GPS Time Server and the new Mushroom Antennas

Galleon Systems, one of the world’s leading time synchronization specialists are now stocking a new mushroom GPS antenna to provide increased reliability in receiving GPS timing signals for NTP GPS time servers.

The new Exactime 300 GPS Timing and Synchronization Receiver boasts waterproof protection, anti-UV, anti-acidity and anti-alkalinity properties to ensure reliable and continual communication with the GPS network.

The attractive white mushroom is smaller than conventional GPS antennas and sits just 77.5mm or 3.05-inch in height and is easily fitted and installed thanks to the inclusion of a full installation guide and CD manual.

Whilst an ideal unit for a GPS time server this industry standard antenna is also ideal for all GPS receiving needs including: Marine Navigation and Control Vehicle Tracking.

The main features of the Exactime 300 mushroom antenna are:

• Built-in patch antenna • 12 parallel tracking channels • Fast TTFF (Time to first fix) and low power consumption • On-board, rechargeable battery sustained Real-Time Clock and control • parameters memory for fast satellite acquisition during power-up • Interference filter to major VHF channels of marine radar • WAAS compliant with EGNOS support • Perfect Static Drift for both of speed and course •  Magnetic Declination compensation • Is protected against reverse polarity voltage • Support RS-232 or RS-422 interface, Support 1 PPS output.

Exacttime 300 Mushroom Antenna

How a GPS Time Server Works

A GPS time server is really a communication device. Its purpose is to receive a timing signal and then distribute it amongst all devices on a network. Time server s are often called different things from network time server, GPS time server, radio time server and NTP server.

Most time servers use the protocol NTP (Network Time Protocol). NTP is one of the Internet’s oldest protocols and is used by the majority of machines that use a time server. NTP is often installed, in a basic form, in most operating systems.

A GPS time server, as the names suggests, receives a timing signal from the GPS network. GPS satellites are really nothing more than orbiting clocks. Onboard each GPS satellite is an atomic clock. The ultra-precise time from this clock is what is transmitted from the satellite (along with the satellite’s position).

A satellite navigation system works by receiving the time signal from three or more satellites and by working out the position of the satellites and how long the signals took to arrive, it can triangulate a position.

A GPS time server needs even less information and only one satellite is required in order to receive a timing reference. A GPS time server’s antenna will receive a timing signal from one of the 33 orbiting satellites via line of sight, so the best place to fix the antenna is the roof.

Most dedicated GPS NTP time servers require a good 48 hours to locate and get a steady fix on a satellite but once they have it is rare for communication to be lost.

The time relayed by GPS satellites is known as GPS time and although it differs to the official global timescale UTC (Coordinated Universal Time) as they are both based on atomic time (TAI) GPS time is easily converted by NTP.

A GPS time server is often referred to as a stratum 1 NTP device, a stratum 2 device is a machine that receives the time from the GPS time server. Stratum 2 and stratum 3 devices can also be used as a time servers and in this way a single GPS time server can operate as a timing source for an unlimited amount of computers and devices as long as the hierarchy of NTP is followed.

GPS Time Server – Keeping Time with GPS

The Global Positioning System along with the Internet has changed the way we live our lives. Thousands of motorists use them daily to navigate their around the country’s roads while airline pilots and ship’s captains use them for the same purpose on our seas and in our skies.

But GPS has more uses than just navigation as the technology that GPS utilises is based around the atomic clock. Atomic clocks are highly accurate devices, so accurate that within a billion years they will not lose a second in time.

It is this accuracy that allows satellite navigation devices to triangulate the positioning by measuring the time it takes for the GPS signals to arrive. As radio waves, such as those broadcast by the GPS satellites travel at the speed of light, an inaccuracy of just one second could see the positioning device inaccurate by 300,000 km (the speed light travels per second).

This timing signal broadcast by the satellites can also be utilised by a GPS time server. GPS time servers use the atomic clock signal and convert it into UTC (Coordinated Universal Time) which can be used by network time servers.

These time servers are often referred to as a GPS time server as they use GPS as a timing source to synchronise entire computer networks to.  GPS signals are highly accurate and available anywhere on the planet.

Receiving UTC

A simple source of UTC (Coordinated Universal Time) is the Global Positioning System. GPS offers reliable, worldwide coverage and the potential for extremely accurate timing via a GPS time server.
When you use a GPS time server to receive, be sure to let it obtain a good satellite lock so it can update correctly.

This is the main cause for GPS time servers to display the incorrect time. To test the accuracy of a GPS time server, you should verify the accuracy of your GPS’ displayed UTC by comparing it against an accurate time standard such as the MSF signal or by using a guaranteed source of UTC from across the Internet – details of which are posted on the NTP pool.

Reliable, precision timing is available from the Global Positioning System by using a GPS time server as they use the GPS 1PPS signal. Such units provide the current UTC to an accuracy of 1/1000 of a second or better.

GPS Time Server – Common Questions

Is the GPS time signal the same as the GPS positioning signal?

Yes. The signals that are broadcast by GPS satellites contain time information and the position of the satellite it came from (and its velocity). The timing information is generated by an onboard caesium atomic clock. It is this information used by satellite navigation devices (sat navs) that enables global positioning. Sat Navs use these signals from multiple satellites to triangulate a position.

How accurate is GPS positioning?

Because the time signal generated by GPS comes from an atomic clock it is accurate to within 16 nanoseconds (16 billionths of a second). As light travels nearly 186 000 miles in a second this equates to around 16 feet (5+metres) which means a GPS positioning system is usually accurate to this much.

Is GPS time the same as UTC?

No. GPS time, like UTC (Coordinated Universal Time)is based on International Atomic Time (TAI) – the time told by atomic clocks. However as the GPS system was developed several decades ago it is now 14 seconds (and soon to be 15) behind UTC because it has missed out on the Leap Seconds added to UTC to calibrate for the Earth’s slowing rotation.

How can I use GPS as a source of UTC then?

Fortunately a GPS time server will convert GPS to the current UTC time, which as od 1 January 2009 will mean it has to add exactly 15 seconds.