DE102017117900A1 - High-frequency signal generation unit - Google Patents

Abstract

The invention relates to a high-frequency signal generating unit (1), in particular for use in FMCW-based distance and speed measuring devices. According to the invention, the high-frequency generation unit (1) is characterized in that the frequency (f) of its high-frequency oscillator (11) by means of a first, "fine", control signal (s) and by means of a second, "coarse" control signal (s ') is controlled. In this case, the additional second control signal (s') is generated by a first frequency converter (15) which is designed to generate a second control signal (s') with a second control frequency (f ') by means of the actual control signal (s) in that the second control frequency (f ') is divided by a predefined factor (n) relative to the actual first control frequency (f). This results in particular in FMCW-based measuring devices the advantage that the linearity of the sawtooth-shaped high-frequency signal (s) is increased. This in turn increases the maximum achievable resolution in the speed or distance measurement.

Description

The invention relates to a high-frequency signal generation unit for an FMCW-based distance or speed measuring device.

Radar-based distance and speed measurement is used in a wide range of applications, for example for position determination in aviation, for distance or speed measurement in motor vehicles or for level measurement in industrial process plants.

In principle, the so-called pulse transit time method or also the FMCW method ("Frequency Modulated Continuos Wave", also known in German as continuous wave radar) can be used as the measuring method. Both measurement methods are operated within predefined radar frequency bands (in the context of this invention, the terms "high frequency" and "radar" refer to signals or electromagnetic waves with frequencies between 0.3 GHz and 300 GHz).

In the case of level measurement is usually worked in radar frequency bands at 6 GHz, 26 GHz or 79 GHz. In this case, the higher frequency bands are preferred, since a more compact antenna can be used, without the bundling effect of the antenna is reduced.

Another advantage of using higher frequency bands is that greater absolute bandwidth can be used. This in turn allows a higher resolution of the distance measurement. This is an important requirement, especially in the case of level measurement, because here the most accurate possible knowledge of the filling level is required, especially in the case of large containers. Therefore, it is desirable to operate level measurement or distance or speed measurement generally at the highest possible frequencies.

With FMCW-based distance or speed measurement, there are already technically perfected solutions for frequencies up to approximately 79 GHz for generating a high-frequency electrical signal by means of corresponding high-frequency signal generation units. The high-frequency signal generating unit in this case feeds a transmitting antenna, whereby the actual radar transmission signal is generated and emitted. Accordingly, the frequency of the radar transmission signal is determined by the high frequency assembly.

Suitable high-frequency signal generation units for generating high-frequency signals for FMCW radar for frequencies up to about 79 GHz are already known. In this connection, the publication publication is exemplary DE 10 2013 105 A1 called. There is shown a typical high-frequency signal generating unit according to the prior art, which is based on a PLL ("Phase Locked Loop") is constructed:

Core of the local high-frequency signal generating unit is a high-frequency oscillator (usually this is a VCO, so a "Voltage Controlled Oscillator" used), which generates a corresponding high-frequency signal. The FMCW typical sawtooth frequency change of the high-frequency signal is set here via the PLL-based feedback circuit:

The feedback is realized by a control signal is diverted from the high-frequency signal of the high-frequency oscillator via a frequency divider. This is fed to a phase comparator, which compares the instantaneous phase position with that of a frequency-constant reference signal. The frequency of the reference signal is in the range of preferably 10 MHz to 100 MHz and can be generated by means of a corresponding quartz oscillator. The phase comparator controls the VCO via an analog DC signal, wherein the voltage value of the DC signal depends on the instantaneous phase position at the inputs of the phase comparator.

Above all, the realization of a high bandwidth requires a design of the phase comparator with suitable semiconductor components (in particular with suitable charge pumps, also known by the term "charge pump"), whose breakdown voltage is high enough. As a rule, corresponding phase comparators or their charge pumps are therefore designed with a breakdown voltage of more than 2V. A disadvantage of the use of such phase comparators, however, is that they limit the control speed of the PLL loop and thus reduce both the linearity of the sawtooth-shaped high-frequency signal, as well as limiting effect on the spectral purity of the output signal. This in turn limits the achievable resolution and accuracy in the speed or distance measurement.

The invention is therefore based on the object to provide a high-frequency signal generating unit for a FMCW radar-based distance or speed measuring device, with which an increased measurement accuracy is possible.

• - Einen elektrischen Hochfrequenz-Oszillator zur Erzeugung eines elektrischen Hochfrequenz-Signals mit einer steuerbaren Frequenz,
• - einen Frequenzteiler, der ausgestaltet ist, um mittels des Hochfrequenz-Signals ein erstes Regelsignal derart mit einer ersten Regelfrequenz zu erzeugen, dass die erste Regelfrequenz in Bezug zu der Frequenz des Hochfrequenz-Signals um einen Teilerfaktor verringert ist,
• - eine Takteinheit zur Erzeugung eines ersten Taktsignals, mit einer ersten Taktfrequenz, und
• - einen ersten Phasenkomparator (auch bekannt als Phasen-Frequenz-Detektor), der so verschaltet ist, um mittels des ersten Regelsignals und des ersten Taktsignals ein erstes Steuersignal zur Steuerung des Hochfrequenz-Oszillators zu erzeugen.

The invention achieves this object by a high-frequency signal generation unit comprising the following components:

• - A high frequency electrical oscillator for generating a high frequency electrical signal having a controllable frequency,
• a frequency divider configured to generate, by means of the high frequency signal, a first control signal having a first control frequency such that the first control frequency is reduced by a divisor factor with respect to the frequency of the high frequency signal,
• - A clock unit for generating a first clock signal, with a first clock frequency, and
• - A first phase comparator (also known as phase-frequency detector), which is so connected to generate by means of the first control signal and the first clock signal, a first control signal for controlling the high-frequency oscillator.

• - Einen ersten Frequenzwandler, der ausgelegt ist, um mittels des ersten Regelsignals ein zweites Regelsignal derart mit einer zweiten Regelfrequenz zu erzeugen, dass die zweite Regelfrequenz in Bezug zu der ersten Regelfrequenz um einen vordefinierten Faktor geteilt ist,
• - einen zweiten Frequenzwandler, der ausgelegt ist, um mittels des ersten Taktsignals ein zweites Taktsignal derart mit einer zweiten Taktfrequenz zu erzeugen, dass die zweite Taktfrequenz in Bezug zu der ersten Taktfrequenz um den vordefinierten Faktor geteilt ist, und
• - einen zweiten Phasenkomparator, der so verschaltet ist, um mittels des zweiten Taktsignals und des zweiten Regelsignals ein zweites Steuersignal zu erzeugen.

Hierbei ist die Hochfrequenz-Erzeugungseinheit derart ausgelegt, um die Frequenz des Hochfrequenz-Oszillators mittels des ersten Steuersignals und des zweiten Steuersignals steuern.According to the invention, the high-frequency signal generating unit is characterized by:

• A first frequency converter configured to generate, by means of the first control signal, a second control signal having a second control frequency such that the second control frequency is divided by a predefined factor with respect to the first control frequency,
• a second frequency converter configured to generate, by means of the first clock signal, a second clock signal having a second clock frequency such that the second clock frequency is divided by the predefined factor with respect to the first clock frequency, and
• a second phase comparator connected to generate a second control signal by means of the second clock signal and the second control signal.

Here, the high-frequency generating unit is designed to control the frequency of the high-frequency oscillator by means of the first control signal and the second control signal.

An increased resolution can be achieved by means of the high-frequency signal generating unit according to the invention, especially when digital phase comparators are used, so that the first phase comparator, a first charge pump for digital / analog conversion of the first control signal is connected downstream, and that the second phase comparator, a second charge pump downstream of the digital / analog conversion of the second control signal. In particular in this case there is the advantage that the second phase comparator can be designed with a second charge pump, which has a faster switching behavior than the first charge pump of the first phase comparator. Additionally or alternatively, the second charge pump may be designed with a higher breakdown voltage than that of the first charge pump, provided that the factor of the first frequency converter and the second frequency converter is greater than 1. Thus, the high-frequency signal according to the invention can be generated both with a high bandwidth, as well as with a high linearity and spectral purity, so that thereby a high-resolution distance measurement is made possible.

The control of the high-frequency oscillator by means of the first control signal and the second control signal can be made dependent on the particular type of high-frequency oscillator used in the invention: In the event that the high-frequency oscillator only a first control input for controlling the oscillator Frequency or the frequency of the high-frequency signal has (for example, in the case of standard prior art VCO's), an addition node within the high frequency generating unit can be provided, the first control signal and the second control signal (or their voltage or current values) is added to supply the added signals to the first control input of the high frequency oscillator.

In addition, there are also types of high-frequency oscillators, in addition to the first control input for a "coarse", first control signal (ie a comparatively slow control signal with a large voltage range) and a second control input for a second "fine" control signal (ie a faster control signal but with reduced voltage range). Such a type high frequency oscillator is disclosed in, for example, the publication US 20140241335 A1 shown. In the case of the high-frequency generating unit according to the invention, when using a high-frequency oscillator with two control inputs, the first control signal can be supplied to the first control input of the high-frequency oscillator; The second control signal is supplied to the second control input of the high-frequency oscillator.

Which of the two control signals is the "coarse and fast" or the "fine but slow" control signal depends on the factor according to the invention with which the first frequency converter and the second frequency converter divide the clock signal or the control signal If the first frequency converter and the second frequency converter are designed so that the factor is greater than 1, the actual, first control signal is the faster control signal. In this regard, a further development according to the invention is that the first frequency converter and the second frequency converter are designed so that the Factor is changeable (for example in a value range between 1 and 10). This could be implemented, for example, if the high-frequency signal generation unit according to the invention is constructed from hybrid components whose components are to be matched to one another.

The sawtooth-shaped frequency change of the high-frequency signal required by the FMCW principle can be implemented in various ways in the high-frequency signal generation unit according to the invention. First, the frequency divider can be designed such that the divider factor (periodically linear in a predefined value range) can be changed is. For this purpose, the frequency divider can be implemented, for example, as a "fractional N converter". If, however, the frequency divider is designed with a permanently presettable divider factor, a frequency actuator, in particular a DDS component, must be provided by means of which the frequency of the clock signal can be changed. In this case, the frequency actuator is to be placed directly behind the clock unit, so that the frequency for both the clock signal on the first phase comparator and the clock signal on the second phase comparator is changed by the frequency actuator.

Analogously to the prior art, it is also advantageous in the case of the high-frequency signal generation unit according to the invention for increasing the resolution if the high-frequency oscillator is designed to receive the high-frequency signal with a frequency of higher than 70 GHz, in particular higher than 120 GHz produce. A (further) increase in the frequency can also be achieved if a frequency multiplier for frequency multiplication of the high-frequency signal is provided.

In the case of both control signals, for the purpose of filtering in particular high-frequency interference signals, the high-frequency signal generation unit according to the invention offers a first filter, in particular a first low-pass filter for filtering the first control signal, and / or a second filter, in particular a second low-pass filter , for filtering the second control signal. This also improves the control of the entire control loop.

• - Eine Hochfrequenz-Signalerzeugungseinheit in zumindest einer der zuvor genannten Ausführungsvarianten, wobei das Distanz- oder Geschwindigkeits-Messgerät ausgelegt ist, um die Frequenz des Hochfrequenz-Signals innerhalb einer vorbestimmten Frequenzdifferenz periodisch, insbesondere sägezahnförmig zu ändern,
• - eine Sende-/Empfangs-Einheit, die aufgebaut ist, um mittels des Hochfrequenz-Signals ein Radar-Signal in Richtung eines Objektes, dessen Distanz oder Geschwindigkeit zu bestimmen ist, auszusenden, sowie ein vom Objekt reflektiertes Echo-Signal zu empfangen, und
• - eine Auswerte-Einheit, die ausgelegt ist, um anhand des Echo-Signals die Distanz und/oder die Geschwindigkeit des Objekts zu bestimmen.

Since the linearity of the sawtooth-shaped high-frequency signal can be increased with respect to the FMCW principle by means of the high-frequency signal generation unit according to the invention, a preferred implementation is in an FMCW radar-based distance or speed measuring device. Accordingly, such a measuring device comprises:

• A high-frequency signal generating unit in at least one of the previously mentioned embodiments, wherein the distance or speed measuring device is designed to change the frequency of the high-frequency signal within a predetermined frequency difference periodically, in particular sawtooth-shaped
• a transmitting / receiving unit configured to emit, by means of the high-frequency signal, a radar signal in the direction of an object whose distance or speed is to be determined, and to receive an echo signal reflected by the object, and
• an evaluation unit which is designed to determine the distance and / or the speed of the object on the basis of the echo signal.

By implementing the high-frequency signal generation unit according to the invention, the resolution of the distance or speed measurement can thus be increased. Above all, the resolution of the distance or of the filling level represents a central aspect in radar-based level measurement. Therefore, it is also advantageous to use the FMCW radar-based distance or speed measuring device in which the high-frequency signal generation unit according to the invention is implemented to use for measuring a level of a filling material located in a container.

• 1: Eine Hochfrequenz-Signalerzeugungseinheit nach dem Stand der Technik,
• 2: ein für FMCW typisches, sägezahnförmiges Hochfrequenz-Signal,
• 3: eine standartmäßige Verschaltung der Hochfrequenz-Signalerzeugungseinheit zur FMCW-basierten Distanz- oder Geschwindigkeits-Messung,
• 4: eine erfindungsgemäße Hochfrequenz-Signalerzeugungseinheit, und
• 5: eine mögliche Verwendung der erfindungsgemäßen Hochfrequenz-Signalerzeugungseinheit in einem Füllstandsmessgerät.

Based on the following figures, the invention will be explained in more detail. It shows:

• 1 : A high-frequency signal generation unit according to the prior art,
• 2 : a typical FMCW sawtooth RF signal,
• 3 a standard connection of the high-frequency signal generation unit to the FMCW-based distance or speed measurement,
• 4 a high-frequency signal generation unit according to the invention, and
• 5 A possible use of the high-frequency signal generation unit according to the invention in a fill level measuring device.

To understand the high-frequency generation unit according to the invention 1 are in 1a and 1b the embodiments of two high-frequency generating units 1' illustrated in the prior art: The principle of operation of the embodiments shown there is the term "phase locked loop" (in English as "Phase Locked Loop, PLL" known). The high-frequency generation units 1' are each based on one controllable, high-frequency electric oscillator 11 , (implemented by default as a VCO), which is an electrical high-frequency signal s _HF generated. According to the application with FMCW radar the frequency is _HF of the high-frequency signal s _HF in the GHz range between 1 GHz and over 100 GHz.

This is the frequency _HF of the high-frequency signal s _HF controlled by feedback and thus stabilized, for example, to fluctuations in the ambient temperature: the feedback is realized by the high-frequency signal s _HF of the high frequency oscillator 11 a control signal s _c branched off and a phase comparator 14 is supplied.

The phase comparator 14 compares the instantaneous phase shift of the control signal s _c to a frequency constant reference signal s _clock , The reference signal s _clock here has a precisely preset reference frequency f _clock with negligible temperature drift on. As source for the reference signal s _clock For example, a quartz oscillator can be used, which is the reference signal s _clock usually with a frequency f _clock generated in the range between 100 MHz and 1 GHz. To the frequency difference between the reference signal s _clock and the control signal s _c or the high-frequency signal s _HF compensate, the frequency becomes f _c of the control signal s _c through a frequency divider 12 with a corresponding divider factor N reduced.

Depending on the phase difference between the control signal s _c and the reference signal s _clock generates the phase comparator 14 a control signal s _DC which leads to a corresponding control input of the high-frequency oscillator 11 to be led. Here is the control signal s _DC designed so that the phase comparator 14 the phase shift minimizes:

When using a VCO as a high-frequency oscillator 11 this requires the control of the frequency _HF of the high-frequency signal s _HF a DC voltage. Therefore, the digital phase comparator 14 the in 1a and 1b shown embodiments, a charge pump 16 (especially in English known as "charge pump") downstream. Thus, by the charge pump 16 a corresponding digital / analog conversion of the control signal s _DC carried out. Depending on the implementation of the high-frequency signal generation unit 1' it is before or after the charge pump 16 optionally additionally required to perform a level adjustment by means of a level converter (not shown). By means of a filter 19 that between the phase comparator 14 and the high frequency oscillator 11 is arranged, the control signal s _DC Moreover, be cleaned of particular high-frequency noise components. Accordingly, the filter 19 in 1a and 1b designed as a low pass.

The usual with FMCW radar, sawtooth waveform of the high-frequency signal s _HF (please refer 2 ) can in the previously described control loop of the high-frequency generating unit 1' alternatively be set at two points:

Either it is possible to use the frequency divider 12 interpreted in such a way that its divider factor N constant in time, that is to say change in a kind of sawtooth shape. This alternative is in 1a In such a design, the divider factor N assume any rational value. In this case, the control loop is also referred to as a "fractional-N PLL".

Alternatively, it is also possible to use the frequency divider 12 be interpreted as the divisor factor N of the frequency divider 12 is preset to an integer value. This is in 1b In this case, the frequency must be f _clock the reference signal s _clock at the corresponding input of the phase comparator 14 be suitably modulated to the sawtooth frequency change of the high-frequency signal s _HF to reach. For this purpose, a suitable frequency converter 17 For example, a DDS module ("Direct Digital Synthesis") can be used.

The realization of the high-frequency oscillator 11 By means of a VCO's is technically justifiable expense only up to frequencies of about 80 GHz makes sense. Also with the frequency divider 12 the power consumption increases with increasing frequency and the input sensitivity decreases. To the high-frequency signal s _HF Nevertheless, to be able to produce at a higher frequency, the high-frequency oscillator 11 , as in 1a and 1b represented, a frequency multiplier 18 with a corresponding multiplication factor M be followed (for example, M = 8).

Im gezeigten Fall handelt es sich, wie beim FMCW-Verfahren üblich, um eine periodische, sägezahnförmige (also innerhalb dieser Periode zeitlich linear ansteigende) Änderung der Frequenz f_HF . Theoretisch ist auch die Implementierung jeglicher anderer Frequenzänderung, wie beispielsweise einer Dreiecks-förmigen oder Sinus-förmigen Änderung der Frequenz f_HF möglich. 2 shows the frequency response of a FMCW radar typical high-frequency signal s _HF , which by means of in 1 shown high frequency signal generating units 1' can be generated. In the diagram shown there is the frequency _HF of the high-frequency signal s _HF plotted against time t. As in 2 is clarified, the frequency changes _HF of the high-frequency signal s _HF within a frequency difference .delta.f around $\pm \frac{1}{2}*\Delta \text{f}\text{,}$

In the case shown, it is, as usual in the FMCW method, a periodic, sawtooth (ie time-linearly increasing within this period) change in frequency _HF , Theoretically, the implementation of any other frequency change, such as a triangle-shaped or sinusoidal change in frequency _HF possible.

The periodicity of the sawtooth change, as typical in the FMCW method, may be on the order of up to a few hundred MHz. The frequency difference .delta.f is preferably sized to include the maximum possible bandwidth (as previously mentioned, a high bandwidth potentially increases the resolution of the distance measurement). In the frequency band of 79 GHz, the bandwidth is for example 4 GHz, ie from 77 GHz to 81 GHz.

In 3 is a possible interconnection of the high-frequency signal generation unit 1 . 1' based on which an FMCW-based distance or speed measurement can be performed. In the illustration is the high-frequency signal generation unit 1 . 1' as known from the prior art, to a transmitting / receiving unit 2 connected. In this case, that of the high-frequency signal generating unit 1 . 1' generated high-frequency signal s _HF within the sender / receiver unit 2 via a signal divider 21 (and optionally an output amplifier 22 ) of a transmitting antenna 23 fed. In this case, the transmitting antenna 23 For example, as a planar antenna, in particular as a patch or fractal antenna realized. There is the electrical high-frequency signal s _HF in the actual radar signal S _HF converted and emitted accordingly.

By the reflection of the radar signal S _HF the measured object receives a corresponding echo signal E _HF at a receiving antenna 24 the transmitting / receiving unit 2 receive. The transmitting antenna 24 can be analogous to the transmitting antenna 23 also be realized as a planar antenna. It is also conceivable to use a combined transmit-receive antenna, the corresponding via a transmitting / receiving switch with the signal divider 21 is contacted.

Upon receipt, the echo signal E _HF in the receiving antenna 24 converted back into a purely electrical signal (which, in turn, optionally by a receiving amplifier 25 can be strengthened). This is then connected by means of a receiving mixer 26 with the high frequency signal s _HF the high-frequency signal generation unit 1 . 1' mixed, with the high-frequency signal s _HF for this purpose from the signal divider 21 is branched off. This becomes a difference signal typical of the FMCW method e _LF generated, which forms the basis for determining the distance or speed. In this case, according to the FMCW principle, the frequency of the difference signal e _LF proportional to the distance of the measurement object, so that a suitable evaluation unit 3 by measuring this frequency the distance to the corresponding object 5 can determine.

As in the context too 2 mentioned, the resolution with which the distance can be determined depends essentially on the bandwidth .delta.f of the high-frequency signal s _HF and the linearity of its temporal frequency change. The linearity is in the case of in 1a and 1b shown high-frequency generating units 1' essentially dependent on the control speed of the PLL-based control loop. To maximize the control speed, it is especially necessary to charge the charge pump 16 to design with correspondingly fast transistors in order to achieve a suitable switching behavior.

In particular, fast CMOS transistors with switching frequencies above 1 GHz, as required for charge pumps, however, have a comparatively low forward voltage of less than 1V. This again makes it impossible for the charge pump 16 to realize that the control signal s _DC can be varied in a wide range of taxation. Because of this can be with this charge pump 16 , if constructed with fast transistors, only a small frequency difference .delta.f or a narrow bandwidth of the high-frequency signal s _HF to adjust. Thus, the achievable resolution with the in 1a and 1b shown high frequency generating units 1' limited in total.

A high-frequency signal generation unit according to the invention 1 , with which an improved resolution can be achieved, is in 4 shown: The high-frequency signal generation unit shown there 1 includes next to the first phase comparator 14 a second phase comparator 14 ' , In this case, the second phase comparator 14 ' in contrast to the first phase comparator 14 not directly by the control signal s _c or the reference signal s _clock driven. But both the control frequency f _c as well as the reference frequency f _clock each by a frequency converter 15 . 15 ' by a factor n (For example, n = 4) before dividing the second phase comparator 14 ' be supplied. Accordingly, the high-frequency oscillator becomes 11 by the first control signal s _DC of the first phase comparator 14 and additionally by a second control signal s _DC 'of the second phase comparator 14 ' driven.

This has the advantage that the first phase comparator 14 ' with a second charge pump 16 ' It is conceivable that a faster switching behavior than the first charge pump 16 ' of the first phase comparator 14 having. Analogously, the first charge pump 16 with a higher breakdown voltage than the second charge pump 16 be interpreted. Thus, that can High-frequency signal s _HF according to the invention both with a high bandwidth .delta.f , as well as be produced with a high linearity, so that in this way a high-resolution and accurate distance measurement is possible.

The control of the oscillator 11 by means of the first control signal s _DC and the second control signal s _DC 'is how in 4 shown, possible in at least two different ways: Depending on the type of high-frequency oscillator used 11 become the respective voltage or current value of the first control signal s _DC and the second control signal s _DC 'by a summation node 10 added before the added signal to the first control input of the high-frequency oscillator 11 is supplied. This is the high frequency oscillator 11 For example, to control if this only a first control input for controlling the oscillator frequency or the frequency _HF of the high-frequency signal s _HF having. This applies, for example, to standard VCOs which have only one analog, voltage-dependent control input.

Alternatively, the high frequency oscillator 11 , provided he next to the first control input for the "rough and fast", first control signal s _DC also a second control input for the second "fine" control signal s _DC (Such a type of high frequency oscillator is for example in the publication US 20140241335 A1 described), even without the use of the summation node 10 directly across the two control inputs. This is the high frequency oscillator 10 in 4 represented by dashed lines.

At the in 4 illustrated embodiment is the frequency divider 12 designed as a "fractional-N converter". Accordingly, the divider factor N changeable, so that analogous to 1b the ramped frequency change of the high frequency signal S _HF is adjustable. It goes without saying that for the purposes of the invention, the in 1a shown variant for adjusting the frequency change by means of an additional frequency actuator 17 can be implemented. In this case, the frequency actuator 17 directly behind the clock unit 13 arrange so that the clock frequency f _clock of the clock signal s _clock through the frequency actuator 17 both at the first phase comparator 14 as well as the second phase comparator 14 ' is changed.

In 5 is a possible application of the high-frequency signal generation unit according to the invention 1 in a level measuring device working according to the FMCW radar principle 1 . 2 . 3 shown. It is a typical measurement situation, which is seen inside a container 4 a product 5 located. Here is the level L of the contents 5 through the level gauge 1 . 2 . 3 in relation to the container bottom.

For this purpose, the level gauge 1 . 2 . 3 in a known installation height H above the contents 5 on the container 4 appropriate. In this case, the container 4 Depending on the area of use, be up to more than 30 m high.

The level gauge 1 . 2 . 3 is for example by means of a flange at the top of the container 2 arranged that it is the radar signal S _HF via the transmitting / receiving unit 2 in the direction of the contents 5 sending out. After reflection on the product surface, the level gauge receives 1 . 2 . 3 the echo signal E _HF again via the transmitting / receiving unit 2 , The transit time between transmission of the radar signal is S _HF and receiving the echo signal E _HF , which is measured on the FMCW principle in the form of a difference frequency, depending on the distance d to the surface of the filling material 5 , The subsequent calculation of the fill level L from the distance d to the product surface occurs through the level gauge 3 with knowledge of its installation height H : L = h - d. In this case, the level L due to the high frequency signal generating unit according to the invention 1 be determined with a very good resolution. As a rule, the level gauge is 1 . 2 . 3 via a bus system, such as "PROFIBUS", "HART" or "Wireless HART" with a higher-level unit 6 , for example, a process control system connected. On the one hand, this can be the value of the filling level L be transmitted to control any inflows or outflows on the container. In addition, however, for example, additional information about the operating state of the level gauge 1 . 2 . 3 be communicated.

LIST OF REFERENCE NUMBERS

1, 1 '

High-frequency signal generation unit

2

Transmit / receive unit

3

Evaluation unit

4

container

5

filling

6

Parent unit

10

Summing node

11

High-frequency oscillator

12

frequency divider

13

clock unit

14, 14 '

phase comparators

15, 15 '

frequency converter

16, 16 '

charge pumps

17

Frequency actuator

18

frequency

19, 19 '

filter

21

Transmit / receive switch

22

Transmit amplifier

23

Transmit antenna

24

Receive antenna

25

Receiving amplifier

26

mixer

d

distance

E _HF

Echo-signal

e _LF

Difference signal

f _c , f _c '

rule frequencies

f _clock , f _clock '

clock frequencies

_HF

Frequency of the high-frequency signal

H

installation height

L

level

M

multiplication factor

N

division factor

n

factor

S _HF

Radar Signal

s _c , s _c '

control signals

s _clock , s _clock '

reference signals

s _DC , s _DC '

control signals

s _HF

High-frequency signal

.delta.f

frequency difference

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013105 A1 [0007]
• US 20140241335 A1 [0016, 0043]

Claims (13)

High-frequency signal generating unit, comprising the following components: - A high frequency electrical oscillator (11) for generating a high frequency electrical signal (s _HF ) with a controllable frequency (f _HF ), - a frequency divider (12) which is designed to to generate the first control frequency (f _c) with respect to the frequency (f _HF) of the high frequency signal of the high frequency signal (S _HF) a first control signal (s _c) is connected to a first control frequency (f _c) (S _HF ) is reduced by a divisor factor (N), - a clock unit (13) for generating a first clock signal (s _clock ), with a first clock frequency (f _clock ), and - a first phase comparator (14), which is connected, for generating, by means of the first control signal (s _c ) and the first clock signal (s _clock ), a first control signal (s _DC ) for controlling the high-frequency oscillator (11), characterized by - a first frequency converter (15) which is designed um by means of ers th control signal (s _c ) to generate a second control signal (s _c ') with a second control frequency (f _c '), that the second control frequency (f _c ') in relation to the first control frequency (f _c ) by a predefined factor (n) is divided, - a second frequency converter (15 ') which is designed to generate by means of the first clock signal (s _clock ), a second clock signal (s _clock ') with a second clock frequency (f _clock ') that the second clock frequency (f _clock ') is divided by the predefined factor (n) with respect to the first clock frequency (f _clock ), and - a second phase comparator (14') connected so as to use the second clock signal (s _clock ') and the second control signal (s _c ') to generate a second control signal (s _DC '), wherein the high-frequency generating unit (1) is adapted to the frequency (f _HF ) of the high-frequency oscillator (11) by means of of the first control signal (s _DC ) and the second control signal (s _DC ') control. High-frequency signal generation unit according to Claim 1 , characterized in that an addition node (10) is provided to add the first control signal (s _DC ) and the second control signal (s _DC '), wherein the added signals (s _DC , s _DC ') a first control input of the high-frequency oscillator (11) are supplied. High-frequency signal generation unit according to Claim 1 , characterized in that the high-frequency oscillator (11) in addition to the first control input has a second control input, wherein the first control signal (s _DC ) to the first control input of the high-frequency oscillator (11) is supplied, and wherein the second control signal (s _DC ') is supplied to the second control input of the high-frequency oscillator (11). High-frequency signal generation unit according to Claim 1 . 2 or 3 , characterized in that the first frequency converter (15) and the second frequency converter (15 ') are designed so that the factor (n) is greater than 1, and / or that the first frequency converter (15) and the second frequency converter (15 ') are designed so that the factor (s) is changeable. High-frequency signal generation unit according to one of Claims 1 to 4 , characterized in that the first phase comparator (12) is followed by a first charge pump (16) for digital / analog conversion of the first control signal (s _DC ), and in that the second phase comparator (12 ') has a second charge pump (16') for the digital / analog conversion of the second control signal (s _DC ') is connected downstream. High-frequency signal generation unit according to Claim 5 , characterized in that in the event that the factor (n) of the first frequency converter (15) and the second frequency converter (15 ') is greater than 1, the second charge pump (16') has a higher breakdown voltage than the first charge pump ( 16), and / or that the first charge pump (16) has a faster switching behavior than the second charge pump (16 '). High-frequency signal generating unit according to at least one of the preceding claims, characterized in that the frequency divider (12) is designed so that the divider factor (N) is variable. High-frequency signal generation unit according to at least one of Claims 1 to 6 , characterized in that the frequency divider (12) is designed with a fixed presettable divisor factor (N), wherein a frequency actuator (17), in particular a DDS module, by means of which the frequency (f _clock ) of the clock signal (s _clock ) changeable is, is provided. High-frequency signal generation unit according to at least one of the preceding claims, characterized in that the high-frequency oscillator (11) is designed to generate the high-frequency signal (s _HF ) with a frequency of higher than 70 GHz, in particular higher than 120 GHz. High-frequency signal generation unit according to at least one of the preceding claims, characterized in that a frequency multiplier (18) for frequency multiplication of the high-frequency signal (s _HF ) is provided. High-frequency signal generating unit according to at least one of the preceding claims, characterized by a first filter (19), in particular a first low-pass filter, for filtering the first control signal (s _DC ), and / or a second filter (19 '), in particular a second Low-pass filter, for filtering the second control signal (s _DC ). An FMCW radar-based distance or velocity measuring device, comprising: - A high-frequency signal generating unit (1) according to at least one of the preceding claims, wherein the distance or speed measuring device is designed to control the frequency (f _HF ) of the high-frequency signal (S _HF ) within a predetermined frequency difference (.DELTA.f) periodically, in particular to change sawtooth, - a transmitting / receiving unit (2) which is constructed to use the high-frequency signal (s _HF ) a radar signal (S _HF ) in the direction of an object (5) whose distance or speed is to be determined to emit, and to receive an object-reflected echo signal (E _HF ), and - an evaluation unit (3) which is designed to to determine the distance and / or the speed of the object (5) on the basis of the echo signal (E _HF ). Using the FMCW Radar Based Distance or Velocity Meter Claim 12 , for measuring a filling level (L) of a filling material (5) located in a container (4).

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