DE102008028804A1 - Device for generating defined defective radio field for calibrating or testing navigation receiver for aircraft, has digital direct synthesis unit with mixer for generating test data set selected by digital data synthesis for sequences - Google Patents

Abstract

The device has a signal generator comprising a data storage (1) for storing a digital data set (Ti) for radio signal sequences. The sequences are defined over a movement path depending on a position of varying sequences and are received along a movement path of a navigation receiver by considering differential Doppler displacement by the receiver and by a noise object reflecting a radio signal. A digital direct synthesis unit (2) has a mixer (3) for generating the test data set selected by a digital data synthesis (DDS) for sequences and converting a radio field defining a carrier frequency. An independent claim is also included for a method for generating a defined defective radio field for calibration or testing a navigation receiver.

Description

The The invention relates to a device for generating defined disturbed Radio fields for the calibration or investigation of navigation receivers containing a signal generator for generating a parasitic effects Radio field.

The The invention further relates to a method for generating defined disturbed radio fields for calibration or Examination of navigation receivers.

The current navigation of aircraft is based next to the use of GNSS (satellite-based navigation) primarily on the reception of terrestrial radiated transmission signals with defined, location-dependent modulation contents. The The backbone of air traffic control is monitoring (Surveillance) of the airspace by aviation detection systems, which is based on the primary or secondary principle lies. In this case, either reflection echoes emitted electromagnetic Waves (primary radar) and the emissions from aboard the Aircraft of installed responders (transponders, Secondary radar) evaluated to the three-dimensional position to determine.

Especially Precision landing approach is the instrument loading system (ILS), currently the only system worldwide is used nationwide and approaches the Bad weather category III (CAT III) allowed. That for Replacement of the ILS designed microwave charging system (MLS) offers improved properties, but has a barely significant worldwide Number of installations at airports. Instrument charging systems (ILS and MLS) consist of two components, one of which is the horizontal angle deviation from the nominal path (here: approach baseline) and the other is the angular deviation of the nominal slip angle supplied by a spatially modulated signal. Further terrestrial navigation systems for route navigation are non-directional beacons (ADF principle) and the directional beacon VOR for angle determination and the DME (Distance Measurement Equipment) for distance determination. The military navigation system TACAN (Tactical Air Navigation) is a combination of distance measurement the DME principle and an azimuth component by angle-dependent Amplitude modulation.

In Similarly, navigation transceivers and navigation receivers known for land and water vehicles.

The Problem with receiving transmissions from the navigation and positioning systems is that the radio fields u. a. through multipath propagation electromagnetic waves may be disturbed and thus a demodulation of the payload sustainably impaired but this is mandatory for security reasons is.

For example must not signal the ILS during the precision landing approach by interfering with large reflecting surfaces be disturbed, as a result of the safe placement of the aircraft is endangered on the runway. Such reflective surfaces For example, by within or near the so-called ILS protection zones located objects in magnitude several wavelengths with good conductivity being represented. The problem is intensifying with rising Size of aircraft such. B. the Airbus A380, whose tail and in particular its height (25 m) under certain conditions a strong diversification of the ILS Localizers (horizontal guide component) triggers.

It There is therefore a need to use the navigation receiver Help to calibrate or disturbed radio fields to investigate and thus ensure that on reason detected by disturbing navigation errors detected and possibly even be compensated.

Under Navigation is hereafter the location, d. H. the finding a position in space, the guidance of a vehicle, as well including the combination of location and guidance the route calculation understood. The location can be an own location for Flight guidance or foreign location for monitoring through air traffic control (surveillance). Under navigation receiver are thus also understood below tracking receiver.

An example of a navigation receiver is the VOR / ILS Analyzer R & S EVS 300 the company Rohde & Schwarz. The testing of such a navigation receiver can be done, for example, with the signal generator SMT from Rohde & Schwarz, which in HG Titze: "VOR / ILS Testing with Signal Generator SMT", Application Note 1GPAN09E, Rohde & Schwarz, June 1994 is described.

S. Watier: New Way of ILS calibration using the availability of high precision digital receivers ", in 14th IFIS Proceedings, 12-16 June 2006, Toulouse, France, pages 168-170 describes a method for calibration of navigation receivers for instrument landing systems (ILS), in which different components of the global error are separated in instrument landing systems by synchronization of raw data and filtered data.

to Calibration and inspection of navigation receivers are the useful signal information contained, undisturbed Sollfunkfelder generated with a first generator and with help a second signal generator generated interference signals Information containing radio field superimposed. With that you can but only static interferers and noise are simulated and in fed to the receiver. By reflections occurring Doppler effects, but also from the geometric condition dependent, can not be simulated.

DE 42 35 915 A1 discloses a device for generating a multipath interference-simulating test signal for the testing of radio receivers. A digitized test signal is defined delayed and summed at a predetermined level with the instantaneous high frequency signal. Thus, multipath interference can be simulated by adjusting the time delay and the amplitude of the echo signal.

WO 01/06684 A1 describes a test apparatus for high-frequency receiver with a signal generator and for generating a test signal and at the superimposition unit for modifying the test signal.

US 5,862,455 describes a heterodyne simulator for generating multipath superimposed signals by splitting an input signal into two phases with quadrature phase relationships to each other. The signals are influenced by attenuation and delay elements and combined to form an output signal.

US 4,977,607 describes a method for generating a short information signal-modulated radio signal which is disturbed by a predetermined static cross-fading signal for testing radio receivers. A short sequence of digital phase and amplitude values, which correspond to the message modulation, from the trajectory of the receiving location and in particular from the geometrical contexts that change during the movement, is arithmetically processed by a predefined cross-fade profile and the result is stored. A radio frequency carrier is modulated with the stored values to produce a test signal for the radio frequency receiver.

Also the US 6,061,394 A describes such a process independent of the trajectory.

In Combination with different message signals thus become different static overlay profiles in the form of phase and Amplitude values are generated and stored separately to access a carrier signal to be modulated.

task It is therefore an improved device of the present invention for generating defined radio fields for the calibration or examination of navigation receivers taking into account dynamic disturbances, which are dependent on a movement that is for testing the time-critical recipient properties a period of time of a few seconds or minutes.

The Task is characterized by the device of the type mentioned by solved that the signal generator a data memory for Storage of digital test records for Has radio signal sequences, each along a movement path a moving navigation receiver under consideration of useful signal information and disturbing influences including location-dependent differential Doppler shifts by the moving navigation receiver and by at least one in the vicinity of the movement path located, radio signals reflective interfering object to receiving, location-dependent via the movement path define varying radio signal sequence. A digital direct synthesis unit with a mixer is to generate one by means of digital direct synthesis selected test data sets for radio signal sequences and conversion to a carrier frequency to produce a defined disturbed radio field provided.

In contrast to the simple method of superimposing interference on a useful field-containing radio field, which are generated by means of a separate signal generator, according to the teaching of the present invention, a digital direct synthesis of digital test data sets already having an overlay of Represent useful and interference signals and define an associated path of motion varying radio signal sequences. The disturbing effects are therefore no longer limited to periodic interference signals or static Doppler effects. Rather, user-signal-dependent interference effects, such as Doppler effects that are dependent on interfering objects and a motion path, can be included in the test data sequence.

The For example, digital test records can in real operation z. B. in a landing approach measured radio signals be with known disturbing influences.

Out a set of different stored digital test records Depending on the calibration or examination task a suitable Test record selected and defined to create one disturbed radio field are used.

On this way can be caused by multipath propagation dynamic disturbances and, such. B. in Gleichkanalsystemen (Secondary radar) overlays by uncoordinated Emission of other aircraft for calibration in the laboratory simulated become. By reproducing real radio field environments with help The digital test datasets can be artifacts and quasi-random results of leadership in Avoid navigation receivers. Only through the use by changing itself defined along a movement path Radio signal can be a meaningful investigation and Perform calibration of navigation receivers.

The Radio signal sequences may be bandpass signals from interference fields according to specific geometric conditions define. A specific geometrical condition can be, for example be determined by an airplane, on a landing path an airport approaches, with landing localized interference due to interference due to reflections on wings, for example other aircraft arise.

The digital direct synthesis device preferably has a digital-to-analog converter for converting a sequence of stored amplitude values of a by a test data set defined radio data sequence in an analog Signal and a mixing unit with frequency limiting filters and a mixer for converting the filtered analog signal a carrier frequency. The converted analog signal is thereby preferably low-pass filtered and in a mixer to a carrier frequency modulates and then passes to bandpass filtering for feeding into the navigation receiver to be examined.

• - Auswählen eines digitalen Testdatensatzes für Funksignalsequenzen, entlang eines Bewegungspfades eines sich bewegenden Navigationsempfängers unter Berücksichtigung von Nutzsignalinformationen und Störeinflüssen einschließlich von ortsabhängigen differentiellen Dopplerverschiebungen durch den sich bewegenden Navigationsempfänger und mindestens ein sich in der Umgebung des Bewegungspfades befindlichen Funksignale reflektierenden Störobjekt zu empfangende, über den Bewegungspfad ortsabhängige variierende Funksignalsequenz für ein definiert gestörtes Funkfeld definiert, aus einem Satz vordefinierter, abgespeicherter Testdatensätzen;
• – Generieren einer analogen Funksignalsequenz durch digitale Direktsynthese und Digital-Analog-Wandlung des ausgewählten digitalen Testdatensatzes;
• – Modulieren der analogen Funksignalsequenz auf eine, um ein Trägerfrequenzsignal zu erhalten Trägerfrequenz; und
• – Einspeisen der auf die Trägerfrequenz modulierten Funksignalsequenz als definiert gestörte Funkfeldumgebung in den Navigationsempfänger.

It is also an object of the present invention to provide an improved method for generating defined controlled radio fields for the calibration or investigation of navigation receivers. The problem is solved by the method mentioned by

• Selecting a digital test data record for radio signal sequences, along a movement path of a moving navigation receiver, taking into account payload information and disturbing influences including location-dependent Doppler shift by the moving navigation receiver and at least one radio object reflecting in the vicinity of the travel path, via the movement path location-dependent varying radio signal sequence for a defined disturbed radio field defined from a set of predefined, stored test data records;
• Generating an analog radio signal sequence by digital direct synthesis and digital-to-analog conversion of the selected digital test data set;
• Modulating the analog radio signal sequence to a carrier frequency to obtain a carrier frequency signal; and
• - Feeding the carrier frequency modulated radio signal sequence as a defined disturbed radio field environment in the navigation receiver.

The Test data sets are preferably by simulation or Measuring characteristic disturbed radio field sequences won at the receiving location of a navigation receiver and stored. The radio field sequences contain besides navigation information on geometrical conditions, such as interference, based disturbing effects.

advantageous Embodiments are in the subclaims described.

The The invention will be described below with reference to the accompanying drawings exemplified in more detail. Show it:

1 Block diagram of a device for generating defined radio fields;

2 - Sketch of a plan view of a runway with interference of a radio field by reflection on a plane waiting next to the runway.

1 has a block diagram of a device for generating defined disturbed detect radio fields for the calibration or investigation of navigation receivers.

In a database 1 is a variety of digital test data sets T ₁ , T ₂ , ..., T _i stored. This test data sets T _i define radio signal sequences, which in addition to payload information and interference. The test data sets T ₂ define the radio signal sequences that serve to generate a bandpass signal in the interference field according to geometric conditions. With the help of the test datasets it is possible to simulate real defined disturbed radio fields taking into account dynamic signal changes. The test scenarios are identically repeatable with the aid of the stored test data sets T _i and thus permit a calibration and investigation of navigation receivers in the laboratory.

After selecting a test data set T _i , the digital data is converted into an analog signal by means of digital direct synthesis and digital-to-analog conversion. This is a digital direct synthesis device 2 with a digital direct synthesis unit DDS, a digital-to-analog converter DAC and a mixer 3 intended. In the mixer 3 the analog signal is mixed to a carrier frequency that is connected to a local oscillator 4 is produced.

Before that, the analogue intermediate frequency (bandpass) signal becomes low-pass 5 limited in bandwidth upwards. A dedicated bandpass filter is not yet required, because below the intermediate frequency level no spectral components outside the nominal bandwidth arise. The signal converted to the carrier frequency is mixed with one, the mixer 3 downstream bandpass filter 6 bandpass filtered and then passes to feed via a cable or antenna 7 in a navigation receiver for calibration or examination.

With the aid of the digital test data sets T _i , it is thus possible to examine and calibrate the time-critical parameters of navigation receivers. Disturbed radio fields are thereby generated with the aid of the test data sets T _i , which contain disturbance effect sequences in addition to the useful signal information. The parasitic effects are not limited to periodic noise, but may contain interference phenomena in consideration of geometric conditions.

The 2 shows an example scenario as a top view of a runway. From a position x _LLZ , an instrument landing system (ILS) radio field (here: localizer) is emitted in the direction of a first aircraft F ₁ moving at a constant speed v along the runway over the path x (t). A part of the radio signal is reflected by an adjacent to the runway and inclined aircraft F ₂ , for example of the type Airbus A380, which has an extremely high tail. During the movement occurs interference of the directly received radio signal and the reflected radio signal, which has due to the different relative movement no static, but only dynamic components that can be described with the Doppler effect.

mit f₀ = 110.7 MHz als ILS-Trägerfrequenz und der Lichtgeschwindigkeit c₀ sowie der Geschwindigkeit v des ersten Flugzeugs F₁ beschrieben.During the movement, the Doppler shift in the direction of the reflecting aircraft F ₂ decreases due to its lateral distance y _r . The difference of the Doppler shift against the transmit antenna x _LLZ is given by the equation:

with f ₀ = 110.7 MHz as ILS carrier frequency and the speed of light c ₀ and the speed v of the first aircraft F ₁ described.

The path x (t) is determined by the initial distance x ₀ from the reflecting object F ₂ , the distance x _{r of} the first and second aircraft F ₁ and F ₂ in the x-direction, the speed r of the first aircraft F ₁ and the time t after the equation x (t) = x 0 - v · t - x r ,

Assuming an intermediate frequency f _IF is the angular frequency ω r (t) = 2π · f IF + 2π × Δf (t).

Hierbei ist Ψ_r die anfängliche Phase.Since the instantaneous frequency is time-varying, the instantaneous phase is obtained by the integral as follows:

Here Ψ _{r is} the initial phase.

The complete amplitude modulated signal over time is the superposition of the direct signal (index d) and the reflected fraction (index r): y (t) = s d (T) * cos (φ d (t)) + s r (T) * cos (φ r (T)), where s (t) describes the modulation. When moving along the approach baseline, the modulation content of an ILS localizer is given by the equation: s d (i) = 1 + 0.2 * (sin (3Ω · t) + sin (5Ω · t)) given with Ω = 2π x 30 Hz.

ergibt.In the sketched arrangement, the reflected component produces a difference of the modulation degrees ddm _r of 0.328, so that, taking into account the ILS sum modulation degree SDM of 0.4 (localizer) and a course of the reflection coefficient a _r (t) to be defined, the equation:

results.

For the radio signal sequence y (t) a test data record is stored, with the by direct digital synthesis a corresponding radio signal can be generated. The test data set contains the Amplitude of a signal representing a given time digital values. Form a field of data in a data store then a table of amplitudes with through the position in the table implied times. Each for the radio signal sequence y (t) required waveform can be generated by alternating the data become.

On this way can define disturbed radio fields be set with the help of test records that are realistic are and can be reproduced repeatedly.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4235915 A1 [0013]
• WO 01/06684 A1 [0014]
• US 5862455 [0015]
• US 4977607 [0016]
• - US 6061394 A [0017]

Cited non-patent literature

• - EVS 300 [0010]
• - HG Titze: "VOR / ILS Testing with Signal Generator SMT", Application Note 1GPAN09E, Rohde & Schwarz, June 1994 [0010]
• - Watier: New way of ILS calibration using the availability of high precision digital receivers ", in 14th IFIS Proceedings, 12-16 June 2006, Toulouse, France, pages 168 to 170 [0011]

Claims (5)

Device for generating defined radio fields for the calibration or investigation of navigation receivers with a signal generator for generating a radio field containing interference signals generated by the signal generator, characterized in that the signal generator stores a data memory ( 1 ) for storing radio signal sequence digital test data sets (T _i ), each along a motion path of a moving navigation receiver, taking into account payload information and disturbances including location dependent Doppler differential shifts by the moving navigation receiver and at least one located in the vicinity of the motion path , Radio signals reflecting the interfering object to define, via the path of travel location-dependent varying radio signal sequence define, and a digital direct synthesis unit ( 2 , DDS) with a mixer ( 3 ) for generating a selected by digital direct synthesis (DDS) test data sets (T _i ) for radio signal sequences and implementation on a carrier frequency defined disturbed radio field. Device according to claim 1, characterized that the radio signal sequences by bandpass signals of the interference fields according to specified geometrical conditions being represented. Device according to claim 1 or 2, characterized in that the digital direct synthesis device ( 2 , DDS) a digital-to-analog converter (DAC) for converting a sequence of stored digital amplitude values of a bandpass signal into an analog signal and a frequency-limiting filter ( 5 . 6 ) with a mixer ( 3 ) for converting the filtered analog signal to a carrier frequency predetermined by the navigation receiver. Process for generating defined disturbed Radio fields for the calibration and analysis of navigation receivers, marked by - Selecting a digital Test data set for radio signal sequences, each one along a moving path of a moving navigation receiver taking into account payload information and Interference, including location-dependent differential Doppler shifts through the moving Navigation receiver and at least one in the environment the motion path located radio signals reflecting disturbing object to be received, location-dependent over the movement path define a varying radio signal sequence, from a set of predefined, stored test records; - To generate an analog radio signal sequence by digital direct synthesis and Digital-to-analog conversion of the selected digital test data set; - Modulate the generated analog radio signal sequence to a carrier frequency, to obtain a carrier frequency signal; and - Feed the carrier frequency signal as defined disturbed Radio field environment in the navigation receiver. Method according to claim 4, characterized by simulating or measuring characteristic disturbed radio field sequences at the receiving location of a navigation receiver, next to a Navigation useful information based on geometric conditions Interference effects, in particular interference, and Storing the simulated or measured radio field sequences as digital test records.