Posts Tagged ‘computer’

The Global Positioning System (GPS) consists of a number of orbiting satellites that provide precise positioning information for navigation purposes. Positioning is calculated by using accurate timing information and triangulation. However, the accurate timing system can also be used for computer network time synchronisation purposes. Each orbiting satellite has an onboard atomic clock that can provide highly precise time. This article describes how precise GPS timing information can be utilised to provide network timing via GPS NTP servers. It also discusses the type of equipment required to process GPS signals for time and frequency applications.

Time is referenced to Universal Coordinated Time (UTC), which is the same worldwide and does not vary with time zones. The GPS satellites continuously transmit precise time information. GPS time is not affected by leap seconds and is currently 14 seconds ahead of UTC time. GPS time can easily be adjusted to provide UTC time for computer network time synchronisation. The GPS satellites broadcast a very weak low-power radio signal. The signal has two frequencies, L1 and L2. L1 is intended as a civilian GPS band broadcast at 1575.42 MHz. L2 should provide stronger signal transmissions in the future. The signal travels in a straight line and can pass through clouds, glass and plastics but is blocked by objects such as metal and brickwork. Therefore, ideally, a GPS antenna requires a good view of the sky. The ideal location for a GPS antenna is on rooftop with a good view of the sky. If it is impractical to locate a roof-mounted antenna, installation on the side of a building can be adequate.

The GPS system provides a subscription-free accurate timing resource. Many computer networks utilise the GPS clock as an accurate timing reference for computer synchronisation. Precise GPS NTP server systems utilise GPS reference clocks as an external synchronisation source. The GPS system can supply highly precise time and frequency information accurate to a couple of nanoseconds. This accuracy is generally more than enough for most computer network timing applications.

Most GPS receivers transmit time and positioning information in a serial format using the standard NMEA protocol. Information is transmitted as sentences of character strings. Additionally, a highly accurate timing pulse is generated which marks the beginning of each second. This timing pulse can be converted to a RS232 signal level and fed into a RS232 control line interrupt to provide a precise timing reference. When the timing pulse is combined with the NMEA output sentences, a very accurate timing reference becomes available for use by NTP servers or computer timing equipment.

The GPS system is global navigation system introduced by the US military. The system provide navigation and positioning information anywhere on the face of the Earth. The GPS system also provides a highly accurate and precise time and frequency signal ideal for computer timing applications. The GPS system is a orbiting constellation of 24 satellites, each broadcasting time and position information around the globe.

This article describes how the GPS system can be used to provide an accurate time and frequency reference for NTP servers and computer network time synchronisation.

GPS timing information is continuously broadcast by each GPS satellite. GPS time is not affected by leap seconds. Therefore, GPS time is currently about 14 seconds ahead of UTC time. However, offset information is available to readily convert GPS time to UTC time, which is used in NTP server and computer time server systems.

Each GPS satellite transmits information as very low-power radio frequency transmission. Two frequencies are used, one for civilian use coded L1, and one for military use coded L2. The civilian L1 frequency is the most widely used and is transmitted at 1575 MHz. The broadcast GPS signal can easily penetrate less dense material such as plastic, but cannot penetrate higher density materials such as brick.

An antenna is utilised to boost the GPS signal and pass the signal along a coax cable. Ideally, a GPS antenna needs to have as good a view of the sky as possible to receive from as many satellites as possible. Ideally, it should be located outdoors on a rooftop with a good 360-degree un-obscured view of the sky.

GPS antenna systems transmit signals down a coax cable and are sensitive to coax quality and cable length. The coax type and antenna gain determines the cable length that can be utilised by a GPS antenna. Higher quality coax cable generally have much lower attenuation figures and hence provide much longer cable runs between the receiver and antenna. Typically, a low-quality coax can run to 20-30m, while a high quality coax can be used in excess of 100m cable runs. To increase these distances still further, a GPS amplifier can be used to amplify and boost the received GPS signal.

GPS timing systems also utilise a GPS receiver in order to decode the received GPS transmission and convert it to a computer readable format. The GPS receiver processes the transmitted GPS positioning information and provides a readable serial transmission as output. GPS NTP servers and computer time servers may also utilise a precise pulse per second output generated by the GPS receiver to provide ultra-precise timing. The pulse per second timing pulse on most receivers is accurate to within a few milliseconds of UTC.

To summarise, the GPS system is ideal for synchronising NTP server and computer time servers. Accuracies of a few hundred nanoseconds can be reasonably achieved with low-cost GPS receiving equipment.

I am doing a project for school and I have the basic fundamentals down for implementing the system. I was wondering if it was possible with a functional VoIP Phone at an office for a user to connect to his/her phone from their home?

I do NOT want to use an internet service such as Skype, Yahoo, etc.

I want to be able to connect my phone line to the computer modem, and be able to make telephone calls using my existing land line service.

How would I be able to do this? It should be possible.

Thanks to reverse phone detective websites, it is now very much possible for anyone to trace any phone number and do investigative works just like the CIA. With reverse phone detective, you can now easily track down any phone number. It is now possible to find a person’s name, address, and other information from public records.

Do you need to use reverse phone number lookup?

* Find out more about an unlisted phone number
* To find out the caller of the prank call
* Find out about suspicious numbers
* Get the address of friend and colleague

To find out who own that land line or mobile phone numbers, you can use reverse phone detective. There are so many websites on the internet that offers these services, some even do it for free as long as it is not a mobile phone line.

Bad News…

It is not possible to do a reverse phone look up on a cell phone number for free. Public phone directories exist for landlines that allow you to find the name of a person if you have their phone number. Unfortunately, because cellular phones are not associated with addresses and their owner information tends to frequently change address, a public or free cell phone directory does not exist.

Good News…

Though there are no free reverse phone detective directories or website for cell phone numbers, there are websites or businesses who offer this service for a fee. These websites or businesses also pay major cell phone carriers to get access to their internal databases and because they pay to get access to this datas, they also charge whoever wants to use their services a fee. The good thing is that this fee is not so high. You can pay about $14.95 to run a single search but there is also a premium service that allows you to conduct unlimited searches for a one time fee of $39.95.

Many of this reverse phone detective websites are not able to generate the results you need but still charge you. But there are of course many reverse phone detective websites that will guarantee you stisfaction and are very reputable.

Which is the best reverse lookup directory?

Do visit reverse phone detective. It is regarded by many as the best reverse phone look up directory. Click on the link below to go to the official reverse phone detective site.

Click here for the Reverse Phone Lookup website to perform reverse phone lookup and find the owner of any cell phone, landline or unlisted number.

Still wonder if your spouse is cheating on you? There is always such possibility. If you see your spouse having weird calls and is acting not normal, it could be mean you need to do some investigation instead of just suspecting is your spouse cheating on you.

There are many possible suspicious scenario. Maybe you have find unrecognized numbers on your spouse cell phone and on your phone bills. Or maybe there are situations when you see your spouse talking to someone you do not know over the phone in a whispering tone and suddenly end the call when you come in.

Seeing these things, you will get suspicious that your spouse is fooling around and you want to catch your cheating spouse.

There is a 50% chance that your spouse is cheating on you or it could also be a false alarm and nothing serious is happening. If you try ask your spouse about the calls, you also can’t be sure you will get an honest answer.

Your doubts are still there when your spouse keeps receiving calls and acting strange. It is natural to have doubts and get suspicious and there are tools available for you to catch your cheating spouse.

You may think that there is nothing you can do but actually there are things you can do to catch your cheating spouse. This is real. You can now access any public information on any phone number in question. This can help you catch a cheating spouse.

With services like reverse phone detective, you can now find out who is the owner of that number, his or her address and other public information. If you really think that your spouse is betraying you, use this search to confirm.

Before you check, please be mentally prepared. You might find some shocking information like your spouse is having an affair with an old flame. If the number are from some business partner or colleague, you probably can feel more relieved.

You do not need to remain clueless. Instead of letting your imagination go wild trying to think what could have happen, use reverse phone detective to find out the truth.

You can check the number instantly and put your worries to an end. Your spouse will never know you have check up on him or her. Use reverse phone detective now to check out any suspicious phone numbers.

Visit the Reverse Phone Lookup website to perform reverse phone lookup and find the owner of any cell phone, landline or unlisted number.