Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/69—Spread spectrum techniques
  • H04B1/707—Spread spectrum techniques using direct sequence modulation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B14/00—Transmission systems not characterised by the medium used for transmission
  • H04B14/02—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation
  • H04B14/026—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation using pulse time characteristics modulation, e.g. width, position, interval
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L1/00—Arrangements for detecting or preventing errors in the information received
  • H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
  • H04L1/04—Arrangements for detecting or preventing errors in the information received by diversity reception using frequency diversity
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/38—Synchronous or start-stop systems, e.g. for Baudot code
  • H04L25/40—Transmitting circuits; Receiving circuits
  • H04L25/49—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems
  • H04L25/4902—Pulse width modulation; Pulse position modulation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/02—Channels characterised by the type of signal
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/69—Spread spectrum techniques
  • H04B2001/6912—Spread spectrum techniques using chirp

Definitions

• the invention relates to methods and devices for transmitting, transmitting and / or receiving information.
• Rigidly fixed carrier frequencies are generally used for the transmission of information by means of waves, the quality and speed of the transmission often being impaired by interference in the transmission link.
• Real transmission channels can be of very different types, have different transmission properties, which can include linear and nonlinear distortions, temporally constant and time-variant influences as well as additive disturbances such as noise ("Noise”), influences of external signals, etc.
• Noise noise
• ISI inter-symbol interference
• multipath propagation A particularly complex problem is the (often time-variable) multipath propagation ("multipath propagation"). It occurs, for example, during transmission through inhomogeneous media, in structured transmission rooms, etc., in which the transmitted signal can be reflected by various interfaces and / or diffracted or scattered at edges. The signal then not only arrives on the direct connection path (direct path), but also at the same time or at different times ("time delay spread” or overall “delay spread”) with different attenuation and also via different detours at the receiver (multiple reception). Apart from the different length, the individual paths can impart different changes to the signal components concerned due to their respective geometry and / or individual physical properties (different attenuation, non-deterministic and / or deterministic internal phase shifts, etc.).
• multi-path components (“multipath arrivals”, echoes).
• multi-path arrivals”, echoes Each of these multi-path components thus brings its own story to the receiver, where they overlap.
• the overlaying of the multi-path components in the reception area can lead to distortions that are difficult to predict in terms of location and time, Amplitude fluctuations and phase shifts (fading, fading), in the worst case also to extinguishing the signal.
• This effect has a disadvantageous effect particularly in the case of time variant transmission conditions and when using mobile transmitter and receiver systems.
• the fading is often frequency-selective and time-selective Transfer function usually cannot be determined deterministically.
• the problem of multipath propagation can be mitigated by microwave and / or angle-selective receiving antennas.
• directional reception on the other hand, attempts are made to mask out undesired multipath components or to overlap them by means of a large number of specially interconnected receiving elements cancel each other out (in other words, the energy of the signal components in question is destroyed) and if possible only one multipath component of the useful signal remains.
• This signal component is amplified accordingly. By tapping the received signal at several spatial points at the same time, an antenna gain can be achieved.
• a further possibility for interference clearing of the transmission consists in the signal processing of the received signals ("signal processing") in the receiver.
• signal processing the signal processing of the received signals
• signal processing the signal processing of the received signals
• FFE the equalizer is adjusted in the runtime compensation
• intersymbol interference conditions consists in the use of multiple modulations.
• the methods for signal spreading are particularly important, in which the modulated signal is spread over a large frequency band.
• the term "signal spread” or “Sread Spectrum” (SS) does not refer to the information to be transmitted, but to the carrier structure. Due to the wide bandwidth of the transmission signal, transmission channels with a comparatively poor signal-to-noise ratio can also be occupied by means of the spread spectrum systems.
• Essential system properties are the type of band spreading, the transmission of the spread signal and the reverse transformation of the spread spectrum into the desired original information bandwidth.
• three basic modulation methods are used: direct sequence modulation (DS), also known as the “pseudonoise method” (PN), frequency hopping modulation (FH) and CHIRP modulation.
• SS method selective addressing, multiple access through code multiplex, message concealment, increased immunity to interference, low spectral power density for signal or eavesdropping protection, suitability for high-resolution distance measurement methods, etc.
• the disadvantages include in the increased system requirements and sometimes the synchronization of the transmitter and receiver is difficult. Distortion due to multipath propagation can be reduced significantly, but still embodies a problem.
• pulsed EM or chirped modulation is of particular interest. It has its main application in radar and sonar technology, but is also used in various ways for communication purposes.
• the special feature is the use of pulsed RF signals, whose carrier frequency is continuously changed or wobbled over a certain frequency range during a defined pulse width.
• Chirps enable a favorable energy distribution over the bandwidth, which makes them robust against interference, good recognition and an improvement in the S / N ratio (signal-to-noise ratio or "signal-noise ratio").
• An advantage of this transmission technology is the possibilityj . to remarkably reduce the transmission power.
• the transmission signal can be generated in various ways, for example by controlling a VCO (voltage control led oscillator) with a linear voltage swing.
• VCO voltage control led oscillator
• LFM linear frequency modulated
• a process for the linearization of wobble systems, as well as the importance of linear chirps, especially for radar technology, for spectrum analyzers etc. is e.g. described in patent DE 195 27 325 AI. It is interesting that the radar technicians apply special markers to the signals in order to improve the signal analysis.
• uncoded chirps are mostly used for message transmission (by means of sound, optical or RF signals), which can easily be generated by means of a chirp generating filter or frequency-dependent delay line (“dispersive deay line, DLL”).
• a chirp generating filter or frequency-dependent delay line (“dispersive deay line, DLL”).
• DLL frequency-dependent delay line
• dispersion filters are used SAW ("Surface Acoustic Wave”) components used.
• SAW Surface Acoustic Wave
• the digital data transmission by means of chirps essentially includes the binary distinction between on and off states, the on states being sent as chirps.
• US-A-5, 748, 670 a technique is described according to which one can additionally distinguish between ascending and descending chirps.
• the amplitude and / or the phase position of the chirps can also be varied, if necessary.
• this does not change the principle that the chirp modulation itself offers only a small possibility of variation of the carrier structure, which is disadvantageous in particular for multiple access in multi-user systems.
• each of the spread spectrum methods mentioned has its specific advantages and disadvantages. However, they can be combined in a variety of ways. By means of hybrid processes, improved system properties can be achieved compared to the individual processes, whereby the system expenditure does not necessarily have to double.
• the best known hybrid systems are: Frequency Hopping / Direct Sequence FH / DS or FH / PN, Time Frequency Hopping TH / FH, Time Hopping / Direct Sequence TH / DS, Chirp / FH and Chirp-PN-PSK.
• the chirp-PN-PSK systems due to the PN modulation a large variety of waveforms and due to the chirp modulation a slight degradation with center frequency shifts e.g. due to double or frequency deviations between transmitter and receiver).
• phase-coherent signal structures can significantly increase the transmission speed of data, but due to the greater susceptibility to interference of these signals, this also increases the effort required for signal processing and also requires other and / or special additional measures.
• the LFM received signal is meanwhile converted into a narrow frequency band with fixed frequencies and filtered.
• the transfer function is estimated on the basis of the filtered signal, the filtered signal itself is transformed back into the sweep form (in order to equalize it as a sweep), then finally demodulated by the sweep and passed on to the parameter analysis as a narrowband signal.
• the equalization signal is formed on the basis of a transmission signal which is narrow-banded, but which is structured in a multi-layered manner, in particular under multipath conditions (which is ultimately the issue here).
• this signal In the case of multipath propagation, this signal always contains a whole spectrum of individual frequencies. However, no reference is made to this. In any case, the consequence of this is that when potentiating and then pulling the roots to remove the information-bearing modulation, a frequency mishmash arises from which the transfer function cannot be derived properly. The more multipath parts and the larger the delay spread, the more noticeable this problem becomes. If the individual multipath components then still have individual or even time-variable distortions (different Doppler loads, etc.), the chaos is perfect. The equalization function is then formed from an extremely smeared signal. Overall, this source of error can hardly be eliminated with the equalizers working in the time domain, the interference problem is essentially only shifted, not solved.
• communication technology endeavors to obtain an image of the transmission signal (useful signal) that is as unaffected as possible.
• all transmission-related changes are treated as disturbances and attempts are made to reduce, compensate for them or ideally also to eliminate them entirely.
• the information that the transmission signal has received in the process of transmission through the transmission link is also rejected.
• the object of the present invention is to provide an improved method and a suitable system for transmitting and receiving information, which is simplified in particular in comparison to signal transmission with several frequency gradient channels and which ensures high transmission quality, robust against the above-mentioned interference and can be adapted to different transmission conditions.
• the method and system for transmitting and receiving information should enable a high bit rate, in particular through improved quality of the signal processing and the recognition of the information-carrying signal parameters, and should be able to transmit a large number of information signals simultaneously or overlapping in a given frequency band, and so on eg make better use of the available frequency bands.
• the possibility of using two or more frequency bands in parallel should also be created.
• the method and system for transmitting and receiving information is also intended, in particular, to provide variable signal generation and processing, which makes it possible to adapt the signal structures to various special tasks. fit to evaluate the received signals from different points of view, in particular to process multi-way components individually, in parallel or also in the overall complex, in order to achieve an additional process gain for the information transmission and / or to extract information about the environment from the received signal that the signal recorded in the transmission process ,
• the basic idea of the invention is to provide only a transmission signal in the form of a carrier wave, the frequency of which is changed or wobbled smoothly in a predetermined time interval and which carries an impressed information signal.
• a carrier wave When the carrier wave is transmitted, no transmission of a reference signal is provided.
• the transmission is free of reference components.
• the evaluation of the transmission signal with regard to the information-carrying signal parameters takes place on its own, since it means exclusively on the basis of the information contained in the transmission signal. No other separately received signals, that is to say no reference signals, are used in the evaluation.
• the continuously flowing frequency change can be regarded as a certain form of spreading an information signal which is present per se, which is generally unproblematic if this information signal itself is already a carrier wave has.
• the information signal only contains the specifications for the modulation of a carrier wave, for example in the form of a so-called baseband modulation, which is then directly impressed on the carrier sweep.
• the flowing frequency change introduces certain properties into the transmission process that can be used advantageously.
• An essential part of the process and device engineering measures of the present invention relates in the first instance to the special properties as well as the treatment, preparation and processing of the carrier frequencies designed as sweep, although it is initially of somewhat minor importance whether and in which form these sweeps are still finely modulated, provided that the modulation in question does not fundamentally change the characteristics of the sweeps. Accordingly, the following description concentrates on a form of observation in which the sweeps are regarded as the basic carrier elements of the signals, but this should in no way preclude other forms of consideration.
• a wave whose frequency is continuously changed in a predetermined time interval is generally referred to as a “sweep” or “carrier sweep”.
• GTW gradient carrier wave
• sweep is treated as a Germanized word, from which" sweep "then emerges as a verb for describing the execution of a continuously flowing frequency change (synonym for, for example "Wobble”) and the adjective “swept” means that there is a continuously flowing frequency change (for example also as a synonym for "wobbled”).
• the present method which is based on the use of a carrier wave with a continuously flowing frequency change, is also referred to here as "floating frequency technology” or “F2 technology” or - based on the internationally used terminology - “sweep spread technology” or “S2” -Technology ".
• F2 technology floating frequency technology
• S2 spread technology
• an additional variable i.e. an additional dimension has been introduced, which, in addition to an advantageous distribution of the signal energy in the spread frequency band (spread spectrum), above all also means that multipath components which may occur in the transmission process can no longer overlap so easily.
• the time spread now represents a shift in the time-frequency range in which the components in question lie next to one another, typically parallel to one another in the LFM, their relative distance being a function of the transit time difference and the frequency increase of the respective carrier sweep is.
• the transit time difference is natural and can hardly be influenced in terms of process technology, but the frequency deviation (frequency increase or frequency gradient) is. This makes it clear that the configuration of the carrier sweeps can be used in the method according to the invention as an instrument, by means of which the distance or the “packing density” of the components in the time-frequency range can be influenced and the interference can be reduced or avoided.
• the signal is converted into an their frequency form is transferred or transformed, the conversion into a frequency band or spectrum with carrier frequencies which no longer change over time, that is to say are constantly fixed, being preferred.
• An alternative, but in practice more difficult to implement, is filtering out a reusable component by means of a moving filter and / or subsequent multiplication, folding etc. with a special function.
• the effect is that the components shifted in the received signal in the time-frequency space now correspond to their relative distances on separate fixed frequencies.
• This surprisingly simple measure achieves a very significant qualitative effect for signal processing, namely that the problem of separating time-shifted signal components is shifted from the time domain to the frequency domain.
• the major advantage is that other methods for signal processing are available in the frequency domain, which usually deliver better results and are also much easier to implement.
• Simple filters for example bandpass filters (BPF) can now suffice in the first instance to separate and / or clean up various interference components.
• the filter or filters can optionally be adapted to the frequency components of interest in each case, or the relevant components can be placed in a predetermined filter window by means of suitable measures during the transformation, for example by synchronizing an auxiliary frequency with a specific multipath component.
• suitable measures for example by synchronizing an auxiliary frequency with a specific multipath component.
• most problems can already be solved with such a bandpass filtering.
• the method according to the invention offers the possibility of Parts of the frequency-transformed received signal can also be processed individually, in parallel or also in blocks using more complex filter systems, if necessary also offset against one another and then evaluated for recovery or extraction or isolation of the information-carrying signal parameters.
• the method according to the invention includes the possibility of extracting a large amount of different information from the received signal or of using the information and / or modulations contained in the transmitted or received signal in different ways. It is at the discretion of the user to what extent or how he makes use of these options.
• a preferred application involves the transmission of information between sender and receiver.
• the received signals can also be evaluated with regard to the changes impressed on them in the transmission path, which provide the receiver with a wealth of equally valuable information about the properties and nature of the environment.
• the quality of individual connection paths can be determined on the basis of an analysis of the frequency spectrum of the frequency-transformed received signal and taken into account in the transmission process (for example to improve the position of the transmitter or receiver, focusing antennas, etc.).
• the person skilled in the art can also derive a large number of other measured values from the signals if processed appropriately.
• the information signal modulated on the transmitter side can include can also be used as a marker, thus supporting the evaluation. Under this aspect, modulation forms can also be selected that are particularly suitable for one or both of the above-mentioned aspects.
• modulation methods which can advantageously be used in the method according to the invention are named within the scope of the embodiments.
• the carrier wave can be a sound wave in a solid, liquid or gaseous carrier medium or an electromagnetic one Wave (z. B. RF signals, light waves) are formed.
• the frequency change in the simplest form which is advantageous for many applications, can be linear in a given time interval or after another suitable continuous, preferably monotonous, function or z. B. after a Gaussian function. Since the width of the available or usable frequency band is generally limited, the sign of the frequency change of the carrier wave must be reversed at the latest at the end of the relevant time interval (turning point) or it must be started again, for example again at the output frequency.
• the carrier wave is thus subdivided into different sections, which are referred to as a sweep or - to emphasize clearly that these are initially only the structural elements of the carrier wave (of the carrier) - as a carrier sweep.
• the invention relates to both transmission and reception methods based on the principle explained above.
• the information to be transmitted is impressed on the carrier sweeps or the gradient carrier wave (GTW), i.e. the relevant signal parameters are modulated according to the coding method chosen by the user.
• GTW gradient carrier wave
• the modulated carrier wave is referred to as an F2 signal or S2 signal.
• the carrier wave embodies a series of uniform sweeps, which can optionally also be separated from one another in time.
• the distances can be advantageous, for example, for the decay of late arriving multi-way components or other channel responses (referred to as reverberation in the case of acoustic signals).
• the option of making the sweep intervals variable can be used, for example, to break down the information into individual information packages. It continues to deliver a basis for use in multi-user systems.
• the carrier sweeps can show a wide variety of variations and can be flexibly adapted to a wide variety of transmission conditions and tasks.
• ascending and descending carrier sweeps can alternate at suitable time intervals, or the sweeps can be configured in such a way that the frequency response of the carrier wave as a whole results in a closed course which oscillates over the frequency band.
• Multiplexing on one or more frequency bands can also be provided by changing the frequency position (initial frequency) of the carrier sweeps from sweep to sweep.
• a higher bit rate is achieved by dividing the carrier sweeps into two or more modulation time cycles (MZT), possibly of variable length.
• MZT modulation time cycles
• it is not the absolute values of the signal parameters that are used, but rather their relative changes from modulation cycle to modulation cycle for the information coding, as a result of which a higher stability of the data transmission is achieved, for example, in relation to dynamic interference.
• several signals can be transmitted in parallel for optimal use of a given frequency band.
• this embodiment can also be used in such a way that instead of multi-user operation, or in combination with this, the sweeps of one and the same F2 signal are pushed together in such a way that they overlap in time.
• chen This variant therefore includes a whole series of options for increasing the transmission rate in a given frequency band.
• the carrier wave is subdivided into two or more sections or intervals with different frequency characteristics. At least one of these sections is designed as a sweep.
• This sweep can now be transmitted in a transmission sequence in time, overlapping or simultaneously with other signal sections, for example with a frequency-shifted but otherwise equally structured carrier sweep and / or in combination with a section with a constant carrier frequency and / or with one or more carrier sweeps, which have a different, preferably opposing, rise and / or a different sweep shape.
• time and frequency patterns can advantageously be used to distinguish, separate or analyze signals in the case of multiple access, i.e. for multi-user operation in the given frequency band.
• the sweeps or carrier segments of the F2 signals are preferably configured according to a specific protocol which is defined both for the transmitter and for the receiver. This protocol can be different for each user pair, for example, which reduces the risk of mutual interference of the signals, in particular in multi-user operation on a common frequency band. If, on the other hand, a similar sweep configuration is used for several F2 signals in parallel operation, the transmission protocol can be used, for example, to establish a suitable staggering in time by setting or assigning time slots. Operational adaptation to the given transmission situation, to special requirements of the application or the wishes of the operator can also be provided. Changing transmission protocols can be used, for example, to achieve better reception quality, for more effective use of the respective frequency band, for avoiding waiting times, for switching another frequency band or to reduce the risk of external detection or eavesdropping etc. may be helpful.
• the methods according to the invention also enable combinations with other modulation methods that have already proven themselves in practice, in particular also the known spread spectrum methods. It can be advantageous for a number of applications to use the possibility of multiple modulation according to the direct sequence method or PN method, for example to make the transmission even less sensitive to interference, to further increase the variety of forms, to increase the channel capacity, and the possibilities for to further improve multiple access, to mask or mask signals or messages, etc.
• the receiver according to the invention is set up to receive the signals emitted by the transmitter, to process them accordingly and to evaluate them.
• the evaluation according to a predefined or time and / or frequency pattern or one agreed in the transmission protocol makes it possible to isolate a specific information signal from the received spectrum and, in particular, also to appropriately combine parts distributed in the time-frequency range.
• the pattern can be composed of different partial patterns which are used in a suitable manner, as a rule in succession.
• various interference components are attenuated or eliminated in the course of the separation or demodulation, which is generally regarded as “modulation gain” with regard to information transmission.
• the method according to the invention provides as standard that the F2 signal after reception in a different frequency form, for. B. to convert to a constant fixed frequency band transform.
• This is done, for example, by mixing or multiplication with an artificially generated auxiliary frequency (heterodyne frequency) which has the same frequency response as the carrier wave (GTW) of the transmitted signal, but is shifted in parallel with respect to this, so that the frequency of the carrier wave of the transformed signal is constant ,
• the transformation can also take place by means of a heterodyne frequency with a frequency response which is opposite in relation to the transmission signal, can be shifted in parallel or can also lie in the same frequency band.
• variants can optionally also be advantageously combined for processing more complex signal structures, for example to arrange transformed signal sections or components in different spectral ranges. It is also within the scope of the method to carry out the transfer in fixed frequencies in several stages, for example in order to iteratively improve the result or to compensate for time-variant changes in certain target components.
• the frequency transformation carried out for sweep demodulation has, in addition to the division of multipath components into narrow-band spectral lines, a further advantageous effect.
• This consists in that the energy of the signal components spread over the frequency band in the received signal is now combined in the relevant frequency cells.
• narrowband interference components contained in the received signal are spread, the energy of which is distributed.
• the S / N ratio is increased in this processing step and thus a modulation or system gain.
• a Doppler frequency shift in the transmission channel may be taken into account when generating the auxiliary frequency. After the conversion into the other frequency form, an advantageous further processing in the frequency range, if necessary filtering for separating individual frequencies or cleaning up interference components, and the evaluation can take place.
• a basic variant provides for isolating and evaluating the most suitable in each case from the spectrum of the individual frequencies contained in the transformed signal, in particular as a result of multipath propagation.
• the suitability can be determined by different criteria, for example by circuitry specifications. Important selection criteria are above all the strength of the respective individual frequencies and / or their distance from the neighboring frequencies.
• the isolated frequency can be evaluated immediately.
• additional filtering in the time domain typically after the isolation, additional filtering in the time domain, in particular by means of adaptive filters such as, for example, equalizers, and / or adaptive phase correction, in particular by means of PLL, can be carried out, for example in order to improve the reconstruction of the transmission signal and / or To be able to determine parameters better.
• a major advantage of the method according to the invention is that after the conversion into fixed frequencies there is compatibility with the known methods and methods of signal processing, and thus, depending on the requirements, an almost arbitrary selection of individual operations or also complex preparations, feedforward or feedback -Procedure can be integrated, by means of which practically all signal parameters in the frequency domain, time domain and / or any other projection levels can be addressed, processed or processed or evaluated.
• the analysis is carried out, for example, to demodulate phase-modulated F2 signals by breaking them down on auxiliary components generated by the receiver (auxiliary vibrations, quadratic turko components, PLL, FFT or a flip-flop circuit), for example, the phase difference between two, preferably adjacent modulation clocks is determined.
• auxiliary components generated by the receiver auxiliary vibrations, quadratic turko components, PLL, FFT or a flip-flop circuit
• a further development of the method includes that two or more frequency components are isolated from the spectrum of the individual frequencies contained in the transformed signal and are shifted and frequency-transformed relative to one another in such a way that the carrier waves are coherent, then offset with one another, in particular projected or added over one another , and will then be analyzed.
• the advantage of this type of processing is above all the combination of the signal energy of the relevant parts, so that the result is a much stronger signal for evaluation.
• Another important effect is that the noise components are added up in the same step, but this is added does not necessarily lead to a total increase in the noise level. Since each multi-path component has its own noise component, particularly in the case of multipath propagation, the energy components of the noise spectrum are correspondingly leveled when superimposed.
• the advantageous effect is that the correction parameters determined or used for the coherent adaptation of the components contain information about the spatial-structural and physical nature of the transmission channel, which to a certain extent are already prepared.
• the further processing and evaluation for the extraction of such information embodies a design or expansion possibility of the method according to the invention.
• blind means that special measures for exact time synchronization of the transmitter and receiver can be dispensed with, and the receiver automatically recognizes and evaluates the signal intended for it without additional adaptation measures for synchronization.
• F2 process in addition to automated sweep demodulation, there is another option that the various multipath components contained in the received signal are drawn automatically and coherently and the signal energy of all components are combined in a continuous narrow-band signal, which is then used for evaluation provided. This basic principle can be implemented in different ways in terms of process engineering.
• a preferred embodiment which can be used advantageously in particular when using LFM carrier sweeps, essentially consists of three processing stages or steps, which can be expanded individually and in the overall complex as desired.
• the basic idea includes the following features: a) Projection of the received signal onto two different auxiliary frequencies (sweeps) to generate two separate frequency spectra with internally (i.e. within the spectra) mirror-inverted arrangement of the constant-frequency spectral elements, possibly phase transformation of one or both spectra!
• the above-mentioned method enables the S / N gain from the use of the multipath to be maximized. It is also of great advantage that the sweep-modulated transmission signal is received. can be put together again to form a coherent shaft. These are important prerequisites, for example for increasing the transmission rate, transmission security, etc., but can also be used in other ways, for example to reduce the transmission power required in mobile communications (longer battery life, improved health compatibility, etc.).
• Another embodiment includes adaptation measures, in particular for combinatorial tasks, for example in underwater technology, in location, orientation, etc., which are often at least as important as communication.
• a principle solution is provided that can be used in the presented or similar form in many areas of signal technology (including the HF range, laser technology, etc.).
• a copy of the transmission signal and / or a transformation of the same is generated at the receiver end and this artificially generated signal, which is free of all interference, interference Distortion and other changes occurring in the transmission channel is offset against the received signal and / or its processing stages in order to qualitatively and / or quantitatively evaluate the transmission-related changes and from this information about the environment, for example for determining positions and movement parameters, for spatial-structural and physical nature of the transmission channel, its profile and the objects it contains, etc., in general: to obtain any type of information that the transmission signal has received in the process of transmission through the transmission link.
• the information signal impressed on the transmission signal by the transmitter can either be calculated out or can also be expediently included in the evaluation, for example as a marker.
• the transmitter can also be enabled for such an analysis. Accordingly, it is provided that the transmission device is designed in such a way that the transmitter receives images or components of the transmission signal, typically emitted by itself, that are reflected by the transmission channel or by interfaces or objects contained therein, and this with the original transmission signal for extracting information about processed the environment.
• the information about the respective properties and other characteristics of the transmission channel, during signal generation and / or signal processing is taken into account, for example in order to improve the transmission result and / or the ambient analysis. to specify or expand.
• the invention also relates to transmitting and receiving devices for implementing the signal transmission according to the invention.
• transmission and systems consisting of combinations of such transmitting or receiving devices.
• the transmitting device comprises at least one generator device for generating carrier waves with a continuously flowing frequency change (carrier sweeps, GTW) and correspondingly at least one modulator device for modulating them.
• GTW continuously flowing frequency change
• the receiving device is designed to detect signals with carrier sweeps. It has a structure with a reference generator device for generating at least one auxiliary signal with an artificial auxiliary frequency, at least one mixing device for superimposing the received signal with the respective auxiliary signal, possibly one or more filter devices and at least one analyzer device.
• the invention has the following advantages in particular.
• the use of broadband frequency channels with sweep-modulated signals is realized for the first time, which enables additional information transfer across the existing, rigidly defined frequency bands without causing a significant disturbance of the transmission systems based on fixed frequencies.
• the noise effects are leveled (averaging over a larger frequency range) and the prerequisites for an improvement in the S / N ratio in the receiver-side signal processing are created.
• the carrier wave or carrier sweeps can be modulated on the basis of digital or analog coding.
• the carrier sweeps used here each embody a coherent signal section, which requires the use of phase-coherent modulation methods. drive and thus enables a higher information rate.
• the multipath gain that can be achieved in this way can be regarded as a certain parallel to the antenna gain that is achieved by simultaneously tapping the signal at several spatial points, only that the temporal staggering of the multiple reception (the echoes) is used here at one spatial point. Both methods can be advantageously combined.
• the main concern of the present invention is, however, in the first instance to provide the instruments for a preferred compact solution.
• the high quality of the recognition makes it possible to carry out a much finer variation of individual or possibly several signal parameters simultaneously for the purpose of information transmission.
• the user of F2 technology is thus free to impress the information of the carrier wave in the form of analog wave signals or in the form of another suitable modulation curve.
• amplitude, phase and / or frequency modulations can also be carried out individually or in suitable combinations such that discrete states are generated. those that can be used for digital data transmission.
• suitable digital combinations can be realized by suitable combinations.
• the digital form of modulation can also be used advantageously for individual sweeps, which is also beneficial for multi-user operation.
• an overall more balanced reception quality can be achieved in the respective transmission area, with it being particularly advantageous for the use of mobile transmission and / or reception units that the fluctuations (fading) and especially the "dead spots" are eliminated.
• the F2 signals can hardly be disturbed from the outside with a correspondingly broadband design.
• the entire frequency range can hardly be blocked by interference frequencies.
• Another advantage is that the energy (power spectral density) is distributed over a correspondingly wide frequency range in the carrier sweeps of the F2 signals.
• FIGS. la, lb Curve representations to illustrate the time course of carrier sweeps with linearly increasing (a) or decreasing (b) frequencies;
• FIGS. 2a, 2b waveform representations of two F2 signal sections
• FIGS. 3a, 3b Curve representations with examples for
• Superposition of carrier waves a carrier sweep and a constant-frequency carrier (a) two carrier sweeps with a linearly increasing or decreasing frequency (b), which may belong to one information signal or to different information signals;
• 4a, 4b, 4c a schematic representation to illustrate the spectral energy density distribution of superimposed signal components and the redistribution in connection with a frequency transformation: sweep-spread signal (F2 signal), narrowband interference signal plus noise (a) Um- reversal of the conditions as a result of transformation (b) transformed useful signal plus noise component after filtering (c);
• Carrier sweeps of an F2 signal in a frequency band
• FIGS. 13a, 13b Curve representations for illustrating spectral components of a frequency-transformed received signal
• FIGS. 14a, 14b block diagrams of a transmitting device (a) and a receiving device (b) according to the invention
• 16 a block diagram of a transmission device for generating F2 signals with temporally superimposed carrier waves
• FIG. 17 shows a block diagram of a receiving device with separate processing channels
• FIG. 18 shows a block diagram of a receiving device for the combined evaluation of reusable components
• 20 is a block diagram of a receiving device with an equalizer
• 21 shows a block diagram of a receiving device for the combined evaluation of multi-way components with individual equalization
• 22 shows a block diagram of a receiving device for blind signal processing
• FIGS. 26a, 26b Illustrations for the mirror-inverted arrangement of the frequency components in the transformed spectra and for the correction of the time offset using special filter functions;
• FIGS. 27a, 27b illustrations of the position of the frequency components after shifting along the time axis
• Fig. 28 an illustration of the formation of a coherent wave and the concentration of the signal energy in the frequency window of the corresponding central frequency (before filtering away the stray components).
• FIGS. 29a, 29b block diagrams of a transmitting device (a) or a receiving device (b) for PN-modulated F2 signals;
• FIG. 30 is a block diagram of a receiving device with Doppler adjustment.
• 31 shows a block diagram of a receiving device with an integrated spectral analysis unit, in particular for “on-line” analysis of the multipath structure;
• the signal transmission according to the invention is described below with reference to the signal generation (generation of the carrier frequency on the transmitter side and its modulation) and the signal processing and demodulation on the receiver side.
• the physical-technical measures known per se for signal generation or extraction, for digital information coding, for transmitting and for receiving are not shown in detail.
• FIGS. 1 a and 1 b each show a single carrier sweep with a different frequency increase, which in this simplest variant is linear.
• FIGS. 2a and 2b schematically show the oscillation course for a few oscillation periods based on FIG. 1a, the frequency increase being the same in each case, but the initial phase differing by 180 degrees.
• the setting of the initial phase is an example of a (phase) coding for F2 signals.
• Other coding options are based on the known amplitude and frequency modulations or combinations of all types of modulation.
• FIGS. 3a and 3b illustrate the possibility of simultaneous transmission of a carrier sweep with an otherwise configured section of a carrier wave, with FIG. 4 using the schematically illustrated spectral energy density distribution to illustrate that, for example, an F2 sweep signal and a narrowband frequency component (show here as interference signal with regard to the sweep signal) influence each other only insignificantly. While the narrowband component clearly emerges in the transmission or reception signal, If the energy of the F2 signal is widely distributed over the frequency band (FIG. 4a), the situation is reversed after the frequency transformation by means of the sweep auxiliary frequency generated on the receiver side (FIG. 4b).
• a carrier sweep can be a carrier of one or more bits or (in the case of analog information processing) one or more information units.
• a carrier sweep is subdivided into modulation time cycles (MZT), as is illustrated by way of example in FIG. 5.
• MZT modulation time cycles
• modulation clock cycles serves in particular for the separation of the bits or the recovery in the transmission of digital information. If, for example, two zeros are transmitted in succession, they can be used as two bits are kept apart by the modulation timings. With large cycle numbers (for example 10 cycles per sweep), particularly high bit rates advantageously result.
• the introduction of the modulation clock cycles shows an important difference compared to the conventional use of chirps for signal transmission mentioned above.
• the sweeps are not simply switched on and off, but are modulated in a clocked manner.
• the MZT cycle times can be changed continuously or step-wise depending on the application in relation to the frequency of the carrier wave. It is assumed that only a certain number of oscillation periods of the carrier wave are required for the demodulation of the F2 signals. However, since the number of oscillation periods per unit of time changes constantly in the sweeps, a significant increase in the bit rate may be achieved by reducing the modulation clock times to the minimum required, i.e. be adjusted to the current frequency level of the carrier sweeps.
• FIG. 6 illustrates the structure of a multiple modulation when generating an F2 transmission signal using the example of a known offset QPSK of the information signal and the subsequent modulation with a carrier sweep, only the transmission signal being shown.
• the side band that is not required is filtered out.
• the information signal itself has a carrier wave, which is then modulated with the sweep or onto the sweep. No matter how you look at it, the result is identical in both cases.
• it is preferred as initially mentioned was explained to consider the sweep as a carrier of the overall signal.
• the formation of F2 signals does not necessarily require that the information signal has an independent carrier. It is entirely possible to modulate the sweep signal directly. Accordingly, the intermediate stages marked in FIG. 6 with e) or c) to e) may also be skipped.
• FIG. 7 shows an example of the multiple occupancy of a frequency band with F2 signals of the same configured carrier sweeps.
• the two thick printed lines represent the sweeps belonging to a signal with the time window t w .
• the sweeps belonging to different signals differ by predetermined time offset values t s (time slot).
• the sweeps of the F2 signals can be configured according to a specific protocol which is defined both for the transmitter and for the receiver.
• the protocol specifies what the sweep looks like (time function of the frequency change) and how it may be distributed over frequency bands.
• the protocol can be different for each pair, for example, which reduces the risk of the signals influencing one another, in particular in multi-user operation on a common frequency band.
• the transmission protocol can be used, for example, to establish a suitable staggering in time by setting up or assigning the time window or time offset values (see example in FIG. 7) ,
• Another way to prevent a random complete transmission of several F2 signals is to set up unequal distances between the sweeps.
• 8 shows an example of a pseudo-random arrangement of the sweeps of an F2 signal in a frequency band (random temporal mixing).
• the dotted lines indicate where the sweeps in question would have been expected if the distances were even.
• the introduction of pseudo-random distances has the advantage that even without the assignment of special time slots (time slots), i. H. If signals are mixed at random in multi-user mode, the complete overlay of two or more different signals is practically impossible.
• the overlay of individual sweeps can be compensated for using suitable correction algorithms.
• FIG. 9 illustrates an example of a transmission protocol in which the carrier sweeps of an information signal are distributed over two different, preferably adjacent frequency bands ⁇ f a and ⁇ f b . There is an alternating switching to 2 different channels or bands without changing the characteristic frequency increase.
• the receiver-side demodulation of sweep carrier waves according to the invention is carried out according to the same principles as described in PCT / DE99 / 02628 (WO0011817).
• the principles of converting the information signal into a constantly fixed frequency band for example by mixing or multiplication with an artificially generated auxiliary frequency (sweep heterodyne frequency). Additional measures known per se for improving the S / N ratio and bandpass filtering can be provided.
• FIG. 10 shows in the upper part schematically the reception result on a frequency band which is used by several users simultaneously in parallel operation.
• the F2 signal intended for the given receiver is highlighted by a bold line and the time window in which the sweep currently being analyzed is indicated by dashed vertical lines.
• the weaker printed lines refer to foreign F2 signals.
• an artificial wave (auxiliary sweep frequency or heterodyne frequency) is generated in the system, which in the present example has the same relative frequency change ⁇ fhe in the relevant time window t SW e- P as the carrier sweep of the F2 signal to be processed, of itself but this differs in terms of frequency, for example - as shown in the lower part of FIG. 10 - is lower.
• the respective received sweep is then mixed or multiplied by the heterodyne frequency.
• FIG. 11 shows an initial configuration similar to FIG. 10 in the upper part.
• the carrier frequencies of all sweeps of this pattern lying in the relevant time window are converted into constantly fixed frequencies which differ in their level (lower part of FIG. 11).
• the desired signal component is then easily generated, for example by means of a bandpass filter, here the frequency-transformed sweep, filtered out.
• the side bands that may arise during the transformation are also filtered out.
• the thus transformed and "cleaned” sweep can then be further processed using the methods used in signal processing like a "normal” signal with a constant carrier frequency and, with regard to the information-bearing parameters, about the phase angle, the amplitude or, in the case of frequency modulation, also with regard to the then after the transformation, the remaining frequency curve or the dynamics of the phase change are analyzed.
• the F2 method also includes the possibility, for example, of recognizing a Doppler shift that may occur based on the deviation of the transformed carrier frequency from the expected setpoint, for example in order to determine the speed of the change in distance between transmitter and receiver, or to take into account the Doppler shift determined in this way or in another way when generating the sweep auxiliary frequency and thus to improve the quality or stability of the data transmission.
• This design is particularly advantageous for communication between or with rapidly moving objects. Again, the possibility of using the received signals to derive further environmental data has already been mentioned several times.
• Another important advantage of the invention is that it results from the frequency transmission described formation with the auxiliary frequency in the case of multipath propagation is possible, for example by using correspondingly sharp filters or a suitable FFT analysis, to separate and separate an individual or the most suitable one, for example the strongest channel response, from the different channel responses analyze.
• FIGS. 12 and 13 in analogy to FIGS. 10 and 11) a more detailed representation is given, on the basis of which this performance capability, which justifies a completely new quality of information transmission especially in inhomogeneous media and structured spaces, is further explained below ,
• the respectively most suitable component for example the most strongly received component, preferably by means of filter devices or is isolated and evaluated on the basis of simple or complex FFT analyzes.
• the continuous frequency shift means that the individual channel responses arrive at the receiver as parallel sweeps due to their time offset.
• the strength of the parallel shift is also determined by the steepness of the sweeps.
• the frequency gradients mean that the time offset, ie the transit time differences between the channel responses, no longer interfere, but rather can be separated from one another on the basis of their different frequencies, or the influences of the side frequencies can be weakened.
• FIG. 12 shows a series of channel responses (symbolized by Rl to R5) which arrive at the receiver with different time offsets (generally denoted by t C r_ for channel response delay) as parallel sweeps.
• t C r_ time offsets
• 13a shows schematically that the respective transit time differences are represented as different frequency positions as a result of the frequency transformation.
• the transformation pushes the energy originally distributed over the frequency range ⁇ F swept by the sweeps into one frequency cell in each case (FIG. 13b), as a result of which a considerable improvement in the S / N (Signal-to-noise ratio) is achieved and at the same time the accidental influence of individual frequency components of the noise is mitigated.
• the transformed channel responses can have different strengths depending on their previous history in the transmission process. It is advisable to determine the frequency with the greatest amplitude and the corresponding one as a selection criterion that is easy to implement in terms of process technology Filter out component, for example, by means of a controllable, appropriately sharp filter.
• the corresponding setting of the filter can, for example, be carried out analogously to the method referred to as channel tuning in PCT / DE99 / 02628 (WO0011817). It is also possible to place the desired component in a given filter window by changing the frequency position (initial frequency) of the auxiliary frequency.
• One of these measures can ensure that the best possible S / N is used.
• the channel responses can also be separated from one another, the transit time difference of which leads to a phase shift of ⁇ , with which the cancellation due to interference can be excluded with a high degree of certainty.
• the noise can still cause random phase scattering, particularly in the case of very short cycle times.
• attempts are usually made to counteract these influences by means of extended cycle times, which results in averaging over time.
• the parallel offer made available by nature in the form of the various reusable components (echoes) can also be used by evaluating the information-bearing signal parameters, for example in a parallel evaluation process, for several reusable components and then calculating them in a suitable manner ,
• FIGS. 23 to 28 illustrate the procedure for blind signal processing.
• the received signal shown schematically in the form of two multipath components with the time offset ⁇
• the received signal is multiplied in two parallel processing steps, on the one hand, with an artificially generated heterodyne frequency.
• is multiplied which is in a higher frequency band and secondly is multiplied by a second heterodyne frequency, which has the same frequency characteristic compared to the first heterodyne frequency, but is in a lower frequency band.
• 23 shows that the two auxiliary frequencies are generated in synchronism with one another, but the generation need not be synchronized with the received signal.
• the length of the sweeps T sw is "the same in all cases.
• the arrows denoted by ⁇ and corresponding indices illustrate the respective instantaneous propriety relationships that result from the random time offset between the multipath components of the received signal and the auxiliary sweeps.
• FIGS. 24 and 25 show the relevant sections again in detail.
• 24 shows a detailed representation for the projection onto the upper auxiliary frequency
• FIG. 25 shows a detailed representation for the projection onto the lower auxiliary frequency.
• a phase transformation of one or both spectra can optionally also be carried out.
• FIGS. 26a and 26b schematically show the two spectra which result after multiplication by the relevant auxiliary frequencies.
• the individual spectral components are shown mirror-inverted in relation to the central frequency of the respective spectrum (referred to here as ⁇ in both cases). If the center frequencies of the auxiliary sweeps (heterodyne frequencies) are not arranged symmetrically to the received signal, the central frequencies of the two spectra can also differ.
• FIGS. 27a and 27b in analogy to FIGS. 26a and 26b, show schematically the position of the frequency components after shifting along the time axis. If the spectra shown in FIGS. 27a and 27b are now multiplied with one another, the previously synchronized elements collect in the form of a coherent wave with the frequency 2 ⁇ , the signal energy also being concentrated in the corresponding frequency window.
• Figure 28 shows schematically the result of such an operation.
• the new central frequency (shown as a bold line) can now be filtered out and evaluated.
• the 14a shows a transmitter device 10 according to the invention, which has a transmitter-side generator device 11 for generating gradient carrier waves (GTW), a modulator device 12 for modulating it, and a mixing device 13.
• the generator device 11 is designed for generating gradient carrier waves or carrier sweeps according to the principles explained above and is constructed using controllable signal formers which are known per se.
• the modulator device 12 is used to encode the information that is to be transmitted. This is done according to the coding method known per se, depending on the application.
• the mixing device 13 is a module for bringing together carrier and information components (mixer, multiplier or the like). It has an output 14 which may be connected to a filter unit 15 or directly to the physical transmission channel via a transmitter.
• the filter unit 15 is preferably formed by a bandpass filter unit (BPF) which is connected between the output 14 and the transmission antenna or a transmission converter (not shown). can be switched.
• BPF bandpass filter unit
• the filter unit 15 serves to eliminate any secondary frequencies that may occur. If these do not interfere, the module can also be connected directly to the output.
• the input information is converted by the signal modulator 12 and then impressed in the module 13 for the combination of the gradient carrier wave generated by the GTW generator 11, which is also connected to this module.
• the two switches 16 and the bandpass filter (BPF) denoted by a dashed line illustrate that the filter unit 15 can optionally be connected in series with the module.
• FIG. 14b shows an embodiment of a receiving device 20 according to the invention, which has a generator device 21 on the receiver side for generating an artificial auxiliary frequency, preferably a gradient wave or sweep, a projection device 22 for superimposing it on the reception signal received from a reception antenna or a reception converter (not shown), has a separating device 23 for separating signal components and a demodulating device 24.
• the circuits 21-24 form a device for acquiring signals with variable carrier frequencies.
• the generator device 21 is also constructed with controllable signal formers known per se.
• the projection device 22 comprises a mixer, multiplier or the like.
• the separating device 23 contains at least one module for separating signal components, for example a bandpass filter unit (BPF), a controllable filter unit or an FFT unit.
• the demodulator device 24 is used for signal analysis / demodulation and provides the transmitted information mation as a symbol.
• the module for separation and the demodulation device can also be implemented in the form of a common circuit unit.
• FIG. 15 shows a detail of a modification of a receiving device which enables the targeted processing of a multi-way component.
• FIGS. 16 and 17 show examples in which a plurality of parallel generation or processing channels are provided, the respective modulator or generator devices preferably being connected in parallel and being coupled to one another via a central control module (not shown), which has the shape and height and controls the time sequence of the sweeps and / or their modulation (preferably in accordance with the transmission or transmission protocol).
• the receiving devices can also have a control module which controls the signal processing accordingly. If necessary, several circuits according to FIGS. 14a, 14b and 15 are connected in parallel, which are coupled to one another via a common control module and can be supplemented by further circuit elements.
• FIG. 18 shows a block diagram of a receiving device for the combined evaluation of reusable components, with x denoting an assembly for correcting distortions or shifts, for example time shifts.
• FIG. 19 shows, as a further development of FIG. 18, a block diagram of a section of a receiving device for the combined evaluation of multi-way components with individual phase correction.
• 20 shows in detail in the block diagram a processing channel of a receiving device with an additional, non-linear filter unit for equalizing a multi-way component.
• FIG. 21 shows an embodiment for the combined evaluation of reusable components with circuit elements for individual fine correction.
• FIG -22 shows an example of the central part of a receiving device for the "blind" signal processing described above.
• FIGS. 29 to 31 show further embodiments of receiving devices according to the invention which are designed to implement the PN method described above or to take a Doppler shift into account.
• the application of the invention is not restricted to certain information contents, coding methods, transmission techniques, transmission media or the like.
• Other applications include radio communication, data transmission via laser beams or via electrically conductive or optical cables etc., remote controls (TV, keyboard) or underwater controls, as well as combined or separate use for information transmission and / or for determining environmental information.

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