JPS6097287A - Down link system - Google Patents

Abstract

PURPOSE:To improve control efficiency and accuracy while enhancing data transmission efficiency, by transmitting azimuth and distance informations obtained through a navigation apparatus and altitude information possessed by an aeroplane itself from the aeroplane side to a ground station side. CONSTITUTION:A flight data calculator circuit 7 calculates a flight speed, a flight direction and a falling or rising speed and outputs the same to a navigation data generating circuit 8 along with altitude data. The navigation data generating circuit 8 converts navigation data, wherein the machine body discriminating code of an own aeroplane is added to the azimuth and distance data from an azimuth detecting and indicating part 5 and a distance detecting and incidating part 6 and othe flight data from the flight data calculator circuit 7, to a code system and sends the same to a ground station side through a transmission part 1 and an antenna 3. In the ground station, the estimation of a flight path is performed on the basis of navigation data by a covered route estimating circuit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a σ downlink system, particularly for aircraft VC
An interrogation pulse is emitted to the ground station from the onboard station (interrogator) to obtain a response pulse from the ground station, and information on the aircraft's orientation relative to the ground station is also obtained via radio waves transmitted by the ground station. The present invention relates to a downlink system in a navigation device that performs navigation.

The onboard station and the ground station exchange questions and response pulses via radio waves, or receive azimuth radio waves emitted by the ground station, and confirm the position of the aircraft equipped with the onboard station using ranging data and azimuth data. For example, the navigation device that carries out the operation is T A CAN (TACtical Air
Navigation)/DME(Distance)
It is widely known as a digital communication system that transmits interrogation pulses or emergency information from an airborne station to a ground station. It is used as a downlink/stem.

Navigation equipment as mentioned above, e.g. TACAN/DME Vc
In this case, the aircraft fires an interrogation pulse for ranging to the ground station, and after the time required for the system to respond, the aircraft responds via the uplink system (Up Link 5ysteH1), which is used as a communication channel from the ground station to the aircraft. The distance to the ground station is calculated by obtaining a response pulse from the ground station, and the onboard station receives radio waves from the ground station via the uplink to determine the direction of the aircraft. While knowing the above-mentioned distance information and this azimuth information, determine the position of the aircraft including its own altitude information.
- The TACAN/DM
Other navigation devices other than E are basically operated using almost the same method.

However, in conventional navigation devices of this type, the information transmitted from the aircraft side to the ground station side via the downlink system is limited to interrogation pulses or emergency messages. The utilization rate for the aircraft is quite low, and furthermore, the direction and distance information, along with the altitude information, is only used by the aircraft, and therefore, it has the disadvantage that it is not used at all by the aviation 17 system.

OBJECT OF THE INVENTION Air-to-ground digital communication for eliminating the above-mentioned drawbacks and transmitting information from an onboard station of a navigation device to a ground station to support aircraft operations through interrogation system and transmission and reception of response pulses. In the downlink system as a system, by providing a means for transmitting position, distance, and altitude information regarding the own aircraft as well as initial data related to aviation from the onboard station to the ground station via a dedicated downlink, Air traffic control at the station [
It is an object of the present invention to provide a downlink system that significantly increases information related to traffic control and significantly improves control efficiency, and also significantly improves data transmission efficiency.

The system of the present invention determines the position of an aircraft through transmission and reception of interrogation pulses from radio waves from an onboard station and response pulses from a ground station, and data transmitted by an onboard station in a navigation device that operates. Downlink system A (Dou
n Link System), an aeronautical data calculation means for calculating aeronautical data regarding flight speed p, flight direction, and descent or ascent speed on the onboard station side, and a navigation system that includes azimuth, distance, altitude information, etc. along with the aeronautical data. Initial data of the specifications A navigation specification transmission means that transmits all downlinks from the onboard station to the ground station, and a timing set in advance together with the initial data of the navigation specifications transmitted by this navigation specification transmission means. The trajectory of the aircraft is determined at the ground station while receiving correction data regarding the false initial data transmitted via the downlink from the onboard station.
A track estimation means estimates by P (Dynamic Programming) and a distance information direct acquisition means directly acquires distance information between the aircraft and the ground station at the ground station.

Next, the misfire 1i11 will be explained in detail with reference to the drawings.

FIG. 1(5), [F]) is a block diagram showing the first embodiment of the present invention. FIG. 1(5) is a block diagram of the airborne station, and FIG. The embodiment will be described using a '1' ACAN/DME device as an example.

For example, the embodiment of the on-board station shown in FIG. Antenna 3. Receiving section 4. Direction detection instruction section 5.
In addition to the normal TACAN/DME equipment onboard station of the distance detection instruction section 6, the aeronautical data calculation circuit 7 directly related to the present invention
Constructed with a built-in navigation specification generation circuit 8, etc.
c FIG. 1 (5) shows the antenna 9. Transmission/reception switch 10. Transmission unit 11. Normal TACAN/DME that is the receiving section 12 area
In addition to the ground station, the device includes a track estimation circuit 13 and a distance measurement circuit 14, which are directly related to the present invention.

The normal operation of the TACAN/DME device shown in Figures (A) and (B) is as follows. That is, in FIG. 1 (8), a distance interrogation pulse with a predetermined frequency channel selected by a channel selector (not shown) is sent from a transmitter l to a transmitter/receiver switcher 2. The interrogation pulse is transmitted via the antenna 3 to the ground station shown in FIG. The pulse is decoded, and after being given a system delay, it is coded again and is sent as a distance response pulse having a certain frequency difference from the interrogation pulse. It will be reduced.

Further, from the transmitter 11, an azimuth signal consisting of a variable azimuth signal and a reference azimuth signal, in which azimuth information is given by amplitude modulating a carrier radio wave, is sent to the transmission/reception switch 10 along with a station identification signal. It is radiated via antenna 9. The distance response pulse, azimuth signal, station identification signal, etc. are received by the receiver 4 via the antenna 3J transmitter/receiver switch 2 of the onboard station shown in Figure 1 (A). The detection instruction section 5 detects the detection P and the instruction grt, and the distance response pulse is detected and instructed by the distance detection instruction section 6.

The distance information obtained in this way is used as information necessary for aircraft operation, along with the altitude information obtained from the aircraft's altimeter and other VR devices. It is also clear that the information is useful for efficient flight control of aircraft by ground stations. however,
In current navigation systems such as TACAN/DME equipment, this kind of information is not utilized at all by the ground station, and therefore messages sent from the aircraft to the ground station are limited to the transmission of distance inquiry pulses. As mentioned above, there is a problem in that the utilization efficiency of the transmission system, that is, the downlink system, is extremely poor.

Therefore, in the non-embodiment, the above-mentioned problem is solved by the following means.

The aviation data calculation circuit 7 calculates the flight speed, flight direction, and descent or ascent speed, which are the main aviation data of the own aircraft, through various sensors equipped on the own aircraft, such as a speedometer, an altimeter, and a direction indicator. death? %tK
Together with the data, these aeronautical data are sent to the navigation data generation circuit 8 via an output line 701.

The navigation specification generation circuit 8 is the direction detection instruction section 5? Navigation specifications including the bearing and distance data input from the flight distance detection instruction unit 6 and the above-mentioned aeronautical data, that is, the bearing, distance, altitude, speed, direction, descent speed, climb speed, etc., plus the aircraft identification number of the own aircraft. After converting the data into a binary code sequence of logical values "O" and "1" according to the preset number of bits and code format, initial data regarding navigation specifications is sent to the transmitter 1, and the distance question is sent. It is sent to the ground station on the same carrier frequency and via the same downlink system as the pulse.

In this way, the initial navigation specification data sent to the ground station, apart from the aircraft identification number, and other variable data are sent to the ground station as restoring correction data at preset time intervals. Ru.

Now, the ground station shown in FIG. The code is separated and extracted according to its code format, and the output line 1201'
It is sent to the track estimation circuit 13 via.

The track estimating circuit 13 inputs only the initial data and correction data of the navigation specification data, and uses the initial data to correct the measured initial position of the aircraft set by correcting data lCJ: and calculates the track using the DP method. Estimate. In this case, the distance information necessary for track estimation using the DP1000 method is not obtained indirectly via the onboard station, but is directly measured at the ground station as follows, and this distance information is used as a predetermined value. DP processing is performed while automatically obtaining it at the timing of .

The distance measuring circuit 14 obtains distance information directly from the ground station to the aircraft, and sends an interrogation pulse firing command signal to the transmitter 11 via the output line 1401 so that the firing timing can be determined from the onboard station. The receiver unit 12 receives all the interrogation pulses through the output fin 1402, calculates the distance to the aircraft, and outputs the output line 140.
The distance measurement data is automatically extracted by sending it to the track estimating circuit 13 via 3't.

In this way, the estimated trajectory of the aircraft n outputted from the trajectory estimation circuit 13 is sent to a display device, etc. via the output line 1301fz, and can be used for effective and appropriate operation control of the aircraft n, according to Figure 1 (5) and @. Airborne and ground stations significantly increase the efficiency of existing downlink systems.

FIG. 2 is a block diagram showing a second embodiment of the invention.

The second embodiment shown in FIG. 2 is a downlink system in which a means for calling and responding from the ground station side to the onboard station side is added to the first embodiment in Figure 1), 03>. The system is operated as follows.

Figure 2 shows the configuration of the ground station that performs calling and responding, and the configurations other than the mode pulse generator 15 with the same symbols are almost the same as the ground station shown in Figure 1 (B). Further explanation will be omitted.

The mode pulse generator 15 emits a mode pulse that is an interrogation signal to a plurality of aircraft in operation,
Receive a code pulse as a response signal from the designated aircraft. The interrogation and response using mode pulses and code pulses are basically 88R (8eco
ndary 5urveillance'fLadar
) etc.? The mode pulse is similar to that described above, and the mode pulse is composed of a plurality of twin pulse sequences having precisely different time intervals.

Such mode pulses are transmitted from the mode pulse generator 15 to the transmitter 11. It is transmitted to the onboard station via the transmitter/receiver switch IO and the antenna 9, and the code pulse containing a different identification pulse for each aircraft is obtained from the onboard station, and the receiving unit 121C decodes the lrL to identify the desired aircraft. Can communicate.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

The third embodiment shown in FIG. 3 is the embodiment VC? of FIG. 1 α), e). This shows a means for directly obtaining distance information at the ground station by constraining the distance interrogation pulse from the ground station, and the distance measurement circuit 16 is used to automatically acquire distance data by the ground station as follows. It is something.

Figures 4(A) and β) show the conventional distance query and response pulse characteristics (2) and the distance query and response when the ground station directly acquires ranging information in the embodiment of Figure 3. It is a pulse characteristic diagram (B).

In the prisoner in Figure 4, the airborne station fires 't1. The time axis of the interrogation pulse for distance measurement is represented by P above. In navigation devices, the second pulse of the twin pulse is usually used as the pulse for distance measurement.

This interrogation pulse is captured by the ground station and input as the received pulse P'.
At, later emitted to the airborne station as a response pulse Q,
The airborne station captures the signal as a received pulse ', and calculates the system delay t from the time T between the interrogation pulse P and the received pulse Q'.

The distance to the ground station is calculated based on the time excluding the time and the radio wave propagation speed. Note that in FIG. 4, 0 indicates the airborne station and the ground station.

The above are the characteristics of the conventional distance inquiry two-step response pulse, but in this embodiment, as shown in FIG. 4 (ar/c), the response pulse Q sent out after the system delay t0 is Only when measurement data is required is an interrogation command signal sent from the distance measuring circuit 16 to the transmitting section 11 via the output line 1601 (see FIG. 1).
Make the airborne station shown in The onboard station receives the response pulse Q converted into the interrogation command signal in this way, and when it obtains the received pulse Q' by this method, it emits an additional interrogation pulse PO as shown by the dotted arrow, and replaces the normal interrogation pulse. The firing is restrained. The interrogation pulses P are emitted in search and track mode with different average repetition rates, but the additional interrogation pulses are equivalent to the response pulses from the ground station with vc2 between the transmission of the interrogation pulses with this repetition rate. It is received by the ground station as an equivalent response pulse when used as an interrogation pulse for an onboard station, so the ground station automatically sends an onboard interrogation pulse every time this additional interrogation pulse whose emission timing is known is input. Track estimation circuit 1 measures the distance to the station.
This data is provided as necessary distance measurement data after inputting the initial data in the DP processing in step 3. It should be noted that it is sufficient to secure the distance measurement data directly acquired by the ground station in this way for the IMF processing, and the distance measurement processing by the aircraft can also be performed using past data. Even the intervention of such a small number of additional interrogation pulses has almost no substantial effect. By means of constraining the interrogation pulse in this manner, the downlink system shown in FIG. I can do it.

FIGS. 5A and 5B are block diagrams showing a fourth embodiment of the present invention.

In the fourth embodiment shown in FIGS. 5(A) and 5(B), the data to be transmitted from the airborne station to the ground station is pulse modulated, and this also includes majority decision 2 and block error. This is a downlink system that uses a distance measurement channel to perform communication with a significantly improved error transmission rate by applying a transmission system using correction codes, and its operation is as follows.

FIG. 5(G) shows the fourth embodiment vcj? airborne station, No. 5
) in the figure shows the configuration of the ground station in the fourth embodiment, and the pulse modulation circuit 17° encoding circuit 18 in FIG.
9. All components with the same symbols other than the decoding circuit 20 are the same as those shown in FIG.

In FIG. 5(8), the pulse modulation circuit 17 pulse-modulates the refined navigation specification data output from the navigation specification generation circuit 8 using a predetermined modulation method. This pulse modulation method is PW
Either so-called pulse parameter modulation such as M (pulse width modulation) or so-called pulse code modulation such as PCM (pulse code modulation) may be used.

The output of the pulse modulation circuit 17 is then sent to the encoding circuit 18, where it is encoded with a predetermined number of bits, and a block error correction code is added to it. The signal is configured as a niblock signal and is then sent to the transmitter 1 a predetermined number of times. The transmitter/receiver switcher 2 sends it to the ground station via the antenna 3 in the same manner as the distance interrogation pulse.

The block error correction code described above as well as multiple transmissions [
The majority decision is that navigation specification data is being transmitted 1c.
This is done with the aim of significantly changing the error transmission rate of the P code.

FIG. 6 is a majority decision characteristic diagram illustrating an example of the code error rate modification characteristic based on the majority decision in 2 in the fourth embodiment according to FIG. 5 (5), however.

It can be seen that the code error rate increases with the line error rate, and when the line error rate is constant, it decreases significantly as the number of code transmissions increases. Figure 5 (A).

CB) The fourth embodiment shown in K shows that the line error rate e is given by Vcw.
For example, if the number of communication target aircraft is 100, and the average number of interrogation pulse repetitions is 25 pps (pair pulse pe
If we assume that the time range in which one communication may interfere with other communications is approximately 30μSEC for TACAN/DME equipment, then e=100X2
5X30X10 =0.075. That is, 9 per bit
I think it's around 75%. The time range in which one communication may probabilistically interfere with another communication can be established by taking into consideration the transmission and reception times of the two communications.

The line chain wheel 0.075 mentioned above has a signal with a binary logical value m
1 m, When constructing and protecting the ``0# series, @
The probability of occurrence of l jZ @ Q” is about 50%.
Therefore, if you consider it per bit, roughly this 1
/2 can be considered as 0.0375. In the non-example, the code is sent seven times, and the code error rate based on the majority decision VC is suppressed to approximately 0.0001 or less.

FIG. 7 is an error correction code effect display diagram showing an example of the effect of the error correction code in the block code format in the fourth embodiment according to FIGS. 5(A) and 5(B) Vc.

Figure 7 shows that when the information bits are 21 bits, data is transmitted in a block code format expanded to 31 bits by adding 10 bits of parity pits to this module, and only 2 bits out of 31 bits have code errors. The effect of the error correcting code is shown by comparing the J code error rate and the i car by taking the case where the error rate is n as an example. It gets worse. In this embodiment, in order to improve the code error rate by majority decision, the data transmitted in block code format is sent seven times, and the code error rate is calculated based on this and the TACAN/DME line error rate of the line error rate described above. 1σ3 or less is ensured, and therefore a complete decoding rate close to 1 is obtained at the code error rate IF3 to 10' in FIG. 7, which is n7'c.

Now, in Fig. 5 ■, p is captured by the ground station and n receiving section 12
The block code related to the navigation specifications inputted to the error judgment circuit 19&C through the code block is processed by a parity code VC for each code block to perform error judgment, and then sent to the decoding circuit 20VC.
A signal is generated for each data of the navigation specifications, and the track estimation circuit 131C sends f'L, which is used as a criterion for determining the number of tracks to be estimated in the DP processing. In this way, the pulse modulation is n and the majority decision 2
It is possible to realize a downlink system having a highly accurate data transmission means that effectively utilizes the distance measurement channel directly by using the block error correction code and the block error correction code.

In addition, in each of the above-mentioned 'fcil' to fourth embodiments, the airborne station and the ground station are shown as an example of an nTACAN/DME device, but this is a It is clear that other navigation devices with similar functions to support navigation could also be implemented, and
c In the fourth embodiment shown in Fig. 5 (6), @, and Figs. It is obvious that it can be set arbitrarily depending on the decoding rate and the like.

As explained above, in a downlink system of a navigation device in which an airborne station and a ground station support the operation of an aircraft through the transmission and reception of interrogation pulses and response pulses via radio waves, it is possible to By providing a means for transmitting the direction and distance information that was acquired and used only by the aircraft and the altitude information possessed by the aircraft itself from the aircraft to the ground station, the efficiency of control by the ground station of the navigation equipment can be improved. This has the effect of realizing a downlink system that can significantly improve accuracy and data transmission efficiency.

[Brief explanation of drawings]

1(8) and (b) are block diagrams of an airborne station (8) and a ground station (c) in the first embodiment of the present invention, and FIG. 2 is a block diagram of the ground station (c) in the second embodiment of the present invention. station block diagram,
FIG. 3 is a block diagram showing the ground station in the third embodiment of the present invention, and FIG. Distance interrogation and response pulse characteristic diagram in the third embodiment, FIG.
4), Q3) are block diagrams of the airborne station (4), block diagrams of the ground station (B), and FIG.
1 A majority decision characteristic diagram showing an example of the bit error rate improvement characteristic by majority decision in the fourth embodiment according to FIG. 5 (A), ■), FIG. 7 is based on FIG. 5 (8), ■) FIG. 7 is an error correction code display diagram showing an example of the effect of the error correction code using the block code format in the ICP according to the fourth embodiment. 1... Transmitter, 2... Transmit/receive switch, 3
...Antenna, 4...Receiving section, 5.
...Direction detection instruction unit, 6...Distance detection instruction section, 7...Aeronautical data calculation circuit, 8...
Aviation specification generation circuit, 9... Antenna, 1°...
... Transmission/reception switch, 11... Transmission section, 12.
...Receiving unit, 13...Track estimation circuit, 1
4...Distance measurement circuit, 15...Mode pulse generation circuit, 16...Distance measurement circuit, 17
...Pulse modulation circuit, 18... Encoding circuit, 19... Error determination circuit, 2o...
-Decoding circuit. t' Agent Patent Attorney Uchihara To.

Claims (4)

[Claims] (1) The position of the aircraft is determined through transmission and reception of interrogation pulses by radio waves from the onboard station installed on the aircraft, response pulses, etc. from the ground station, and the data transmitted by the onboard station in the navigation system is transmitted from the ground. Downlink system A constitutes a transmission channel for transmitting to stations.
8 system), the onboard station side calculates aeronautical data regarding flight speed, flight direction, and descent or ascent speed; Initial data of navigation specifications including altitude information All downlinks are used to transmit data from the airborne station to the ground station. At the same time, the ground station processes the aircraft's trajectory using DP (Dynamic Pro) while receiving correction data for the initial data transmitted from the onboard station via the downlink.
gramming, dynamic programming) [Thus, it is equipped with a track estimation means for estimating the trajectory, and a distance information direct acquisition means for directly acquiring distance information between the aircraft and the ground station at the ground station, and is used only on the aircraft side. This downlink system is characterized by transmitting distance and altitude information from ground stations to the ground station and providing it to aircraft air traffic control. (2) The downlink system according to claim (1), further comprising means for causing the ground station to call and respond to the on-board station. (3) The range information obtained by the distance information direct acquisition means is obtained by constraining the emission timing of interrogation pulses emitted from an airborne station at a ground station. The downlink system described in paragraph (1). (4) The scope of the patent claims characterized in that the data to be transmitted from the aircraft to the ground station is made into a pulse modulated signal and is transmitted using a ranging data channel by majority voting and block error correction code transmission method. The downlink system described in paragraph (1).