EP2025067A1

EP2025067A1 - Radio transmitter, radio receiver, system and method with a radio transmitter and radio receiver

Info

Publication number: EP2025067A1
Application number: EP07722496A
Authority: EP
Inventors: Martin Vossiek; Peter Gulden; Sven RÖHR
Original assignee: Symeo GmbH
Current assignee: Symeo GmbH
Priority date: 2006-05-31
Filing date: 2007-05-31
Publication date: 2009-02-18
Also published as: KR20090031379A; DE102006038857A1; JP5243412B2; US8559554B2; US20090285313A1; WO2007137573A1; JP2009539282A; KR101564556B1

Abstract

The invention relates to a radio transmitter (1, 4) comprising at least one signal generator (SGEN1) for producing a continuous signal (sFMTx (t) ) and an antenna (ANT1) for emitting a transmitted signal (sTx(t)). At least one outlet of the signal generator (SGEN1) is connected to at least one inlet of the antenna (ANT1). The signal generator (SGEN1) is connected to the antenna (ANT1) by means of an interconnected interrupter unit (SW1) for selectively interrupting and maintaining a signal connection between the signal generator (SGEN1) and the antenna (ANT1).

Description

description

Radio transmitter, radio receiver, system and method with radio transmitter and radio receiver

The invention relates to a radio transmitter, a radio receiver, combinations thereof, as well as methods for operating the devices, in particular for synchronization and / or distance measurement by means of UWB (Ultra Wide Band) signals.

Modern radio location systems and radio identification systems increasingly use very broadband UWB signals. The term UWB is used as defined by the US Federal Communications Commission

(FCC) is typically used when the sigrial bandwidth is either at least 20% of the center frequency of the signal or greater than 500 MHz.

One problem with UWB systems is the generation and detection of the UWB signals. When generating UWB signals, strict legal regulations must be adhered to and the signal spectra must be within sharply defined frequency masks. For example, such claims to the spectral masks have been published in the public notices of the FCC or the European Electronic Communications Committee (ECC). In conventional UWB systems very short pulses (pulse duration typically in the range 100 ps-1 ns) and comparatively low pulse repetition rates (1-100 MHz) are used as signals. The selected pulse-pause ratios of typically 1: 100 are necessary so that the signals generated have the very low average power required by the legal provisions.

Due to the very short pulse durations and amplified by the long pulse pauses, however, it is expensive to synchronize the signals from two UWB radio stations. These Synchronization usually takes place by means of special hardware correlators. These hardware correlators are necessary because, due to the extreme bandwidth of the UWB signals, it has not yet been possible to inexpensively digitize the signals with an analog-to-digital converter and perform the correlation or synchronization by software purely mathematically. A disadvantage of a signal comparison with hardware correlators is that the correlation for different shift times can only be determined sequentially and thereby is required for a time - ie the synchronization is only gradual or slow - and on the other unnecessary power is consumed because of the synchronization process Variety of signals must be sent to sequentially find the synchronization optimism - ie the correlation maximum.

Significantly cheaper would be a software correlation, since in this case only one UWB signal would have to be sent and received in order to calculate a complete correlation and around that

Find correlation maximum. However, this possibility is not feasible economically today, as with large

Signal bandwidths the necessary hardware requirements are missing or extremely expensive.

As already stated, current UWB systems often work with pulse signals and very simple types of modulation such as the pulse position modulation or the

Amplitude modulation. Basic principles are e.g. in "Terence W.Barrett" History of UltraWideBand (UWB)

Radar Communications: Pioneers and Innovators; http: // www. ntia. doc. gov / osmhome / - uwbtestplan / barret_history_ (piersw-figs) .pdf ".

One of the first publications specifically dealing with UWB location systems is US 5,748,891. Further

Descriptions of UWB location systems can be found e.g. in US

6,054,950, US 6,300,903, and US 6,483,461. Common among simple pulse systems is that it is extremely complicated to shape the spectra of the generated pulses in a targeted manner. Usually, and in particular with the planned European approval regulations, it is necessary for the pulses to have a very defined envelope, such as a gaussian or cos ² shaped envelope, to remain in the spectral masks required by the regulatory agencies and to produce extremely little power in the sidebands , Such a targeted

Amplitude influencing within such short pulse times is technically very difficult solvable.

For the reasons mentioned above, newer UWB systems are increasingly using alternatively more complex types of modulation, such as OFDM modulation. Since the baseband signals are usually generated with a D / A converter, however, it is still necessary to limit the signals to a relatively small bandwidth or to distribute the signals to different subbands, since the D / A converters these days direct generation of signals with eg not allow a bandwidth of several GHz efficiently. An approach already discussed is e.g. the so-called UWB-MB-OFDM, e.g. Liuqing Yang, Giannakis, G.B., Signal Processing Magazine, IEEE Volume 21, Issue 6, Nov. 2004 Page (s): 26-54 "is presented in" Ultra-wideband Communications. In this case, the available spectrum is divided into several bands and in each band the information is transmitted by OFDM modulation.

From DE 101 57 931 C2 a possibility for synchronization of radio stations for FMCW systems under transmission and reception of continuous waves is known. A switch serves as a duplexer, ie as a switch between transmit and receive operation. The duplexer is not used for signal generation but only for switching between sending and receiving. US 2,379,395 A also shows a switch which forms a duplexer a transmit-receive switch. A method for frequency stabilization for a data / communication system with analog frequency modulation, ie classical radio technology, is described. The method is used exclusively for frequency stabilization of a pure

Communication system, wherein no synchronization of clocks of different system components is specified.

WO 2005/098465 A2 discloses a method for synchronizing clock devices based on FMCW systems while transmitting and receiving continuous waves.

From DE 199 46 161 Al a method for distance measurement on the basis of FMCW systems under transmission and reception of continuous waves is known.

It is therefore the object of the present invention to provide a simple and inexpensive possibility for the synchronization of UWB radio stations, in particular for UWB radio location systems.

The object is achieved by a radio transmitter according to claim 1, a radio receiver according to claim 8 or 16, a radio transmitting / receiving system according to claim 10, an apparatus according to claim 12, and a method according to claim 18, 20 or 21. Advantageous embodiments are in particular the dependent claims individually or in combination removed.

The radio transmitter according to the invention comprises at least one signal generator for generating a continuous signal and an antenna for outputting a transmission signal, wherein at least one output of the transmission signal generator is connected to at least one input of the antenna. Further, the transmission signal generator with the antenna via a this interconnected breaker unit for selectively interrupting and maintaining a signal connection between the transmit signal generator and the antenna, wherein a duration of a pulse period is less than a duration of a frequency modulation of the continuous signal generated by the transmit signal generator.

This radio transmitter converts a continuous signal generated in it, in particular a frequency-modulated continuous signal, into a pulsed signal. Since the generation of a continuous signal is well known and can be implemented inexpensively, the radio transmitter is realiserbar with little extra effort. In particular, when using frequency-modulated pulse-shaped signals can be for frequency-modulated continuous

Using signals of proven methods with knowledge of the inventive teaching and corresponding inventive adjustments for synchronization and distance measurement in UWB signals.

Advantageously, the optional interruption and maintenance of the signal connection by the interrupter unit by means of an externally applied to the interrupter unit switching signal.

Advantageously, the selective interruption and maintenance of the signal connection by the interrupter unit takes place in at least partially regular intervals.

It is in particular favorable if the optional

Interrupting and maintaining the signal connection by the interrupter unit with a fixed pulse period takes place.

It is also advantageous if the continuous signal generated by the transmission signal generator is an at least partially linearly frequency-modulated signal. It is advantageous if the duration of the pulse period is shorter than a duration of a frequency modulation of the continuous signal generated by the signal generator, in particular at least 10 times smaller.

It is also advantageous if a duration of a frequency modulation of the continuous signal generated by the signal generator is between 100 μs and 100 ms.

Particularly favorable is a radio transmitter, in which the

Transmit signal generator for generating the continuous signal and the interrupter unit for selectively interrupting and maintaining the signal connection are driven by respective clock signals which are in a known deterministic relationship to each other.

Then it is particularly advantageous if the transmission signal generator and the interrupter unit are connected to the control with a digital electronics, which generates the respective clock signals on the basis of a common clock base.

A radio transmitter which has a clock generator for outputting a clock signal generated by it to the digital electronics is / are particularly favorable, wherein the digital electronics generate a first derived clock signal for input into the transmission signal generator and a second derived clock signal for input into the interrupter unit; and wherein the transmission signal generator generates, based on the first derived clock signal, the continuous signal input to the interrupter unit; and wherein the interrupt unit selectively disrupts and maintains the signal connection between the transmit signal generator and the antenna based on the second derived clock signal. In this radio transmitter, it is particularly advantageous if the interrupter unit comprises an externally controllable switch, in particular a PIN diode, a mixer, a transistor or a micromechanical component.

The object is also achieved by a radio receiver for receiving frequency-modulated and pulsed radio signals which is adapted to extract at least one pair of associated spectral lines from the received frequency-modulated and pulse-shaped radio signals. In particular, according to the invention, variables can be calculated from a pair of associated spectral lines which make it possible to use the known methods for frequency-modulated continuous signals.

It is particularly advantageous if the spectral lines of the pair of associated spectral lines have a same order and a known symmetry position.

The radio receiver is suitably arranged to determine a frequency offset and / or a time offset from the pair of associated spectral lines.

The radio receiver is also advantageously configured to synchronize itself to a clock of a radio transmitter transmitting the frequency-modulated and pulsed radio signals on the basis of the calculated frequency offset and / or time offset.

Advantageously, the spectral lines of the pair of associated spectral lines have a same order and a known symmetry position.

Conveniently, the radio receiver is adapted to determine from the pair of associated spectral lines a frequency offset and / or a time offset. Conveniently, the radio receiver is then adapted to synchronize based on the calculated frequency offset and / or time offset to a clock of the frequency-modulated and pulsed radio signals emitted radio transmitter.

The object is also achieved by a radio transmitting / receiving system comprising at least one radio transmitter as described above and at least one suitably configured radio receiver, in particular as described above.

Particularly advantageous is a system in which the radio transmitter and the radio receiver have the same clock source for providing a common clock base.

The object is also achieved by an arrangement having at least one radio transmission / reception system for synchronization of the radio transmission / reception system and / or for distance measurement to a response device.

Advantageously, the answering device is embodied as a transponder comprising a second radio transmitting / receiving system, as also described below.

Alternatively, the answering device may conveniently be referred to as

Backscatter transponder be executed, as also described below.

The invention is also achieved by a radio receiver, in particular for use in a radio transmitting / receiving system having at least one mixer, which mixes a received signal with a mixed signal and thereby forms a measuring signal for the purpose of synchronization or distance measurement, wherein the mixed signal has a similar or identical modulation as the signal of the transmission signal generator. In this case, 'similar' means in particular that the modulation has a time offset .DELTA.t and / or a frequency offset .DELTA.f with respect to the signal of the transmission signal generator. By a frequency offset in the carrier signal frequency is usually, and in particular when all take are derived from a common clock, the modulation rate, ie the speed at which the modulation takes place, different.

The invention is also solved by a method for

Generation and evaluation of the measurement signal of the radio receiver wherein interrupting and maintaining a signal connection between the signal generator and the antenna is performed so that represents the signal connection in the measurement signal as a time discretization with a real scanner, and wherein interrupting and maintaining the signal connection by means of the interrupter unit time is performed so that the sampling theorem is satisfied for the measurement signal.

For this purpose, it is particularly favorable if at least the sampling frequency is selected twice as large as the bandwidth of the measurement signal and the duration of maintaining the signal connection significantly smaller, e.g. smaller by a factor of 10 than the inverse of the highest frequency occurring in the measurement signal.

As a result, the information of the thus time discretized measurement signal can be completely reconstructed and extracted with the aid of a filtering or spectral analysis; In principle, therefore, a measurement signal is formed as if the interrupter unit were not present.

The object is also achieved by a combination of a corresponding radio transmitter and radio receiver. Furthermore, the invention is achieved by a method for synchronization of at least one radio transmitter and at least one radio receiver, wherein at least one of the radio transmitters comprises at least one signal generator for generating a continuous signal and an antenna for outputting a transmission signal, wherein the radio transmitter from the continuous signal by selectively interrupting and maintaining a signal connection to the antenna via the antenna radiates a pulsed radio transmission signal, and wherein the radio receiver from the received pulse-shaped

Radio signals extracted at least one pair of associated spectral lines and determines therefrom a frequency offset and / or a time offset on the basis of which the radio receiver synchronizes to a clock of the radio transmitter.

The invention is also achieved by a method for distance measuring and / or locating a transponder, wherein a radio transmitter comprises at least one transmission signal generator for generating a continuous signal and an antenna for outputting a transmission signal, wherein the radio transmitter from the continuous signal by selectively interrupting and maintaining a Signal connection to the antenna via the antenna emits a pulse-shaped radio transmission signal in the direction of the transponder, and wherein the transponder this

Modulated signal to a radio receiver modulated and wherein the radio receiver extracts from the received pulse-shaped radio signals at least one spectral line and determines therefrom a distance and / or position of the transponder.

In the following the invention is not restricted and purely schematically explained by means of embodiments:

FIG. 1 shows a sketch of a UWB radio transmitter; FIG. 2 shows a sketch of a first embodiment of a UWB radio receiver;

FIG. 3 is a sketch of a second embodiment of a UWB radio receiver; FIG.

FIG. 4 is a sketch of a third embodiment of a UWB radio receiver; FIG.

Fig. 5 shows a plot of a frequency spectrum with spectral lines;

Fig. 6 shows a plot of a frequency of a received and a locally generated signal over time.

Fig. 1 shows the basic principle of the arrangement for generating the used radio transmission signals (radio transmitter 1). The signal generator SGEN1 of the radio transmitter 1 generates a preferably linearly frequency-modulated signal SFMTx (t). This signal is blanked by a switch SWl by a switching signal ssw (t), so that a pulse-shaped modulated and additionally frequency-modulated UWB transmission signal Sτ _x (t) is generated. Typically, the switch is closed with the switching signal, for example, for a period of about 100 ps to 10 ns and opened about 10 to 1000 times as long. It is known to the person skilled in the art that such a switch can be realized in a very wide variety of ways, for example with PIN diodes, with a mixer, with a transistor or possibly with micromechanical components. The frequency modulation - ie the duration of the frequency ramp in a linear frequency modulation - should have a duration which is several orders of magnitude above the pulse period. Meaningful values can be in particular in the range of 100 microseconds to 100 milliseconds. Preferably, a central element of the circuit is a digital electronics DIGEl from a common clock base - eg a quartz oscillator CLKL - Derives all clock signals, so that all clock periods or frequencies of all signals in the circuit in a known deterministic relationship to each other; if this is not done, it can often not be concluded from the frequency offset to the time offset arising during the measurement and synchronization. With a frequency difference of only 1 ppm and 30 ms of passing time, 30 ns of additional time offset can be achieved. In a distance measurement with radio signals, this time offset corresponds to a distance measuring error of several meters.

Fig. 2 shows the basic principle of the arrangement for receiving the radio signals generated by the arrangement of Fig. 1 (radio receiver 2). According to the invention, the arrangements of FIGS. 1 and 2 together represent a first arrangement according to the invention with which two radio stations can be synchronized with one another. A second arrangement according to the invention results when two radio stations each contain both arrangements - that is to say in each case those from FIG. 1 and FIG. 2 - so as to be able to send radio signals back and forth; This second arrangement according to the invention is particularly suitable for determining the distance between the two radio stations.

Also in the arrangement in FIG. 2, as in the arrangement in FIG. 1, preferably (see above), all the clocks or signals are derived from a common clock base (CLK2, DIGE2).

The signal generator SGEN2 generates a frequency-modulated signal SFMRx (t) in a manner analogous to that of FIG. This signal should preferably be constructed according to the same law of formation, that is to say have as identical an as possible modulation as the signal SFMTx (t). In a mixer MlX, this signal is mixed with the received UWB signal sRx (t), thus obtaining the signal Smix (t). Assuming in simplified terms of an ideal distortion-free channel, the received signal sRx (t) corresponds to the transmission signal sTx (t) although it is delayed by the signal propagation time τ and attenuated by the factor α due to the transmission.

From the mixer, the mixed signal through a filter FLT and an analog-to-digital converter ADC in a

Signal evaluation unit SAE out, where the signal is evaluated and other sizes can be calculated. With these parameters, the clock and frequency para- meters of the signal generator can then be changed.

To increase the input power, but in particular for better isolation of any, by the mixer MIX to the outside urgent high-frequency signal components, between the antenna ANT2 and mixer MIX a LNA (low noise amplifier, low-noise amplifier) are used, which amplifies the received signal. Alternatively, a directional coupler can be used.

For system-theoretical consideration, it is assumed that the switching signal s _sw (t) periodically weights the frequency-modulated signal SFMTx (t) with a pulse-shaped aperture function p (t), ie:

^ (O = WOZ zK '- "-? ¹ ) ⁽ D n = -oo

A simple aperture function could e.g. B. be a rectangular function, ie pulses with the width T ₀ which repeat with the period T. In this case follows:

Since the mixer works like a multiplier, a signal of the form arises behind the receive mixer MIX ^s "'x (0 = sin * (0 ^{• s} i * (0 = s _mRx (0 ^• % (* - *) = S ^ g _x Jt)' S _{11 n} QT) -Σ-p (t -τ -nT) (3)

^■ W (')

To simplify matters, all amplitude and damping factors have been neglected, since they would scale the result only linearly in any case.

From the formula it follows that the mixed signal smix (t) results as a mixed product of two non-pulse-modulated signals, ie smixc (t), and this mixed product of the continuous signals is to be weighted only with the pulse sequence. From the sampling theory for a real sampler with a finite aperture time, it is known that the periodic sampling with an aperture function leads to the following effects:

a) the sampling of smixc (t) with the periodic

Pulse train with the period T leads in the spectrum of smix (t) to a periodic repetition of the spectrum of smixc (t) with the period l / T

b) the signal smixc (t) can be completely reconstructed from the sampled signal smix (t) if the well-known sampling conditions are met

c) the periodic multiplication with the aperture function p (t) in the time domain leads in the spectrum to the fact that the spectrum of smixc (t) not only repeats periodically, but also has to be weighted with the Fourier transform of the aperture function.

It can be concluded from the above that after the treatment according to the invention of the pulsed signals, the calculated output variables advantageously and surprisingly in all methods for the synchronization of clock devices and for distance or transit time measurement between radio stations with FMCW-

Radio signals can be used when sampling or in the formation of the pulse sequences certain rules are observed and in the evaluation of the signals, the effects of the sampling are taken into account.

As a consequence of the above-mentioned relationships between the pulsed and the unpulsed signal, we now consider the continuous case in the representation of the method and the arrangements for the synchronization of UWB radio stations. The considerations thus provide e.g. First, smixc (t), the transmission to the pulsed case can then be done easily as shown above.

At the beginning of a measurement (t = 0), one of the two radio stations (station 1) involved in the synchronization or distance measuring process transmits a linearly frequency-modulated signal. This signal reaches the second station after the transit time τ. The frequency characteristic of the signal sRx (t) received by the station two, which is characterized by the bandwidth Bs, the ramp duration Ts and by the starting frequency fs, is shown in FIG.

With the signal generator of the second station, a signal similar to the received signal is generated. This locally generated signal sFMRx (t) differs from the received signal by a time offset Δt, since both stations have been activated at different times, and a frequency offset Δf, which is caused by the deviation of the clock sources used for signal generation of both stations. The frequency response of the locally generated signal is also shown in FIG.

In order to enable the first station to measure the distance, the second station must first synchronize its locally generated signal with the received signal. After time and

Frequency offset were corrected, the locally generated signal is finally with a known delay time for the first Station sent back. This allows the first station to determine its distance to the second station according to the standard FMCW radar principle.

In order to determine the time and frequency offset between the received and locally generated signals, both signals are mixed / multiplied together and the mixed signal is low pass filtered. The low-pass filtered mixed signal s _md , _f i _t (t) is passed through

S _nJj11 (0 = C ₁ cos 2πAf {t - At) + π ± (- 2tAt + At ² ) + C ₂ V / e (τ + At, τ + T _s ) (4)

described. Here, Ci represents a constant which is determined by the amplitudes of the received and the locally generated signal. The constant C ₂ depends on the starting frequency f _s and the initial phases of the two sinusoidal signals.

The frequency of the low-pass filtered mixed signal,

f _smdjit Vt≡ (τ + At, τ + TX (5)

depends only on time offset .DELTA.t and frequency offset .DELTA.f. B ₃ and T _s are constant system parameters. If the frequency of the low-pass filtered mixed signal is determined during an up-ramp (fi) and a down-ramp (fs) by means of the FFT algorithm, then

given a linear system of equations. The solution is time and frequency offset too _{Af =} AlA ₍₈₎

After calculating time and frequency offsets according to equations (8) and (9), the locally generated signal can be adapted to the received one.

A crucial difference when using UWB signals, which were generated in accordance with FIG. 1, is that the frequency lines at f _x and Ϊ ₂ - and also those at ~ fχ and -f ₂ when using no IQ mixer and thus only real-valued measurement signals are present - now repeat periodically and according to:

(10)

Since the sampling pulses are to be relatively short pulses, and the spectra of the measurement signals in a linear modulation are primarily line spectra, the effects of the spectral weighting shown under point b) are generally negligible.

Therefore, the effects of the periodic repetition of the spectra as described under a) must be taken into account. It is necessary to extract in the measured spectrum two spectral lines flk and f2k, preferably of a same and known order k and known symmetry position (+ or -), in order to derive fl and f2 therefrom and to convert them into the o.g. To use formulas.

There are different possibilities for a clear detection of the order and symmetry position of the spectral lines. 1) Presync with narrow band FM:

If a bandwidth of B _s <0.5 / T is used for the synchronization, no image frequencies due to the periodic continuation because of the UWB sampling (see FIG. 5) are present in the spectral range to be evaluated. For the order of the spectral lines, therefore, n = 0 and the symmetry position is unique.

2) Additional frequency offset Δf _z :

One of the two stations is detuned by an additional frequency offset Δf _z in _{such a} way that the frequencies fx and fΣ according to the equations (β) and (7)

always positive. As a result, the symmetry position is uniquely determined.

3) It is assumed that Δf is small: a correction can then be achieved with permutations of plausible frequency pairs.

4) Change of sweep parameters: will be higher

Bandwidth Bs <0.5 / T used for synchronization, so arise due to the periodic continuation of the spectrum due to the UWB sampling mirror frequencies in the spectral range to be evaluated. If sweep parameters, such as the sweep bandwidth Bs or the sweep time Ts, are changed, the position of the image frequencies shifts. From this shift can be closed to order and symmetry position.

5) A pre-synchronization can be over a normal

Radio communication can be achieved. These can be recordable Both stations known binary sequences are transmitted over the correlation of a rough synchronization of the clocks can be achieved.

example 1

The FMCW-modulated signal is blanked out in a rectangular manner. The switching signal used for this is 9 ns on and 991 ns off. The starting frequency of the sweep is 6.8 GHz, the final frequency 7.7 GHz and thus the bandwidth B _s = 900 MHz. The sweep duration is T ₃ = 10 ms and the peak power -3 dBm.

If a presynchronization to 5 μs is exactly achieved by a normal radio communication, a maximum frequency deviation of about 0.45 MHz results for the spectral lines to be examined. Since the period of the spectrum is 1 MHz due to the UWB sampling, a direct assignment of the spectral lines is possible (n = 0).

Example 2

For the FMCW modulated signal the same frequency range as in example 1 is used, also the switching times are identical. However, the sweep duration is only 2 ms. Normal radio communication achieves pre-synchronization to 100 μs exactly.

Now, in the first synchronization step, the sweep bandwidth is reduced to 10 MHz. This results in a maximum frequency deviation of about 0.5 MHz, so that in turn a direct assignment of the spectral lines is possible. The low bandwidth will presync to 1 μs so that full bandwidth synchronization can occur in the second synchronization step.

A pre-synchronization is also possible by using N time-shifted sweeps and the Amplitude curve of the measurement signal (or its spectral lines) evaluates. The larger the amplitude the better the synchronization or the lower the order of the frequency pairs.

It may be favorable to switch to an S & H mode after a first presynchronization, as shown in the example of a second embodiment of a radio receiver 3 in FIG. 3. In the receiver 3, a "Sample & Hold" (S & H) element is now provided which always samples the received pulse sequence and holds the value, even if a reflected pulse actually arrives. For this purpose, however, it is necessary to synchronize the Abtastpulsfolgen to the received pulse train. The pre-synchronization can be done with the o.g. Methods are performed without S & H or adaptively in the sense of a correlation, by slowly shifting the two pulse sequences one over the other and determining the maximum of the correlation.

The advantage of this variant with synchronous sampling compared to the variant without S & H is that in the receiving branch only a much lower gain is necessary and you can expect a much better signal-to-noise ratio, because not over the long periods in which no signal but only noise is present must be averaged.

Even if an additional effort arises in the synchronous sampling by the required Vorsynchronisierung, this is still much smaller than normal correlating pulse systems: the pulse duration can be significantly longer and the synchronization does not have to be very accurate (it is sufficient in principle, if the Somehow overlap pulse sequences), since the high-precision correlation still takes place mathematically based on the FM modulation and the large bandwidth is generated with the FM modulation, and not necessarily with the Pulse. This makes the synchronization or hardware correlation much easier and much faster than with normal pulse UWB systems. Also, the measurement can be performed faster and more energy efficient, since you can cover a running time range, which is 10 to 100 times the size of the pulse system with each measurement.

Generally, pre-synchronization can be accomplished by sampling a first pair of spectral lines and then synchronizing to a switching clock after the first sample to improve the signal-to-noise ratio.

The basic idea of the o.g. UWB-FMCW radar can also be transmitted in analog form to location systems with a so-called backscatter modulator or transponder, see FIG. 4. For this purpose, the transmitters and receivers are arranged in a common transmit / receive unit 4 and the runtime is backscattered signals.

For measuring the distance to a backscatter modulator or transponder 5, the arrangement of FIG. 1 with elements from FIG. 2 to FIG. 4 is expanded. As can be seen, the transmit signal is blanked out with a periodic aperture function so as to be able to generate an ÜWB signal in accordance with legal regulations. At the backscatter modulator 5, the transmission signal is reflected modulated, usually the modulation function modulates the complex reflection factor behind the antenna ANTB respect. Amount and / or phase with a modulated matching network MAN. The mixed signal behind the receive mixer MIX results to

s _mbc (0 = s _mιlx (0 • s _lh (0 = s _FM7 , (0 • s _Tx (t-T) • m (t) = s _mrx (t) -s _FMrx (t-τ) _-m ( t) - Σ -p (l - τ - n - T)

(12) It can be seen from the formula that the mixed signal smix (t) is a mixed product of two non-pulse modulated ones Signals, ie smixc (t), results and this mixed product of the continuous signals is weighted only with the sampling sequence.

If, therefore, the modulation frequency of m (t) is selected to be low enough or the period T of the sampling is sufficiently small and the aperture time sufficiently short, then the information in the signal smix (t) corresponds exactly to the information which is a continuously transmitting variant (ie if SW 1 would always be closed) would deliver.

Preferably, the highest frequency of m (t) is to be chosen to be less than half the sampling frequency than none to 0.5 / T. Preferably, furthermore, the lowest frequency of m (t) is to be chosen so that it is much larger than the reciprocal of the sweep duration. Preferably, the duration of the UWB pulses is to be chosen so that they are significantly shorter than the reciprocal of the highest frequency that occurs in the signal m (t).

Meaningful parameters for interpreting a system of FIG. 4 would be and for generating the UWB pulses by pulsed blanking of the FMCW modulated signal would be e.g. pulse duration 9 ns; Pulse break 991 ns; lowest frequency of the FMCW sweeps: fMinSweep 6.8 GHz; highest frequency of the FMCW

Sweeps: fMaxSweep 7.7 GHz; Duration of the FMCW sweep 100 ms; and highest frequency of m (t) about 400 kHz.

If m (t) is a periodic band-limited signal with the period Tm = 1 / fm and a bandwidth «0.5 / T, then a spectrum Smix (f) of the time signal smix (t) results in the form as shown in FIG. 5 is shown.

The distance Δf of the spectral lines lying symmetrically about the modulation frequency (the left spectral line is in each case the reflection of the negative frequency components on the ordinate) is proportional to the distance. It can also be the Phase of the two lying symmetrically about the modulation frequency spectral lines are used for distance and speed measurement.

The executed backscatter system is ideal for low-cost, low-power, low-range location systems, such as home, vehicle, and computer access systems, context-sensitive information transfer systems (at trade fairs, in museums, in machinery production and maintenance, and in assisted or disabled older people), RFID systems, logistics but also for the high-precision location of tools and robots / robot arms in automation technology or ^' medicine.

The embodiment described above is not intended to limit the invention or its applications in any way.

Claims

claims

1. Radio transmitter (1,4), at least comprising

a signal generator (SGEN1) for generating a continuous signal (sFMTx (t)),

an antenna (ANT1) for outputting a transmission signal

(STX (t)),

- Wherein at least one output of the transmission signal generator

(SGEN1) is connected to at least one input of the antenna (ANT1), characterized in that

- The transmission signal generator (SGENL) with the antenna (ANTL) via an intermediate interrupter unit

(SW1) for selectively interrupting and maintaining a signal connection between the transmission signal generator (SGEN1) and the antenna (ANT1), and in that

- The optional interrupting and maintaining the signal connection by the interrupter unit (SWl) by means of an interrupt unit (SWl) externally applied switching signal (ssw (t)), and in that

- The optional interrupting and maintaining the signal connection by the interrupter unit (SWL) takes place in at least partially regular intervals, wherein a duration of a pulse period is less than one

Duration of a frequency modulation of the continuous signal generated by the transmit signal generator (SGEN1).

2. Radio transmitter (1,4) according to claim 1, characterized in that the continuous signal generated by the transmission signal generator (SGEN1) is an at least partially linearly frequency-modulated signal (sFMTx (t)).

3. Radio transmitter (1,4) according to claim 2, characterized in that the duration of the pulse period, in particular with a fixed

Pulse period is less than a duration of a frequency modulation of the transmission signal generator (SGENl) generated continuous signal, in particular at least 10 times smaller.

4. radio transmitter (1,4) according to one of the preceding claims claims, characterized in that the signal generator

(SGEN1) for generating the continuous signal (sFMTx (t)) and the breaker unit (SW1) for selectively interrupting and maintaining the signal connection by respective clock signals (ssw (t)) which are in a known deterministic relationship with each other Transmit signal generator (SGENL) and the interrupter unit (SWl) for driving with a digital electronics (DIGEl) are connected, which generates the respective clock signals (ssw (t)) based on a common clock base.

5. radio transmitter (1,4) according to claim 4, characterized in that it comprises a clock generator (CLKL) for outputting a clock signal generated by it to the digital electronics (DIGEI); the digital electronics (DIGEl) generating a first derived clock signal for input to the transmit signal generator (SGEN1) and a second derived clock signal (ssw (t)) for input to the interrupter unit (SW1); and wherein the transmission signal generator (SGEN1) generates, based on the first derived clock signal, the continuous signal (sFMTx (t)) input to the interrupter unit (SW1); and wherein the interrupt unit (SW1) selectively disrupts and maintains the signal connection between the transmit signal generator (SGEN1) and the antenna (ANT1) based on the second derived clock signal (ssw (t)).

6. radio receiver (2,3,4) for receiving frequency-modulated and pulsed radio signals (sRx (t)) in particular a radio transmitter according to any preceding claim, characterized in that it is adapted to receive from received frequency-modulated and pulsed radio signals (sRx (t )) to extract at least one pair of associated spectral lines (flk, f2k), in particular spectral lines (flk, f2k) of the same order (k) and known symmetry position.

7. Radio receiver (2,3,4) according to claim 6, characterized in that it is adapted to determine from the pair of associated spectral lines (flk, f2k) a frequency offset and / or a time offset and in particular on the basis of the calculated

Frequency offset and / or time offset to synchronize a clock of the frequency-modulated and pulsed radio signals (sRx (t)) emitted radio transmitter (1,4).

8. radio transmitting / receiving system of at least one radio transmitter (1,4) according to one of claims 1 to 5 and at least one radio receiver (2,3,4) for receiving from the radio transmitter (1,4) emitted signals, in particular with a radio receiver (2,3,4) according to any one of claims β to 7.

9. radio transmitting / receiving system (4) according to claim 8, characterized in that the radio transmitter (1,4) and the radio receiver (2,3,4) have the same clock source (CLKL) for providing a common clock base.

10. Arrangement with at least one radio transmitting / receiving system (4) according to one of claims 8 or 9 for the synchronization of the radio transmitting / receiving system (4).

11. Arrangement with at least one radio transmission / reception system according to one of claims 9 or 10 for distance measurement to a transponder.

12. Arrangement according to claim 11, wherein the response device is embodied as a transponder comprising a second radio transmission / reception system (4) according to one of claims 16 or 17.

13. Device according to one of claims 8 to 11, wherein a response device is designed as a backscatterer transponder (5).

14. A radio receiver (2,3,4) for use in a device according to one of claims 8 to 13, comprising at least one mixer (MIX), which mixes a received signal with a mixed signal (sFMTx (t), sFMTx (t)) and thereby forming a measurement signal (smd (t)) for the purpose of synchronization or range finding, the mixed signal having a similar or identical modulation as the signal of the transmit signal generator (SGEN1).

15. A radio receiver (2,3,4) according to claim 14, wherein the similar modulation has a time offset and / or a frequency offset with respect to the signal of the transmit signal generator (SGEN1).

16. A method for generating and evaluating the measurement signal (smd (t)) of the radio receiver (2,3,4) according to any one of claims 14 or 15, characterized in that interrupting and maintaining a signal connection between the signal generator (SGENL) and the Antenna (ANTI) is performed so that the signal connection in the measurement signal (smd (t)) represents a time discretization with a real scanner, and that interrupting and maintaining the signal connection by means of the interrupter unit (SWl) is performed in time so that the sampling theorem is satisfied for the measurement signal (smd (t)).

17. The method of claim 16, wherein at least the sampling frequency is selected twice as large as the

Bandwidth of the measurement signal, and wherein and the duration of maintaining the signal connection significantly smaller, in particular smaller than by a factor of 4, is the inverse of the highest frequency occurring in the measurement signal.

18. A method for synchronizing at least one radio transmitter (1,4), in particular a radio transmitter (1,4) according to one of claims 1-5, and at least one radio receiver, in particular a radio receiver according to one of claims 6, 7, 14 or 15, wherein at least one of the radio transmitters comprises at least one signal generator (SGEN1) for generating a continuous signal (sFMTx (t)) and an antenna (ANT1) for outputting a transmission signal (sTx (t)), characterized in that

- The radio transmitter (1,4) from the continuous signal (sFMTx (t)) by selectively interrupting and

Maintaining a signal connection to the antenna (ANT1) via the antenna (ANT1) emits a pulse-shaped radio transmission signal (sTx (t)), wherein a duration of a pulse period is less than a duration of a frequency modulation of the continuous signal generated by the transmission signal generator (SGEL),

- And that the radio receiver (2,3,4) from the received pulse-shaped radio signals (sRx (t)) at least one pair of associated spectral lines (flk, f2k) extracted and determines therefrom a frequency offset and / or a time offset on the or Basis of the radio receiver (2,3,4) synchronized to a clock of the radio transmitter (1,4).

19. A method for distance measuring and / or locating a transponder, wherein a radio transmitter (1,4) has at least one signal generator (SGEN1) for generating a continuous signal (sFMTx (t)) and an antenna (ANT1) for outputting a transmission signal (sTx ( t)), characterized in that

- The radio transmitter (1.4) from the continuous signal (sFMTx (t)) by selectively interrupting and maintaining a signal connection to the antenna (ANTl) via the antenna (ANTl) a pulse-shaped radio transmission signal

(sTx (t)) in the direction of the transponder (5), wherein a duration of a pulse period is less than a duration of a frequency modulation of the continuous signal generated by the transmission signal generator (SGEN1), - and that the transponder (5) this signal to a radio receiver (4) reflects in a modulated manner and in that the radio receiver (4) extracts at least one spectral line (flk, f2k) from the received pulsed radio signals (sRx (t)) and determines therefrom a distance and / or position of the transponder (5) on which or not . whose basis the radio receiver synchronizes to a clock of the radio transmitter (1,4).

20. The method according to any one of claims 18 or 19, characterized in that wherein the transponder as a

Backscatterer transponder (5) is executed.