DD240825A3 - LOCATION PROCESS WITH DIRECTIONS, ESPECIALLY FOR THE PANORAMIC PRESENTATION OF ROOMED AND / OR LIGHTED ROOMS, PREFERABLY OF UNDERWATER ROOMS - Google Patents

Abstract

The invention relates to a method for panoramic detection, for measuring the distance and the angular position of a reflecting object, such as a school of fish in the underwater space. The aim of the invention is the elimination of the disadvantages that occurred in the panoramic positioning by means of the previously used methods for electronic or mechanical beam steering. The object of the invention is the specification of a locating system which allows to radiate a large angular range without beam sweep at the same time, to search for reflective objects and to determine their position. The essence of the device required for this purpose consists in a transmitting-receiving antenna with regions of different, above all linearly increasing resonance frequency (eg wedge-shaped piezoceramic plate), a frequency-modulated pulses (especially with linearly increasing frequency) generating generator and a series circuit of many compression networks in the receiving channel. An object located at a certain angle of reflection reflects the transmitted pulse to the receiver where, due to the number of that compression network behind which the maximum amplitude is measured, the attitude angle can be determined based on previously performed calibrations or calculations. Because the number of compression networks to be traversed up to the maximum compression is directly related to the position comparison of the object.

Description

The invention relates to a positioning method with direction determination, in particular for the panoramic representation of irradiated and / or scanned rooms, preferably of underwater spaces by means of sound or ultrasonic transmitting and / or receiving converter.

A panorama representation includes the specification or representation of spatial coordinates of the sound-reflecting, angeloteten objects in space, d. H. the indication or representation of the distance as well as the horizontal and vertical angles under which the object appears from the location of the plumb line.

The determination of the distance is relatively simple, since it is equivalent to the duration of the sonic or ultrasonic pulse from the transmitting transducer to the reflecting object and back to the receiving transducer. Each sonar or radar device determines the distance of the reflecting object in this way.

It is much more difficult to determine the horizontal and vertical angles at which the object appears from the location of the plumb line.

It is already known to determine the lateral or horizontal angular position according to the radar principle in that a converter with high directivity, which is operated at relatively high frequencies, such as a radar antenna is mechanically rotated. The angular position of the transducer when receiving an echo signal is then identical to the desired angular size.

The high directivity of the transducer is essential for a useful angular resolution.

However, since the group velocity of the sound waves in the water is about 2 × 10 ⁵ times lower than the group velocity of the radar electromagnetic waves in air, the transducer may only rotate relatively slowly so that the echoes of distant objects are still received, ie still too belong to the angular range for which the transducer is sensitive due to its high directivity.

Thus, a transducer with a main lobe width Δα = 1 ° in the time step At = 4sec should continue to turn only by 1 °, if echoes from 3km distance are to be received. The scanning of an angular range of 60 ° would thus be finished only after 4 minutes.

The application of this principle is therefore not useful because of navigational reasons and because of the sometimes large ship speed or object speed. In addition, only one of the two desired angles is determined at this relatively high cost.

The still known electronic beam sweep, which can replace the mechanical rotation of the transducer, brings no advantages in terms of temporal resolution.

- ζ - ^. tu οί -'- j

To solve this problem, it has been proposed to use a plurality of high-resolution, slightly mutually inclined transducers, which simultaneously emit a pulse in their respective assigned direction, these transducers differing in their resonance frequency or another identifier. The pulses emitted by the individual transducers and also received in the case of the existence of reflecting objects have different carrier frequencies adapted to the resonance frequencies of the transducers. From the frequency of the received pulse, therefore, it is easy to deduce the transducer which has received this pulse, and also the direction from which the pulse was received.

For this arrangement to achieve a panoramic reception in particular the amount of required transducers, but also the electronic effort considerably, because on the transmitting side for each converter a separate pulse generator for generating the specific carrier frequency is required.

A substantial reduction of the effort does not bring the use of multiple transducers with the same resonant frequency. Since each transducer must have a good directivity for high angular resolution, it is first possible to arrange a plurality of similar transducers so that they are not immediately adjacent, so that their main lobes do not overlap each other. For the group of these transducers with the same resonant frequency, a pulse generator is sufficient. But now that the direction of the incoming pulse can be determined, each converter requires a separate amplifier.

In this arrangement, practically the electronic effort has been shifted from the transmitting side to the receiving side. The reduction in the number of different transducers must be paid for by an increase in the individual transducers, since these must now have a better directivity.

Other proposals are based on connecting these converters with the mutually inclined directional lobes to the contacts of a switch level and query these converters by means of the rotary switch chronologically or to put on the pulse generator.

The difference to the already discussed at the beginning rotatable transducers or transducers with electronically pivotable directional pattern is only that another element, namely the switch, has taken over the function of pivoting. However, the main disadvantage of the low time resolution is not eliminated.

If the entire angular range is sampled within the duration of a pulse, for example, by increasing the angular velocity of the interrogating switch or by performing the electronic beam sweep at the required sweep rate, the disadvantage of the low time resolution is eliminated. However, since on the one hand the mechanical angular velocity limits are set and on the other hand a minimum action quantum is required for the detection of the received pulse, the pulse length is chosen to be relatively large in this case, whereby the distance resolution of the system is relatively low and thus does not provide a perfect result.

Another known method no longer uses a large number of high-resolution, mutually inclined transducers with different resonance frequencies in order to transmit signals with different identifiers in the different directions or to receive such signals from these directions, but broadband transducers are arranged in a row, which are connected to a runtime or all-pass chain. When sending a broadband signal is given to the input of the delay line. It reaches the individual transducers according to the transit time differences specified by the delay line. The same differences in transit times result in different phase differences for different frequencies.

Since the vectorial addition of the signals from all the transducers yields the resulting radiated acoustic signal, the maximum of this sum for each frequency arises in a different direction. In the same way, a different frequency is received from each direction. For each frequency, a selective receive amplifier is used. A frequency analyzer can be seen with a suitable calibration scale directly the origin direction of the incoming pulse.

The expense has not decreased over the previously described methods because of the use of a large number of selective receive amplifiers. However, crucial difficulties arise in the realization of the transmission-side delay chain, which must be designed for high power.

Modern methods mainly use the principle of undirected energy radiation and the directional selection or direction detection of the received echoes by the receiving arrangement. In this case, therefore, the transmit transducers are operated at a frequency and are designed so that the entire search sector is durchschallt. The receiving transducer consists of a system of elements arranged in one plane, which are interconnected according to the principle of electronic beam tilting. The arrival of a wavefront from the normal direction of the plane causes all the transducer elements to simultaneously convert this acoustic wave into electrical signals. In an adder, which forms the vectorial sum, the amplitudes are added to a total amplitude because of the in-phase of all signals.

When the wave fronts arrive from another direction, on the other hand, runtime differences occur, which cause each element to emit a signal with a different phase. The vectorial sum only gives an amplitude which corresponds to the sum of the individual amplitudes if the phase differences resulting from the propagation time differences are compensated by phase shifters.

Variable phase shifters thus allow a pivoting of the directional lobe, depending on the setting of the phase shifter, the maximum of the sensitivity is coupled to another direction of incidence of the acoustic wave.

For the reasons already outlined, however, electronic beam tilting for panoramic display has not been successful in practice. In general, therefore, an entire group of differently adjusted phase shifters is connected in parallel to each transducer element and also increases the number of summing. The number of phase shifters required per transducer element and the associated number of summing elements depends on the required angular resolution and the total angular range, ie. H. according to the number of simultaneously requested angles.

The cost of this type of panoramic display is so significant, especially when larger angular ranges are to be searched.

The purpose of the invention is to eliminate the disadvantages listed.

The invention has for its object to provide a hydroacoustic system for directional determination of georteter objects, preferably a panoramic system, in which the disadvantages are eliminated and the hitherto customary effort is substantially reduced.

According to the invention, the object is achieved in such a way that caused by extensive transmitting and / or receiving antennas angle-dependent distortions of the transmitted udn received modulated pulses can be supplemented by additional introduced into the receiving channel signal converter, preferably matched filters to optimal pulse distortion, the size of the supplemented Distortions are indicative of the angles from which the received signal appears.

In detail, the transmitting and / or receiving antenna is designed such that it allows to send out of individual locations on this antenna assignment in succession signals of certain identifier, these signals after reception on the basis of their different identifier in a compression network to a sub-optimal or Distort the super-compressed signal and read the location angle from the network parameters leading to optimal compression.

As an identifier of the signals emanating from the different locations of the antenna, the frequency is used, which as a function of the location is discrete or continuous, linear or nonlinear, monotone or non-monotone variable.

Together with the frequency, or independently of it, amplitudes are used as identifiers which can be digitally processed analogously or after appropriate conversion.

Sound or ultrasonic transducers are all materials which make it possible to impose certain identifiers on the signal, such as, for example, converters with a discrete or constant resonance frequency distribution, due to constant or discrete function of the location of variable design parameters.

These include, in particular, wedge-shaped piezoelectric or magnetic ceramic transducers, but also nickel transducers with location-dependent design parameters. The arrangement is also applicable to passive locating systems when the identifier radiated by the transmitter is known.

Amplifier or other signal altering electronic circuits may be included in the output coupling lines at certain angles.

The transducers themselves can consist of individual elements teilteil separate connections or even undivided

Converters with only one feedline. ,

The invention will be explained in more detail below using an exemplary embodiment. In the accompanying drawings show:

Fig. 1: a piezoelectric transducer with x-dependent resonant frequency;

Fig. 2a: the radiation of a pulse in the normal direction;

FIG. 2 b: the radiation of the same excitation in the direction γ <0; FIG. '

Fig. 2c: the radiation of the same excitation in the direction Y> O;

Fig. 3a: the two-way directivity at space-time coupling of the excitation and sensitivity distribution with subsequent compression for the transducer length χ = 0.5 m and the frequency deviation 2 βτ = 4π · 13.61 kHz for the sake of panoramic representation (parameter is the delay time δ in the unit 10 " ^{11s 2} ; pulse length τ = 2.1ms; special resonance frequency ω ₀ = 2π * 40kHz);

3 b shows the two-way directivity with the changed pulse length τ = 20 ms. FIG. 4 shows relative amplitude as a function of the delay time, shown for signals from two different angles

(Parameter: Frequency deviation 2 βτ = 4π · 13,61 kHz and pulse length τ = 20 ms).

In the exemplary embodiment, the carrier frequency represents the different identifiers of the signals emanating from the individual locations of the transmitting and / or receiving antenna.

In Fig. 1, a piezoelectric transducer is shown, which is formed so that the resonant frequency of the transducer is no longer a single, the entire transducer characterizing size, but that they depending on the just to be considered location on the transducer surface a specific and thus location-dependent Owns value.

On the side with the largest converter plate thickness 1 of the converter beam surface 2, the resonance frequency ω = ω _o with ω ₀ as a specific resonance frequency, while increasing on the side with the smallest converter plate thickness 3 to the resonance frequency ω = ω ₀ + 2βτ> ω _ο ,

Although such transducers are known per se and sufficiently tested, but their use for direction determination, in particular for the panoramic representation on the way according to the invention, has not yet been specified.

Instead of this piezoelectric transducer and piezomagnetic ceramic or nickel converter can be used, consisting of sheets with decreasing or increasing resonant frequency, as well as converters of other materials with a constant or discrete resonant frequency distribution.

This converter is fed with a frequency-modulated pulse, which expediently contains the special resonant frequencies ω ₀ to ω _ο + βτ as carrier frequencies. As a result, the individual sections on the transducer beam surface 2 are excited to oscillate successively in time, so that a wave-like excitation pulse runs over the entire transducer beam surface 2. Depending on the type of frequency modulation and the local distribution of the resonance frequencies on the transducer, the direction of rotation is the direction of the positive or negative x-axis, possibly also in alternating sequence.

In other cases, monotonic or alternating other directions of propagation of the excitation on the transducer surface or in the transducer space can be used, for example, the y and / or z-direction. For the following explanations, it is assumed that the frequency modulation is from the lower to the higher frequencies, so that the direction of the excitation wave according to the in-FIG. 1 position of the transducer coincides with the x-direction. The oscillations of different frequencies originating from the individual locations on the transducer surface χ are transmitted into the propagation medium and settle again in the direction of the propagation angle γ = Oim far field, where the wave normal to each point of the transducer is considered to be parallel the frequency modulated pulse together. In the direction of the propagation angle γ> 0, however, the higher frequencies follow faster to the lower, while in the direction of the propagation angle γ <0 between the vibrations of the individual locations on the transducer surface χ greater time intervals. These facts are caused by the propagation-related pulse distortions and explained in more detail in FIG.

FIG. 2a, the ω with the lowest specific resonant frequency ₀ beginning at the transducer face with the largest transducer plate thickness 1 of the transducer radiating surface 2 excitation shows 4. moves depending on the ratio of the resonance frequency change Δω in the transducer per spatial section Δχ and matching according to this change in resonant frequency Δω Frequency change in the excitation pulse per time step Δι with a certain propagation speed

(D ν = χ / τ

in the direction of the positive x-axis, if χ means the transducer length, which contains all specific resonant frequencies ω ₀ to ω ₀ + 2 βτ linearly distributed and if the pulse length τ means the length of the pulse linearly modulated in the same frequency limits. In the propagation medium, on the other hand, the excitation along the wave normal continues in the direction of the propagation angle γ with the group velocity c.

The ratios c> ν shown in Fig. 2a will find application in most practical cases. However, the invention is not limited to the cases shown itself. Since two adjacent transducer elements are not excited simultaneously, but successively, it follows from FIG. 2a that the radiation in the normal direction ti does not produce any special effects. Rather, it is irrelevant at the remote point whether the excitation wave runs over the converter surface or not. If the entire pulse including all frequencies could be radiated from the transducer side with the largest transducer plate thickness 1, the receiver would receive u> the same frequency modulated pulse at the far point as in the actual case indicated by the excursion hike.

On the other hand, it is not irrelevant for the propagation angle γ Φ 0 whether the entire frequency-modulated pulse is radiated successively only from the transducer side with the largest transducer plate thickness 1 or, as in the actual case, from the different locations on the transducer surface χ of the transducer.

FIG. 2 b illustrates that the high frequencies radiated from the transducer side with the smallest transducer plate thickness 3 arrive later at the receiver than the pulse width τ radiated from the transducer side with the largest transducer plate thickness 1, but additionally a delay interval

(ID

I ATI = | / sin fI

need. So the whole impulse is on τ

(III)

T + / ΔΠ-Τ-ΔΤ

stretched.

In contrast, it can be seen from Fig. 2c, that although the transducer edge point with the smallest transducer plate thickness 3, the high frequencies a pulse length τ radiates later, but this radiation takes place at a location opposite the transducer edge point with the largest converter plate thickness 1 a delay interval

(IV) Δ Χ

closer to the far point io where the impulse can be thought of as being composed. The entire pulse is thus compressed with respect to its length from τ to τ - Δτ. This results in an angle-dependent frequency modulation of the propagating pulse.

The transducer thus acts solely on the basis of its spatial extent and the particular arrangement of the resonance frequencies ω as an angle-dependent delay propagation filter.

It can be calculated that an electrical transmission pulse of the form

(V) U ₅ = U ₅₀ sin (LOot + Pt ² ) [9U) ~

at the place of receipt as

(VI)

is perceived, where

(VII)

  cos

LDO

* 2i

= Jl sin * ·

Here, U _{s is} the transmission voltage, U _is the amplitude of the transmission voltage, t is the time coordinate, β is the frequency modulation factor, θ is the step function, U _{e is} the reception voltage, U _{eo is} the amplitude of the reception voltage, η is the relative pulse length change and t * is the retarded time.

Essential here are the arguments of the trigonometric functions indicating the frequency change discussed, but in particular also the change of the frequency modulation factor from β to β / (1-η), as well as the arguments of the step functions which make up the pulse compression for the propagation angle γ> O or γ <O is readable.

A similar effect occurs when receiving the pulse reflected by the locating object in a monostatic converter. The angle-dependent time-of-flight distortion effect is reinforced once again, although not doubled, as might be expected at first glance. The frequency modulation factor β now has the frequency modulation factor changed by the propagation delay

Changed, which is strongly dependent on the angle according to equation (VII).

One can analyze the angle-dependent frequency modulation generated in this way by a delay filter in the receiving channel and thus determine the angle from which the locating signal arrives at the receiver. Runtime distortion filters in the known form of cross members are known to pass the higher frequencies faster than the lower ones. The difference in the transit time velocity of adjacent frequencies is characterized by the so-called transit time gradient δ.

Pulses which have a linearly increasing frequency can be densified by an appropriate choice of the delay time. The more frequencies with the same phase appear at the output, the greater the amplitude of the pulse at the output. There is an optimal runtime steepness δ ₀ , which generates a maximum amplitude increase. Lower amounts of the time-of-flight slope δ mean that the high frequencies are not yet running fast enough to "catch up" with the previous lower frequencies. Too large amounts of the time-of-flight slope δ cause the higher frequencies to "overtake" the lower frequencies In this case, the pulse diverge.

It is possible to specify how the optimum delay time δ _{ο of} the filter must be designed to act on the pulse generated by the converter used in accordance with the invention of a positionally variable resonance frequency. One calculates:

1+

^{: a} ^ -n-Tz

for the propagation angle γ> 0 and

(X) O ₀ =

for the propagation angle γ <0.

The optimal delay δ ₀ is also strongly dependent on the relative pulse length change η according to equation (VII).

If an impulse passes through a filter having a fixed value of the optimum time-of-flight steepness δ ₀ , this value is optimal for a certain optimum propagation angle γ ₀ , but not for adjacent angles. The pulses which do not originate from the optimal propagation angle γ _{0 associated} with the optimum time-of-flight slope δ ₀ are thus not optimally compressed. The result is a directivity whose maximum is at an optimal propagation angle γ _ο . An adjacent value of the optimum term steepness δ ₀ is optimal for an adjacent propagation angle.

In this way, directional effects can be generated by time-delay distortion filters of different transit time steepness which have their main lobe at a respectively different optimum propagation angle γ _o .

The directional effects are at suitably chosen transducer length χ. Pulse length τ and frequency modulation factor β in certain sectors quite narrow.

FIG. 3 a shows a series of such directivities for a transducer with a transducer length χ of 0.5 m at a frequency sweep 2 βτ of the transmission pulse of 2 × 13.61 kHz and a pulse length τ = 2.1 ms. A chain of propagation delay terms is used and after each term the amplitude U of the pulse is examined. The relatively largest among the pulses of adjacent delay elements indicates that link of the chain, after the effect of the optimal term steepness δ _{0 is} reached and thus the angle from which the pulse has arrived.

Fig. 3 b shows as well as Fig. 3 a, the two-way directivity. However, the pulse length τ has been changed to 20 ms.

Here 30 °, which including all the preceding members δ optimal running time of rise of, for example, behind that member _ο = -5,653 x 10 ~ s causes ^{11 2,} a maximum amplitude fürSignalemiteinem optimal propagation angle γ ₀ = as noted is read from the directional effect curve. 5 Signals from neighboring angles are strongly attenuated.

4 again illustrates the procedure on the receiving side. A runtime chain 6 is used, which is shown in sections. After each of the chain links, preferably in the form of cross links, the continuous signal can be coupled out via the taps a, b,..., G. Each additional link causes a further increase in the amount of the time of flight steepness δ of the chain section, to which this cross member is coupled. Thus, each tap corresponds to a certain value of the term steepness δ, which is optimal with respect to a certain angle, but not with respect to adjacent angles. Considering a manbeispielsweise from an optimum propagation angle _γ ο of 30 ° reflected from a positioning object and received by the transducer signal after each chain link of the delay line 6, we obtain different amplitudes. For the selected signal parameter, the amplitude distribution 7 shows the maximum thereof located at tap b, ie, approximately at an optimal slope term δ ₀ = 5653 × 10 ^"11 s ^2.

Neighboring outputs, on the other hand, provide only very strongly damped amplitudes. Likewise, one obtains the maximum for signals from an optimal propagation angle γ _o of -30 ° behind the chain link of the delay line 6 with the tap f. It is located in the recently observed signal parameters, the amplitude distribution 8 prior to the maximum at optimum maturity slope δ = ₀ -6,043 x 10 ^"11 S ^2nd Other taps provide such a signal only very small amplitudes.

With increasing number of links and correspondingly smaller jumps of the delay time δ per link, the resolution increases. In general, high resolving power is required only for a certain angular range, for example, between -30 ° and + 30 °. Then, according to Figure 4, the four links with the taps c, d, e, f and a

Total run time increase of 0.004 (ms) ² , which requires an increase of 0.001 (ms) ² per link, replaced by a higher number of links, for example 40, with each link only increasing 0.0001 (ms) ² Runtime slope δ has. This results in a resolution of 1.5 °.

The solution according to the invention is not limited to underwater rooms, but it can be applied to all modulated wave trains emitting antennas.

It is also not limited to the active location, but can also be used in passive location systems use.

For example, if an object to be constantly monitored is equipped with a transmitter emitting a signal of linearly increasing frequency, for example, where the frequency modulation factor β is known, a converter similar to FIG. 1 is used as the receiving transducer and the direction-dependent frequency-modulated output signals received thereby given to a delay line, wherein the maximum amplitude tap allows the determination of the angle of incidence.

Particular advantages arise in the application of the solution according to the invention for panorama display, if in addition to the position of the object and the shape of the object to be determined in more detail.

Claims (9)

claims: 1. Location method with direction determination, in particular for the panoramic view of irradiated and / or scanned rooms, preferably underwater spaces by means of sound or ultrasonic transmitting and / or -empfängerwandler, characterized in that caused by extensive transmitting and / or receiving antennas angle-dependent distortions the transmitted and received modulated pulses can be supplemented by additional signal transducers introduced into the receiving channel, preferably matched filters, to give optimum pulse distortions, the size of the added distortions being indicative of the angles from which the received signal appears. 2. Positioning method with direction determination according to claim 1, characterized in that the transmitting and / or receiving antenna is designed such that it allows to send from individual locations on this antenna occupancy temporally successive signals of certain identifier, these signals after receiving due to their different To distort the identifier in a compression network to a sub-optimal or super-compressed signal and to read the location angle from the network parameters leading to optimum compression. 3. locating method with direction determination according to claim 1 and 2, characterized in that the frequency is used as an identifier of the signals emanating from the different locations of the antenna, which is arbitrarily variable as a function of the location. 4. locating method with direction determination according to claim 1 to 3, characterized in that together with the frequency or independently of the amplitude as an identifier is adjustable, which is then analog or digitally processed after appropriate conversion. 5. locating method with direction determination according to claim 1 to 4, characterized in that as sound or ultrasonic transducer find such materials use that allow it to impose certain identifiers due to constantly or discretely depending on the location of variable design parameters of the signal. 6. locating method with direction determination according to claim 1 to 5, characterized in that the arrangement for passive positioning systems is applicable when the radiated by the transmitter identifier is known. 7. locating method with direction determination according to claim 1 to 6, characterized in that belonging to certain angles Auskopplungsleitungen contain amplifiers or other signal-changing electronic circuits. 8. locating method with direction determination according to claim 1 to 7, characterized in that the transducers are provided with only one feed line. 9. locating method with direction determination according to claim 1 to 7, characterized in that the converter consist of individual elements teilteilweise separate terminals. For this 3 pages drawings