DE19801552A1 - Tracking system implementation - Google Patents

Abstract

The method involves evaluating signal carriers of reception signals in a first channel, for determining an optimal antenna characteristic. Inphase- and Quadrature components of reception- and/or transmission signals of associated antenna elements are formed for each overlap receiver and/or transmitter, and are weighed and superimposed in a second channel, in such way, that the directional characteristic of the antenna is thereby formed. The method involves implementing a tracking system consisting of an antenna group from two or several antenna elements or antenna subgroups, of respectively an overlap receiver and/or transmitter for each antenna element or antenna subgroup, and a signal evaluation circuit implemented in hard- and/or software. Both Inphase- and Quadrature component and/or amplitude and phase of reception- and/or transmission signals of the associated antenna element and/or antenna subgroup are formed in each overlap receiver and/or transmitter, and the Inphase- and Quadrature components of the output signals of the individual overlap receivers and/or transmitters are weighed and superimposed in such way, that the directional characteristic of the antenna group is thereby formed. The Inphase- and Quadrature components of the individual overlap receivers and/or transmitters are evaluated in a first and a second channel, whereby signal carriers of the reception signals are evaluated in the first channel for determining an optimal antenna characteristic, and the I/Q components and/or amplitudes and phases of the reception- and/or transmission signals are weighed and superimposed in the second channel, and are supplied to an evaluation.

Description

The problem is known that signals from moving transmitters with a relatively low transmission power poorly at a greater distance from receivers with a relatively constant, uniform Reception characteristics can be demodulated. For this purpose, antenna groups are often used used, with the help of which specific reception characteristics are formed and accordingly the Reception of the transmitters through increased gain and increased signal-to-noise ratio can be improved.

With moving transmitters, however, it is necessary to track the receiving lobes to the transmitters, what happens in conventional systems after demodulation. The Demodulation of the received signals is considered, and depending on the usability and quality of the Signals the club adjusted accordingly. Consequently, this leads to complex signal Decodings for slower and delayed tracking. To solve this problem fix, the carriers of the transmitter signals are temporally used to form the directional characteristic located parallel to the demodulation or decoding and spatially determined, and depending on Position of the transmitter shaped and updated the characteristics of the receiving antenna group.

The invention specified in claim 1 is based on the problem, the transmitter to receive and by gain shaping with higher gain and signal-to-noise ratio additionally their relative movement to the receiver by changing its directional characteristic to pursue. Due to the temporally parallel location of the transmission signals can be independent of Successful demodulation adapted the reception characteristics of the current transmitter position become.

This problem is solved by the features listed in claim 1.

The advantages achieved by the invention are in particular that with the help of a such digital beamforming system (DBF) with adaptive, swiveling antenna lobe both a higher sensitivity or range or lower transmission power same distance can be achieved, as well as one or more independently pivoting antenna lobes can be generated.

By separating the digitized useful signal into two paths, it becomes very fast Adaptation of the antenna characteristics to the spatial positions of the desired transmitters  enables. For this purpose, in a first path by locating the carrier (s) Position / positions of the transmitter determined and the results in weighting factors for the Changed the reception characteristics. These factors (parameters) are described in a second path multiplied by the digitized signal data, and then to Generation of the overall characteristics added. To the entire information (amount and Phase) from the analog to the digital part of the signal processing will both the in-phase as well as the quadrature component of the signal is generated and used.

An embodiment of the ending is given in claims 2 to 4.

Such a system can generally be used for very flexible stationary, mobile and directional Radio transmission links (e.g. mobile radio in vehicles with low transmission power, autonomous base stations) can be used.

The system shows a reciprocal structure, which can be used both for Send, as well as for receiving or a combination of sending and receiving system results. The signals of the individual antennas or antenna groups are each assigned to one usable intermediate frequency (ZF) usable by processors and digital hardware units mixed, digitized accordingly, and two branches for further processing Provided.

In a first branch, the phase differences or runtime differences become the incoming signal carriers, the position of the transmitter with respect to the antenna field or Antenna group and from it the weighting factors for the antenna characteristic of a each element is determined in a processor, in the second path in-phase and Quadrature component or amount and phase of each individual antenna element or each Antenna group multiplied by the parameters determined in branch one and summed up. Because the received signals are often below the noise level of the background by means of Fourier transformation, filtering and / or addition of a large number of periods Carrier of the transmitter lifted out of the background noise.

The phase differences determined in branch one are processed in the processor in accordance with Array geometry converted into weighting factors, in branch two with the digitized ones Signal data linked multiplicatively and then added up to the desired To obtain directional characteristics.

To multiply the weighting factors with the signal data, either in serial Processing a signal processor can be used, or else, especially at faster Data rates or larger antenna arrays to maintain performance, one on The multiplication and addition circuit constructed at the gate level make the connection. The fact that in branch one the positions through the parallel to the decoding The location of the carrier frequencies can be determined and the data can be updated Antenna characteristics can be adapted to the satellite positions in real time, and on the other hand can be compared to the results of demodulation jammers or unwanted transmitters due to selected zeros in the antenna characteristic at their position can be specifically hidden or suppressed. The demodulation of the signals can be done with a Mobile radio receivers, GPS receivers or other receivers take place.

An embodiment of the tracking system is shown in FIGS. 1 and 2 and is described in more detail below.

The method is demonstrated in combination with the GPS system (three-dimensional Position determination on earth at 1,575 GHz) with quite complex System requirements due to the boundary conditions of the GPS (received signal is 19 dB under the background noise).

In contrast to conventional GPS dipole or helix antennas, Antennas uses a planar 5 × 5 clockwise circularly polarized antenna array, which has a beam angle of approx. 30 ° and a Antenna gain of approx. 18 dB in comparison with a Lambertian radiator (Single patch) reached. With digital beamforming (DBF) z. B. four beams simultaneously on the four required GPS satellites with an antenna gain of approx. 12 dB be judged.

In order to keep the system effort low and to align the clubs precisely, this is done adaptive beamforming in the intermediate frequency using a combination of programmable logic (hardware: linking the weighting factors with digitized IF signal in real time) and signal processor (software: location and Tracking of the carriers and determination of the weighting factors).

The block diagram of the antenna array is shown in Fig. 1.

The antenna array (Fig. 1, 1) is constructed in the form of 5 × 5 at right angles at a distance of λ _0/4 disposed rectangular individual patches that because of the necessary circular polarization has an aspect ratio of 1: 1,029 with the feed point at a corner of λ _wff / Own 2 large patches. In order to reduce the overcoupling of the fields of adjacent antenna elements, the elements are each rotated through 90 ° to one another. The individual patches are connected via microstrip lines to amplifiers (Low Noise Amplifier, LNA) that are arranged directly underneath and feed the received signals to the subsequent superimposed receivers. In the superimposed receivers ( Fig. 1, 2 ), here the front end GP2010 of the GPS chipset GP2000 from GEC Plessey is used, the signals are mixed down to an analog intermediate frequency (IF) of 4,309 MHz in three stages on the one hand, and 2-bit digital on the other hand scanned with the clock of the associated GPS correlator. In order to maintain the phase of the individual signals, it is necessary to supply all mixers of the superimposed receivers with the same reference.

The further processing of the IF signals follows two paths: First, the 25 in the IF digitized signals are weighted and their sum evaluated, on the other hand uses the analog signals to detect the position of the carriers in the sky.

To direct the individual lobes to certain positions in the sky, phase and Amplitude, or in-phase and quadrature component, the individual signals are changed. There each overlay receiver takes a 2-bit scan, this is called In-phase component used and by shifting the sampling clock by π / 2 the Quatrature component additionally generated externally.

The two components of each antenna element are transferred to a programmable logic device (PLD) ( Fig. 1, 6 ), which is weighted in terms of sign and amount, depending on the position of the lobe, and finally added to give the sum signal of the desired directional characteristic from the 50 signals to receive one bit each for sign and amplitude for the subsequent correlator.

To evaluate the weighted signal, the correlator GP2021 belonging to the GEC Plessey chipset with software (GPS Builder) for GPS signals is used ( FIGS. 1, 5 ), which takes over the presentation of the results on the PC.

The analog IF outputs are fed in a second path via multiplexers one after the other to an analog-to-digital converter (ADC) ( FIGS. 1, 3 ), which in turn uses an π / 2 shift clock to in-phase and quadrature components of the analog signal 10 bit digitized. A digital signal processor (DSP) stores the digital data in its memory and compares the phases of the individual patch signals by means of FET (Fast Fourier Transformation) and averaging a large number of periods or filtering (FIGS . 1, 4 ). The weighting coefficients are calculated from the phase differences, which correspond to the positions in the sky, and handed over to the PLD. Fig. 2 shows schematically the linkage of the digitized data with the parameters from the signal processor ( Fig. 1, 6 ). In order to be able to track the lobes of the satellites moving in the sky, the DSP must continuously evaluate the phase differences and recalculate and transfer the current beam directions or parameters. With sufficient computing power, club shaping and tracking in real time is also possible in mobile use.

Claims (4)

1.Method and arrangement for realizing the tracking system consisting of an antenna group consisting of two or more antenna elements or antenna sub-groups, one superimposed receiver or transmitter per antenna element or antenna sub-group and a signal evaluation circuit in hardware or software each overlay receiver or transmitter forms both the in-phase and the quadrature component or the amount and phase of the receive or transmit signal assigned to the respective antenna element or the respective antenna sub-group, the in-phase and quadrature components of the output signals of the individual overlay receivers or - weighted transmitters are superimposed in such a way that the directional characteristic of the antenna group is shaped, characterized in that the in-phase and quadrature components of the individual overlay receivers or transmitters are selected in a first channel 1 and a second channel 2 in channel 1 the signal carrier or signals of the received signal or signals are evaluated to obtain the information about the formation of the optimal antenna characteristics ( FIGS. 1, 3 and 6 ) and in channel 2 the in-phase and quadrature components or The amount and phase of the individual receivers or transmitters are superimposed weighted on the basis of the information obtained in the channel ( FIGS. 1, 6 ; Fig. 2) and the evaluation ( Fig. 1, 5 ) are supplied. 2. The method and arrangement for realizing the tracking system according to claim 1, characterized in that the carrier of the signal or the carriers of the signals in channel 1 are detected by determining the phase differences or transit time differences of the individual antenna subgroups or antenna elements by means of known computing methods ( Fig. 1, 4 ), and thus the position of the carrier or carriers can be determined, the signal or signals in channel 1 by averaging a plurality of periods and / or filtering and / or Fourier transformation and / or other computing method is lifted from the background noise, and that a receive or transmit array ( Fig. 1, 1 ) is used, whereby the antenna gain and the signal-to-noise ratio by application-related shaping of the directional characteristic significantly improves, and that the position determined in channel 1 or positions of the signal source or signal sources in channel 2 in the links the signals of the antenna subgroups or antenna elements are included in the form of weighting factors ( FIGS. 1, 6 ; Fig. 2) and the weighted signals of the antenna subgroups or the antenna elements summed up to a resultant signal or resultant signals, which receives or sends with the set characteristic. 3. The method and arrangement for realizing the tracking system according to claim 1, characterized in that it for the alignment, optimization and tracking of the receiving or transmitting lobe, the weighting factors for the in-phase and quadrature component or amount and phase of the individual antenna elements or Antenna sub-groups in a digital processor ( Fig. 1, 4 ) and / or in digital hardware generated and renewed, and the linking of the digital complex weighting factors in software by a processor and / or in hardware ( Fig. 1, 6 ; Fig. 2) linked with the aid of correspondingly linked gates to the digitized useful signals generated from the superimposed receivers ( FIGS. 1, 2 ) or code generators, and thus achieving or adapting the optimum directional characteristic, and that by means of continuous carrier detection running parallel to the signal linkage ( FIG. 1 , 3 ) jammer due to lack of information replenishment or unwanted recipient of the broadcast The signals are determined by their known or detected position and these data are included in the weighting factor calculation ( FIGS. 1, 4 ), and the reception or transmission characteristics for masking out the jamming transmitters or unwanted receivers can accordingly be modified to include only the desired ones Include transmitter or receiver in the characteristics and specifically hide jammers or receivers. 4. The method and arrangement for realizing the tracking system according to claim 1, characterized in that the signal or the signals in channel 2 with a GPS receiver or a mobile radio receiver or transmitter ( Fig. 1, 5 ) are evaluated and both can be used for sending as well as receiving signals and that the carrier or reference vibration of the transmitter or receiver is used to determine the transmitter position with respect to the receiving array or to determine the receiver position with regard to the position of the sending array, and thus by narrowband evaluation determines the position of the transmitter or receiver, and therefore can also track or target the transmitter or receiver under the noise.