DE102013109439B3 - A method, apparatus, system and computer program for providing a common received signal to a plurality of receivable transmitters - Google Patents

Abstract

Embodiments relate to a device (100) for providing a common received signal (120) for a plurality of receivable transmitters (140a-140c), based on a plurality of received signals (110a-110d), each of the signal components of at least one transmitter of the plurality of transmitters. The device (100) comprises a position finder (102) which is designed to use the plurality of received signals (110a-110d) to determine position information (112a-112c) for each transmitter for at least a subset of the receivable transmitters, the Position information contains information about a position of the respective transmitter. A grouper (104) is designed to determine at least one group position (114) for at least one first transmitter (140a) and a second transmitter (140b) of the subset, the group position (114) being related to the position of the first transmitter (140a) and the second transmitter (140b) corresponds. A signal generator (106) is designed to determine a directional common group signal (116) for the first transmitter (140a) and the second transmitter (140b) using the group position (114) and the plurality of received signals (110a-110d) and using the position information (112c) of the third transmitter (140c) and the plurality of received signals (110a-110d) to determine a directional received signal (118) for the third transmitter (140c). A signal combiner (108) is designed to combine the group signal (116) and the directional received signal (118) in order to provide the common received signal (120).

Description

Embodiments are concerned with a method and apparatus for providing a common receive signal to a plurality of receivable transmitters based on a plurality of received signals each having signal components of at least one transmitter of the plurality of transmitters.

Applications in which the signal received from a plurality of spatially separated transmitters is evaluated together are numerous. For example, in satellite navigation systems, the signals emitted by the transmitters of the individual satellites are received and evaluated together. In order to enable a position determination, it is necessary to extract from the received signal the components of the individual satellites or of the individual transmitters and to analyze the signal components of the respective satellites for position determination separately of one another.

Such systems are also referred to below as Global Navigation Satellite Systems (GNSS). Due to the low power levels of GNSS signals on the earth's surface (about -130 dBm) and the large distance between satellite and receiver, the reception of the satellite signals can easily be disturbed. Disturbances can be caused, for example, by objects in the direct line of sight between satellite and receiver. This can lead to additional attenuation in the transmission, which may make the GNSS receiver difficult or even impossible to detect the satellite signals. Similar effects can also be achieved by deliberate noise / radio frequency noise emitted in the same frequency range as the GNSS signals. This can severely disturb the reception and possibly prevent positioning. There are various approaches to minimize the influence of these interfering signals. One possibility of interference suppression is based on the use of variable antenna multiple antenna systems ("Controlled Radiation Pattern" or CRPA antennas). Among other things, already existing receivers or GNSS receivers can be retrofitted by a ballast in conjunction with a CRPA antenna and corresponding interference suppression. The connection between ballast and GNSS receiver can take place via the radio frequency (RF interface) of the GNSS receiver.

By means of a CRPA antenna and by weighting the input data with corresponding filter coefficients, it is possible, for example, to generate spatial zeros in the direction of the interference signals. This procedure is also referred to as zero steering. The zero steering minimizes the influence of interfering signals. It is also possible to use filters, for example the implementation of an FIR filter for the suppression of narrow-band interference signals. The filtering of the FIR filter takes place in the time domain and not in the spatial domain as with a CRPA antenna. Due to the size limitation and the resulting low number of elements of a CRPA antenna, it may not be possible to form an arbitrary number of spatial zeros. Sometimes spatial and temporal filtering are combined. This is also known as space-time filtering or space-time adaptive processing (STAP). In this approach, usually only a single noise-reduced output signal is generated for all satellites. This processing technique exploits the properties of a CRPA antenna for zeroing.

Another useful feature of CRPA antennas is the ability to pan the antenna pattern maximum into any spatial direction ("beamsteering"). By the beamsteering, for a previously determined spatial direction, e.g. the direction of a GNSS satellite, using the CRPA antenna to make a profit. This improves the usable signal level or the signal-to-noise ratio (SNR) for the set viewing direction. The additional gain makes it possible to detect even very weak satellite signals despite poor reception conditions and to use them in the calculation of the navigation solution (i.e., position, speed, and time).

When using the Beamsteering method for generating a common received signal for a receiver of a satellite navigation system, for example in a ballast for retrofitting an existing receiver, the individual beamsteering signals of the satellites are reunited. However, this addition significantly decreases the noise power ratio (SNR) of each individual satellite since the noise component is uncorrelated and each doubling of the beamsteering signals to be added reduces the SNR values of the signal components of the individual satellites in the output signal by approximately 3 dB.

US patent application 2005/0228841 relates to electrical and electronic systems and methods. In particular, the document relates to systems and methods for processing GPS signals and other signals.

US patent application 2002/169578 relates to a GPS receiver which can determine its position even under disturbed reception conditions by using an antenna array with a new signal processing system. The assistive signal processing system includes a blind adaptive nulling processor to allow the receiver to work with a noise canceling signal.

There is thus a need to generate a common received signal for a plurality of receivable transmitters with improved characteristics.

Embodiments make this possible by first determining at least for at least one first transmitter and one second transmitter, in the method for providing a common received signal for a plurality of receivable transmitters, a common group signal which is combined with further directed received signals in order to obtain a common received signal with improved reception To provide characteristics. Embodiments of the method in this case use a plurality of received signals which each have signal components of at least one transmitter of a plurality of transmitters. In particular, for at least the first and second transmitters, a common group position is initially determined which corresponds to the position of the first transmitter and the second transmitter and which in turn is determined by a comparison of position information containing information about a position of the respectively assigned transmitter ,

That in other words, according to the embodiments, a grouping of the transmitters based on the particular position of each individual transmitter is first performed. As far as the individual transmitters are spatially adjacent, they can be represented by a common group signal, due to the spatial proximity of the transmitter to each other, a signal component of each transmitter can be present within the group signal generated for example by means of beamsteering with a high signal-to-noise ratio. Compared with approaches in which for each individual transmitter initially a separate directional received signal is generated by means of beamsteering, which is then combined with the other directional received signals, by determining a group position for a plurality of transmitters, the number of signals to be combined can be reduced. which is required to generate a common received signal. This reduces the number of incoherently adding noise signals and thus increases the signal-to-noise ratio of the signal components of the signals of the individual transmitters in the common received signal.

In other words, this may possibly provide a common received signal, which is improved in terms of the signal-to-noise characteristic of the signal components of the individual transmitters.

In addition, according to some embodiments, the signal component of the first transmitter, the second transmitter and the third transmitter is determined in the common received signal. This can make it possible to adapt the signal components of the individual transmitters during the combination or generation of the common received signal to the needs of a receiver, by means of which the common received signal is further processed. In particular, this may possibly achieve that in the common received signal each transmitter has approximately a signal component with identical signal-to-noise ratio, even if signals from individual transmitters are received at significantly lower levels than those of other transmitters. In other words, in the combination of a group signal and a directional received signal, for example, the directional received signal can be weighted less if the signal component of the third transmitter associated with the directional received signal is higher in the common received signal than if the signal component of the third transmitter in the common received signal is lower.

According to some embodiments, an apparatus for providing a common receive signal is used to provide a common receive signal for a receiver of a satellite-based location system. That is, the generated common reception signal is suitable or intended to be used by a receiver of a satellite navigation system. This can be achieved, for example, by providing a representation of the common received signal as an analog signal such that it is directly connected to a signal input of a conventional signal Receiver can be created for a satellite navigation system. For example, a common received signal generated in the intermediate band can be modulated or mixed by means of a mixer to a carrier frequency which corresponds to the carrier frequency of a satellite navigation system. According to some embodiments, such a device is thus used as a ballast for a conventional satellite receiver to improve the positioning accuracy or the receiving power of the receiver by means of the ballast. In order to efficiently enable the signal processing for generating the common received signal, it is performed in the digital domain according to some embodiments. Some embodiments, therefore, include one or more analog-to-digital converters or A / D converters to transfer an analog representation of the plurality of received signals that may be provided by a multiple antenna system into the digital domain. In order to be able to be used as a ballast, some exemplary embodiments additionally have a digital-to-analog converter in order to transfer the common received signal into the analog domain so that it can be used directly by a conventional receiver.

Embodiments are explained below with reference to the accompanying figures. Show it:

1a an embodiment of an apparatus for providing a common received signal;

1b an illustration of an arrangement of several transmitters;

2 a further embodiment of an apparatus for providing a reception signal within a ballast for a satellite navigation system;

3 a possible implementation for a part of a grouper for determining a group position for at least a first and a second transmitter;

4 an example of a signal combiner of the ballast of 2 ;

5 a flowchart of an embodiment of a method for providing a common received signal; and

6 a flowchart of a possible implementation of generating one or more group positions, each associated with multiple transmitters.

Various embodiments will now be described in more detail with reference to the accompanying drawings, in which some embodiments are illustrated. In the figures, the thickness dimensions of lines, layers and / or regions may be exaggerated for the sake of clarity.

In the following description of the attached figures, which show only some exemplary embodiments, like reference characters may designate the same or similar components. Further, summary reference numerals may be used for components and objects that occur multiple times in one embodiment or in a drawing but are described together in terms of one or more features. Components or objects which are described by the same or by the same reference numerals may be the same, but possibly also different, in terms of individual, several or all features, for example their dimensions, unless otherwise explicitly or implicitly stated in the description.

Although embodiments may be modified and changed in various ways, exemplary embodiments are illustrated in the figures as examples and will be described in detail herein. It should be understood, however, that it is not intended to limit embodiments to the particular forms disclosed, but that embodiments are intended to cover all functional and / or structural modifications, equivalents and alternatives that are within the scope of the invention. Like reference numerals designate like or similar elements throughout the description of the figures.

Note that an element referred to as being "connected" or "coupled" to another element may be directly connected or coupled to the other element, or intervening elements may be present. If an item is labeled as "directly connected" or "directly coupled "with another element, there are no intervening elements. Other terms used to describe the relationship between elements should be interpreted in a similar fashion (eg, "between" versus "directly in between,""adjacent" versus "directly adjacent," etc.).

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the embodiments. As used herein, the singular forms "a," "a," "an," and "the" are also meant to include the plural forms unless the context clearly indicates otherwise. Furthermore, it should be understood that the terms such as e.g. "Including," "including," "having," and / or "having," as used herein, indicates the presence of said features, integers, steps, operations, elements, and / or components, but the presence or addition of a resp one or more features, integers, steps, operations, elements, components, and / or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly assigned to one of ordinary skill in the art to which the embodiments pertain. Further, it should be understood that terms, e.g. those that are defined in commonly used dictionaries are to be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not to be interpreted in an idealized or overly formal sense, unless this is so is explicitly defined.

The 1a shows a block diagram of a device 100 for providing a common received signal for a plurality of receivable transmitters and the 1b an exemplary arrangement of multiple transmitters relative to a receiving antenna. The illustration of 1b Primarily serves the better understanding of the processes that the device of 1a performs and the two figures are therefore described together below.

The device 100 has a position finder 102 , a grouper 104 , a signal generator 106 and a signal combiner 108 on. The position finder 102 is designed to be using the received signals 110a to 110d determine a position information for each transmitter of at least a subset of the receivable transmitters, the position information containing information about a position of the respective transmitter. The operation of the device 100 will be exemplified based on the use of four received signals 110a to 110d discussed. It goes without saying that further embodiments can use any other number of received signals to a common received signal at its output 120 provide. For the sake of simplicity, let us first assume that the device processes the signals from three independent transmitters 140a - 140c , the respective signal components in the received signals 110a to 110d produce. The received signals 110a to 110d For example, four antennas of a multiple antenna system 150 or a CRPA antenna system.

The received signals can either be present directly in a digital representation or they can, as in the following example of the 2 can also be generated by means of an analog-to-digital converter of analog signals.

In the basis of 1 Simple case discussed by the position finder 102 a first position information 112a for a first transmitter 140a , a second position information 112b for a second transmitter 140b and third position information 112c for a third transmitter 140c certainly. The position information contains information about a position of the respective transmitter. In this case, the information about the position can be present in any desired manner or in arbitrary coordinate systems. For example, the position information may include an azimuth angle and an elevation angle, that is, indicate the position of the transmitter in the form of a direction. In other embodiments, the position information may also be given in absolute coordinates, for example in a Cartesian or a spherical coordinate system. Any other coordinate system may be used that allows for unambiguous assignment of a position of the transmitters, possibly relative to the position of a receiver.

The grouper 104 is trained to get the position information 112a to 112c to determine at least one group position for at least a first transmitter and a second transmitter of the subset which to the position 142 the first station 140a and the second transmitter 140b corresponds. That is, the grouper 104 generates, for example, using the first position information 112a and the second position information 112b a group position 114 that the first transmitter 140a and the second transmitter 140b is assigned together when the position information 112a the first station 140a and the position information 112b the second transmitter 140b fulfill a predetermined distance criterion. An example of a possible distance criterion is based on the examples of 2 to 4 shown in the following paragraphs.

For the discussion of how it works based on 1a Let's assume now, the third transmitter 140c be spatially separated from the first transmitter 140a and from the second transmitter 140b arranged. That is, a group position 114 will only be for the first station 140a and the second transmitter 140b determined, whereas the grouper 104 for the third station 140c unchanged the position information 112c to the signal generator 106 outputs. This is designed to work using the group position 114 and the plurality of received signals 110a to 110d a directed common group signal 116 for the first station 140a and the second transmitter 140b to determine. That is, the common group signal 116 contains signal components from both the first transmitter 140a as well as from the second transmitter 140b , For example, the group signal 116 by beamsteering, ie, by suitable adding or superposing of reception signals which are phase-shifted relative to one another 110a to 110d be generated. The signal generator 106 is further configured to use the position information 112c the third station 140c and the plurality of received signals 110a to 110d a directed received signal 118 for the third station 140c to determine. That is, the directional received signal 118 contains predominantly signal components of the third transmitter 140c , Also the directional received signal 118 for the third station 140c can in any way, for example by beamsteering from the received signals 110a to 110d be won.

The signal combiner 108 is formed, the group signal 116 and the directional received signal 118 combine to the common received signal 120 provide. At the in 1 shown simple embodiment of the signal combiner 108 a combination of only two noisy signals made. This leads to a signal-to-noise ratio (SNR) or a C / N ₀ ratio for the individual signal components which are assigned to the respective transmitters within the common received signal 120 can be better than a conventional approach in which three directional receive signals are formed and combined for each of the transmitters.

The signal combiner, for example, the common received signal by weighted summation or superposition of the group signal 116 and the directional received signal 118 produce.

According to some embodiments, when generating the common received signal 120 a weighting of the group signal 116 and the directional received signal 118 made such that the signal portion of the third transmitter 140c in the common received signal 120 has a signal-to-noise ratio that is the signal-to-noise ratio of the first transmitter 140a or the second transmitter 140b corresponds or corresponds to this. Corresponding in this context may mean, for example, that the signal-to-noise ratios of the mutually corresponding transmitter have a relative deviation that does not exceed a predetermined limit.

The following is a description of an embodiment of a ballast 200 , In 2 is a system block diagram of a ballast 200 which shows a noise-corrected high-frequency output signal 242 as a representation of a common receive signal 120 returns and the signal levels of the output signal 242 satellite signals.

An optional input stage 210 contains a group antenna 212 consisting of several individual antennas connected to a group antenna frontend 214 are connected. The with the group antenna 212 received GNSS signals are within the array antenna frontend 214 downsampled to baseband and sampled and quantized using analog-to-digital converters. The group antenna frontend 214 thus provides a multi-channel digitized signal 216 (corresponding to the number of antenna elements of the CRPA antenna 212 ). The digitized signal 216 is a baseband signal, so it is in baseband. The signal 216 is sent to a noise suppression module 218 and to a module for calculating the filter coefficients for noise suppression 220 forwarded. The in the module 220 calculated filter coefficients 222 be from the interference suppression module 218 used for interference suppression. The interference suppression module 218 For example, it may include an FIR filter.

The interference suppression module 218 provides a multi-channel noise-reduced signal (corresponding to the number of antenna elements of the CRPA antenna 212 ). This signal corresponds to the plurality of received signals 110 of the 1 , The majority of received signals 110 are sent to a Beamsteering module or to a signal generator 106 and to a cluster module or position finder 102 forwarded. The position finder 102 is in 3 described in more detail. The preprocessing in the position finder 102 provides position information 112 for each transmitter or satellite at least a subset of the receivable transmitters, for example direction information (azimuth and elevation angle) and optionally also C / N ₀ values of the satellite signals. C / N ₀ values indicate the ratio of the power of the carrier to the power of the noise and therefore, similar to SNR values indicating the ratio of the power of the signal to the power of the noise within a certain bandwidth, is a measure of the quality of the received signal. Both of these quantities, as used herein, thus describe a signal-to-noise ratio of the signal components of the respective transmitters in the received signal.

This information is sent to a clustering module or a grouper 104 and to a cluster weighting or signal combiner 108 to hand over. The grouper 104 calculated based on the position information 112 the coordinates of the cluster centers or group positions 114 and provides this information to the signal generator 106 and to the signal combiner 108 , The signal generator 106 uses the group positions 114 to calculate the required Beamsteering coefficients. These Beamsteering coefficients are in the signal generator 106 to control the antenna pattern of the CRPA antenna 212 or to combine the interference-reduced received signals 110 used. The signal generator 106 thus generates one of the number of group positions depending on the reception situation 114 corresponding number of cluster signals or group signals 116 and possibly also several directional received signals 118 , which can each correspond to a single transmitter or satellite. The signal combiner 108 is in 4 described in more detail.

The signal combiner 108 generated from the group signals 116 and the directional received signals 118 a single noise reduced and optimized with respect to the signal level of the satellite digital baseband signal, the common received signal 120 , The common received signal 120 is connected to a digital / analogue converter 230 forwarded, which generates an analog signal, so an analog representation 232 the common received signal 120 , This is from an RF up converter or from a mixer 240 mixed on a high frequency carrier and finally generates an analog high frequency signal 242 at a signal output 244 of the ballast. This can be forwarded directly to a conventional receiver for a satellite navigation system, which, as a result, can lead to an improved performance of the overall system without the receiver itself having to be changed.

The 3 shows a possible implementation of a position finder 102 , The position finder 102 contains several multi-channel tracking loops 301 . 302 and 303 , (The term "multichannel" refers to the number of CRPA antenna elements.) Each multichannel tracking loop 301 . 302 and 303 only tracks a specific satellite signal or the signal component of a single transmitter in the received signal, which consists of the multi-channel signal or of the plurality of received signals 110 is extracted. The multi-channel tracking loops 301 . 302 and 303 provide multichannel complex correlation values at the output 304 . 305 . 306 each consisting of an in-phase and a quadrature component (I / Q values). These are determined by correlations of the received signals with pseudorandom sequences (PRN codes) which are different but known for each transmitter or satellite.

For each channel of the multi-channel tracking loop 301 . 302 . 303 For example, these may be the I / Q values of the correlation to the sampling timings of the early, prompt, and late correlators, which are commonly used in GNSS receivers. Based on the complex correlation values 304 . 305 . 306 be in the modules 307 . 308 . 309 determines the directions of incidence of the respective satellite signal. The direction information is then used to estimate the signal levels to the modules 310 . 311 . 312 passed. The C / N ₀ estimator 310 . 311 . 312 In addition to directional information, they require the multichannel complex correlation values 304 . 305 . 306 , The results of the C / N ₀ estimation 316 . 317 . 318 can be optional along with the appropriate directional information 313 . 314 . 315 the position information 112 form.

The system block diagram in 4 shows an implementation of a signal combiner 108 with a control loop for the adaptive weighting of the group signals 116 , Hereinafter, those signals are also referred to as group signals, which may contain substantially signal components of a single satellite. The signal combiner 108 includes a module for calculating cluster weight coefficients 401 , This module determines the cluster weight coefficients 402 , These are based on the direction information 104 , the group positions 114 and on additional feedback values 409 , in the module 403 become the group signals 116 with cluster weight coefficients 402 multiplied. This provides the weighted group signals 404 , By adding the individual weighted group signals 404 will be in the module 405 a noise-reduced and optimized with respect to the signal level of the satellite digital sum signal as a common received signal 120 generated. The common received signal 120 is on the one hand to the D / A converter 230 and on the other of several single-channel tracking loops 406 (according to the number of satellites) used, based on the common received signal 120 more complex correlation values 407 to determine.

The other complex correlation values 407 are used for the calculation of C / N ₀ values 409 using the C / N ₀ estimator 408 needed. The C / N ₀ values 409 are then connected to the module 401 to calculate the cluster weight coefficients.

A description will now be given of a specific embodiment of the method and, in particular, the calculation of the cluster weight coefficients for improving the characteristics of the common received signal. This may be used, for example, in a noise suppression system as a ballast in conjunction with a CRPA antenna. An improvement in the signal levels of the satellites at the output of the ballast can be achieved by additionally swiveling the antenna diagram maximum of the CRPA antenna in the direction of the satellites after the interference suppression. This causes an increase of the SNR for the set viewing direction of the antenna. The antenna diagram describes the sensitivity of the antenna system depending on the direction from which a signal is received.

The control of the antenna viewing direction or of the antenna diagram is carried out for different directions in parallel, corresponding to the direction of incidence of the different satellite signals in the respective scenario. The beamsteering signals thus generated are then weighted and added to obtain a single output signal as a common receive signal. The determination and continuous optimization of the weighting coefficients is an optional advantageous feature. The system uses a group antenna (CRPA antenna) consisting of M individual antennas to receive the satellite signals and feed them to a group antenna front-end, which then mixes and digitizes the received data into baseband. Furthermore, the system contains a noise suppression module which generates an M-channel interference-reduced antenna output signal from the M-channel antenna input signal. One possible implementation may be, for example, M parallel space-time adaptive processing (STAP) filters, each providing a 1-channel output. The M-channel output of the noise suppression module forms the basis for the further signal processing steps. This includes initially determining the synchronization parameters (i.e., frequency Doppler and code phase) of the GNSS satellite signals in the acquisition phase and then tracking these two parameters in the tracking phase. Both the acquisition and tracking modules are based on the correlation between a locally generated PRN code in the receiver and the received antenna signal. The correlation occurs on the M-channel output signal for each channel individually. The correlation on the different channels is synchronized in time via a common clock. The M-channel complex correlation values form the basis for determining the direction of the respective GNSS satellite.

With the aid of a suitable method for determining the direction, the azimuth angle α and the elevation angle ε of the GNSS satellites in the local coordinate system of the antenna result therefrom, for example in the case of a planar CRPA antenna. Often, in the context of array antennas, an alternative (u, v) coordinate system is used. For the transformation between azimuth / elevation angles and (u, v) coordinates, the following applies: u = sin (α) cos (ε) v = cos (α) cos (ε).

mit w_i = Gewichtungskoeffizient für Satellit i, (x, y) = x- bzw. y-Koordinaten der Einzelelemente der Gruppenantenne und (u_i, v_i) = u- bzw. v-Koordinaten der Satellitenrichtung von Satellit i. With the azimuth and elevation angles or the associated (u, v) coordinates, for each individual antenna, the weighting coefficients for shaping the antenna pattern in the respective direction can be calculated as follows:

with w _i = weighting coefficient for satellite i, (x, y) = x- or y-coordinates of the individual elements of the array antenna and (u _i , v _i ) = u- or v-coordinates of the satellite direction of satellite i.

Based on the weighting coefficients wi, a separate directional received signal could be determined for each GNSS satellite. In this case, a separate beam steering signal would be generated for each coefficient vector: y _i = w H / i * x, with y _i = beamsteering signal for satellite i, x = interference-reduced multichannel input signal.

However, a direct summation of beaming signals generated in such a way for generating a common digital output signal would be disadvantageous since the noise power in the output signal increases with each addition of a further beam steeringsignal. The gain previously achieved by the antenna pattern formation would be largely lost by this addition.

Therefore, according to the embodiments, first the number of beam steering signals, i. reduces the number of satellite directions by the substitution of multiple beam steering signals by a single group signal.

For this purpose, at least one or more clusters or groups and their cluster centers or group positions are determined with the aid of a suitable clustering or grouping method from the previously determined spatial directions or positional information of all satellites. For clustering, the azimuth and elevation angles can be previously transformed into (u, v) coordinates.

Generally speaking, two transmitters are grouped together if the position information for the first transmitter and the second transmitter meet a predetermined distance criterion, that is, if they are close according to a suitable metric.

wobei Richtungskoordinaten u_c und v_c der Clusterposition und Richtungskoordinaten u_i und v_i dem ersten und dem zweiten Sender zugeordnet sind. For example, to decide which of the individual satellites or transmitters should belong to a common cluster or to a group, the following metric can be used:

wherein direction coordinates u _c and v _{c of} the cluster position and direction coordinates u _i and v _{i are} assigned to the first and the second transmitter.

Since the (u, v) -coordinates lie in the value range [-1, 1], the result for the given cluster metric t is a value range of [0, 1] (t = 0: low similarity or large distance, t = 1 identity or same position or direction relative to the antenna). Frequently, the number of cluster centers or groups assigned to individual groups will be smaller than the number of GNSS satellites in the field of view of the array antenna. The signals resulting from the groups are referred to below as group signals. New coefficient vectors for antenna pattern formation are calculated based on the (u, v) coordinates of the previously determined group positions. In order to minimize potentially annoying multipath effects from the other group signals during the addition, additional zeros at the (u, v) coordinates of the other cluster centers can be taken into account in the calculation of the coefficient vectors. These zeros could more effectively suppress the satellite signals from other clusters and minimize multipath effects.

Before generating the digital sum signal or the common received signal by adding the group signals, each individual group signal is additionally weighted by multiplication by a scalar: y _sum = Σ C / c = 1k _c y _c = Σ C / c = 1k _c w H / c x, with y _sum = common received signal, C = number of groups, k _c = weight for group c, y _c = group signal c, w _c = weighting coefficients for antenna pattern shaping and x = noise reduced multichannel input signal.

The weighting of the individual group signals can be carried out because the signal levels of the visible satellites can vary greatly in one scenario. Due to the different propagation conditions for a satellite in the zenith and a satellite on the horizon, in the case of a GNSS Receivers often signal level differences of 10-15 dB occur. In addition, the satellite signals can be differently affected or attenuated by the optional previous interference suppression, which in turn can lead to differences in the reception levels. The aim of weighting the group signals is to achieve the best possible signal level for all satellite signals at the output of the ballast in the respective scenario.

For example, a favorable signal level may be equivalent to an approximately identical signal level for all satellites. In order to achieve this goal (ie a nearly equal signal level for all satellites), a control loop can be used to set the scalar weight coefficients as described in US Pat 4 for an exemplary implementation. The setting of the cluster weight coefficients k _c is based mainly on the signal levels or the signal components of the satellite signals in the sum signal. The signal levels or the C / N ₀ values of the satellites are previously determined using a C / N ₀ estimator. On the basis of the determined C / N ₀ values, the cluster weight coefficients are then updated continuously, for example every millisecond. The cluster weights k _c can be initialized with one at the beginning. This corresponds to an equally weighted addition: k _c = 1 with c ε {1, ..., C}.

Subsequently, the cluster weights k _c can be continuously updated each time iteration as follows:

The weighting coefficients are thus readjusted at each iteration until the differences between the C / N ₀ values of the satellites in the output signal have theoretically dropped to zero. This is a continuous control process because the levels of the satellite signals in the scenario are constantly fluctuating and also the estimation of the C / N ₀ values may vary.

5 FIG. 12 shows a flowchart of one embodiment of a method of providing a common receive signal to a plurality of receivable transmitters based on a plurality of received signals each having signal components of at least one transmitter of the plurality of transmitters. The method includes determining 600 position information for each transmitter of at least a subset of the receivable transmitters using the received signals, wherein the position information includes information about a position of the respective transmitter.

The method further includes determining a group position 602 for at least a first transmitter and a second transmitter of the subset using the position information of the first transmitter and the second transmitter.

The method further includes determining a directional common group signal 604a for the first and second transmitters using the group position and the plurality of received signals and determining a directional received signal 604b for at least a third transmitter of the subset using the position information of the third transmitter and the plurality of received signals.

The method further comprises providing a common received signal 606 under combination of the group signal 116 and the directional received signal 118 ,

6 illustrated, also in the form of a flowchart, how based on the position information for each transmitter of the subset the assignment of the respective transmitter to a group or the definition of multiple groups and their respective associated group positions can be done.

In a test step 700 For the currently observed transmitter, it is checked whether the position information of the transmitter fulfills a predetermined distance criterion with respect to another transmitter or a group position. If this is the case, it is in an association step 702 the relevant station has been added to the group. If this is not the case, will be in a test step 704 checks if there are any more channels that have not yet been edited by the grouping algorithm. If this is not the case, the grouping procedure is ended. If this is the case, the step is 700 continued to try to group the next station.

Of course, other methods are conceivable how the individual transmitters or satellites can be combined into groups. In some cases it is also possible to proceed iteratively several times. For example, to predetermine a coarse group position, it can first be checked whether two of the transmitters are so close that they fulfill the distance criterion. Thereupon, based on the two grouped transmitters, a first improved group position can be determined, for example by averaging the two position information or positions of the two transmitters already added to the group, whereupon the distance criterion for the further transmitters can be applied to the provisional group position thus determined ,

Although discussed in the preceding paragraphs primarily in connection with a satellite navigation system, other embodiments may also be applied in other scenarios where multiple transmitters wirelessly transmit signals to a receiver which analyzes the various signal components in a common received signal.

In summary, some embodiments are concerned with a device for providing a noise-reduced GNSS signal to existing GNSS receivers, comprising: an array antenna (CRPA antenna) and a cluster antenna front-end for generating digital baseband signals; a noise suppression module linked to a cluster antenna front-end for generating noise reduced multi-channel antenna signals; a module for further processing of the interference-reduced antenna signals for a downstream clustering method; and a module for implementing a clustering method; a beam steering module for generating one or more group signals based on the noise reduced antenna signals and the results of the clustering method; a module for weighting and adding the group signals to generate a single noise-reduced signal; combined with a digital / analog converter and an RF up converter for generating an optimized and interference-reduced RF output signal for coupling into a GNSS receiver; and a module with a control loop for calculating the optimized cluster weight coefficients.

Further embodiments are concerned with a reduction in the number of beamsteering signals, comprising the steps of: performing the correlation with the PRN code of the desired satellite signal using a multi-channel tracking loop; Direction determination for each of the received satellite signals from the calculated correlation values; Determination of the C / N ₀ values based on the correlation values and the direction information (azimuth and elevation angles); Evaluation of the direction information of all receivable satellites and determination of one or more cluster centers; Formation of one or more group signals by pivoting the antenna diagram maximum in the direction of the respective cluster center point; Reduction of interfering multipath influences of adjacent group signals in the output signal by taking into account secondary conditions in the calculation of the weighting coefficients, ie additional zeroing in the direction of the corresponding or disturbing cluster signals.

Further embodiments are concerned with a method of adjusting the cluster weight coefficients to produce an output signal by weighted addition of the individual cluster signals, comprising: calculating the cluster weight coefficients based on the C / N ₀ values of the individual satellite signals; Calculation of the C / N ₀ values of the individual satellite signals on the basis of the interference-reduced multi-channel digital antenna signals; Calculation of the C / N ₀ values of the individual satellite signals based on the single-channel digital output signal; Implementation of an adaptive control loop for the calculation of the optimal cluster weight coefficients and summation of the weighted cluster signals.

Although some aspects have been described in the context of a device, it will be understood that these aspects also constitute a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.

Depending on particular implementation requirements, embodiments of the invention may be implemented in hardware or in software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-Ray Disc, a CD, a ROM, a PROM, an EPROM, an EEPROM or FLASH memory, a hard disk, or other magnetic disk or optical memory are stored on the electronically readable control signals, which can cooperate with a programmable hardware component or cooperate such that the respective method is performed.

A programmable hardware component may be integrated by a processor, a central processing unit (CPU), a graphics processing unit (GPU), a computer, a computer system, an application-specific integrated circuit (ASIC) Circuit (IC = Integrated Circuit), a system on chip (SOC) system, a programmable logic element or a field programmable gate array with a microprocessor (FPGA = Field Programmable Gate Array) may be formed.

The digital storage medium may therefore be machine or computer readable. Thus, some embodiments include a data carrier having electronically readable control signals capable of interacting with a programmable computer system or programmable hardware component such that one of the methods described herein is performed. One embodiment is thus a data carrier (or a digital storage medium or a computer readable medium) on which the program is recorded for performing any of the methods described herein.

In general, embodiments of the present invention may be implemented as a program, firmware, computer program, or computer program product having program code or data, the program code or data operative to perform one of the methods when the program resides on a processor or a computer programmable hardware component expires. The program code or the data can also be stored, for example, on a machine-readable carrier or data carrier. The program code or the data may be present, inter alia, as source code, machine code or bytecode as well as other intermediate code.

Another embodiment is further a data stream, a signal sequence, or a sequence of signals that represents the program for performing any of the methods described herein. The data stream, the signal sequence or the sequence of signals can be configured, for example, to be transferred via a data communication connection, for example via the Internet or another network. Embodiments are also data representing signal sequences that are suitable for transmission over a network or a data communication connection, the data representing the program.

For example, a program according to one embodiment may implement one of the methods during its execution by, for example, reading or writing one or more data into memory locations, optionally switching operations or other operations in transistor structures, amplifier structures, or other electrical, optical, magnetic or caused by another operating principle working components. Accordingly, by reading a memory location, data, values, sensor values or other information can be detected, determined or measured by a program. A program can therefore acquire, determine or measure quantities, values, measured variables and other information by reading from one or more storage locations, as well as effect, initiate or execute an action by writing to one or more storage locations and control other devices, machines and components ,

Claims (17)

A method for providing a common received signal ( 120 ) for a plurality of receivable transmitters ( 140a - 140c ) based on a plurality of received signals ( 110a - 110d ), each having signal components of at least one transmitter of the plurality of transmitters, comprising: for at least a subset of the receivable transmitters, determining position information ( 112a - 112c ) for each transmitter of the subset using the received signals ( 110a - 110d ), wherein the position information includes information about a position of the respective transmitter; determine at least one common group position ( 114 ) for at least one first transmitter ( 140a ) and a second transmitter ( 140b ) of the subset using the position information ( 112a . 112b ) of the first transmitter ( 140a ) and the second transmitter ( 140b ), whereby the group position ( 114 ) to the position of the first transmitter ( 140a ) and the second transmitter ( 140b ) corresponds; determine a directional common group signal ( 116 ) for the first transmitter ( 140a ) and the second transmitter ( 140b ) using the group position ( 114 ) and the plurality of received signals ( 110a - 110d ); determine a directional received signal ( 118 ) for at least one third transmitter ( 140c ) of the subset using the position information ( 112c ) of the third transmitter ( 114c ) and the plurality of received signals ( 110a - 110d ); and combine the group signal ( 116 ) and the directional received signal ( 118 ) to receive the common received signal ( 120 ). The method of claim 1, further comprising: determining a first signal portion of the first transmitter ( 140a ), a second signal portion of the second transmitter ( 140b ) and a third signal portion of the third transmitter ( 140c ) in the common received signal ( 120 ). Method according to claim 2, wherein in the combination of the group signal ( 116 ) and the directional received signal ( 118 ) the directional received signal ( 118 ) is weighted less if the signal portion of the third transmitter ( 140c ) is higher than if the signal component of the third transmitter ( 140c ) is lower. Method according to claim 3, wherein in the combination of the group signal ( 116 ) and the directional received signal ( 118 ) the directional received signal ( 118 ) with respect to the group signal ( 116 ) is weighted such that the signal portion of the third transmitter ( 140c ) in the common received signal ( 120 ) has a signal-to-noise ratio which corresponds to the signal-to-noise ratio of the first transmitter ( 140a ) or the second transmitter ( 140b ) corresponds. Method according to one of claims 1 to 4, wherein the provision of the common received signal ( 120 ) forming a weighted sum from the directional received signal ( 118 ) and the group signal ( 116 ). Method according to one of the preceding claims, wherein a group signal ( 116 ) for the first transmitter ( 140a ) and the second transmitter ( 140b ) is determined when the position information ( 112a . 112b ) for the first transmitter ( 140a ) and the second transmitter ( 140b ) satisfy a predetermined distance criterion. The method of claim 6, wherein the position information each comprises information about a receive direction and wherein the distance criterion is met when a first receive direction associated with the first transmitter and a second receive direction associated with the second transmitter are deviated from one another which is smaller than a predetermined limit. The method of claim 7, wherein the distance criterion is met when a metric t,

is greater than a predetermined limit, with direction coordinates u _c and v _{c of} the group position ( 114 ) and direction coordinates u _i and v _i the first transmitter ( 140a ) and the second transmitter ( 140b ) and wherein the direction coordinates are determined from their associated azimuth angles α and elevation angles ε as follows: u = sin (α) cos (ε) v = cos (α) cos (ε). Method according to one of claims 1 to 8, further comprising: providing a representation of the common received signal ( 120 ) as an analog signal ( 242 ). Contraption ( 100 ) for providing a common received signal ( 120 ) for a plurality of receivable transmitters ( 140a - 140c ) based on a plurality of received signals ( 110a - 110d ), each having signal components of at least one transmitter of the plurality of transmitters, comprising: a position finder ( 102 ) configured to use the plurality of received signals ( 110a - 110d ) for each transmitter at least a subset of the receivable transmitter position information ( 112a - 112c ), wherein the position information includes information about a position of the respective transmitter; a grouper ( 104 ), which is designed to be at least one group position ( 114 ) for at least one first transmitter ( 140a ) and a second transmitter ( 140b ) of the subset, the group position ( 114 ) to the position of the first transmitter ( 140a ) and the second transmitter ( 140b ) corresponds; a signal generator ( 106 ), which is designed to work using the group position ( 114 ) and the plurality of received signals ( 110a - 110d ) a directed common group signal ( 116 ) for the first transmitter ( 140a ) and the second transmitter ( 140b ) and using the position information ( 112c ) of the third transmitter ( 140c ) and the plurality of received signals ( 110a - 110d ) a directed received signal ( 118 ) for the third transmitter ( 140c ) to determine; and a signal combiner ( 108 ), which is designed to receive the group signal ( 116 ) and the directional received signal ( 118 ) to combine the common received signal ( 120 ). Contraption ( 100 ) according to claim 10, which is designed to generate a common received signal ( 120 ) for a receiver of a satellite positioning system. Contraption ( 100 ) according to claim 10 or 11, further comprising: a signal input, which is adapted to a representation of the plurality of received signals ( 110a - 110d ) to obtain; and a signal output ( 244 ), which is designed to be a representation ( 242 ) of the common received signal ( 120 ). Contraption ( 100 ) according to claim 12, further comprising: an analog-to-digital converter adapted to transfer the received at the signal input representation of the received signals from the analog domain into the digital domain to the plurality of received signals ( 110a - 110d ) to obtain; and a digital-to-analog converter ( 230 ), which is designed to receive the common received signal ( 120 ) to transfer from the digital domain to the analog domain to obtain an analog representation ( 232 ) of the common received signal output signal. Contraption ( 100 ) according to claim 13, further comprising: a mixer ( 240 ), which is adapted to the analog representation ( 232 ) of the common received signal ( 120 ) to a high-frequency carrier. A satellite-based location system, comprising: a device ( 100 ) according to any one of claims 10 to 14; and a receiver coupled to the device and configured to receive the common received signal ( 120 ) and based on the common received signal ( 120 ) to determine a position of the receiver. The satellite positioning system of claim 15, further comprising: a multiple antenna system ( 150 ; 212 ) for receiving the plurality of signals ( 110a - 110d ) connected to the signal input of the device ( 100 ) is coupled. A computer program comprising program code for performing a method according to any one of claims 1 to 9 when the method is run on a computer.

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