Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
  • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
  • G01S13/06—Systems determining position data of a target
  • G01S13/08—Systems for measuring distance only
  • G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
  • G01S13/34—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
  • G01S13/343—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal using sawtooth modulation
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
  • G01S7/35—Details of non-pulse systems
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
  • G01S7/40—Means for monitoring or calibrating
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
  • G01R29/26—Measuring noise figure; Measuring signal-to-noise ratio
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
  • G01R31/282—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
  • G01R31/2822—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere of microwave or radiofrequency circuits
  • G01R31/2824—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere of microwave or radiofrequency circuits testing of oscillators or resonators
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
  • G01S13/87—Combinations of radar systems, e.g. primary radar and secondary radar
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
  • G01S13/88—Radar or analogous systems specially adapted for specific applications
  • G01S13/93—Radar or analogous systems specially adapted for specific applications for anti-collision purposes
  • G01S13/931—Radar or analogous systems specially adapted for specific applications for anti-collision purposes of land vehicles
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
  • G01S7/023—Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques
  • G01S7/0232—Avoidance by frequency multiplex
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
  • G01S7/03—Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
  • G01S7/032—Constructional details for solid-state radar subsystems
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
  • G01S7/40—Means for monitoring or calibrating
  • G01S7/4004—Means for monitoring or calibrating of parts of a radar system
  • G01S7/4008—Means for monitoring or calibrating of parts of a radar system of transmitters
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
  • G01S7/40—Means for monitoring or calibrating
  • G01S7/4004—Means for monitoring or calibrating of parts of a radar system
  • G01S7/4017—Means for monitoring or calibrating of parts of a radar system of HF systems
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
  • G01S7/40—Means for monitoring or calibrating
  • G01S7/4052—Means for monitoring or calibrating by simulation of echoes
  • G01S7/406—Means for monitoring or calibrating by simulation of echoes using internally generated reference signals, e.g. via delay line, via RF or IF signal injection or via integrated reference reflector or transponder
  • G01S7/4069—Means for monitoring or calibrating by simulation of echoes using internally generated reference signals, e.g. via delay line, via RF or IF signal injection or via integrated reference reflector or transponder involving a RF signal injection

Definitions

• the invention relates to a method for monitoring an FMCW radar sensor having a plurality of local oscillators.
• Radar sensors are increasingly being used in motor vehicles for detecting the traffic environment and provide information about distances, relative speeds and directional angles of located objects to one or more assistance functions that relieve the driver when driving the vehicle or replace the human driver in whole or in part , With increasing autonomy of these assistance functions, not only the performance, but also the reliability of the radar sensors are increasingly demanding.
• the object of the invention is therefore to increase the reliability of the frequency generation of a radar sensor.
• the object is achieved according to the invention by a method for monitoring an FMCW radar sensor which has a plurality of local oscillators
• a first local oscillator signal of a first local oscillator of the local oscillators is mixed with a second local oscillator signal of a second local oscillator of the local oscillators in a mixer to form a baseband signal and the baseband signal is evaluated, based on a result of the evaluation Error is detected.
• the monitoring can thus be carried out as an internal function of the radar sensor during operation.
• local oscillator signals which are frequency-modulated ramp-shaped, allows monitoring of the generation of the FMCW frequency ramps.
• a local oscillator signal constant frequency can be monitored, but also parameters of the FMCW frequency ramps can be monitored without the need for external, expensive measuring devices are required.
• the evaluation in the baseband signal can also take place via an analog / digital converter for the channels of the radar sensor which is provided anyway in the FMCW radar sensor.
• an FMCW radar sensor with a plurality of local oscillators, wherein the FMCW radar sensor is set up for carrying out the method described here.
• the FMCW radar sensor may be, for example, an FMCW radar sensor with a plurality of FM frequency components, each having a transmitting and receiving part and a local oscillator.
• the method is preferably a method for monitoring an FMCW radar sensor, which has a plurality of radio-frequency components, each of which has a transmitting and receiving part for outputting a transmission signal to at least one antenna assigned to the radio-frequency module and for receiving a reception signal from at least one antenna assigned to the radio-frequency module wherein a first high-frequency component of the FMCW radar sensor comprises the first local oscillator and a second high-frequency component of the FMCW radar sensor comprises the second local oscillator, wherein in the method the first local oscillator signal of the first local oscillator of the first high-frequency component to the second high-frequency component is transmitted and mixed with the second local oscillator signal of the second local oscillator of the second high frequency component in a mixer of the second high frequency component to the baseband signal.
• the first local oscillator signal and the second local oscillator signal have a frequency offset from each other.
• a desired value of the frequency offset is constant.
• the first local oscillator signal and the second local oscillator signal may each be a local oscillator signal in the form of an FMCW frequency ramp, which have the same setpoint of their ramp slope.
• first and second local oscillator signals with constant frequency can also be used for certain evaluations.
• a reference clock signal of first and second high-frequency sources of the FMCW signal is generated. Radarsensors supplied, wherein the first high frequency source comprises the first local oscillator and the second high frequency source comprises the second local oscillator.
• a reference clock signal can be fed to reference clock signal inputs of the first and second high-frequency components for establishing a time reference between start times of the first and second local oscillator signals.
• the reference clock signal can serve, for example, to set identical start times of FMCW frequency ramps.
• the reference clock signal may be used to set a time base for driving the first and second local oscillators. For example, the start times of the first and second local oscillator signals can be synchronized.
• each of the first and second local oscillator signals is a local oscillator signal in the form of an FMCW frequency ramp, wherein the FMCW frequency ramps have an equal setpoint of their slope.
• a desired value of a frequency offset between the FMCW frequency ramps and a frequency shift that corresponds to a signal propagation time of the transmission path are taken into account.
• the setpoint of a frequency offset between the FMCW frequency ramps is not equal to zero.
• the transmission of the first local oscillator signal from the first local oscillator to the mixer, or from the first high frequency component to the second high frequency component, can be done in different ways.
• the first local oscillator signal can be supplied to the mixer via a transmission path with a known signal propagation delay.
• the first local oscillator signal can be supplied from a signal output of the first high-frequency component via a signal line to a signal input of the second high-frequency component.
• the baseband signal can be evaluated taking into account the signal transit time of the transmission path.
• the FMCW radar sensor may be designed for normal operation, in which the first high-frequency component operates as a master and the second high-frequency component operates as a slave and for synchronization of the second high-frequency component with the first high-frequency component of a synchronization signal input of the second high-frequency component, a local one Oscillator signal of the first radio-frequency module is supplied from a synchronization signal output of the first radio-frequency module, wherein the method is carried out in a measuring operation, and wherein in the measuring operation, the first local oscillator signal from the synchronization signal output of the first radio-frequency module via a signal line the synchronization input the second radio-frequency module is supplied.
• the first local oscillator signal can be supplied from a transmitter output of a transmitting and receiving part of the first high-frequency component via a signal line to a receiver input of a transmitting and receiving part of the second high-frequency component.
• the normal high-frequency components for normal operation in a master / slave configuration in the high-frequency components operated as slaves can actually be unnecessary local oscillators for the Monitoring the frequency generation of the local oscillator of the operated as a master radio-frequency module can be used.
• the use of identical high-frequency components also results in a cost-effective realization of powerful radar sensors.
• the first local oscillator signal is further processed by a first transmitting and receiving part of the FMCW radar sensor into a transmission signal, transmitted via at least one first antenna and supplied by crosstalk to at least a second antenna to a second transmitting and receiving part of the FMCW radar sensor.
• the first local oscillator signal is further processed by a transmitting and receiving part of the first radio-frequency module to form a transmission signal, transmitted via at least one first antenna and supplied by crosstalk to at least one second antenna to a transmitting and receiving part of the second high-frequency component.
• the signal transmitted via the antenna can crosstalk in example in the sensor or the radome of the sensor to a second radio-frequency module associated antenna.
• each of the first and second local oscillators is controlled by a phase locked loop of the respective first or second RF module, synchronizing input signals of the phase locked loops, and wherein evaluating the baseband signal comprises: determining a noise level in one Baseband range outside a peak of the baseband signal, and comparing the determined noise level with an expected noise level.
• the method according to the invention can also be used for mutual monitoring of the signal generation of the first local oscillator and the second local oscillator, or for mutual monitoring of the signal generation of the first high-frequency component and of the second high-frequency component.
• the inventive method can also be extended to the use of more than two local oscillators of the FMCW radar sensor whose local oscillator signals are evaluated separately in the baseband.
• the method according to the invention can be extended, for example, to the use of more than two local oscillators of more than two high-frequency components whose local oscillator signals at at least one high-frequency component in the baseband are evaluated separately.
• a third local oscillator signal may be a setpoint of a frequency offset to that second local oscillator signal, which is different from a target value of a frequency offset, having the first local oscillator signal to the second local oscillator signal.
• the first local oscillator signal of the first local oscillator of the first high frequency component of the FMCW radar sensor and a third local oscillator signal of a third local oscillator of a third FM component of the FMCW radar sensor can be transmitted to the second RF component of the FMCW radar sensor and are mixed with the second local oscillator signal of the second local oscillator of the second radio frequency component in the mixer of the second radio frequency component to the baseband signal, wherein a frequency offset between the third and the second local oscillator signal differs from a frequency offset between the first and the second local oscillator signal ,
• Figure 1 is a sketch of a radar sensor with four high-frequency components, which are connected to each other via an oscillator signal network.
• Fig. 2 is a frequency-time diagram of local oscillator signals and an amplitude spectrum of a baseband signal
• FIG. 3 shows a frequency-time diagram of local oscillator signals and an amplitude spectrum of a baseband signal according to a modified embodiment
• FIG. 4 shows an amplitude spectrum of a baseband signal for explaining the evaluation of a noise level.
• FIG. 1 shows four high-frequency components 10, 12, 14, 16 of a radar sensor, which are arranged on a common substrate 18. Each of the high-frequency components is an integrated circuit in the form of an MMIC (Monolithic Microwave Integrated Circuit) chip.
• Each high-frequency module contains a transmitting and receiving part 20 which comprises at least one transmitter output 22 and one receiver input 24, which are connected to associated antennas 26, 28 of the radar sensor.
• Each radio frequency module may have a plurality of transmission antennas 26 and / or a plurality of reception antennas 28 assigned to it. By way of example, a transmitting antenna 26 and a receiving antenna 28 are shown.
• the transmitting and receiving part 20 can serve to amplify and divide the oscillator signal, which for example has a frequency of the order of 76 GHz, and to divide it into the transmitting antennas.
• the receiving antennas can be identical to the transmitting antennas.
• the transmitting and receiving parts 20 can also contain circuits with which the transmitting signals to the individual antennas are modified in their phase position and possibly also in their frequency position, in order to ensure suitable beam shaping and the best possible angular resolution of the radar system to reach.
• each high-frequency component contains a high-frequency source 30 which comprises a local oscillator 32 with a phase-locked loop 34 and is set up to generate a local oscillator signal which can be supplied to the transmitting and receiving unit 20 via a switching network 36.
• the phase locked loop 34 comprises a frequency divider.
• the local oscillator signal is mixed at a mixer 38 of the transmitting and receiving part 20 with a received signal to form a baseband signal and fed to an evaluation via an A / D converter 40 in a manner known per se.
• Several such receiving channels may be provided with a respective mixer and A / D converter. , g.
• the local oscillator signal can also be supplied to an HF distributor 42 operating as a synchronization signal output.
• the RF distributor of the high-frequency components which can work as a synchronization signal output or synchronization signal input, are connected to one another via an oscillator signal network 44.
• each high-frequency module comprises a reference clock signal input 46 for a reference clock signal, which is supplied via a reference clock signal line 48 from a reference clock source 50 and serves to synchronize the frequency generation of the high-frequency sources 30 with one another.
• the antennas 26, 28 of the radar sensor are arranged behind a radome 52.
• the radio-frequency source 30 is configured to generate a frequency-modulated local oscillator signal in the form of an FMCW frequency ramp.
• the frequency modulation can also take place within each individual transmitting and receiving part 20.
• the switching networks 36 are configured to configure the radar sensor for a master / slave configuration in normal operation. In a normal mode with a master / slave configuration, the local oscillator signal of the local oscillator 32 of the first radio-frequency module 10 from the HF distributor 42 operating as a synchronization signal output via a signal line of the oscillator signal network 44 to the other high-frequency components 12, 14 configured as a slave 16 fed.
• the first radio-frequency module 10 is configured as a master.
• the local oscillator signal supplied externally via the oscillator signal network 44 is transmitted to the transmitting and receiving amplifier via the HF distributor 42, which operates as the synchronization signal input, and the switching network 36. is used to generate the transmission signals for one or more associated radar antennas 26.
• the high-frequency module operate synchronously using the local oscillator signal of the first radio-frequency module 10th
• Measuring cycles of normal operation of the radar sensor temporarily switched to a measuring operation which can also be referred to as monitoring measurement operation.
• the measuring mode differs from the normal mode.
• For the measuring operation there is a reconfiguration of the generation and distribution of the local oscillator signals.
• the local oscillator signal of the other high frequency component is supplied via a transmission path with a defined signal propagation time and mixed with its own local oscillator signal and digitized in the AD converter and a further evaluation fed.
• a frequency shift resulting from the signal propagation time of the transmission path of the received baseband signal can be taken into account and, for example, eliminated.
• the consideration allows a particularly accurate monitoring of the frequency of the generated local oscillator signals. This will be explained below by way of example with reference to the first and second high-frequency components 10, 12.
• the local oscillator 32 of the first radio-frequency module 10 generates a local oscillator signal, which is supplied to the second radio-frequency module 12 on a transmission path to be described in more detail.
• the local oscillator 32 of the second high-frequency module 12 simultaneously and in synchronism with the local oscillator 32 of the first high-frequency module 10 generates its own local oscillator signal.
• Both local oscillator signals are transmitted in a mixer, for example a mixer 38 of the transmitter and receiver. 20, mixed into a baseband signal and supplied to the A / D converter 40.
• the two active signal sources 30 of the first and second RF components 10, 12 are configured such that the generated FMCW ramps have an identical start time and an identical ramp slope, but the center frequency is slightly offset.
• the signal generation is synchronized, for example, via the reference clock signal.
• FIG. 2 schematically shows the frequency ramp 54 of the local oscillator signal of the first flocc frequency component and the frequency ramp 56 of the local oscillator of the second high-frequency component 12 shifted by a frequency offset Fa.
• the local oscillator signal of the first high-frequency component is released with a time delay - Speaking of a signal delay tb obtained, which corresponds to a frequency shift Fb due to the ramp slope.
• a resulting frequency shift Fab which corresponds for example to the sum of Fa + Fb.
• a peak is obtained at the corresponding frequency shift Fab. This is stored in a corresponding bin of the spectrum.
• the spectrum is calculated in a manner known per se by Fourier transformation of the digitized baseband signal.
• the shift Fa of the center frequency is selected within the bandwidth of the base band. For example, with a sampling rate of 10 MHz, corresponding to a baseband width of 5 MHz, a frequency offset Fa of 2.5 MHz is selected.
• the transmission of the local oscillator signal from the first high-frequency component 10 to the second high-frequency component 12 can be done in various ways.
• the local oscillator signal of the first high-frequency component can be supplied via a signal output, for example the RF distributor 42, and via a signal line, in particular via the oscillator signal network 44, to a signal input, somewhat to the RF components 42 of the second high-frequency component 12.
• the oscillator signal network 44 via which the synchronization of the slaves with the master takes place in normal operation, used.
• a separate signal line for supplying the local oscillator signal of a high-frequency component to another high-frequency component may also be provided.
• a transmitter output 22 of the first radio-frequency module 10 can be connected to a receiver input 24 of the second radio-frequency module 12 via a correspondingly connected signal line.
• the effect can be used that in the radar sensor or on the radome 52 of the radar sensor crosstalk of a signal transmitted via an antenna 26 takes place on a receiving antenna 28 of another high-frequency module.
• This transmission path between a first high-frequency component and a second high-frequency component also has a defined signal propagation time, which can be taken into account as a frequency shift Fb in the evaluation. If a transmission occurs by crosstalk, there are no dedicated signal lines for connecting the first radio-frequency module 10 to the second radio-frequency module 12 is required.
• Monitoring the ramp center frequency of the local oscillator signal or the frequency offset between two local oscillators can be done as follows. Since in the example of FIG. 2 the expected frequency of the signal (peak 58) in the baseband signal is known and corresponds to the configured or desired frequency offset Fa combined with the expected frequency shift Fb due to the transit time of the crosstalk or the signal transport between the high frequency components, the expected frequency to be compared with the measured, resulting frequency offset Fab. If a difference of the compared values exceeds a threshold value, then the error case is detected. In particular, a faulty frequency offset is detected, and thus an erroneous frequency of a frequency ramp is detected, such as a faulty ramp center frequency.
• the accuracy of the estimate of the measured baseband frequency depends on the duration of the signal to be evaluated, i. of the duration of a frequency ramp. Even with a fast ramp of, for example, 15 ps duration and a corresponding width of an FFT bins of 20 kHz, the high signal strength can cause a high
• Deviations in the frequency generation between the two local oscillators of the first and second high-frequency components 10, 12 can thus be determined very accurately. Thus, it is even possible to monitor the generation of fast ramps.
• a monitoring of the ramp slope of a frequency ramp can be done as follows.
• the local oscillator signals according to the example game of Fig. 2 are used. If the ramp gradient of the local oscillators of the first and second high-frequency components 10, 12 is different, a baseband signal is produced which corresponds to a frequency chirp. The baseband signal has a time-varying frequency. If a shift in the frequency position of the peak 58 is detected in the temporal course of the local oscillator signals, the error is detected. In particular, then a faulty ramp slope is detected. A frequency chirp can be detected based on the obtained baseband signal and detected as an error case.
• a parametric estimation method can be used, a chirpet transformation, or sections of the frequency ramps can be separately transformed into spectra over the course of time so that a temporal profile of a peak in the baseband signal can be detected.
• phase noise of the high-frequency source 30 can be done as follows.
• the two high-frequency sources 30 of the first high-frequency component 10 and of the second high-frequency component 12 are synchronized with their respective phase locked loop, PLL, 34 to a common reference clock of a reference clock signal.
• the reference clock signal is supplied via the reference clock signal line 48, for example.
• the local oscillator signal of the first radio-frequency module 10 is transmitted to the second radio-frequency module 12 and in turn mixed with a mixer 38 with the local oscillator signal of the second radio-frequency module 12 into the base band.
• the transmission paths described above can optionally be used as a transmission path.
• the noise received in the baseband signal is examined.
• Fig. 4 shows schematically an amplitude spectrum of the baseband signal.
• the phase-locked loop 34 Within the loop bandwidth of the phase-locked loop 34 is the Phasenrau- see the individual local oscillator of the noise of the reference clock dominated.
• the phase noise of the local oscillators 32 of the high-frequency components is strongly correlated.
• the phase noise 60 within the loop bandwidth around the carrier signal (the peak 58 in the frequency spectrum) in the baseband signal is strongly suppressed.
• the frequency of the peak 58 in the frequency spectrum again corresponds to the frequency offset between the first and second local oscillator signals present at the mixer.
• the expected frequency offset again corresponds to an optional nominal frequency offset between the two local oscillators, combined with the frequency shift resulting from the transit time of the transmission path.
• the loop bandwidth can correspond, for example, to a frequency range of 300 kHz around the carrier signal. Outside the loop bandwidth, the phase noise of the individual local oscillator 32 is dominated by the noise behavior of the voltage-controlled oscillator 32. In the baseband signal, therefore, outside the loop bandwidth, the phase noise 62 is uncorrelated and therefore comparatively strong.
• the evaluation of the baseband signal may include, for example: determining a noise level in a band area out of a peak of the baseband signal; and comparing the particular one
• Noise levels with an expected noise level For example, within a bandwidth around a peak of the baseband signal, which corresponds to the bandwidth of the loop bandwidth of the phase locked loops of the local oscillators, the noise level can be determined and compared with a corresponding, expected noise level. For example, outside a bandwidth around a peak of the baseband signal, which corresponds to the bandwidth of the loop bandwidth of the phase locked loops of the local oscillators, the noise level may be determined and a corresponding expected one
• No noise level can be compared. If an expected noise level is exceeded or exceeded by more than a threshold, the fault is detected. In particular, a faulty phase-locked loop is then detected.
• the evaluation of the baseband signal may include, for example:
• Noise level in a band area outside a peak 58 of the baseband signal
• Noise level within a surrounding area with a higher one
• a difference of the compared values exceeds a threshold value, then the error case is detected. In particular, a faulty phase locked loop is then detected. Thus, a check of the loop bandwidth can take place. A deviation of the width of the low noise level from a width which is expected for the desired value of the loop bandwidth of the phase locked loops can thus be detected and detected as an error case.
• the monitoring of the phase noise of a local oscillator phase-locked loop can usually only be performed in CW operation of a radar sensor, i. at a constant frequency, but not when generating an FMCW ramp. By means of the method described, a noise level of the phase noise can also be evaluated and monitored when an FMCW frequency ramp is generated.
• FIG. 3 differs from the example of FIG. 2 in that different ramp slopes of the FMCW frequency ramps 54, 56 are selected for the two local oscillators.
• Frequency offset is then possible in the time domain, in which the time is determined at which intersect the frequency ramps of the mixed signals.
• the time point S at which the ramp of the local oscillator of the second flocc frequency component intersects with the frequency ramp of the local oscillator of the first high-frequency component 10 obtained at the mixer of the second high-frequency component i. has the same frequency.
• this corresponds to a DC pass of the peak, that is, the difference frequency of the signals is zero.
• a deviation of a ramp slope from a target value of the ramp slope also leads to a time offset of the ramp intersection point and can thus be detected. If successive measurements are carried out with several frequency ramps of different ramp slopes, a deviation of the ramp slope from a deviation of the ramp center frequency can be distinguished.
• monitoring of the first radio-frequency module can be carried out by using the second radio-frequency module as the reference signal source. However, it is also conceivable to provide a mutual monitoring of the high-frequency components in a corresponding manner.
• the described embodiments also make it possible to monitor the frequency generation of a local oscillator with regard to parameters which are difficult to determine with measuring instruments, such as phase noise, center frequency of the ramp and ramp slope.
• monitoring is enabled during operation of the radar sensor.
• more than two high-frequency components can also be operated simultaneously as signal sources during measurement operation. For example, monitoring can be done in pairs.
• a frequency offset of, for example, 1 MHz between the first high-frequency module 10 and the second high-frequency module 12 can be selected, which differs from a frequency offset of, for example, 1.2 MHz between the second high-frequency component 12 and the third high-frequency component 14 as well as from one Frequency offset between the first high-frequency component and the third high-frequency component 14 is different.
• the respective mixed baseband signals at the corresponding positions of the frequency offsets are then obtained in the baseband of an evaluating high-frequency module and can be evaluated separately.
• signals at 1 MHz and 2.2 MHz can then be received at the first radio-frequency module, signals from 1 MHz and 1.2 MHz can be received at the second radio-frequency module, and signals from 1, 2 MHz and 2 at the third radio-frequency module, 2 MHz can be received.
• high-frequency components 10, 12, 14, 16 instead of separate high-frequency components 10, 12, 14, 16 with respective local oscillators 32, it is also possible to provide high-frequency components which each contain a plurality of local oscillators 32 or a high-frequency component which contains a plurality of local oscillators 32.
• two or more high-frequency sources 30, respective mixers 36, transmitting and receiving parts 20 and A / D converter 40 may be integrated in a high-frequency component.
• the oscillator signal network 44 may be, for example, an internal network.

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• Engineering & Computer Science (AREA)
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• Remote Sensing (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Computer Networks & Wireless Communication (AREA)
• General Engineering & Computer Science (AREA)
• Electromagnetism (AREA)
• Radar Systems Or Details Thereof (AREA)

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• 2018
  • 2018-05-02 DE DE102018206701.5A patent/DE102018206701A1/de active Pending
• 2019
  • 2019-01-31 WO PCT/EP2019/052351 patent/WO2019211010A1/de unknown
  • 2019-01-31 US US16/772,125 patent/US20210072349A1/en not_active Abandoned
  • 2019-01-31 CN CN201980029690.4A patent/CN112074753B/zh active Active
  • 2019-01-31 MX MX2020011584A patent/MX2020011584A/es unknown
  • 2019-01-31 JP JP2020560834A patent/JP7032570B2/ja active Active
  • 2019-01-31 EP EP19702873.1A patent/EP3788394A1/de not_active Withdrawn
  • 2019-01-31 KR KR1020207034241A patent/KR20210003891A/ko not_active Application Discontinuation

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