Aircraft data transmission system

0001The present invention relates to a data transmission system which is embarked on an aircraft, in particular a transport aircraft, and which is intended for the transmission of data between the aircraft and at least one transmission station situated outside said aircraft aircraft, during an internal / external communication.

0002The documents <patcit id="pcit0001" dnum="WO2004045106A"><text>WO2004045106</text></patcit> and <patcit id="pcit0002" dnum="US6181990B"><text>US6181990</text></patcit> describe internal / external communications systems on board an aircraft.

0003Document XP002377427, "<nplcit id="ncit0001" npl-type="s"><text>Information technology - ASN.1 encoding rules: Specification of Packet Encoding Rules (PER) ", ITU-TX691 </text></nplcit>describes the PER coding.

0004Although not exclusively, said transmitting station is preferably located on the ground so that said internal / external communication represents a common ground / edge type data communication between the crew of the aircraft and a station located on the ground and in particular for air traffic control. The data transmitted during such ground / edge communication are generally coded and standardized for reasons of optimization of transmission performance and interoperability between the crew of the aircraft and the station situated on the ground.

0005It is also known that such a data transmission system generally comprises:<ul><li>a transmitting / receiving device which is capable of transmitting outgoing data messages outside the aircraft and receiving incoming data messages from outside the aircraft, said incoming and outgoing messages passing through by said transmitting / receiving device being encoded;</li><li>a-message management device:<ul><li>▪ which is connected to said transmitting / receiving device;</li><li>▪ which receives said encoded incoming messages from said transmitting / receiving device and transmits said encoded outgoing messages to said transmitting / receiving device; and</li><li>▪ which comprises coding / decoding means capable of performing coding / decoding, for example of the PER type specified below, said coding / decoding means decoding said encoded incoming messages so as to form decoded incoming messages and encoding messages outputs decoded to form said coded outgoing messages; and</li></ul></li><li>at least one man / machine interface means:<ul><li>▪ which is connected to said message management device;</li><li>▪ which is capable of presenting to an operator the decoded incoming messages which originate from said message management device and which originate from said transmission station situated outside said aircraft; and</li><li>▪ which allows an operator to generate messages representing decoded outgoing messages which are then transmitted to said message management device and which are intended for said transmission station situated outside said aircraft.</li></ul></li></ul>

0006Due to an increasing number of data communications between the ground and aircraft, including transport aircraft, the certification authorities (EASA) have imposed [through a certification directive ("<nplcit id="ncit0002" npl-type="s"><text>Certification Review Item: CRI-F26 Issue 03 ", dated June 30, 2003</text></nplcit>) based on a standard document ED112 ("<nplcit id="ncit0003" npl-type="b"><text>Minimum operational performance specification for crash protected airborne recorder systems "March 2003 edition</text></nplcit>) and ED93 ("<nplcit id="ncit0004" npl-type="s"><text>Minimum aviation system performance specification for CNS / ATM message recording systems "November 1998</text></nplcit>)] the recording, at the cockpit voice recorder ("Cockpit Voice Recorder") of all the data exchanges carried out between the crew and the ground. This data record is made mandatory for any aircraft whose type certification occurs after January 1, 2005.

0007To meet this requirement, it is therefore necessary to provide means on board the aircraft for recording said ground-to-board or internal / external communications (in relation to the aircraft). However, such an arrangement has some disadvantages.

0008The addition of new means is sometimes difficult to implement, and often costly and cumbersome. Moreover, such an addition makes the architecture of said data transmission system more complex.

0009Furthermore, since the cockpit voice recorder must record a minimum of two hours of communication and the volume of data to be recorded varies greatly depending on the communication between the ground controllers and the crew of the aircraft , the storage volume to be provided must be particularly high, which of course has a negative influence on the cost and the space requirement.

0010The present invention relates to a data transmission system which makes it possible to remedy the aforementioned disadvantages.

0011According to the invention, the data transmission system, which is embarked on an aircraft and which is intended for the transmission of data between the aircraft and at least one transmission station situated outside said aircraft, during a internal / external communication, in particular ground / edge communication, said data transmission system comprising:<ul><li>a transmitting / receiving device which is capable of transmitting outgoing data messages outside the aircraft and receiving incoming data messages from outside the aircraft, said incoming and outgoing messages passing through by said transmitting / receiving device being encoded;</li><li>a message management device:<ul><li>▪ which is connected to said transmitting / receiving device;</li><li>▪ which receives said encoded incoming messages from said transmitting / receiving device and transmits said encoded outgoing messages to said transmitting / receiving device; and</li><li>▪ which comprises coding / decoding means capable of performing PER coding / decoding, said encoding / decoding means decoding said encoded incoming messages so as to form decoded incoming messages and encoding decoded outgoing messages so as to form said coded outgoing messages; and</li></ul></li><li>at least one man / machine interface means:<ul><li>▪ which is connected to said message management device;</li><li>▪ which is capable of presenting to an operator the decoded incoming messages which originate from said message management device and which originate from said transmission station situated outside said aircraft; and</li><li>▪ which allows an operator to generate messages representing decoded outgoing messages which are then transmitted to said message management device and which are intended for said transmission station located outside said aircraft,</li></ul></li></ul>is remarkable in that:<ul><li>said system further comprises an encoding device which performs a PER coding for any non-encoded data message related to said internal / external communication which passes through said message management device and which is intended for be recorded, for the purpose of performing a compression of these data messages;</li><li>said encoding device comprises at least one encoding function of said encoding / decoding means which is integrated into said message management device; and</li><li>said system further comprises a recording device which is connected to said encoding device and which is formed to record, on at least one recording medium, any incoming or outgoing data message related to said which is transmitted by said message management device and which is encoded according to a PER coding.</li></ul>

0012Thus, by virtue of the invention, the data to be recorded are all previously compressed, all of which are subjected to PER coding, which corresponds to an encoding according to an international standard defined in the document "EUROCAE ED-100"<nplcit id="ncit0005" npl-type="s"><text>Interoperability Requirements for ATS Applications using ARINC 622 Data Communications Final Draft (RTCA DO-258) ", September 2000</text></nplcit>). In the usual way, coding corresponds to a transformation of data by means of a code, which allows their representation in a different form, and offers the possibility of returning to their original form, by means of a decoding corresponding. However, in addition to encoding the data in this manner, a PER coding also performs a compression of said data, that is, a modification of said data so as to reduce their volume. Accordingly, a reduced storage volume for said recording medium can be provided for recording all (thus compressed) data relating to internal / external communication. This makes it possible in particular to reduce the cost and the space requirement of said recording medium.

0013Furthermore, as a result of the invention, said encoding device uses the coding function of the encoding / decoding means existing in the data transmission system (for the usual encoding / decoding of incoming and outgoing messages) it is not necessary to provide a specific coding device (more precisely a specific compression device).

0014Moreover, since the encoding device is thus integrated directly into the message management device through which all the messages to be transmitted pass through, it is not necessary to provide special means for receiving these messages to be recorded. The latter are in fact all directly accessible, in said message management device, to the recording device which is connected to said encoding device.

0015Consequently, the aforementioned features in accordance with the invention have reduced cost and space and do not complicate the architecture of the data transmission system.

0016In a first embodiment, said encoding device generates (and transmits to said recording device) a frame comprising a PER-type frame including at least one data message, as well as additional information such as time, for example.

0017Furthermore, in a second embodiment, said encoding device generates (and transmits to said recording device) a frame containing all the data to be recorded. This implementation requires the definition of a more complete syntax than that used for internal / external communication, preferably ground / edge exchanges. This frame is always sent by the message processing function.

0018The present invention also relates to a communication set comprising at least:<ul><li>a data transmission system which is embarked on an aircraft; and</li><li>a data transmission station which is located outside the aircraft, in particular an air traffic control station located on the ground.</li></ul>

0019According to the invention, said data transmission system of said communication set is of the type mentioned above.<ul><li>The figures of the accompanying drawing will clearly show how the invention can be realized. In these figures, identical references designate similar elements.</li><li>The <figref idrefs="f0001">figure 1</figref> is the block diagram of a data transmission system according to the invention.</li><li>The <figref idrefs="f0002">Figure 2</figref> illustrates schematically a communication set according to the invention and comprising a data transmission system.</li></ul>

0020The data transmission system 1 according to the invention and shown schematically on the <figref idrefs="f0001">figure 1</figref>, is carried on an aircraft A, in particular an airplane, and is intended for the transmission of data between the aircraft A and at least one data transmission station 2 located outside said aircraft A. This data transmission is carried out during a communication called "internal / external" within the scope of the present invention, that is to say between the interior and the exterior of the aircraft A. Although not exclusively, said communication internal / external communication is preferably a communication of the conventional ground / edge type between the crew of the aircraft A and a station 2 located on the ground S and intended in particular for aerial control, as shown in FIG. <figref idrefs="f0002">Figure 2</figref>. However, this internal / external communication may also be communication between the crew of aircraft A and the crew of another mobile (air, land or sea), in particular of another aircraft.

0021Said data transmission system 1 is of the type comprising:<ul><li>a transmitting / receiving device 3 which is capable of transmitting outgoing data messages outside the aircraft A, for example via electromagnetic waves 4, and receiving from the outside of said aircraft aircraft A, also by means of electromagnetic waves 4 which are transmitted by an appropriate means of said transmission station 2, incoming data messages. Of course, this transmitting / receiving device 3 may correspond to any type of known device allowing data transmission / reception between the aircraft A and an external transmission station 2. In addition, said incoming and outgoing data messages, which pass between the exterior and said transmitting / receiving device 3, are all encoded, as specified below;</li><li>a message management device 6:<ul><li>▪ which is connected via a double link 7 to said transmitting / receiving device 3;</li><li>▪ which receives said encoded incoming messages from said transmission / reception device 3;</li><li>▪ which transmits said coded outgoing messages to said transmission / reception device 3; and</li><li>▪ which comprises a coding / decoding means 8, capable of performing a PER coding / decoding. A PER coding represents a usual coding according to an international standard which is defined in the aforementioned "EUROCAE ED-100" document. Said coding / decoding means 8 comprises for this purpose, on the one hand, a decoding function which decodes the encoded incoming messages so as to form decoded incoming messages and, on the other hand, an encoding function which codes the encoded messages outgoing messages decoded to form said coded outgoing messages; and</li></ul></li><li>at least one man / machine interface means 9:<ul><li>▪ which is connected via a double link 10 to said message management device 6;</li><li>▪ which is capable of presenting, for example on a display screen 11, to an operator of the aircraft A, in particular to a pilot, the decoded incoming messages originating from said message management device 6 and which originate from said transmission station 2 located outside the aircraft A; and</li><li>▪ which allows an operator to generate, by means of an appropriate means 12, for example an alphanumeric keyboard or a computer mouse, messages representing decoded outgoing messages which are then transmitted to said management device messages 6 and which are intended for the transmission station 2 located outside the aircraft A, for example on the ground S.</li></ul></li></ul>

0022As a result, an incoming message is transmitted in coded manner via the means 5 of the transmission station 2. This encoded incoming message is received by the transmitting / receiving device 3 and is transmitted, via the link 7, to the message management device 6. The latter decodes this encoded incoming message, via the encoding / decoding means 8, so as to form a decoded incoming message which is then transmitted by means of an encoded message, man / machine interface 9 via the link 10. Said interface means 9 finally presents this decoded incoming message to the operator, for example via the display screen 11.

0023In addition, an outgoing message is generated by the operator, for example via the means 12 of said man / machine interface means 9. Said interface means 9 transmits this unencoded outgoing message to the management device of messages 6 via the link 10. The latter encodes this outgoing message, via the encoding / decoding means 8, so as to form an encoded outgoing message which is transmitted via the link 7 to the transmitting / receiving device 3. Said transmitting / receiving device 3 can finally transmit this encoded outgoing message to said transmission station 2 situated on the ground S, for example in the form of electromagnetic waves 4.

0024According to the invention, in order to be able to record all the data relating to an internal / external communication:<ul><li>said system 1 further comprises a coding (or compression) device 13 which performs data compression, by performing PER-type encoding for any data message (not encoded and therefore not compressed):<ul><li>▪ which relates to said internal / external communication;</li><li>▪ which passes through said message management device 6; and</li><li>▪ that is to be registered, as specified below;</li></ul></li><li>said encoding device 13 comprises the coding function of said encoding / decoding means 8 which, as specified above, is directly integrated into said message management device 6; and</li><li>said system 1 further comprises a recording device 14 which is connected via a link 15 to said coding device 13 and which is formed so as to record, on at least one usual recording medium 16 , any incoming or outgoing data message, which is related to said internal / external communication, which is transmitted by said message management device 6, and which is coded according to a PER (and therefore compressed) coding.</li></ul>

0025Thus, thanks to the use of PER coding (ISO-8825-2), which represents, as indicated above, a usual coding according to an international standard defined in the document "EUROCAE ED-100" the system 1 according to the invention reduces the volume of the data (relating to said internal / external communication) to be recorded, which makes it possible to considerably reduce the storage volume of said recording medium 16. Indeed, coding of the PER type realizes, in addition to the coding itself, a data compression, which is sufficiently large to obtain such a result.

0026In a preferred embodiment, said recording device 14 corresponds to the cockpit voice recorder of aircraft A, of the CVR ("Cockpit Voice Recorder") type.

0027Furthermore, as a result of the invention, said coding (or compression) device 13 uses the encoding function of the encoding / decoding means 8 existing in system 1 (for encoding / decoding incoming and outgoing messages, such as indicated above), it is not necessary to provide a specific coding device (more precisely for compression) to reduce the volume of the data to be recorded.

0028Moreover, since the encoding device 13 is thus integrated directly into the message management device 6, through which all the messages to be recorded are transited, it is not necessary to provide special means for receiving these messages to be recorded, which are therefore all directly accessible in said message management device 6 for recording.

0029Consequently, the aforementioned characteristics according to the invention and making it possible to record all the data relating to the internal / external communication, present a reduced cost and space. Moreover, these characteristics do not make the architecture of the data transmission system more complex.

0030In a first particular embodiment, said encoding device 13 generates (and transmits to said recording device 14) a frame comprising a PER-type frame including at least one data message, as well as additional information such as the time , the status of the processing of the message and the issuing ATC application. Usually, a frame represents the set of consecutive bits forming a block within which there are zones for the transmission of data of a user and of service information.

0031Furthermore, in a second particular embodiment, said encoding device 13 generates (and transmits to said recording device 14) a PER frame containing all the information intended for the message recording device. This implementation requires the definition of a more complete syntax than that used for internal / external communication, preferably ground / edge exchanges. This frame is always sent by the message processing function.

0032As shown on the <figref idrefs="f0002">Figure 2</figref>, the data transmission system 1 according to the invention, which is embedded on the aircraft A, forms part of a communication assembly 17 which comprises, in addition to said system 1, at least one data transmission station which is located outside the aircraft A, in particular an air traffic control station 2 which is located on the ground S.