SU709013A3 - Receiving device of an aircraft navigation system over signal tower radiosignals - Google Patents

Abstract

The airport aircraft landing system employs a HF source and at least one associated HF source which is movable relative to the first source in two coordinate directions, with the aircraft having a receiver determining the angular position of the aircraft from the received phase modulated signals. Pref. the antenna system comprises a main antenna (17) extending along an axis (16) and two further parallel antennae (21, 22) at each end (18, 19) of an arm (20) rotating about the latter axis (16). The arm (20) rotates about the axis (16) at a uniform speed and the two ends (18, 19) of the arm are pref. at different distances from the axis (16) so that the respective antennae (21, 22) describe circles of different diameter.

Description

katsii. In this case, the first input of the synchronization unit of the controlled motor is connected to the first photodetector, the second input is one of the inputs of the correlator, and the output is connected to the controlled motor. The outputs of the second and third photodetectors are connected to the corresponding inputs of the modulation unit, the remaining inputs of which are other inputs of the optical correlator. The outputs of the modulation unit are connected to the inputs of the respective modulated light sources, the optical input of the Vidicon is connected to the output of the image combining unit, the input of the Vidicon is connected to the output of the display unit, the input of which is connected to one of the modulated light sources.

FIG. 1 shows a block diagram of the receiving device; in fig. 2 - functional optical correlator circuit.

The receiving device of the navigation system of the aircraft using radio signals of poppies contains an antenna 1 with a receiving-amplifier path 2, to the output of which is connected a beacon separation unit 3, a rotating antenna extracting unit 4, an optical correlator 5, an auxiliary local oscillator 6 and two groups of 7 and 8 multipliers 9-11 and 12-14. The first inputs of the multipliers 9-11 are connected to the corresponding outputs of the beacon signal extraction unit 3. The second entrance; - with the first output of the auxiliary local oscillator 6, and their outputs with the first inputs of the respective multipliers 12-14, the second inputs of which are connected to the corresponding outputs of the block 4, the allocation of signals of the rotating antenna. The outputs of the multipliers 12-14 and the second output of the auxiliary local oscillator 6 are connected to the inputs of the optical correlator 5. The correlator contains a controllable motor 15 s mounted on the shaft 16 with light-modulating disks 17-22, of which are disks. 17-19 are equipped with appropriate sources 23-25 of unmodulated light and photodetectors 26, 27 and 28, disks 20-22 having variable transparency along one diameter and uniform transparency in the perpendicular direction are equipped with modulated light sources 29-31; a synchronized motor 15 synchronizing unit 32, a modulation unit 33, an image adding unit 34, a Vidicon 35 and a display unit 36. The first input of the synchronization unit 32 of the controlled motor 15 is connected to the photodetector 26, the second input is one of the inputs of the optical correlator 5, and the output is connected to the engine 15, the outputs of the photoreceivers 27 and 28 are connected to the corresponding inputs of the modulation unit 33,

The tonal inputs of which are other inputs of the correlator 5. The outputs of the modulation unit 33 are connected to the inputs of modulated sources 29-31 of light, the optical input of the Vidicon 35 is connected to the output of the image addition unit 34, the input of the Vidicon 35 is connected to the output of the display unit 36, the input which is connected to a modulated light source 29.

The device works as follows.

The spectrum of the signals received by the antenna 1 is made up of the spectrum of the signals emitted by the beacon and the rotating antenna corresponding to a specific runway

airfield. It emits a signal at the assigned frequency level of 5 MHz at the given aerodrome, which is amplitude modulated by several frequencies fj, f2, f 3, for example 10, 160 and 3200 Hz.

The stationary central antenna of the rotating beacon emits a signal with a frequency P „which differs from the frequency Rd by the value D F. The rotating antennas of this beacon, for controlling the movement of which signals with frequencies fi, f2 and f3 are used, emit signals with frequencies FQ-f4 and Fg + fs. The antenna 1 of the aircraft is connected to a high frequency amplifier 37, the output of which is the first frequency conversion: oscillations generated by the local oscillator 39 are applied to the frequency converter 38. Thus, the intermediate frequency value supplied to the amplifier 40 lies in the range 10 -100 MHz. Bandwidth

amplifier 40 is sufficient to cover the entire emission spectrum of the ground-based aerodrome system. The local oscillator frequency 39 may be switched depending on the frequency RD assigned to the aerodrome at which the aircraft must

to land.

The signal from the intermediate frequency amplifier 40 is divided into a signal extraction unit 3 transmitted by a beacon and a rotating antenna extraction unit 4. Block 3 highlighting

The signals on the output of amplifier 40 contain a frequency converter 41, to another input of which oscillations generated by a local fixed-frequency local oscillator 42 that shifts the signals fed to the frequency converter 41 from amplifier 40 to the second intermediate frequency. The value of the second intermediate frequency may lie, for example, in the range of 100500 KHz, to the signal of this frequency is applied to

intermediate frequency amplifier 43. The beacon signal extraction unit 3 is designed to process reference signals with a carrier frequency Pd. Consequently, the width of the bandwidth of the amplifier 43 is approximately twice the highest reference frequency, namely fj, equal to 3200 Hz, increased by the maximum possible value of the Doppler effect. Thus, the bandwidth of amplifier 43 is about 9 kHz wide. The local oscillator 39 frequency is controlled by the signal of the second intermediate frequency using frequency discriminator 44. Fj is the average value of the tuning frequency of the amplifier 43, then F -RZ9- 42 Rd, where Рз9 and р42 are the frequencies of the local oscillators 39 and 42, respectively. The signal from amplifier 43 is subjected to amplitude detection by means of a valve 45, the signal from which is divided into three channels, each of which contains a pore 46, 47, .48. These filters are tuned respectively to the three frequencies emitted from the earth, the frequencies f., F2 and fa, in this case Yu, 160 and 3250 Hz. Their bandwidth is in the order of 1 Hz. They are connected downstream to phase correctors 49-51, which are intended for. compensation for phase delays introduced by filters 46-48, respectively. Thus, the phase correctors 49-51 remove the reference signals with the corresponding phase shift, which reliably reproduces the conditions of the aerodrome. The outputs of the phase correctors 49-51 are connected to the coincidence element 52, the output of which generates a pulse at the time of the coincidence of the fi-fs signals. Since the latter are used to control the rotation of the beacon, a pulse at the output of the coincidence element 50 occurs every time An antenna, the emission of which is received, passes a fixed direction, for example, geographical north. In addition, the outputs of the phase correctors 48-51 are associated with a frequency synthesizer 53, which, using the fi-fa reference frequencies, creates the spectral lines necessary for processing the measurement signals. Thus, the aircraft reproduces not only the reference frequencies fi-fs, but also the frequencies f4 - 4800 Hz, fs 6400 Hz, contained in the signals fed respectively to the antennas of the rotating beacon, as well as the frequency fft, which is the sum of the previous frequencies, and the signals of all these frequencies are not shifted in phase. The signal of the amplifier 40 is also supplied by the frequency converter 54 of the block 4 to the high signals of the rotating beacon. Vibrations generated by the local local oscillator 55 are supplied to its other entrance. This local oscillator has a tunable frequency and thus makes it possible, when approaching an aerodrome, to choose a landing strip to which the frequency FQ is assigned. If FS 5 is the local heterodyne frequency 55, and F42 is the local heterodyne 42 frequency, then the second one should be subtracted if the corresponding landing band corresponds to the frequency. The signal from the frequency converter 54 is fed to the intermediate frequency amplifier 56. With digital values chosen as an example, the bandwidth of amplifier 56 is about 16 KHz and centered on the average value between 100 and 500 KHz. If FO is the value chosen for the bandwidth center of amplifier 56, then FQ- is F39-F5, Fo, r-e is 4ac-f: 3 local heterodyne 55. corresponding to a positive final finjioce. Signal.p with amplification 4 and 56 is divided into three channels, which contain 57, 58 and 59. centrioBg; r on the feet, respectively F,, (p-S-f4) to (F, -bf5). From the spectrum; 1-beam rotating antenna received by samslet, filter 58 separates the signals of the frequency range centered on the F value transmitted by the unsupported central rotating antenna and received either after r; directing from the antenna to Ci: - .: olet LPGs after reflection from immobile LPK mobile obstacles. At 3TOh, signal signals are affected by the effect of the Dop1ere effect due to the displacement of reflective obstacles. Filter 57 vydg /: lr signals, lying in cyap. the frequency band, which is located on the value of FQ-f4 and the corresponding spectrum of the sequence created by the rotation, its antenna ,, nz.chu-ayugtsy at the frequency FQ-f4, and independent) -7m from whether these signals were passed on PL-million with one IL of several otkazhkk GLK from fixed or moving forces, and smnalyed sshnaly affected by the Doppler effect due to movement of the aircraft or moving reflective obstacle. The filter 59 selects setals lying in the frequency range centered on the Fo + fs value and corresponding to the spectrum of signals from the rotating antenna radiating at the Foi-fs frequency, either directly or after reflection and also subjected to the Doppler effect. In mixer 60, the signals from filters 57 and 53 are multiplied. With the mixer 60, a signal is picked up centered on the frequency fa. This information has been provided for by the insertion of one of the antennas of the rotating beacon. This information does not depend on whether the path is direct or with reflection and is affected by any Doppler effect. Similarly, the multiplication of signals from filters 58 and 59 in mixer 61 provides for the selection of information f 5 due to the rotation of the other antenna of the rotating beacon. This information, which also does not depend on whether the path is direct or with reflections, is transmitted by fs signals. At the output of the mixer 62, multiplying the signals of the filters 57 59, a signal is formed, centered at the frequency (f4fs) f6 And 200 Hz and carrying information Hj ,. This additional information represents the information that would have been obtained if a third antenna was inserted into the rotating mother, rotating along a radius equal to the sum of the radii of the other two antennas and emitting signals at frequencies Fo + f4 + fs- But this information is received, not resorted to installing antenna with a large radius of rotation. The signals from mixers 60-62 are fed respectively to phase correctors 63-65, which compensate for the phase shift introduced by filtering, in particular, in amplifier 56. Signals from the phase correctors 63-65 combined with the frequency signal f4, fs, fe from synthesizer 53, they are used to select the desired information 4.5V. The f - V data is contained in the Si-Sj signals from the multipliers 12-14 with the frequency f, which is the frequency of the auxiliary LO. 6. S, -. u; t.4 - .. V J its -14 where P and Q j are the amplitudes corresponding to the i-th and j-th path m; circular frequency and phase angle of the auxiliary local oscillator 6; oTsf cjUg. circular frequencies corresponding to frequencies f4r fs and FQ; i are the distances traveled by the energy of it by the ith and jth path, respectively; ii and the phases introduced by rotating the rotating beams of the antennas into the radiation signal of the corresponding antenna traveling along path 1; C is the speed of light. 38 2.ftR -cos0C09 (Slt-e), where R is the distance from the rotating antenna to the center of rotation; 5i is the angular velocity of rotation of the rotating beacon; L is the wavelength corresponding to the frequency F; i - time; φ is the elevation angle of the aircraft relative to the plane of rotation of the antenna of the rotating head; 0 - azimuth or bearing. The signals Si, 82 and 83 and the reference signal with the frequency f of the auxiliary local oscillator 6 are fed to the optical correlator 5. Here, the light-modulating disk 17 on the shaft 16 of the controlled engine 15 has a central zone 66, an annular intermediate zone 67 and a peripheral annular zone 68. Diameter 69 The disk 17 delimits the central zone 66 into an opaque and transparent semicircle. In annular intermediate zone 67, diameter 69 is the boundary of the opaque sector adjacent to the opaque semicircle of central zone 66 and having an angle of 23 ° 30, with annular alternating opaque and transparent sectors in the annular intermediate zone 67. The arrangement of opaque and transparent sectors in the peripheral annular zone 68 is analogous, but their number is three hundred and twenty. One side of the light modulating disk 17 is illuminated by a beam of parallel rays created by a lens 70 from a constant light source 23 installed at its focus. On the other side of the disk, there are three sensors 71, 72, 73 of the photodetector 26, respectively located opposite the central zone 66 of the annular intermediate zone 67 n and the peripheral annular zone 68 and having sufficiently small angular fields of view for this. So that each of them is affected by changes in the transparency of only the zone against which it is installed. Pulses are removed from the photodetector 26 when diameter 69 passes in front of the line connecting sensors 71, 72 and 73. These pulses are fed to the first input of the synchronized motor control unit 32 15, to the other input of which pulses are supplied Tacho 3, which correspond to the passage of a rotating antenna of the direction of geographic north. Thus, the motor J5 is controlled so that at any moment the movement of its shaft 16 is strictly synchronized with the movement of the rotating antenna, whose operation is controlled (UT signals of the reference frequency fi 10 Hz, f2 160 c and fa 3200 Hz, when the angular velocity of the rotating antenna is it is of the order of 10 revolutions per second The synchronization accuracy is 0.1 °. The light transmission function of the light-modulating disk 18 is modulated by a number of parallel lines that create a sinusoidal law of the amplitude of light transmission perpendicular to the direction of the signal due to transparency or fencing. If the disk is transparent, a photograph of interference fringes is made with the help of a laser creating plane waves. Thus, the law of transmission of G.ch V mc is obtained: v) V l o / where X is the value measured along the coordinate axis, perpendicular to the strokes; - value, measured on an axis parallel to the strokes; is the length of the spatial wave corresponding to the aforementioned transparency law; some initial phase. Thus, the law of transparency does not depend on y, i.e. it is the same on all straight lines perpendicular to the direction of the strokes. The source 24 of unmodulated light, mounted opposite one side of the light modulating disk 18, has a luminous intensity 3. On the other side of the disk, i.e. opposite the other surface, a sensor 74 of the photodetector is mounted 27. The angular field of view of this sensor is narrow; in principle, it is less than the value corresponding to half of the spatial wave on disk 18. Sensor 74 receives energy equal to the product of the light cycle 3 by the transparency law of disk 18 opposite it, which has the following form: T.CtV-t cos py coeCSlt-G - fo where p is the distance from sensor 74 to the axis of shaft 16; Gp is the angle between the axial plane containing the sensor 74 and the axial plane containing the reference direction. The parallel-stroke light-modulating disk 19 rotates at the same speed as the disks 17 and 18. The interference fringes obtained photographically on this disk are identical to the interference fringes of the disk 18, but are shifted along the x axis by a distance equal to a quarter of the length of the spatial wave. The transparency law of disc 19 is as follows: - cosCstt-eol. 310 A source of constant light 25 is installed opposite one of the surfaces of the disk 19, and against the other surface of the disk there is a sensor 75 of a photoelectric receiver 28 with a narrow field field located at the same distance from the axis of the shaft 16 as the sensor 74; the same axial plane passes through it. By eliminating the constant component from the photodetectors 27 and 28, sn27als are removed; p1 cos I-y-cosCsit-ei - JH cai-Qo n These signals are fed as modulating signals to two inputs of a single-pole amplitude modulator 76, to two others the input of which receives the reference signal + from the auxiliary local oscillator 6 and the reference signal sintojt + p from the phase shifter 77. Thus, the reference signal is removed from the modulator 76, the cos ("Jut -" - 4-fo-4QX-coscsit-e). This reference signal is fed to multipliers 78-80, to the other inputs of which, respectively, signals Si-8z are fed from multipliers 12-14. The signals from multipliers 78-80 are passed through filters 81-83, respectively, which exclude a harmonic of 2 w from them. The signals at the outputs of the filters 81-83 have the following form: s; % 1 e, .. - “i” it ° Vili45f V iV i5l functions denote phase differences due to the difference between the i-th and j-th paths of radio waves from two valid sources or from one real and one fictitious sources, or two fictitious sources; the actual source is one of the antennas of the rotating beacon, and the fictitious one is the source resulting from the reflection of the radiation energy of the actual source from the obstacle, which can be stationary or mobile, function “04 function corresponding to circular frequencies and Sd, function . g5 corresponds to the circular frequencies Oi and Lejg, the function corresponds to the circular frequencies CW and su.

Functions are linearly and quadratically time-varying functions when i differs from j. When the paths are spread. are the same, the function f is equal to zero.

The output from filter 81 is supplied to amplifier 84 of modulated light source 29, and the amplified current feeds electroluminescent diode 85, the luminous intensity of which is proportional to the intensity of the light of the thread and which creates uniform illumination in the working area. By including the gain control element 86, the signal at the output of amplifier 84 has a constant average amplitude value relative to the selected DC value, with the result that the full signal supplied to the electroluminescent diode 85 is never negative, and the DC component is close to to the amplitude value of the signal Sj. Light intensity of the modulated light source diode 85

CtHS Ct ttVS CtV

The average light intensity of the diode is 85.

Diode 85 is located opposite the light-modulating disk 20, the law of transparency of which

t ,, - isof - - cosCat-e -),

where the phase is relative to the origin;

R. - the distance from the point of the light-modulating disk 20 to the axis of the shaft 16 ;.

&. - polar angle Regarding the initial radius of the light-modulating disk 20;

 the length of the spatial wave corresponding to the law of transparency of the light-modulating disk 20 ..

The light passes through the disk 20 in the form of parallel rays created by the lens 87. The intensity of the light transmitted by this disk is the product of the values of i and T3.

The area of the disk 20, illuminated by a beam of pas (hollow rays emanating from lens 87, has an illumination corresponding to the signal from amplifier 84. The luminous energy that depends on phase modulation, which is a consequence of both the mutual movements of radio emission sources and the receiving device, and the modulation introduced into the receiver encounters, due to the rotation of the disk 20 with parallel strokes, a zone of constantly varying transparency, following a two-dimensional law, which takes into account the radius of the disk 20 and its rotational motion.

The similarity of the two-dimensional laws of change in the transparency of the disk 20 and the change in its illumination allows to establish a correlation between these two phenomena, namely, one phenomenon created by the light beam, and another phenomenon created by the rotation of the disk 20 with stripes or strokes. Practically, it follows from this that there exists at least one dotted or quasi-dotted area of the disk 20 through which the light rays constantly pass, which is not present in the other areas.

Thus, the disk 20, in conjunction with the modulated light source 29, plays the role of a modulator and at the same time a correlator.

The mirror 88 and the lenses 89 and 90 direct the light flux to the image addition unit 34 and further to the vidicon 35. In the time interval T, each surface element of the vidicon 35 defined by two coordinates accumulates energy. The integration time T of the vidicon 35 using the switch 91 can be 1 second or 0.1 second.

On the screen 92, images that are symmetrical about the center and corresponding to the optical correlation occurring at two diametrically opposite points — images for which

-co5 (a-t-e ,.

 VH,

Where

During the preliminary study, the maximum phase deviation of the phase modulation due to different positions of the aircraft relative to the aerodrome is determined, and then, taking into account the offset introduced by the value But, depending on the strokes on the disks 18-19, the length of the spatial wave D. is chosen for the pattern of strokes on disk 20 so that the latter creates an ensemble of modulations with a deviation sufficient to cover all possible values.

If the axis of the shaft 16 passes through the disk 20 in the central part of the stroke, whether it is transparent or opaque, two images appear on screen 92 due to the symmetry of the disk 20 relative to the axis of the shaft 16 and the conditions of light passing through for two diametrically opposite zones. By shifting the position of the axis of rotation of the disk 20 relative to the line drawing, one of these images is removed, i.e. no ambiguity is excluded.

The law of light transmission, determined by the length of the spatial wave of the disks 18 and 19, the angular position of the sources 24 and 25 of unmodulated light relative to the axial density of reference, the distance from the sources 24 and 25 of unmodulated light From the axis of the shaft 16 is chosen so that the image is formed on the screen 92 desired zone.

On screen 92, not only the images corresponding to the direct paths of the signals passing between the rotating antenna and the plane appear, but also the images corresponding to one or several reflections of these signals. Thus, the overall image is formed from bright points on the FLEXIBLE background of uniform intensity. One of the coordinates of each of the bright points can be directly transferred to the azimuth, while the distance of the others, from bright points to the origin (p 0), is such that

21 SCR; TTSRd.

where the radius of rotation of the antenna radiating at the frequency

Zfcc

and;"

F

elevation angle or elevation angle of the aircraft in the i-th image. Parasitic reflections, for which i d, disappear in the integrator with a constant integration time of 1 s.

Signals

S, is processed as the signals S ,, using modulated sources 30 and 31 of light and disks 21 and 22, the law of transparency of which is the same as the law of transparency of disk 20, but with the length of the spatial wave L, and AZ, respectively.

Although the receiver can operate on the same 5 |, S, or Sj signal, it functions better when processing several, in this example, three signals, at which apodization is introduced and secondary responses are reduced around the central bright point.

The optimum weight distribution of the three light beams is achieved due to the light transmission of the semitransparent mirrors 93 and 94 of the image addition block 34.

To eliminate the constant component of the signal applied to the screen 92, the background regulator 95 serves.

To eliminate the effects of non-linear scanning, which would cause distortion during image reproduction, mask 96 optically or electronically superimposed on azimuth and elevation values is optically or electronically superimposed on the photosensitive surface of the vidicon 35.

With the help of the target position generation unit 97 and the comparison unit 98, the target values of the azimuth and elevation of the aircraft are compared with the current values. Mismatch signals from comparing node 98 are provided to autopilot.

Claims (2)

1. Receiver of the aircraft navigation system using radio signals of poppies, comprising an antenna with a receiving-amplifier path, to the output of which a separate signal unit transmitted by the beacon and a rotating antenna signal separation unit are connected, in order to improve the positioning accuracy of an aircraft by simultaneously determining two angular coordinates and eliminating parasitic modulation errors caused by multipath propagation of signals. A solid correlator, an auxiliary local oscillator, and two groups of multipliers; the first inputs of the first group of multipliers are connected to the corresponding outputs of the beacon extraction unit, the second inputs are connected to the first output of the auxiliary heterodyne, and their outputs are connected to the first inputs of the corresponding multipliers the second group, the second inputs of which are connected to the corresponding outputs of the rotating antenna signal extraction unit, the outputs of the multipliers of the second group and the second output of the auxiliary hetero d1sha connected to the inputs of the optical correlator. 2. The receiving device according to claim 1, characterized in that the otic correction. The torus contains a controlled motor, on the shaft of which there are mounted light-modulating disks, of which the first three disks are supplied with a source of unmodulated light and a photoreceiver, and the other three disks having variable transparency along one diameter and uniform transparency in the perpendicular direction are equipped with modulated light source, motor controlled synchronization unit, modulation unit, image addition unit, vidicon and display unit, with the first input of the control synchronization unit The connected motor is connected to the first photodetector, the second input is one of the inputs of the optical correlator, and the output is connected to. controlled motor, the outputs of the second and third photodetectors are connected to the corresponding inputs of the modulation unit, the remaining inputs of which are other inputs of the optical correlator, the outputs of the modulation unit are connected to the inputs of the corresponding modulated light sources, the optical input of the Vidicon is connected to the output 45709013/6 image addition block, vidicon inputSources of information, connected to the output of the display unit, taken into account during the examination which is connected to one of the modulation- .I. US Patent No. 3778831, cl. 343-106, Myh sources of light. Rep. 1973 (prototype).