My Bite Into The Apple

by mroach

Ntp Server Static GPS Antenna Systems

The Global positioning System (GPS) is often used by computer equipment, such as NTP Server systems, to provide an accurate timing reference for time critical applications. This article provides an overview of GPS for timing applications and describes the equipment used to install a GPS antenna in a static location.

Overview – Using GPS for Accurate Time

The Global Positioning System is a US military system for worldwide navigation. The system consists of 24 orbiting satellites, each satellite has a highly accurate atomic clock on-board synchronised to UTC time. The satellites continuously broadcast time and position information. The time and position information can be obtained worldwide with a GPS receiver and antenna. GPS works continuously in any whether conditions, anywhere in the world. Additionally, there is no set up fee or subscription charges to utilise the GPS systems. Many computer timing systems and NTP Server systems utilise GPS as an accurate external timing reference.

The Accuracy of GPS Timing Systems

GPS receivers provide highly accurate position and timing information. Typically, a GPS receiver can provide positioning information to an accuracy of 15m. NTP Server systems can obtain timing information from GPS to a resolution of a few nanoseconds.

The GPS Signal

The transmitted GPS signal is very weak low-power radio signal, designated L1 and L2. L1 is the civilian GPS frequency transmitted at 1575.42 MHz. The signals travel by line of sight and can pass through clouds, glass and plastics but are blocked by objects such as metal and brickwork. Therefore, the ideal location for a GPS antenna is on rooftop with a full 360-degree view of the sky. However, often installation on the side of a building or in a window can provide adequate results. As a rule of thumb, the better the view of the sky, the greater the likelihood of a good consistent signal lock.

GPS Timing Antenna Types

The GPS antenna acts as an amplifier to boost the GPS signal for transmission along a cable, usually coax, to the GPS receiver. GPS Timing antenna’s provided with NTP server systems utilise a pole-mounting system. The antenna screws to a threaded pole for installation on rooftops. This arrangement provides the GPS antenna with a rigid mount easily able to withstand high winds without damage. Typically the GPS antenna is fairly small in size, measuring less than 90cm in diameter. Low-cost patch type antennas are also available, but these are generally better suited to vehicle applications.

GPS Antenna Cable Types and Cabling Distances

The cable distance that can be utilised by a GPS antenna depends mainly on the amplification of the GPS antenna and the quality of coax used in the installation. A typical GPS timing antenna may have a gain of 35 db. Relatively low-quality coax such as RG58 has an attenuation of 0.64 db/m at 1575 MHz. Therefore, a cable run of 55m can be obtained using RG58 cable. With very high quality coax cable, such as LMR400, an unaided cable run of 200m can be achieved. However, very high quality coax can be expensive. A good price-performance compromise is LMR200 cable, which can be run unaided to 80m.

Extending Cabling Distance with In-Line GPS Amplifiers

In-line GPS amplifiers provide further amplification of the GPS signal to increase the cable distance between the GPS antenna and receiver. GPS amplifiers are fitted in-line with the antenna cable and obtain power from the receiver via the coax cable. No external power-supplies are required. Typically, a GPS amplifier may add a further 20 dB of gain, adding 30m of low-quality RG58 coax, 40m of LMR200 coax or 100m of high quality LMR400 coax. Additionally, multiple in-line amplifiers may be utilised to further increase cable distance.

Sharing a Single Antenna Between Multiple Receivers – GPS Splitters

GPS splitters allow a single GPS antenna to be utilised by two or more NTP server systems. The GPS splitter splits the signal received from the GPS antenna into multiple outputs for synchronizing multiple NTP servers. GPS splitters are generally available with 2, 4 or 8 outputs.

Protecting GPS Systems – GPS Surge Suppressors

Surge suppressors protect expensive NTP server equipment from electro-static discharges, such as lightning, that may be picked up by an externally mounted GPS antenna. Surge suppressors are installed in-line on the coax cable between the antenna and receiver, ideally where the cable enters the building. Surge suppressors require a low-impedance ground, to discharge any received surge. The surge suppressor requires no power-supply or additional cabling.

Portable GPS Device – Finished (Kinda)


Image by 3D King
The portable GPS device properly fiinished off with a pcb I knocked together in Eagle CAD, a nifty blue LCD from Crystalfontz, and a proper basic stamp module. The good bad leds are not mounted in this picture and the whole thing needs to go in a box, at some time….Like I said, it’s finished – Kinda
Also in this image it is not connected to a gps hence the display.

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by Jivo2010

What Is A Data Recovery Disk And How To Get The Most Out Of It

If your computer does not have a data recovery disk, then you will face problems once you lose a file that you desperately need to recover. Such disks guard your computer from drivers, system components, drives, and application troubles. One can differentiate two types, one where operating system files can be recovered and another where data files are stored.

The key of course is to back up your system. Once you do so, recovering data such as emails, text files, or anything else you can think of is very easy. Any old rewritable CD where data or any other recent saved files can be written and re-written on it again and again is suitable for this job.

Of course, there is another kind of data recovery disk saves things such as deleted partitions or even corrupted files. Such a disk will most likely contain data recovery, disk image, password resetting, partition management, system utilities, data erasure as well as network access tools.

Anyone can buy a data recovery disk varying on the kind of recovery that can be made. Most disks have certain specializations. You can set them to recover images only, or e-mails only or anything from your hard drive. You can even recover data from any removable disk.

The operating system disc (usually drive C) can also be used to recover data. One just needs to boot from there then you run any of the following depending on what kind of recovery you want to do. These run commands are either fdisk, chkdsk, or testdk. Just press F12 when the operating system is starting as you turn the PC on. You could also boot from a CD or your disk. That will enable you to get inside and fix the kinks out.

There are however, some special circumstances when data recovery is no longer possible. And this is funny because there are those who think that banging or dropping the computer, or even heating it can fix it. Of course most of the time, this just makes the problem worse.

Of course, a computer that has been hit or fallen will have physical damage. During this kind of circumstances, your hard drive might just be damaged. Then you will never be able to get back that lost data. The most you can try to do is to pay the guys from crime scene investigations to have a look at your data. But that is of course highly unlikely.

Therefore, as a warning, one should never do anything silly as physically banging on the PC if you are only looking for attention. Simply use disk to back up your data most of the time as well as other tools for recovering data. Remember though that some day, your pc will go bust. This is why one must be ready by backing up or having a data recovery disk.

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by a.bendix

Do You Need Internet Fax Services?

The traditional fax machine has been the companion of many offices and workplaces for many years, and the standard way to send and receive documents. Yes it had its flaws and inconveniences but people were used to it – after all, there wasn’t a better alternative.

But all that changed some time ago, when a more efficient way of faxing appeared.

They say “Everything changes” and this sounds true in the World of faxing. Now, Internet Fax or Email Fax is becoming the preferred way to send and receive documents. The change is in that you now use an Internet connection and an email account to send and receive faxes. You only need to sign up with an online fax service provider and you’ll be able to access your faxes always without the need of a dedicated phone line.

And if you care about old technology, well, Internet fax can be received by all traditional fax machines!

At first many people and businesses were reluctant to adopt this new technology; this is something that happens every time something new appears. And this caution has probably cost great amounts of money and time to these people and businesses. A common question people ask is “Do I really need Internet Fax?”

Let’s take a look at some of the benefits you can enjoy with Internet faxing, and what this all means when you apply it to be on a competitive business.

With Internet fax you will be able to access your faxes any time you like, from any place in the world as long as you have a computer and an Internet connection. This means that you no longer have to be tied to your office’s fax machine. For people who are always on the move the choice for Internet fax is a no-brainer. Are you a real estate agent, a salesman, a manager? Then you’ll understand what this feature means.

Having access to fax at all times, anywhere can mean a lot for a business and can really give you a major advantage in time-sensitive matters. Your communications will be faster and you will be able to close a deal pretty quickly.

Add to this the fact that Internet fax is inexpensive compared to traditional faxing, and from the start you cut the necessity of having a big machine and the cost of a secondary phone line. Nowadays there are many great companies offering fax services such as Ringcentral Fax, MyFax, Rapidfax, eFax, Send2Fax, among others, but you should make a wise decision.

Some of these companies even have bigger solutions. For example, Ringcentral allows you not only to handle Internet fax, but also virtual phone call from one place.

When it comes to choose a web fax service provider, spending some time researching and comparing can make a huge difference in your level of satisfaction. It all comes down to choosing a service that offers the best option according to your needs and budget. The market standard for this type of faxing starts at per month to send and receive 300 pages. From this, you can find different plans and even have a special quote if you have a big company with increased faxing needs.

So, the question arises again: Do you need Internet Fax?

Nowadays in times where computers and the Internet play a big role in communications, is it realistic to stay competitive without Internet Fax? This is a question that only you can answer given all the information. Does your business rely heavily on communications? Are you wasting too much money with traditional faxing and shopping for supplies? Is faxing crucial to close deals and make sales? If you find out that faxing is a critical component in the success of your business, I would suggest you make the jump to online faxing as soon as possible if you want to remain competitive.

A huge number of companies are making the jump to Internet fax, and cutting their costs greatly. Some companies even report a decrease of 89% de money spent with traditional faxing. Take into account that this way of faxing is inexpensive and it offers features a fax machine simply doesn’t have. The opportunities to test Internet faxing are out there, the best email fax companies offer free 30 day trials of their service.

Group FAX (Mexico City)


Image by Independent Curators International
For 3 hours on Saturday, July 25, 2009 faxes were exchanged between participating venues in Istanbul, New York, Paris, Mexico City, and Cape Town in the spirit of sharing ideas and information through informal networks. Artworks, texts, and provocations were created and sent ‘live’ in response to what was transmitted.

This event launched a world tour of FAX, curated by João Ribas.

FAX is a traveling exhibition co-organized by iCI (independent Curators International) and The Drawing Center.

For further information on the exhibition and tour go to
www.ici-exhibitions.org/exhibitions/fax/fax.html

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