DE102017128051A1 - Method for locating an object that is floating on a water surface and marked with a transponder by means of a radar - Google Patents

Abstract

A method for locating an object floating on a water surface, marked with a transponder by means of a radar, wherein the receiver of the radar is able to accurately measure a vectorial signal of the transmitter of the radar despite changed frequency and the transponder a receiving antenna for the reception of the Radar transmitted signal, either a purely passive circuit for multiplying the frequency of the signal received from the transponder or an active circuit for multiplying the frequency of the signal received from the transponder, optionally one or more amplifier stages and a transmitting antenna for transmitting the received signal with a multiplied frequency as a response signal, characterized by the steps of: transmitting a first sine signal at a first predetermined frequency, transmitting a second sine signal at a second predetermined frequency, receiving the response signals transmitted from the transponder and determining the distance tion of the transponder to the radar from the over the transmission frequency of the radiated from the radar sinusoidal phase change of the response signals of the transponder.

Description

The invention relates to a method for locating an object marked with a transponder by means of a radar, wherein the transponder has a receiving antenna for receiving the signal transmitted by the radar, a passive circuit for multiplying the frequency of the signal received by the transponder and a transmitting antenna for transmitting the Having received signal with a multiplied frequency as a response signal.

Such a system is already being used as an avalanche search system. The system works with passive reflectors (transponders) and active search devices according to the principle of harmonic radar. The reflectors do not require their own power supply, are easy to manufacture and are easily installed in winter sports clothing and equipment. Searching for burials by professional salvage teams is greatly facilitated and accelerated by the system, which is often lifesaving.

Although the known method has been tried and tested successfully for avalanche victims, the method can not readily be applied to other applications, e.g. to the rescue of shipwrecked, transferred. In particular, the known method lacks the possibility of estimating the distance of the seeker to the person in need of assistance - this is not necessary in the rescue of avalanche victims due to the relatively low burial depth. At sea, on the other hand, the estimation of the distance between the ship and the shipwrecked is a prerequisite for a quick and safe locating of the shipwrecked and its rescue.

The object of the invention is therefore to further develop the known method so that shipwrecked ships equipped with a transponder can be found quickly.

This object is achieved by the method with the features of claim 1 and the system with the features of claim 4. The subclaims reflect advantageous embodiments of the invention.

The basic idea of the invention is to deduce at least two sinusoidal signals of different frequency instead of the frequency-offset "reflection" of a sine signal emitted by the radar, with the phase shift of the two "reflected" by the transponder, i.e. the presence of a needy including directional information. radiated response signals is used to calculate the distance between radar and transponder.

According to the invention, a method is provided for locating an object floating on a water surface, marked with a transponder by means of a radar, the transponder having a receiving antenna for receiving the signal transmitted by the radar, a passive circuit for multiplying the frequency of the signal received by the transponder and a transmitting antenna for transmitting the received signal with a multiplied frequency as a response signal. This consists in transmitting a first sine signal at a first predetermined frequency, transmitting a second sine signal at a second predetermined frequency, receiving the response signals sent by the transponder, and determining the distance of the transponder to the radar from the phase change of the sinewave signal emitted by the radar over the transmission frequency Response signals of the transponder.

The accuracy of the distance determination can be increased by transmitting at least a third sine signal at a third predetermined frequency and removing the transponder from the radar from the phase change of the three response signals of the transponder determined via the transmission frequency of the sine signals emitted by the radar.

Particularly preferably, the transmission of the sinusoidal signals takes place as a stepped sweep over 10-20 frequency points.

Furthermore, a system is provided for carrying out the aforementioned method, comprising a ship radar with a transceiver comprising a control unit, a transmitting unit connected to the control unit, a receiving unit likewise connected to the control unit, a diplexer connected to both the transmitting unit and the receiving unit a first antenna connected to the diplexer, and a transponder having a second antenna and a diode configured for frequency doubling.

The transponder is designed either as a purely passive transponder or as an active transponder. The latter consists of the modules of the passive transponder, possibly an active frequency conversion unit, possibly a small signal amplifier in the reception area, possibly a small signal amplifier in the transmission range and a power supply (often battery), etc. by seawater, push of a button. is activated.

In this case, the first antenna of the ship's radar is preferably composed of a first waveguide slot antenna configured for emitting sinusoidal signals in a first frequency range and one for the reception formed of the signal emitted by the transponder second waveguide slot antenna.

• 1 eine schematische Ansicht des grundsätzlichen Aufbaus eines Systems zur Durchführung des erfindungsgemäßen Verfahrens;
• 2 eine schematische Ansicht eines besonders bevorzugt ausgestalteten ersten Ausführungsbeispiels eines Systems nach der Erfindung; und
• 3 eine schematische Ansicht eines besonders bevorzugt ausgestalteten zweiten Ausführungsbeispiels eines Systems nach der Erfindung.

The invention is explained in more detail below with reference to an embodiment shown in the attached drawings, particularly preferred. Show it:

• 1 a schematic view of the basic structure of a system for carrying out the method according to the invention;
• 2 a schematic view of a particularly preferred embodiment of a first embodiment of a system according to the invention; and
• 3 a schematic view of a particularly preferred embodiment of a second embodiment of a system according to the invention.

1 shows a schematic view of the basic structure of a system for carrying out the method according to the invention.

Specially shows 1 the necessary system components of the maritime rescue system according to the invention, consisting of a transceiver unit, in short transceiver 10 coming from a sending unit 40 and a receiving unit 50 and a diplexer connected to them 60 exists, and at least one transponder 20 (also known as day). The day 20 consist in the simplest case of a diode for frequency doubling and a dual-band antenna for the transmission and the reception frequency and is therefore purely passive.

The control computer 30 of the transceiver 10 determines the distance and using the information of the antenna orientation and the measured values the position. This data is transferred by the control computer to the central computer of the ship. The transceiver 10 sends a sine signal with frequency fi (i: running index) to one day. In day 20, this sinusoidal signal is offset in frequency. For example, there is a duplication. The frequency offset signal is further from the transponder 20 reflected, ie radiated.

The transceiver 10 receives the reflected and frequency-changed sinusoidal signal and evaluates the phase φ (f _i ). This measurement is carried out at additional frequencies. From the phase above the transmission frequency can then determine the distance information.

wobei c₀die Lichtgeschwindigkeit angibt. Aus den Grundlagen der nichtlinearen Frequenzumsetzung ist bekannt, dass sowohl beim quadratischen Term, der für die Frequenzumsetzung bei Verdopplern herangezogen werden muss, wie auch beim kubischen Term, der für IM-Produkte 3. Ordnung herangezogen werden muss, die durch die Frequenzkonversion veränderte Phase des ankommenden Signales um den festen Faktor 2 verändert wird. Es gilt somit für die gesamte Phasendrehung der frequenzumsetzenden Reflexionsmessung über die Entfernung ℓ_x für den Frequenzpunkt f₁ am Eingang und den Frequenzpunkt f₂ am Empfänger: $$\angle {\text{r}}_{\text{g}}^{21}=2{\mathrm{\beta }}_1{\mathcal{l}}_{\text{x}}+{\text{r}}_{\text{x}}^{21}+{\mathrm{\beta }}_2{\mathcal{l}}_{\text{x}}$$

wobei ${\text{r}}_{\text{x}}^{21}$

der bekannte ${\text{S}}_{\text{ii}}^{\text{kl}}-\text{Reflexionsfaktor}$

der Referenzstation bei der Frequenz f₁ auf die Frequenz f₂ ist (z.B. die doppelte Frequenz f₂ = 2f₁).This maritime rescue system can be implemented in principle in various technologies (microwave technology, optics, ultrasound, etc.). In the high-frequency and microwave range, the propagation coefficient in the free space is the propagation coefficient $$\beta \left(f_i\right)={\beta }_i=\left(2\pi f_i\right){\text{/ <figure-callout id="0" label="c" filenames="DE102017128051A1\_0014.png" state="{{state}}">c</figure-callout>}}_0$$

where c ₀ indicates the speed of light. From the basics of nonlinear frequency conversion it is known that both for the quadratic term, which has to be used for frequency conversion in doublers, as well as for the cubic term, for IM products 3 , Order must be used, the phase of the incoming signal, which has been changed by the frequency conversion, by the fixed factor 2 is changed. It thus applies to the entire phase rotation of the frequency-converting reflection measurement over the distance ℓ _x for the frequency point f ₁ at the input and the frequency point f ₂ at the receiver: $$\angle {\text{r}}_{\text{G}}^{21}=2{\mathrm{\beta }}_1{\mathcal{l}}_{\text{x}}+{\text{r}}_{\text{x}}^{21}+{\mathrm{\beta }}_2{\mathcal{l}}_{\text{x}}$$

in which ${\text{r}}_{\text{x}}^{21}$

the known ${\text{S}}_{\text{ii}}^{\text{kl}}-\text{reflection factor}$

the reference station at the frequency f _{1 is} at the frequency f ₂ (eg the double frequency f ₂ = 2f ₁ ).

in Abhängigkeit vom Messwert $\angle {\text{r}}_{\text{m}}^{21}\text{:}$

$$\angle {\text{r}}_{\text{g}}^{21}=\angle {\text{r}}_{\text{m}}^{21}+\text{n}\cdot \text{2}\mathrm{\pi }$$

wobei n eine ganze Zahl ist, die im Weiteren noch bestimmt wird.The phase of the frequency-converting component is measured only in the uniqueness range of 360 °. Consequently, the whole phase value applies $\angle {\text{r}}_{\text{G}}^{21}$

depending on the measured value $\angle {\text{r}}_{\text{m}}^{21}\text{:}$

$$\angle {\text{r}}_{\text{G}}^{21}=\angle {\text{r}}_{\text{m}}^{21}+\text{n}\cdot \text{2}\mathrm{\pi }$$

where n is an integer, which will be determined later.

liegen von einer unteren Frequenz f_1u bis zu einer oberen Frequenz f_1o als ${\angle }_{\text{m}}^{21\text{u}}\text{ und }\angle {\text{r}}_{\text{m}}^{21\text{o}}$

vor. Zwischen den verschiedenen Messpunkten soll es keine Phasensprünge geben, die sich in der praktischen Mathematik auch einfach eliminieren lassen. Aus diesen beiden Messwerten und den bekannten zugehörigen Frequenzpunkten lässt sich die Steigung der Phase über der Frequenz ermitteln: $$\text{S}=\frac{\mathrm{\Delta \varphi }}{\mathrm{\Delta }\text{f}}=\frac{\angle {\text{r}}_{\text{m}}^{21\text{o}}-\angle {\text{r}}_{\text{m}}^{21\text{u}}}{{\text{f}}_{1\text{o}}-{\text{f}}_{1\text{u}}}$$

The measured values of the ${\text{S}}_{\text{ii}}^{\text{kl}}-\text{reflection factor}$

are from a lower frequency f _1u up to an upper frequency f _1o than ${\angle }_{\text{m}}^{21\text{u}}\text{and}\angle {\text{r}}_{\text{m}}^{21\text{O}}$

in front. Between the different measuring points, there should be no phase jumps, which can be easily eliminated in practical mathematics. From these two measured values and the known associated frequency points, the slope of the phase over the frequency can be determined: $$\text{S}=\frac{\mathrm{\Delta \phi }}{\mathrm{\Delta }\text{f}}=\frac{\angle {\text{r}}_{\text{m}}^{21\text{O}}-\angle {\text{r}}_{\text{m}}^{21\text{u}}}{{\text{f}}_{1\text{O}}-{\text{f}}_{1\text{u}}}$$

wird der richtige Wert für n gefunden. Es gilt für die Längenbestimmung der Entfernung ℓ_x basierend auf den Gleichungen [2] und [3] für jeden Frequenzpunkt: $${\mathcal{l}}_{\text{x}}=\frac{\angle {\text{r}}_{\text{g}}^{21}-\angle {\text{r}}_{\text{x}}^{21}}{2{\mathrm{\beta }}_1+{\mathrm{\beta }}_2}$$

At the arbitrary frequency f _i , due to the slope, there is a fundamental phase rotation of φ _i = f _i S. This equation can also be obtained with f _o = f _i and f _u = 0 Hz and the associated phase values from derive the above equation. By the following condition $$180°\le \left|\angle {\text{r}}_{\text{m}}^{21\text{i}}+\text{n}\cdot \text{2}\mathrm{\pi -}{\text{f}}_{\text{i}}\text{S}\right|$$

the right value for n is found. It applies to the length determination of the distance ℓ _x based on the equations [2] and [3] for each frequency point: $${\mathcal{l}}_{\text{x}}=\frac{\angle {\text{r}}_{\text{G}}^{21}-\angle {\text{r}}_{\text{x}}^{21}}{2{\mathrm{<figure-callout\; id="1"\; label="\beta "\; filenames="DE102017128051A1\_0015.png,DE102017128051A1\_0016.png"\; state="\{\{state\}\}">\beta </figure-callout>}}_1+{\mathrm{\beta }}_2}$$

auch durch eine einmalige Messung bei bekannter Länge bestimmen. In der Praxis wird jedoch Gleichung [6] für jeden gemessenen Frequenzpunkt ausgewertet, damit durch eine anschließende Mittelung stochastische Fehler minimiert werden.In addition to the exact solution can be ${\text{r}}_{\text{x}}^{21}$

also determined by a single measurement at a known length. In practice, however, equation [6] is evaluated for each measured frequency point so that subsequent averaging minimizes stochastic errors.

The accuracy of this measurement increases with the bandwidth (f _1o - f _1u ) and the number of measurements, thus with the measuring time. For the rescue of the sea one will work out a compromise of accuracy and measuring time, which may also be dependent on distance.

This mathematical description can be summarized as a literal description so simplified that this distance measurement works with frequency conversion similar to a standard measurement of a vector network analyzer (VNA) and its evaluation of the reflection size S _11th The negative slope of the phase from the vectorial variable S ₁₁ is referred to as a group delay and indicates the transit time to a reflection object. If the transmission channel (in this case air) is not dispersive, then this time can be determined in each frequency range by measuring at least 2 frequency points.

In contrast to this VNA measurement, however, not every object (such as waves) is detected in the frequency-converting measurement.

As can be seen in Equation 6, the distance determination is not as easy as the group delay calculation, the results of which the VNA also displays directly.

2 shows a schematic view of a particularly preferred embodiment of a first embodiment of a system as a pure rescue radio radar with frequency doubling according to the invention.

The control computer 30 outputs a low-frequency sine wave signal through the integrated baseband signal processing unit. This sinusoidal signal is in the transmitting unit 40 by means of the mixer, which is additionally pumped by the large signal of the local generator (LO), in the frequency (usually in the GHz range) implemented. This high-frequency signal is in the power amplifier (PA: power amplifier) of the transmitting unit 10 amplified and to the diplexer 60 passed on. There, this transmission signal can pass through the filter properties of the diplexer only to the rotary coupling, the part of the antenna unit 70 is.

On the one hand, this rotary coupling allows the high-frequency signal to be transmitted in a low-loss manner and, on the other hand, allows the rotation whose simple control has not been shown here for reasons of clarity.

In addition, this signal passes through another diplexer in the transmitting antenna, which is marked by LO. The signal transduced by the transponder in the frequency and reflected back is detected by the antenna indicated by 2LO, via the diplexer of the antenna unit 70 directed to the rotary coupling and then over the diplexer 60 the receiving unit 50 fed.

There, this small signal is boosted by a low-noise preamplifier (LNA: low noise amplifier) and other amplifier stages in the performance. Thereafter, it is via the mixer of the receiving unit, in addition by the large signal of the local generator via the frequency doubler X2 is pumped by the signal 2LO, converted to a low frequency without loss of information. Finally, the measurement signal is vectorially digitized via analog / digital converter (AD) and evaluated in the control computer.

The mode of the transmitter and the receiver hardware must be designed for this method so that the receiver of the radar is able to accurately measure a vectorial signal of the transmitter of the radar despite changed frequency. For this purpose, all oscillators (quartz oscillator and high-frequency oscillator (s) must be constantly in phase with each other.

3 shows a schematic view of a particularly preferred embodiment of a second embodiment of a system as combined marine and rescue radar frequency doubling according to the invention.

3 differs from 2 by a slight extension of the diplexer unit 60 by a circulator and an additional receiving unit 80 for ship radar operation.

This Schiffsradarbetrieb can be carried out without interruptions parallel to the rescue operation.

The circulator ensures that the small signal reflected by the vessel, which is picked up by the antenna LO and passed through both diplexers and the rotary coupling as the electromagnetic wave (high-frequency signal), is fed to the receiver unit for the LO signal. The further signal processing is the same as with the receiver for 2LO, except that the pump signal of the local oscillator pumps at half the frequency of the mixer.

In practice, it is also possible to switch over from a magnetron transmitter of a pulse radar system to the transmitter unit 40 switch over and the receiver shown here 80 replace with the only slightly different receiver of a magnetron pulse radar.

Claims (6)

A method for locating an object floating on a water surface, marked with a transponder by means of a radar, wherein the receiver of the radar is able to accurately measure a vectorial signal of the transmitter of the radar despite changed frequency and the transponder a receiving antenna for the reception of the Radar transmitted signal, either a purely passive circuit for multiplying the frequency of the signal received from the transponder or an active circuit for multiplying the frequency of the signal received from the transponder, optionally one or more amplifier stages and a transmitting antenna for transmitting the received signal with a multiplied frequency characterized by the steps of: transmitting a first sine signal at a first predetermined frequency, transmitting a second sine signal at a second predetermined frequency, receiving the response signals transmitted by the transponder, and determining the Distance of the transponder to the radar from the phase change of the response signals of the transponder determined via the transmission frequency of the sine signals emitted by the radar. Method according to Claim 1 characterized by transmitting at least a third sine signal at a third predetermined frequency and determining the distance of the transponder to the radar from the phase change of the response signals of the transponder determined via the transmission frequency of the sine signals emitted by the radar. Method according to Claim 2 , characterized in that the sine signals are sent in a sweep. System for carrying out the method according to one of the preceding claims, with a Ship radar with a transceiver (10) comprising a control unit (30), a transmission unit (40) connected to the control unit (30), a reception unit (50) likewise connected to the control unit (30), one with both the transmission unit (40) and diplexers (60) connected to the receiving unit (50) and a first antenna connected to the diplexer (60), and - A transponder (20) with a second antenna and a diode configured for frequency doubling. System after Claim 4 , characterized in that the transponder (20) is a passive transponder. System according to one of Claims 4 and 5 , characterized in that the first antenna is formed of a first waveguide slot antenna configured to emit sinusoidal signals in a first frequency range and a second waveguide slot antenna configured to receive the signal emitted by the transponder.

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