In a recent Concourse article, we explained how we get the Gogo In-flight Internet service to aircraft using our air to ground network. That technology is just one of two ways to get the Internet to your airplane, the second method is by using satellites. The main advantage of satellite technology is of course the ability to connect anywhere in the world – even when you are flying over the ocean. Satellite Internet is far more complex than our air to ground system, but for many aircraft, it is the only option. In this article, we’ll explain what it takes to get connected using Gogo satellite Internet technology.
What’s in a name – Ku and Ka.
If you stay up to date on the developments in satellite Internet, you’ll most likely see a lot of abbreviations – the most common ones you’ll come across are Ku-Band and Ka-Band. The K in this technology name comes from the German word Kurz, which means “short” – a reference to the wavelength used by the signal that travels between the satellite and the antenna. Ku and Ka band are the two major technologies in use today for high speed satellite Internet. Ku means Kurz Unter or short under and Ka means Kurz Above or short above. Under and Above both refer to the frequency bands either under or above the original K-band satellite frequency.
The physical challenges of getting satellite Internet to aircraft.
If you have ever subscribed to satellite TV, you’ll most likely recall getting a dish mounted on the side or roof of your home. This small dish has to point to a satellite just over 22,000 miles away in geostationary orbit. Geostationary means that the satellite moves at the same speed as the earth’s rotation. Because of this, the satellite is always in the same place, and because your home doesn’t move, you only need to position your satellite dish once. Now picture that satellite dish on the top of an airplane – flying all around the world, at speeds of up to 570 miles per hour. As you can imagine, keeping the satellite antenna pointed exactly where the satellite is presents a myriad of challenges.
The first of these challenges is the physical task of getting the antenna pointed in the right direction. To accomplish this, our Ku band satellite service uses an antenna mounted on the top of the aircraft, which can rotate to point directly at the satellite. Of course, pointing an antenna at an object 22,000 miles away all while flying at top speed is extremely complicated. Unlike the antenna you may use at home for entertainment, our antenna needs to transmit as well as receive, which makes its accuracy even more important as being a fraction of a degree off target could accidentally point to a different satellite.
Once the antenna is installed on top of the aircraft, a mounting ring is attached, and the entire installation is covered by a composite dome. If you are flying on an aircraft with satellite Internet, you can easily spot the dome (called a radome) by looking at the top of the plane. As the plane flies, the antenna is constantly adjusting to stay focused on the satellite.
Satellite-specific onboard hardware
Satellite-connected aircraft require specialized equipment – in addition to the antenna, we also install two other satellite specific pieces of equipment – the KANDU and the MODMAN. The KANDU (Ku/Ka Aircraft Networking Data Unit) is what physically controls the antenna. It interfaces with the aircraft navigational systems to control the movement of the antenna. The KANDU is also responsible for making sure the system reconnects to the right satellite as a single satellite can only cover a certain area, which means longer flights may switch between 2 or even 3 different satellites.
In order for connectivity to remain uninterrupted on a satellite-connected aircraft, the antenna must maintain its orientation toward the desired orbiting satellite. As the aircraft progresses along its flight path, eventually it will move beyond the range of the satellite at the other end of the connection. When this occurs, the connection must physically transition from one satellite to another. This is known as a “handoff.” This process is not instantaneous. The equipment onboard the aircraft must register the handoff, reorient the antenna, reacquire the signal, and reestablish the data link to the servers on the ground.
The MODMAN (Modem and Manager) is the interface between the antenna and our equipment, and is responsible for converting the satellite data stream. This in turn feeds into the onboard Gogo server and on to the cabin wireless access points, allowing your devices to connect over Wi-Fi.
On the ground
To get the Internet from your plane, the signal travels from your device to our cabin wireless access points, to our airborne server, through the satellite controller equipment to the antenna, then to the satellite and down to one of several ground stations around the world, and finally on to our data center. This is then done in reverse for data traveling to the plane. All of this happens in a matter of seconds, an amazing accomplishment when you consider the distance this signal has to travel to make it to your personal device. Back on the ground, our global network operations center constantly monitors all of the aircraft in service, along with the status of our satellite ground stations and our data center. Our satellite Internet service is currently installed on over 50 aircraft, and we’re outfitting new aircraft at a rapid pace. You’ll find our international service installed on select Delta Air Lines flights, as well as domestic routes on Japan Airlines.
We hope that this article manages to shed some light on the complex process of getting satellite Internet to your airplane. As always, we’re happy to answer any additional questions you may have- just leave your comments below!