The following announcement gives details of the Swedish system. Sweden claims to be the first country to achieve nationwide ADS-B coverage.
What should be noted is that they are using the ADS-B system known as VDL Mode 4. This is not compatible with the system that Airservices is installing in Australia (the Mode S squitter model), nor is it compatible with the US Universal Access Transceiver (UAT) system. This sounds to be a bit like the cassette versus 8-track system, or Betamax compared to VHS – but even worse.
It should be obvious to anyone that we need one standard ADS-B system for the world. That is because aircraft travel all around the world – not just international ones, but business aircraft and adventurers on long flights.
Surely everyone knows that eventually we will end up with one system. What a pity that countries have to go ahead with their own unique systems. For example, the Airservices plan for the ADS-B Mode S squitter for general aviation aircraft seems to be unique in the world. Whilst the ADS-B Mode S squitter is being installed in airline aircraft, it is not really suited for GA aircraft, as additional features (such as graphical weather etc) cannot be incorporated.
It is good to see that the Swedish system will support FIS-B (flight information). This means that it doesn’t just give a traffic information service, which TCAS (Traffic Alert and Collision Avoidance System) already does.
Just as I have travelled to Alaska to look very carefully at the Capstone project, I will do a trip to Sweden to have a look at their system and report the pros and cons on this website.
Sweden to Deploy ADS-B Network
The Swedish Airport and Air Navigation Services LFV Group is about to begin deploying a nationwide 12-station ADS-B (automatic dependent surveillance-broadcast) network using VDL (VHF digital link) Mode 4 technology.
The network should become fully operational in 2007, according to LFV, making Sweden the first country to achieve nationwide ADS-B coverage.
Along with ADS-B, the network will support broadcast services for TIS-B (traffic information), FIS-B (flight information), and differential augmentation for the Global Navigation Satellite System (GNSS). And because it uses VDL-4, it will enable point-to-point digital communication for aircraft equipped with compliant transceivers.
The LFV Group believes its investment will result in significant future efficiencies both for aircraft control and for users, such as airlines, by enabling new practices such as "green approaches," which Scandinavian Airlines has been flying over the past several months. SAS currently has four of its B-737s equipped with ADS-B as part of its efforts to reduce operational costs and environmentally adverse emissions.
The main long-term motivating factor driving these developments is Sweden's concern over increasing airline traffic. European authorities are planning for a 100 percent increase by 2020, which authorities there fear will inevitably cause congestion issues, environmental concerns, and increasing loads on airports at a time when the option of adding new runways is becoming severely limited and increasingly time-consuming.
The LFV Group believes that by using existing resources combined with new communications technology, the demand for major infrastructure investments will be postponed. In addition, the new network should have substantially lower operational costs than conventional, radar-based air traffic surveillance and control systems, and should more easily accommodate next-generation navigation and communications system upgrades.
VDL Mode 4
The enabling technology of Sweden's ADS-B network, VDL-4, employs a TDMA (time division multiple access) technique that divides the communication channel into "slots" of time, each of which may be used to transmit a unit of data.
But VDL-4 differs from other TDMA systems in that it also uses a self-organizing concept known as STDMA, which requires each transmitting station to reserve in advance the slot it wishes to use, thus avoiding conflicts. The time-slots are synchronized to UTC (coordinated universal time) that is normally provided by a GNSS (Global Navigation Satellite System) receiver.
The development of VDL-4 has been co-financed by the European Union and Eurocontrol. Bo Redeborn, who directs ATM (air traffic management) strategies for Eurocontrol noted that the recent trial of 4D trajectories in Sweden has "made it evident" that VDL-4, will meet all requirements identified for Europe until 2020, and that "the time is now appropriate to put this technology into operation."
Sweden's CNS Systems is the main supplier for the ground network, and is the first vendor to offer a certified, operational VDL-4 ADS-B system that complies with ICAO SARPS (standards and recommended practices) for the technology. CNS has a policy of transferring its technology to licensed avionics suppliers and enters into partnerships with system integrators to enable its more rapid implementation. One such licensee is Rockwell Collins. 06-01-2006.
