阅读说明：本技术 用于在雷达测量系统上单义地确定物体速度的方法 (Method for univocally determining object speed on radar measuring system ) 是由 B·西克 S·策纳 M·瓦尔特 K·辛格兰特 于 2019-02-06 设计创作，主要内容包括：本发明涉及一种用于在雷达测量系统上确定统一的速度的方法,其中两个分别由发射天线和接收天线构成的天线对映射在虚拟的天线布置系统中的同一位置上。(The invention relates to a method for determining a uniform speed on a radar measuring system, wherein two antenna pairs each consisting of a transmitting antenna and a receiving antenna are mapped on the same location in a virtual antenna arrangement.)

1. A method for univocally determining the velocity of an object (16) on a radar measuring system (10),

the measuring system (10) has at least two transmitting antennas (12) and at least two receiving antennas (14),

a first antenna pair (22d) comprising a first transmitting antenna (12a) and a first receiving antenna (14d) is mapped on a virtual antenna arrangement (20) in a first position, and

a second antenna pair (24a) comprising a second transmitting antenna (12b) and a second receiving antenna (14a) is mapped onto a second position on the virtual antenna arrangement system (20),

the first position and the second position are the same,

the transmitting antenna (12) transmits radar waves in the form of frequency-modulated sections (30),

successive sections (30a) of the first transmitting antenna (12a) have a first time interval (t)₁) And successive sections (30b) of the second transmitting antenna (12b) have a first time interval t₁Same second time interval (t)₂)，

The section (30a) of the first transmitting antenna (12a) has a third time interval (t) relative to the section (30b) of the second transmitting antenna (12b)₃)，

Detecting the object (16) by means of a first antenna pair (22d) and a second antenna pair (24a),

determining a distance and an ambiguous first velocity value of the object (16) by means of a first antenna pair (22d) and a distance and an ambiguous second velocity value of the object by means of a second antenna pair (24a),

the ambiguous first velocity value has a first phaseAnd the ambiguous second velocity value has a second phase

By means of a third time interval (t3) determining a third phase for a possible speed of the speed value

Closest to the first phase

2. A method as claimed in claim 1, characterized in that the two transmitting antennas (12) transmit sequentially.

3. Method according to claim 1 or 2, characterized in that said first time interval (t)₁) Or the second time interval (t)₂) Not the third time interval (t)₃) Integer multiples of.

4. A method according to claim 1, 2 or 3, characterized in that the first segments (30a) are identical to each other, the second segments (30b) are identical to each other and/or the first segments (30a) and the associated second segments (30b) are identical.

5. The method according to any one of claims 1 to 4, characterized in that a ramp with a frequency that increases uniformly and linearly is emitted in a section (30).

6. A radar measurement system (10) using the method according to any one of claims 1 to 5.

Technical Field

The invention relates to a method for univocally (i.e. univocally) determining the speed of an object on a radar measuring system.

Background

DE102014212280a1 describes a method which enables a univocal determination of the speed. There is disclosed a radar measurement system having an antenna pair comprising a transmit antenna and a receive antenna. According to the FMCW method, the transmitting antenna transmits a radar wave having a plurality of identical first ramps with a linear frequency increase. These first ramps have a first time interval between each other which is the same for all successively successive first ramps. In addition, the same ramp is transmitted again by the transmit antenna as a second ramp, which also has a linear frequency increase. The second ramps are also designed to be identical to one another and accordingly have identical second time intervals between one another, which are designed to be identical to the first time intervals. The second ramp is transmitted at a third time interval staggered with respect to the first ramp. In this sense, a respective one of the first ramps and one of the second ramps form a ramp pair.

The receiving antenna detects the transmitted and reflected radar waves and creates range-doppler plots for the first and second ramps according to conventional methods. The range-doppler plot assigns the range and radial velocity of the object to the radar measurement system. The radial velocity is generated here by the first phase and the second phase. The first phase and the second phase are different here because the object moves slightly for the duration of the third time interval. With respect to each of the two range-doppler plots, the radial velocity is ambiguous (i.e., one-to-many) because each multiple of a phase shift of 2 pi is possible. Thus, for example, at a velocity resolution of-10 m/s to +10m/s, a velocity of 5m/s may be determined to correspond to a velocity of-15 m/s, 25m/s, 45m/s, etc.

A third time interval is now used and for each actual possible velocity a phase difference is calculated which will be generated based on the velocity and the resulting position offset at the receiving antenna. This phase difference is also referred to as the third phase. At the correct speed, the third phase substantially corresponds to the difference between the first phase and the second phase. Thus, such a velocity is the correct velocity with the smallest distance between the third phase and the difference between the first phase and the second phase.

However, in general, the radar measurement system does not transmit via only one transmitting antenna, but via a plurality of transmitting antennas. The transmit antennas typically transmit one after another. If the speed is now unambiguously determined according to the above description, one transmitting antenna must each transmit doubly, which increases the duration of the measurement process.

Disclosure of Invention

It is therefore an object to provide a method by means of which the speed can be unambiguously determined and at the same time the duration of the measurement process can be kept as short as possible.

This object is achieved by a method according to independent claim 1. Advantageous variants of the method are specified in the dependent claims.

The method is particularly suitable for radar measuring systems which are preferably installed on motor vehicles. The measurement system has at least two transmit antennas and at least two receive antennas. The transmitting antenna may transmit a radar wave, which may be transmitted on the object. The reflected radar waves can then be detected by the receiving antenna. Advantageously, the radar measurement system is designed to operate as a frequency modulated continuous wave radar (FMCW).

The measurement system has a first antenna pair comprising a first transmit antenna and a first receive antenna of the measurement system. In addition, the measurement system has a second antenna pair comprising a second transmitting antenna and a second receiving antenna of the measurement system. In principle, each transmitting antenna transmits a radar wave and each receiving antenna detects a reflection of the transmitted radar wave. However, for further consideration, only these two antenna pairs are correlated. The first transmitting antenna and the second transmitting antenna are each formed by their own antenna in terms of the hardware of the measuring system. As are the receive antennas. In addition to the antennas of the two antenna pairs, the measuring system can also have further transmitting antennas and further receiving antennas.

Each possible antenna pair of the measurement system is mapped onto a virtual antenna arrangement system. It is well known how to create such virtual antenna arrangement systems. When 2 transmit antennas and 4 receive antennas are used, the virtual antenna arrangement system includes 8 virtual antennas. The first antenna pair is mapped to a first location within the virtual antenna arrangement as a first virtual antenna. The second antenna pair is mapped to a second location within the virtual antenna arrangement system as a second virtual antenna. Other possible antenna pairs are mapped onto other virtual antennas. In the application of the method described below, the positions of the first virtual antenna and the second virtual antenna are the same on the radar measurement system. Thus, the first antenna pair and the second antenna pair are mapped to the same position within the virtual antenna arrangement system.

The same position of the two virtual antennas in the virtual antenna arrangement system means that each radar wave always follows the same path for both antenna pairs from transmission to detection, regardless of the position of the reflecting object. This means that the path length of the radar wave from the first transmit antenna to the first receive antenna is the same as the path length of the radar wave from the second transmit antenna to the second receive antenna.

The virtual antenna arrangement system is based on the following assumptions: the distance between the object and the antenna is much larger than the distance between the antennas. An object is spaced apart by an order of magnitude of several meters, each antenna having a distance in the millimeter range. This corresponds to a factor of about 1000.

For example, if the same radar wave is transmitted by the first and second transmit antennas at the same time, the same signal, i.e. having the same frequency and the same phase, is detected at the first and second receive antennas for the associated first and second radar waves. Thus, the first antenna pair and the second antenna pair behave identically.

The transmitting antenna transmits radar waves during the measurement process, wherein the components of the radar waves reflected on the object are detected by the receiving antenna. In the FMCW method, radar waves in the form of a plurality of segments are transmitted for each transmission antenna. The frequency of the radar wave is modulated within such a distance. The modulation increases linearly over time, for example, through the segment. Such a section with a linearly increasing frequency is also referred to as a ramp.

The frequencies of the reflections and the detected segments or ramps are mixed with the current frequency of the same ramp and low pass filtered. In a known manner, a first fourier transform may be used to determine the distance of the object, and a second fourier transform may be used to determine the velocity of the object. This will generate a range-doppler plot for each antenna pair.

Successive first sections of the first transmit antenna have a first time interval. The first time interval is the same for all successively following first segments. The time interval determines the time interval from the start of one first section to the start of the subsequent first section.

In particular, the first segments that are successive in succession are themselves identical, i.e. their duration, starting frequency, ending frequency, phase and frequency variation at the start, etc. are identical. The first transmitting antenna transmits a plurality of first segments, in particular 256 segments, during the measurement process.

Successive second sections of the first transmit antenna have a second time interval. This second time interval is the same for all successively subsequent second segments. The time interval determines the time interval from the start of one second section to the start of the next second section.

In particular, the successive second segments themselves are identical, i.e. their duration, starting frequency, ending frequency, phase and frequency variation at the start, etc. are identical. The second transmitting antenna transmits a plurality of second segments, in particular 256 segments, during the measurement process.

The first time interval and the second time interval are preferably also identical to each other. Therefore, it is preferable that all the sections transmitted by the first and second transmitting antennas are identical to each other. For example, the first and second sections are designed as ramps. A ramp is a segment that starts at a starting frequency and transitions over its duration to an ending frequency. The transition is achieved by increasing or decreasing the frequency, in particular by linearly increasing the frequency.

The first section and the second section have a third time interval. The third time interval describes an interval from the start of the first section to the start of the second section. For example, each first segment is assigned a second segment that is offset in time by a third time interval.

Since the first antenna pair and the second antenna pair behave the same and the first time interval and the second time interval are also the same, the evaluation results are also the same. Due to the third time interval, if the object performs a relative movement, the object has already moved from one section to the next in the case of successive sections. Such a spatial position change is effected, for example, from the first section to the second section and vice versa. Due to the time difference, a first phase of the radar wave of the first antenna pair is different from a second phase of the radar wave of the second antenna pair. This phase information will be retained when creating a range-doppler plot for each antenna pair. The range-doppler plot of the first antenna pair includes a first phase relative to the object and the range-doppler plot of the second antenna pair includes a second phase relative to the object.

The object is then detected by means of the first antenna pair and the second antenna pair.

A first range-doppler plot is created from the measurement data of the first antenna pair using the fourier transform described above. A second range-doppler plot is created from the measurement data for the second antenna pair using the fourier transform described above. As already mentioned, these range-doppler plots contain different phase information. The phase difference between the first phase and the second phase is related to the third time interval.

The first and second range-doppler plots provide ambiguous (one-to-many) velocity values for the object. This value corresponds to a speed within a detectable speed range of the measurement system. The velocity values are ambiguous as also velocities corresponding to a phase shift of 2 pi are possible. At velocity resolutions of-10 m/s to +10m/s, the determined 5m/s velocity may also correspond to velocities of-15 m/s, 25m/s, 45m/s, etc. The speeds-15 m/s, 25m/s, 45m/s, etc. correspond to multiples of 2 π.

In case a known third time interval is used, a third phase corresponding to the phase difference may be determined for each possible one of the velocity values. The phase difference corresponds to a phase change due to a change in the position of the object from a first section to a subsequent second section, i.e. from a first speed value to a second speed value.

Thus, from the set of possible speeds of the ambiguous first speed value or the ambiguous second speed value, it is precisely the speed at which the third phase is equal to the difference between the first phase and the second phase that is the correct speed. In the actual test setup and the actual measurement the third phase is almost the same as the difference between the first phase and the second phase. Therefore, the speed at which the distance of the third phase to the difference between the first phase and the second phase is smallest is correct.

The possible speeds can be all multiples on the one hand or limited to the speeds that can actually occur. In the case of a radar measuring system for a car, for example, the speed range may be limited to +/-400 km/h.

Alternatively, the third phase may be calculated for a possible velocity without a 2 π phase shift, and then it is verified whether the phase distance between the third phase and the difference between the first phase and the second phase is sufficiently small. The next possible velocity with a 2 pi phase shift is then calculated and verified. Then-2 pi, 4 pi, -4 pi, etc. are used until the correct velocity is determined. Thereby performing only a minimal number of computing operations. Therefore, the verification is performed immediately after the third phase is determined. For this reason, a region where the third phase can be maximally deviated may be provided. One possible speed is then determined in turn until the correct speed is verified.

The preceding statements also apply to the sections designed as ramps.

In addition, further transmitting and receiving antennas can be formed on the measuring system in order to be able to detect objects, in particular distances and speeds, with precision. A univocal speed can then be assigned to the object by the method described. Preferably, the further antenna arrangement is arranged at a respective own position within the virtual antenna arrangement.

In addition to the first and second antenna pairs, there are advantageously further antenna pairs or antenna pair groups which are mapped to the same position within the virtual antenna arrangement system. Thus, the method can be implemented by a plurality of mutually independent virtual antenna pairs. The determined unambiguous speeds can thus be verified against one another again by two independent measurements.

Advantageous variant embodiments of the method are described below.

It is proposed that the two transmit antennas transmit sequentially.

Transmission by two or more transmit antennas means that only one transmit antenna transmits and then another transmit antenna transmits within a time frame, e.g. a sector of time. There may be a brief transmission pause between successive transmissions of two transmit antennas, during which time neither transmit antenna transmits radar waves. For example, when four transmit antennas are used, a sector may be transmitted, e.g., first a first transmit antenna, then a second transmit antenna, then a third transmit antenna, then a fourth transmit antenna. This transmission sequence may be repeated a plurality of times, in particular 256 times, for example during the measurement process.

The first time interval and/or the second time interval are advantageously not integer multiples of the third time interval or the second time interval.

The first sections are advantageously identical to each other. The second sections are advantageously also identical to each other. It is further proposed that the first section is identical to the associated second section.

The same may especially be in that the duration, the start frequency, the end frequency and/or the frequency are increased. Advantageously, two successive sections (in particular two successive first sections, two successive second sections or second sections following a first section) start with the same phase. The phase identity at the beginning of the segment is also referred to as the phase synchronization of the segments.

In another embodiment, the transmitted segments are transmitted as ramps having uniformly and linearly increasing frequencies.

This is a well known modulation method for FMCW radars. In addition, the method is particularly advantageous when using a radar measuring system in a motor vehicle.

A radar measuring system is also presented, which uses or performs a method according to at least one of the above solutions or according to any of the claims 1 to 6.

Drawings

The method and the radar measuring system are explained in detail and by way of example in the following with the aid of a plurality of figures. Wherein:

FIG. 1a shows a part of a radar measurement system;

fig. 1b shows a virtual antenna arrangement system of the radar measuring system of fig. 1 a;

fig. 1c shows a hypothesis for a virtual antenna arrangement system;

FIG. 2 shows a sequence of transmitted radar waves;

figure 3 shows a range-doppler plot;

fig. 4 shows a flow chart of a speed determination method.

Detailed Description

Fig. 1a shows a radar measurement system 10 in part. In particular, an antenna arrangement system 11 of a radar measuring system 10 is shown. The radar measurement system 10 also includes electronics for controlling and evaluating various components, including two transmit antennas 12a and 12b and four receive antennas 14a, 14b, 14c, and 14 d. The transmitting antenna 12 transmits radar waves that may be reflected on the object 16. The reflected radar waves may be received by the receiving antennas 14a, 14b, 14c, and 14 d. For ease of illustration, the radar waves are shown in dashed lines 18a and solid lines 18 b. The radar wave 18 and the ratio of the distance between the antenna and the antenna to the distance between the antenna and the object are not proportionally accurate. In particular, the distance between the object 16 and the measurement system 10 is many times greater than the distance between the antennas, so that the far-field assumption is reasonable for all detected objects. This far field assumption is used in FIG. 1aAnd (4) showing.

Thus, each transmit antenna 12 is mapped onto each receive antenna 14. Such an antenna arrangement 11 may also be denoted as a virtual antenna arrangement 20, which is shown in fig. 1 b. Each transmit antenna 12a, 12b is mapped with each receive antenna 14a, 14b, 14c and 14d to a position within the virtual antenna arrangement 20. The transmit antennas and receive antennas together form an antenna pair 22, 24.

The transmit antenna 12a and the receive antenna 14 provide an antenna pair 22, and the transmit antenna 12b and the receive antenna 14 provide an antenna pair 24. In fig. 1b, the position of the virtual antenna is shown below the reference numeral of the antenna pair. The position of virtual antenna 22 is shown as a dashed cross and the position of virtual antenna 24 is shown as a solid cross.

Transmit antenna 12a and receive antenna 14a are mapped to location 22a, receive antenna 14b is mapped to location 22b, receive antenna 14c is mapped to location 22c and receive antenna 14d is mapped to location 22 d. Similarly, transmit antenna 12b is mapped with receive antenna 14a at location 24a, with receive antenna 14b at location 24b, with receive antenna 14c at location 24c, and with receive antenna 14d at location 24 d.

Based on the far-field assumption, the outgoing and incoming radar waves can be treated as wavefronts, as shown in fig. 1 c. The transmitted and received radar waves 18 propagate along parallel paths. The radar wave pattern on the object 16 is used to illustrate the reflection of a radar wave incident on a point on the object. In particular, the path from the transmitting antenna 12a to the receiving antenna 14d and the path from the transmitting antenna 12b to the receiving antenna 14a have the same length. The sum of the path differences 19a and 19b corresponds to the path difference 19c so that radar waves having the same phase arrive at the receiving antennas 14a and 14d when radar waves are simultaneously transmitted through the transmitting antennas 12a and 12 b.

In the virtual antenna arrangement system 20, the position 22d and the position 24a are the same. This identical position means that, when the transmitting antennas 12a and 12b transmit simultaneously, the determined phases of the antenna pairs 22d and 24a with their associated virtual antennas 22d and 24a are always identical, irrespective of the position of the object 10 in the measurement space of the radar measuring system 10. The two antenna pairs 22d and 24a thus provide the same information.

As already mentioned, the virtual antenna arrangement system is based on the far-field assumption, which is explained in more detail with the aid of fig. 1 c. Fig. 1c essentially corresponds to fig. 1a, the radar waves no longer being represented by lines but by wave fronts. The principle of virtual antenna arrangement systems is based on different spacing ratios of antennas to each other and to the object. The antennas 12, 14 are here only a few millimeters apart. In contrast, the distance from the antennas 12, 14 to the object 16 amounts to at least several meters. This large difference in distance corresponds to approximately a factor of 1000, represented in the figure by the band 40.

The radar wave generally propagates as a fundamental wave, as shown by means of the upper part of fig. 1 c. The wavefront 42 propagates spherically. If the distance is large, this spherical wavefront of the fundamental wave can be seen as a straight wavefront 44. The wave fronts 44 are parallel to one another here. The wave front 44 is shown propagating in a propagation direction 48, which forms an angle α with respect to the viewing direction 46 of the radar measuring system 10. When the angle α is 0, all the receiving antennas 14 detect the same phase.

The transmitting antenna 12a is also referred to as a first transmitting antenna, and the transmitting antenna 12b is also referred to as a second transmitting antenna, the receiving antenna 14d is also referred to as a first receiving antenna, and the receiving antenna 14a is also referred to as a second receiving antenna. The first antenna pair 22d corresponds to a first virtual antenna, and the antenna pair 24a corresponds to a second virtual antenna.

In fig. 2, a time course of the transmission of the radar wave is shown. The illustration is here limited to the radar waves 18a and 18b of the antenna pair 22d and 24 a. Time is plotted on the X-axis 26 and frequency is plotted on the Y-axis 28.

According to the FMCW method, a plurality of sectors 30 are transmitted by each of the transmit antennas 12a and 12 b. These sections 30 are realized by ramps. The first transmit antenna 12a transmits a first ramp 30a and the second transmit antenna a second ramp 30 b. The first ramp 30a is shown in solid line in relation to the first antenna pair and the second ramp 30b is shown in dashed line in relation to the second antenna pair.

The transmit section of the ramp begins at a minimum frequency that increases linearly over a transmit duration Δ t to a maximum frequency. Furthermore, the transmitted ramps all start with the same starting phase.

The transmitted ramp 30 is at least partially reflected on the object 16 and is then detected by the receiving antennas 14d and 14 a. For the first antenna pair 22d, the first ramp 30a is detected as a first signal 32a, and for the second antenna pair 24a, the second ramp 30b is detected as a second signal 32 b. The received signal 32 is substantially identical to the associated ramp 30, but staggered in time by the time of propagation of the radar wave. The received signal 32 is represented by a corresponding thinner line, while the transmitted ramp 30 is represented by a thicker line.

The first ramps 30a are identical to each other. In addition, the second slopes 30b are also identical to each other. Further, the first slope 30a and the second slope 30b are identical to each other.

The first ramp 30a is emitted at a uniform first time interval t 1. The second ramp 30b is transmitted at a uniform second time interval t 2. As an example, four ramps 30 are shown in fig. 2, in which case 256 ramps are transmitted for each transmit antenna 12.

A first ramp 30a and a second ramp 30b are associated with each other in such a way that: there is a third time period t between the transmission of the first ramp 30a and the transmission of the second ramp 30b₃. Third time interval t₃The selection is made such that the transmissions of the radar waves do not overlap in time.

From the determined signals 32a and 32b, a range-doppler-map 34(range-doppler-map) shown in fig. 3 can be determined by two fourier transforms for the first antenna pair 22d and the second antenna pair 24a, respectively. The range-doppler plot 34 is substantially the same for both antenna pairs 22d, 24 a. Thus, only one range-doppler plot 34 is shown for both antenna pairs 22d, 24 a. The differences are explained below.

The object 16 is shown in the range-doppler plot 34 as having its data points 36 for range and velocity. This diagram with one data point 36 is exemplarily chosen because radar waves will typically be reflected at several points on the object, which then appear in the range-doppler plot 34. The velocity is plotted on the range-doppler plot 34 on the X-axis 34a and the range of the object to the radar measurement system 10 is plotted on the Y-axis 34 b.

The velocity of the object 16 is not unique (unambiguous or non-unambiguous) for a phase difference of 2 pi. For example, an object 16 mapped to a velocity of 5m/s may correspond to a velocity of-15 m/s, 25m/s, 45m/s, etc., in the case of a detection width of-10 m/s to 10 m/s. For a velocity of 25m/s, an exemplary one of the data points 36a is shown in a phase-extended portion of the range-doppler plot 34 by 2 pi. This expanded portion of the range-doppler plot 34 is shown in dashed lines.

Thus, data point 36a maps to 5m/s according to arrow 38 a. The velocity of 25m/s is shown as 5m/s in the range-doppler plot 34. In addition, an additional arrow 38b is shown which maps a corresponding multiple of the 2 π phase difference to a data point 36.

More specifically, the velocity of data point 36 is a velocity value that includes a plurality of velocities.

The data points 36 of the range-doppler plot 34 for the first antenna pair 22d have a first phaseWhile data points 36 of the range-doppler plot 34 for the second antenna pair 24a have a second phase

First phaseAnd a second phase

Is different because the object is in the third time interval t₃The inside has moved slightly.

Now a third phase is determined for each possible speed of the speed values

At a plurality of possible speeds with a time interval t₃Of two successive ramps 30In case of this third phaseCorresponding to the desired phase difference. Then each determined third phase

And the first phaseAnd a second phase

The difference between them is compared. Closest to the first phaseAnd a second phase

Third phase of difference therebetweenCorresponding to the correct speed.

Thus is suitable for

Thus, the velocity of the object can be univocally determined using the method. Is suitable for

The other speeds of (a) are incorrect and are not adopted.

The relationship between velocity and phase is also described by the following equation:

wherein the content of the first and second substances,

v corresponds to the velocity of the object, where t₃Is the third time interval, c represents the speed of light and f represents the carrier frequency of the radar wave. In this case, the carrier wave corresponds to 77GHz, for example.

Fig. 4 shows the steps of the method in a flow chart.

In a first step 100, radar waves are transmitted by a transmitting antenna and reflected components are received by a receiving antenna.

In a subsequent step 102, the interpreted fourier transform is used to evaluate the received radar waves and create a range-doppler plot at least for the first antenna pair and the second antenna pair.

A next step 104 includes determining a velocity value from the range-doppler plot. The speed value contains information about the possible speed v, which is also determined in step 104 or sub-step.

In the next step 106, the time interval t is defined₃A third phase related to said possible speed v determination

The third phase is advantageously determined for a speed v within reasonable frame conditions

In a subsequent step 108, a first phase is determined

And a second phaseThe phase difference between them. Steps 106 and 108 may also be switched in their order or may be performed simultaneously.

In a subsequent step 110, by

To verify the correct speed of the plurality of speed values.

List of reference numerals

10 radar measuring system

11 antenna arrangement system

12a, 12b transmitting antenna

14a, 14b, 14c, 14d receiving antenna

16 object

18a, 18b radar waves

19. 19a-c path difference

20 virtual antenna arrangement system

22 antenna pair/virtual antenna

24 antenna pair/virtual antenna

26X axis

28Y axis

30. 30a, 30b segments/ramps

32. 32a, 32b signal

34 range-doppler plot

34a X axle

34b Y axle

36. 36a data points

38. 38a, 38b, 38c arrows

40 strap

42 wave front

44 wave front

46 direction of view

48 direction of propagation

100 step(s)

102 step

104 step

106 step

108 step

110 step

t₁Time interval

t₂Time interval

t₃Time interval

Duration of at transmission

Angle alpha

Phase position