Geolocation technologies for aerospace
Contents
Presentation
The purpose of this page is to present:
- The different technological solutions for aeronautics geolocation in terms of:
- data transmission
- installation on board of an aircraft
- The advantages and disadvantages of each type of solution
- the magnitudes of the purchase and operating costs (excluding setting costs)
Geolocation principles
- A mobile device (in our case an aircraft) is equipped with a position receiver (GPS, GLONASS, Galileo, ...) in order to get its location in three dimensions
- And with a transmitting device to send this position to a ground station
- This ground station sends the location data to a server accessible from the internet network for its use by software solutions including mapping applications to display the position of the aircraft.
GNS position reception
Two networks of global navigation system are operational
- GPS: Managed by the U.S.
- GLONASS: Managed by the Space Force of the Russian Federation
GALILEO constellation launched by a European consortium is expected to be available in 2016
Aircraft on board reception is made by an antenna included in a device or external to the equipment and wired to a box housing electronic for decoding and position computation.
The possible combinations are:
- Certified aircraft equipment, fixed to the inside of the aircraft and connected to an external antenna
It is best to have an external GPS antenna for the aircraft to ensure better reception of satellite signals.
- Certified external antenna connected to a non-certified equipment installed in the aircraft with a mouting system dedicated for this purpose
- Bottom reception connected to a tablet or a smartphone wirelessly (Bluetooth, wifi, ...)
- Autonomous box including antenna
Data transmission methods suitable for aerospace
ACARS Transmission
The communication protocol ACARS. started in the late 70s. It uses several modes of transmission: VHF, HF or Satellite. It is a module called Management Unit (MU) or Communication Management Unit (CMU), which determines the best mode of transmission according to the situation of the aircraft. Other electronic equipment of the aircraft can connect to the MU / CMU to exchange data with the outside of the aircraft. This mode of communication is used to exchange any type of data, not only the position of the aircraft. In addition, it is a bidirectional communication: the aircraft can both transmit and receive data. It is commonly deployed on airliners.
The successors of this technology through the project FANS and the ATN are probably the future of information transmission to and from an aircraft because we can consider exchanged based on the TCP/IP protocol.
ACARS transmission benefits
This mode of transmission adapts the actual transmission mode depending on the available network and increase the chances of having coverage available.
ACARS transmission disadvantages
It requires the implementation of an expensive component, large (expected to be in one or more racks avionics compartment) and heavy (about 5kg).
ACARS cost of transmission
- Installation: not encrypted.
- Transmission: 5 € to 50 € per hour of flight.
ADS-B Transmission
The ADS-B (Automatic Dependent Surveillance - Broadcast) is a technology being deployed in Europe. Originally, the ADS was only used in certain airspace or implementing land radars were not possible like North Atlantic oceanic airspaces Gander and Shanwick.
This is a protocol transmission sent by the aircraft radio to indicate its position to air traffic controllers. This is called ADS-B out. From the cockpit point of view, ADS-B is totally transparent to the pilot. It can simply disable through a specific interface but normally the transmission must be permanent.
Subsequently, the ADS-B should be used to a new generation of TCAS for ATSAW (Airborne Traffic Situational Awareness). We then speak of ADS-B in.
EU legislation should make its installation and mandatory use on aircraft of more than 5.7 T for 2015 for new aircraft and for 2017 for from 2017 old aircraft.
Specific activities such as military activities may be excluded from this obligation.
The signal is not encrypted, it may be recovered by any receiving antenna. So you just need an antenna ADS-B network to receive transmissions from the aircraft. This network can be an open third-party network. It is possible to build its own network. A receiving antenna can receive ADS-B aircraft emissions within 200Nm.
ADS-B transmission benefits
The advantage of this solution lies in its obligation if the aircraft must be equipped with a statutorily ADS-B transponder then there is no need to add another device to transmit position.
ADS-B transmission disadvantages
The disadvantages are:
- If there is no requirement to install ADS-B device, the operator may, for reasons of confidentiality, prohibit its use.
- There is not, to our knowledge, open official server to retrieve the position of an aircraft. You need either:
- To build your own antenna array.
- To use "free" private networks.
ADS-B transmission costs
- Installation in the aircraft: 0 € when one considers that the installation of an ADS-B transponder responds to a regulatory obligation. Otherwise it takes €3,000 for ADS-B transponder.
- Transmission: €0.
- Ground building: €1 per flight hour for the use of a network of receiving ADS-B position.
GSM Transmission
The position can be sent through the GSM network used by mobile phones. The equipment that sends the position must have a modem GPRS including a SIM card. It requires a data plan called " M2M" from a telephone operator. In general, the equipment can work with GSM network anywhere in the world according to the membership (taking into account whether or not the Roaming). On the other side, data real-time transmission is subject to the existence of GSM coverage in the survey area and the regulations applicable to the use of mobile devices (see Disadvantages of GSM transmission). In the context of aviation, GSM is an inexpensive solution in the case of transmission of OOOI or if the path does not need to be transmitted after the flight.
Advantages of GSM transmission
- The GSM transmission shifts smoothly through the fuselage of an aircraft. This allows to consider installing a casing independent of the aircraft and therefore do not require certification or even the use of a tablet provided with a SIM card or a smartphone.
Disadvantages of GSM transmission
- Restricting the use of GSM in the air due to local regulations or operator.
- Loss of transmission:
- Does not work beyond 3000ft to 5000ft ground in most countries because the GSM reception antennas are directed towards the ground. Transmission losses are systematic beyond 5000ft, very common beyond 3000ft.
- The high travel speeds can make it difficult to match between a receiving antenna and the transmitter module then jumps transmitter antenna antenna without having time to send data.
The area flown ** may not be equipped with GSM antenna. This is particularly the case in some wooded and unpopulated areas or over the sea Thus transmission losses frequently exceed 5 minutes on uninhabited areas.
Cost of GSM transmission
- Installation:
Uncertified equipment **: Solution *** smartphone: 0 € when one considers that the smartphone is purchased Solution *** tablet: the cost of the tablet (about 1000 €) Solution *** case: the proposed OpenFlyers Aerobox is 990 €. There are boxes with less functionality than the Aerobox 100 to 200 €.
- It is possible to connect an external GPS antenna to some tablets or non-certified equipment. The ideal is that the antenna is outside of the aircraft. In this case, the antenna must be certified and the cost of installation varies between € 1,000 and € 10,000 depending on the nature of the installation and the housing to which it is connected.
Material fully certified **: € 10,000 to € 100,000
- Transmission: € 0.1 to € 1. The price depends on the desired geographical coverage and the amount of data to be transmitted, ie the frequency of sending the position.
Satellite Transmission == ==
Satellite transmissions from aircraft is generally based on the Iridium satellite constellation. Worldwide coverage.
There are 2 types of embedded hardware:
- The hardware independent of the aircraft: it is self-boxes also receive GPS signals and transmit satellite broadcast. This tablet may also be connected to a satellite modem.
- Equipment mounted in the aircraft: the antennas are then located outside the aircraft and that there is therefore no problem of reception and transmission of signals except where the helicopter transmission satellite can be problematic.
Advantages of Satellite transmission
- Global coverage
Disadvantages of Satellite transmission
- Cost
Cost of Satellite transmission
- Installation:
Uncertified equipment **: Solution *** case: about 2,000 € Solution *** tablet: the cost of the tablet (approximately € 1,000) + cost of the satellite modem (about 300 €). Certified ** Material: Module *** tracking simply attached to the fuselage of the aircraft: about 1,000 €
- It is possible to connect an external GPS antenna to some tablets or non-certified equipment. The ideal is that the antenna is outside of the aircraft. In this case, the antenna must be certified and the installation cost is around € 8,000.
- There are also solutions designed for mounting EFB tablet used as class 2 and for connection to the ARINC bus. We have not studied the encryption.
Material fully certified ***: € 15,000 to € 60,000
- Transmission: 5 € to 50 € per hour of flight. The price depends on the refresh rate of the position, the number of hours of flight and also the volume of data in the case where in addition to the position of other data is exchanged. As part of a seasonal activity subscription can be reduced to the only useful month.
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