows XP operating system in your PC, it is important that you use a Window XP registry cleaner to keep your PC registry free from outdated entries, adware and spyware. Since Windows 95, Microsoft adopted a new way of keeping the system information. They introduced the concept of Windows registry. Registry file is created and maintained by the Windows operating system to store information about the hardware and software configuration and other settings of your computer system. Before Windows 95 version this was done by storing the information in the INI files. These INI files were scattered through out the hard disks, making the system slower and vulnerable to frequent problems. With the introduction of registry, the process of storing the system information became much more organized and effective. It made the system more efficient and faster as it took less time to access the vital resources.

Different versions of Windows operating system have different methods of keeping the Windows registry. So, if you want to clean the registry you need specific Windows registry cleaner built for the operating system you are using. Therefore it is important to have the Window XP registry cleaner if you are running a Windows XP operating system in your computer. You can download registry cleaner from the internet, but for that you need some good research. A Microsoft registry cleaner checks the registry file of your computer and removes all the outdated entries that are stored in the registry.

A Windows registry keeps the log of all the system setting. So whenever you install or uninstall any software, make any changes to the system settings or the hardware configuration an entry is added to the Windows registry. As you keep using your computer these entries get piled up in the registry file making it unnecessarily heavier with outdated and unimportant entries. With a Window XP registry cleaner you can avoid these problems and get hassles free computing.

With a bulkier registry file with so many entries the system becomes prone to frequent failures and it takes usually more time to respond. A heavier PC registry is one of the most encountered problems for slow functioning of the computer. So, it is better to use a Window XP registry cleaner to clean the registry of your Windows XP based PC for problem free and faster computing. The registry cleaner checks the registry and removes entries that are no longer important.