CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the European patent application No. 20382567.4 filed on Jun. 26, 2020, the entire disclosures of which are incorporated herein by way of reference.

FIELD OF THE INVENTION

The present invention is directed to a system and a method for transmitting information between pieces of equipment involved in airborne operations, especially in airborne refueling operations. More particularly, the invention relates to a system and a method both for powering sensors and actuators located in the tip of the flying boom (in the case of boom-type refueling) or in the tip of the hose, i.e., the drogue (in the case of the probe-and-drogue-type refueling) and for sending/receiving critical information between the transmitters/receivers located on board the tanker aircraft to/from the sensors and actuators located in the drogue or in the tip of the flying boom.

This invention is applicable in the field of flight communication systems, especially for those systems which operate in fuel environments.

BACKGROUND OF THE INVENTION

There are currently two main systems and methods for refueling an aircraft while it is in the air.

On the one hand, there is the so-called “boom system” which involves the use of a rigid mast or “boom” which has flying control surfaces at its tip. These flying control surfaces are driven by a boom operator. The boom operator is located at the tanker (i.e., the aircraft supplying the fuel) and usually controls the flying control surfaces by means of a joystick.

On the other hand, there is the POD system (also called “probe-and-drogue system”) which involves the launching of a flexible hose which has a drogue at its tip. The drogue serves as a stabilizer during the approaching maneuver of the hose towards the aircraft to be refueled. The aircraft to be refueled extends or deploys a probe which must fit into a valve located at the bottom of the drogue. While the hose and drogue are in the retracted position, they are held within a pod of the tanker.

Both the boom tip (with its control surfaces and its valve to be fitted inside a receptacle of the aircraft to be refueled) and the drogue incorporate several sensors and actuators which have to be powered. Usually, this powering is achieved by means of wiring transmitting the necessary power for feeding them from the tanker to the sensors and actuators. There are also data cables for transmitting and receiving information between the sensors and actuators and the tanker.

The correct performance of the complete refueling system and, particularly, of the sensors and actuators, is considered critical for warrantying the safety of both persons and equipment. Therefore, the whole refueling system is classified according to “Design Assurance Level” DAL A class.

Due to the hazardous fuel environment (which is prone to cause explosions in case of an overheating of the wires or in case of any sparks or electric discharge occurring between the wires and the fuselage of the aircraft to be refueled), Boom systems require special and isolated wires to be able to power and communicate sensors and actuators from the mobile part of BOOM to the central computer place in the fixed part of system at the tanker. This philosophy implies a complex guiding and fuel isolating systems to perform the powering and communication activities in a secure way. Moreover, due to the nature of the flexible hose in POD refueling operations, it is not recommended to arrange sensors/actuators in the drogue that imply data transmission and powering through electric cables, for which current POD systems lack this equipment.

SUMMARY OF THE INVENTION

With the aim of providing a solution to the abovementioned problems, the present invention refers to a communication system and method for equipment in airborne operations, especially in boom and POD airborne refueling operations.

The communication system for equipment in airborne operations, which is object of the present invention, comprises at least one first double transceiver and at least one second double transceiver.

The at least one first double transceiver comprises a first emitting module and a second emitting module.

The first emitting module comprises a control submodule, a first radio frequency submodule and an antenna.

The second emitting module comprises a monitoring submodule, a second radio frequency submodule and an antenna.

The first emitting module is configured to transmit data thorough a first main channel and the second emitting module is configured to transmit the same data through a second main channel.

The control submodule is bidirectionally connected to the monitoring submodule for checking whether the data to be transmitted by the first emitting module matches with the data to be transmitted by the second emitting module.

The at least one first double transceiver is configured to discard the data without sending it through the first main channel and through the second main channel if the data to be transmitted by the first emitting module does not match with the data to be transmitted by the second emitting module.

The at least one second double transceiver comprises a first receiving module and a second receiving module.

The first receiving module comprises a control subblock, a first radio frequency subblock and an antenna.

The second receiving module comprises a monitoring subblock, a second radio frequency subblock and an antenna.

The first receiving module is configured to receive data thorough the first main channel and the second receiving module is configured to receive data through the second main channel.

The control subblock is bidirectionally connected to the monitoring subblock for checking whether the data received by the first receiving module matches with the data received by the second receiving module.

The at least one second double transceiver is configured to discard the data received through the first main channel and through the second main channel without processing it (i.e., without forwarding the data to a corresponding computer or to a corresponding aircraft actuator), if the data received by the first receiving module does not match with the data received by the second receiving module.

Due to the communication system described above, with its control/monitoring architecture, the communication system is suitable for DAL A critical airborne operations. The data are sent in two redundant main channels and the data are verified within the first double transceiver before sending it and within the second double transceiver upon reception of the data through the first main channel and through the second main channel.

Moreover, the above described communication system is suitable for fuel environments in which wire communications may involve fire risk.

Due to this strategy of sending the data through two redundant channels, eventual jammers are prevented.

In a possible embodiment of the invention, the at least one first double transceiver may incorporate a first receiving module and a second receiving module. In an analogue manner, the at least one second double transceiver may incorporate a first emitting module and a second emitting module. This configuration allows the first double transceiver to further receive data from the second double transceiver.

According to a preferred embodiment of the invention, the first double transceiver and the second double transceiver are configured to operate at a frequency of between 2.4 GHz and 2.5 GHz.

According to a further embodiment of the invention, the first emitting module and the second emitting module are configured to respectively send the data to the first receiving module and to the second receiving module through the corresponding first main channel and second main channel by splitting, within each main channel, logic 0's and 1's into two different subchannels.

According to a possible embodiment of the invention, the first emitting module and the second emitting module are connected to respective sensors (e.g., pressure sensors in an airborne refueling system) for measuring one and the same magnitude (e.g., fuel pressure).

Furthermore, according to a possible embodiment of the invention, the first receiving module and the second receiving module are connected to an actuator in an aircraft (e.g., an actuator configured to actuate a valve allowing the passage of fuel from a tanker aircraft to another aircraft which needs to be refueled).

The at least one first double transceiver and/or the at least one second double transceiver may also be connected to a central computer in an aircraft.

According to a possible embodiment of the invention, the communication system comprises one or more energy storage modules for providing energy to the at least one first double transceiver and/or to the at least one second double transceiver and/or to a sensor in an aircraft, and/or to an actuator in an aircraft. The one or more energy storage modules are configured to be recharged when the communication system is not in use (e.g., when the aircraft is landed and/or when the POD or BOOM refueling systems are not in use).

The abovementioned feature allows the communication system and/or the sensors and/or the actuators to be powered without the need of power cables extending among a fuel environment (which would entail a risk of fire and/or explosion).

According to a possible embodiment, each energy storage module comprises a plurality of ultra-capacitors.

According to a possible embodiment of the invention, the first emitting module and the second emitting module of the first double transceiver (and/or of the second double transceiver) comprise:a first FPGA unit of either the control submodule or the monitoring submodule, wherein the emitter FPGA module is connected to;a digital-to-analogue converter of either the control submodule or the monitoring submodule, wherein the digital-to-analogue converter is connected to;a first voltage-controlled oscillator unit of the radio frequency submodule, wherein the first voltage-controlled oscillator is connected to;two variable-gain amplifiers (which may be connected in parallel) of the radio frequency submodule, wherein the two variable-gain amplifiers are connected to;an antenna.

Furthermore, the first receiving module and the second receiving module of the second double transceiver (and/or of the first double transceiver) comprise:an antenna, wherein the antenna is connected to;a low-pass filter of the radio frequency subblock, wherein the low-pass filter is connected to;two low-noise amplifiers (which may be connected in parallel) of the radio frequency subblock, wherein the two low-noise amplifiers are connected to;a mixer (e.g., a downconverter) of the radio frequency subblock, wherein the mixer is configured to receive an LO signal from an amplifying unit to which it is connected, and wherein the mixer is further connected to;a tuned amplifier of the radio frequency subblock, wherein the tuned amplifier is connected to;an envelope detector of the radio frequency subblock, wherein the envelope detector is connected to;an analogue-to-digital converter of either the control subblock or the monitoring subblock, wherein the analogue-to digital converter is connected to;a second FPGA module of either the control subblock or the monitoring subblock, wherein the second FPGA module is connected to;a second voltage-controlled oscillator unit, wherein the second voltage-controlled oscillator unit is connected to;the amplifying unit.

According to a possible embodiment of the invention, within each first double transceiver, the digital-to-analogue converter of either the control submodule or the monitoring submodule, is connected to the first voltage-controlled oscillator unit of the radio frequency submodule through a GFSK submodule.

The abovementioned feature allows for a reduction in the noise in the output of the first voltage-controlled oscillator unit, thanks to a smoothing effect of the GFSK submodule in the signal to be input to the first voltage-controlled oscillator unit.

The present invention further refers to a communication method for equipment in airborne operations.

The communication method for equipment in airborne operations comprises utilizing the communication system for equipment in airborne operations described above.

Furthermore, the communication method for equipment in airborne operations comprises:checking whether the data to be transmitted by the first emitting module matches with the data to be transmitted by the second emitting module, and:discarding the data without sending it through the first main channel and through the second main channel if the data to be transmitted by the first emitting module does not match with the data to be transmitted by the second emitting module, or;sending the data through the first main channel and through the second main channel if the data to be transmitted by the first emitting module matches with the data to be transmitted by the second emitting module.

Furthermore, according to a preferred embodiment of the present invention, the communication method further comprises:checking whether the data received through the first main channel by the first receiving module matches with the data received through the second main channel by the second receiving module, and:discarding the data without processing it if the data received by the first receiving module does not match with the data received by the second receiving module, or;processing the data if the data received by the first receiving module matches with the data received by the second receiving module.

As already mentioned, “processing the data” may involve forwarding the data to an actuator in an aircraft or to a central computer.

According to a preferred embodiment, the communication method comprises sending the data through the corresponding first main channel and second main channel by splitting, within each main channel, logic 0's and 1's into two different subchannels.

The present invention further refers to a computer implemented method for transmitting information (data) between equipment in airborne operations.

The computer implemented method comprises performing the following steps in a first emitting module and in a second emitting module of a first double transceiver:comparing a first sensor signal received by the first emitting module from a first sensor with a second sensor signal received by the second emitting module from a second sensor and, if the first sensor signal is equal to the second sensor signal, generating a bitstream corresponding to the received sensor signal, the bitstream further corresponding to a main signal which is to be transmitted by the corresponding emitting module through a corresponding main channel;converting the bitstream into an analogue signal, where logic 1's of the bitstream are allocated a first voltage and logic 0's of the bitstream are allocated a second voltage;splitting the analogue signal into a first secondary signal and a second secondary signal, wherein each secondary signal has a frequency corresponding to either the first voltage or the second voltage of the analogue signal, wherein the frequency of each secondary signal respectively corresponds to a first subchannel and a to a second subchannel of the corresponding main channel, and;amplifying the first secondary signal and the second secondary signal of the corresponding main signal.

The computer implemented method further comprises performing the following steps in a first receiving module and in a second receiving module of a second double transceiver respectively receiving the amplified main signal through the corresponding main channel:lowering a carrier frequency of the first secondary signal and the second secondary signal of the corresponding main signal;amplifying the first secondary signal and the second secondary signal in the selected lowered carrier frequency;generating a demodulated signal from the first secondary signal and the second secondary signal according to an envelope detection of the amplified first secondary signal and the second secondary signal;converting the demodulated signal into a bitstream;generating an LO command signal based on the bitstream, and;applying the LO command signal to command the lowering of the carrier frequency of the first secondary signal and the second secondary signal.

According to a preferred embodiment of the computer implemented method, the bitstream generated in the first emitting module and in the second emitting module includes a code corresponding to an emission power at which the first main signal and the second main signal are to be transmitted respectively by the first emitting module and by the second emitting module, respectively through the first main channel and through the second main channel.

Thus, the computer implemented method includes, within the first emitting module and the second emitting module, amplifying the first secondary signal and the second secondary signal of the corresponding main signal at the emission power indicated by the generated bitstream.

The abovementioned feature allows for adapting the emission through the first main channel and through the second main channel to any possible EMCON restriction which may be imposed to the airborne operation.

The present invention also refers to a computer program comprising instructions that, when executed in a computer, perform the computer implemented method described above.

The present invention further refers to a computer readable medium comprising instructions that, when executed in a computer, allows the computer to perform the computer implemented method described above.

Thus, the present invention implements a duplex communication with the central computer of system (located at the tanker) to manage the information from sensors and commands to actuators placed into mobile part via wireless communication without any traditional wires. The power required for these sensors and actuators is supplied via an intermediate energy storage allowing the self-powered system.

The system and method of the present invention allows the reduction of complexity of traditional wiring system:In boom system: The spring wiring system required for this equipment that works in a fuel environment in term of complexity, weight and isolation. Current spring wiring that communicates the mobile part of BOOM to central computer located in tanker aircraft requires a huge maintenance tasks and scheduled removals in order to keep the communications.In POD system: no wiring is allowed due to its safety implications required due to fuel environment.

