NL2031184B1 - Frequency modulated continuous wave receiver, transmitter, transceiver and methods - Google Patents

Frequency modulated continuous wave receiver, transmitter, transceiver and methods Download PDF

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Publication number
NL2031184B1
NL2031184B1 NL2031184A NL2031184A NL2031184B1 NL 2031184 B1 NL2031184 B1 NL 2031184B1 NL 2031184 A NL2031184 A NL 2031184A NL 2031184 A NL2031184 A NL 2031184A NL 2031184 B1 NL2031184 B1 NL 2031184B1
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Netherlands
Prior art keywords
continuous wave
signal
modulated continuous
frequency
frequency modulated
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NL2031184A
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Dutch (nl)
Inventor
Petrov Nikita
Yarovyi Olexander
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Univ Delft Tech
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Application filed by Univ Delft Tech filed Critical Univ Delft Tech
Priority to NL2031184A priority Critical patent/NL2031184B1/en
Priority to PCT/NL2023/050106 priority patent/WO2023172129A1/en
Application granted granted Critical
Publication of NL2031184B1 publication Critical patent/NL2031184B1/en

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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
    • 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
    • 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
    • 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
    • G01S13/325—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of coded signals, e.g. P.S.K. signals
    • 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
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
    • G01S15/06—Systems determining the position data of a target
    • G01S15/08—Systems for measuring distance only
    • G01S15/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • 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
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
    • G01S15/06—Systems determining the position data of a target
    • G01S15/08—Systems for measuring distance only
    • G01S15/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S15/325—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of coded signals, e.g. of phase-shift keyed [PSK] signals
    • 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
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
    • G01S15/06—Systems determining the position data of a target
    • G01S15/08—Systems for measuring distance only
    • G01S15/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S15/34—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
    • 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
    • G01S7/352—Receivers
    • 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
    • G01S7/352—Receivers
    • G01S7/356—Receivers involving particularities of FFT processing
    • 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
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/534—Details of non-pulse systems

Abstract

According to the invention, a frequency modulated continuous wave receiver, comprising: an antenna input arranged for receiving an antenna signal from a receiving antenna arranged for receiving a frequency modulated continuous wave; a receiver mixer arranged for providing a mixed received signal based on mixing the received antenna signal of the antenna and a wide band continuous wave chirp; a digitizer arranged for providing a digitized mixed received signal based on digitizing the mixed received signal; and a fractional correlator arranged for determining a range profile signal indicative of the path length traversed by the frequency modulated continuous wave, wherein the range profile signal is based on correlating in a fractional Fourier transform domain the digitized mixed received signal with a narrow band modulation signal; and wherein the frequency modulated continuous wave is based on mixing the wide band continuous wave chirp with the narrow band modulation signal.

Description

FREQUENCY MODULATED CONTINUOUS WAVE RECEIVER,
TRANSMITTER, TRANSCEIVER AND METHODS
FIELD OF THE INVENTION
The invention relates to a frequency modulated continuous wave receiver.
The invention further relates to a frequency modulated continuous wave transmitter, a frequency modulated continuous wave transceiver, a range finder, a method for receiving a frequency modulated continuous wave, a method for transmitting a frequency modulated continuous wave, a method for a frequency modulated continuous wave transceiver, and a computer program product.
BACKGROUND OF THE INVENTION
A linearly frequency modulated (LFM) waveform is used in various radar applications. The simplicity of the hardware with low requirements on analog to digital converter (ADC) sampling frequency, constant peak-to-average power ratio (PAPR) and good Doppler tolerance are advantages of the LFM waveform.
These advantages come with the cost of the limited flexibility of LFM signals, crucial for the realization of multiple-input multiple output (MIMO) radars and interference mitigation between different radars. To associate the received signals with the proper transmit channel, different multiplexing schemes are used in MIMO radars.
They imply that the transmitted signals are different in time, frequency, chirp slope or code domains, but at the same time lead to the degradation of radar performance by shortening the unambiguous Doppler velocity, degrading the range resolution or increasing the sidelobe level.
A promising approach to address the aforementioned limitations consists of applying information-carrying modulation to chirps. In that way, the received waveform can be processed after mixing with the reference LFM signal (known as dechirping, deramping and stretch processing) - preserving all the advantages of LFM signal, mentioned above and adding to them the ability to discriminate different signals, essential for MIMO beam-forming, interference mitigation between different radars and realization of joint communication and sensing.
Current receivers of modulated chirps are realized via a filter bank and have the computational complexity of digital Fourier transform (DFT) i.e. O(N?), where N is the number of ADC samples per chirp. That is significantly larger than that of the standard dechirping realized via the fast Fourier transform (FFT): O(N log2(N)). Thus, high computational complexity of the compensated stretch processing makes challenging its realization on a radar chip, such as an automotive radar chip.
The state-of-the-art approach or architecture to process phase-modulated
FMCW waveforms use the group delay filter in the receiver to align the responses from all the ranges before decoding, followed by FFT for range extraction. The original idea of such delay compensation comes from the correction of non-linearity of chirp slope for stretch processing. This receiver design, derived with an assumption of a narrow- band deviation of the signal from the linear frequency modulation (LFM), significantly degrades for long codes, which are of the main interest in applications mentioned above. An appropriate predistortion of the transmit signal to compensate this effect has been proposed, which leads, however, to the increase of the PAPR of the transmitted signal, undesirable for the transmitting chain.
A conceptually similar approach or architecture is with application to chirps modulated by an orthogonal frequency division multiplexing (OFDM) waveform.
Instead of the group delay filter, a certain rearrangement of the OFDM sub-carriers is done to realize a symbol cancelling receiver. This, however, imposes multiple constraints on the selection of the waveform parameters.
Proposed is a novel receiver design for modulated LFM signals, which demonstrates the ability to recover the range profile accurately, similar to the compensated stretch processing and does it in the computational complexity of FFT. In order to do that, presented below is the signal model and derived is the matched filter receiver, which coincides with compensated stretch processing. It is further shown that due to the linear relation between the time delay and the beat frequency, the matched filter can be realized via the fractional correlation, which can be computed efficiently using the fractional Fourier transforms (FrFT) with the computational complexity of
FFT. The receiver based on fractional correlation is also shown below. The performance of the proposed receiver is evaluated and compared to the other state-of- the-art solutions. Finally, the conclusions are drawn basically confirming that the above mentioned disadvantages are overcome.
SUMMARY OF THE INVENTION
An object of the invention is to overcome one or more of the disadvantages mentioned above.
According to a first aspect of the invention, a frequency modulated continuous wave receiver, comprising: an antenna input arranged for receiving an antenna signal from a receiving antenna arranged for receiving a frequency modulated continuous wave; a receiver mixer arranged for providing a mixed received signal based on mixing the received antenna signal of the antenna and a wide band continuous wave chirp; a digitizer arranged for providing a digitized mixed received signal based on digitizing the mixed received signal; and a fractional correlator arranged for determining a range profile signal indicative of the path length traversed by the frequency modulated continuous wave, wherein the range profile signal is based on correlating in a fractional Fourier transform domain the digitized mixed received signal with a narrow band modulation signal; and wherein the frequency modulated continuous wave is based on mixing the wide band continuous wave chirp with the narrow band modulation signal. The antenna input is arranged for receiving an antenna signal from a receiving antenna arranged for receiving a frequency modulated continuous wave. The antenna input is typically arranged for receiving and optionally amplifying the antenna signal. The antenna input may comprise filtering and/or conditioning of the antenna signal.
The receiver mixer is arranged for providing the mixed received signal. The mixed received signal is based on mixing the received frequency modulated continuous wave of the antenna and the wide band continuous wave chirp. The wide band continuous wave chirp is typically generated by a wide band continuous wave chirp generator shared with a frequency modulated continuous wave transmitter or part of a frequency modulated continuous wave transmitter. The wide band continuous wave chirp may be generated locally if the receiver and transmitter share the parameters of the chirp as well as the timing of the chirp.
The digitizer is arranged for providing the digitized mixed received signal.
The digitized mixed received signal is based on digitizing the mixed received signal.
Digitizing may comprise signal conditioning. Digitizing comprises transforming the signal to the digital domain, typically from the analogue domain.
The fractional correlator is arranged for determining a range profile signal.
The range profile signal is indicative of the path length traversed by the frequency modulated continuous wave. The range profile signal is based on correlating in the fractional Fourier transform domain the digitized mixed received signal with the narrow band modulation signal. Correlation is performed in any fractional domain, such as a fractional domain between the frequency domain and the time domain.
Further, a correlation signal is based on a narrow band modulation signal.
And further, the frequency modulated continuous wave is based on mixing the wide band continuous wave chirp with the narrow band modulation signal.
The receiver, based on Fractional Fourier Transform (FrFT), has demonstrated the technical effect of a comparable performance over the state-of-the- art solutions with lower computational complexity and/or a considerable improved performance over other state-of-the-art solutions with limited increase of computational complexity. Furthermore, the receiver has this technical effect, particularly the second part of the technical effect, for moderate-to-large bandwidth of the narrow band modulation signal relative to the ADC sampling frequency.
According to another aspect of the invention, a frequency modulated continuous wave transmitter, the transmitter comprises: a chirp generator arranged for generating a wide band continuous wave chirp; a signal generator arranged for generating a narrow band modulation signal; a transmitter mixer arranged for providing a mixed transmission signal based on mixing the wide band continuous wave chirp and the narrow band modulation signal; and an antenna output arranged for providing an antenna signal to a transmitting antenna based on the mixed transmission signal for the transmitting antenna transmitting a frequency modulated continuous wave. The transmitter provides the same advantages as mentioned for the receiver.
According to another aspect of the invention, a frequency modulated continuous wave transceiver, comprising: one or more frequency modulated continuous wave receivers according to any of the mentioned embodiments; and one or more frequency modulated continuous wave transmitters according to any of the mentioned embodiments. The transceiver provides the same advantages as mentioned for the receiver.
According to another aspect of the invention, a range finder comprising a frequency modulated continuous wave transceiver according to any of the embodiments, arranged as radar, preferably MIMO radar, or sonar, preferably MIMO sonar. The range finder provides the same advantages as mentioned for the receiver.
According to another aspect of the invention, a method for receiving a frequency modulated continuous wave, comprising: providing a digitized mixed received signal based on digitizing the mixed received signal which is based on:
receiving an antenna signal from a receiving antenna arranged for receiving a frequency modulated continuous wave; and providing a mixed received signal based on mixing the received antenna signal of the antenna and a wide band continuous wave chirp; and determining a range profile signal indicative of the path length 5 traversed by the frequency modulated continuous wave, wherein the range profile signal is based on correlating in a fractional Fourier transform domain the digitized mixed received signal with a narrow band modulation signal; and wherein the frequency modulated continuous wave is based on mixing the wide band continuous wave chirp with the narrow band modulation signal. The method for receiving provides the same advantages as mentioned for the receiver.
According to another aspect of the invention, a method for transmitting a frequency modulated continuous wave, comprising: configuring a chirp generator for generating a wide band continuous wave chirp; and configuring a signal generator for generating a narrow band modulation signal; wherein the configuring steps are performed for: providing a mixed transmission signal based on mixing the wide band continuous wave chirp and the narrow band modulation signal; and providing an antenna signal to a transmitting antenna based on the mixed transmission signal for the transmitting antenna transmitting a frequency modulated continuous wave. The method for transmitting provides the same advantages as mentioned for the receiver.
According to another aspect of the invention, a method for a frequency modulated continuous wave transceiver, comprising: one or more instances of the receiving method according to any of the embodiments; and one or more instances of the transmitting method according to any of the embodiments. The method for a transceiver provides the same advantages as mentioned for the receiver.
According to another aspect of the invention, a computer program product comprising instructions which, when the program is executed by a suitable processor, cause the processor to carry out any of the method embodiments. The computer program product provides the same advantages as mentioned for the receiver.
According to another aspect of the invention, a frequency modulated continuous wave receiver, comprising: an antenna input arranged for receiving an antenna signal from a receiving antenna arranged for receiving a frequency modulated continuous wave; a receiver mixer arranged for providing a mixed received signal based on mixing the received antenna signal of the antenna and a wide band continuous wave chirp; an optical converter arranged for providing an optical mixed received signal based on optical converting the mixed received signal; and a fractional correlator arranged for determining a range profile signal indicative of the path length traversed by the frequency modulated continuous wave based on correlating in a fractional Fourier transform domain the digitized mixed received signal with a narrow band modulation signal; and wherein the frequency modulated continuous wave is based on mixing the wide band continuous wave chirp with the narrow band modulation signal. The receiver provides the same advantages as mentioned for the other receiver.
According to another aspect of the invention, a frequency modulated continuous wave receiver, comprising: an antenna input arranged for receiving an antenna signal from a receiving antenna arranged for receiving a frequency modulated continuous wave; a receiver mixer arranged for providing a mixed received signal based on mixing the received antenna signal of the antenna and a wide band continuous wave chirp; and a fractional correlator arranged for determining a range profile signal indicative of the path length traversed by the frequency modulated continuous wave based on correlating in a fractional Fourier transform domain the digitized mixed received signal with a narrow band modulation signal ; and wherein the frequency modulated continuous wave is based on mixing the wide band continuous wave chirp with the narrow band modulation signal. The receiver provides the same advantages as mentioned for the other receiver.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
In an embodiment of the frequency modulated continuous wave receiver, the fractional correlator comprises: a fractional Fourier receiver transformer arranged for generating a received fractional Fourier signal based on fractional Fourier transforming the digitized mixed received signal; a fractional Fourier mixer arranged for providing a mixed fractional Fourier signal based on mixing the received fractional
Fourier signal and a correlation signal based on the narrow band modulation signal; and an inverse Fourier transformer arranged for providing the range profile signal based on inverse Fourier transforming the mixed fractional Fourier signal. This embodiment advantageously provides an implementation of the fractional correlator.
In a further embodiment of the frequency modulated continuous wave receiver, the fractional Fourier transformer transforms over an angle ¢ based on one or more predetermined parameters, such as one or more predetermined parameters of the frequency modulated continuous wave and/or the receiver, preferably only one or more predetermined frequency modulated continuous wave and/or receiver parameters, more preferably an oversampling factor yr, a bandwidth of the frequency modulated continuous wave B, and/or a sample frequency fs. Differently formulated, in an embodiment, the fractional Fourier transformer transforms over an angle ¢, wherein angle ¢ is independent of the path traversed by the frequency modulated continuous wave. As the angle 9 is independent of the path traversed by the frequency modulated continuous wave, the angle ¢ may advantageously be a design parameter instead of a parameter that needs adjustment during operation or use. The angle ¢ may advantageously be selected or set in advance such that the receiver may be adapted also in advance to the selected or set angle ¢. The adaptation may advantageously comprise pre-calculating data or intermediate values used in the receiver, such as the correlation signal.
In an embodiment of the frequency modulated continuous wave receiver, the correlation signal or a constituent part of the correlation signal is precalculated; and the receiver comprises a memory for storing the precalculated correlation signal or a precalculated constituent part of the correlation signal. The memory advantageously allows to reuse precalculated data, more specifically the memory and the pre- calculating reduce energy usage of the receiver, response time of the receiver and/or a processor load, if a processor is part of the receiver or at least partly implementing the receiver.
In an embodiment of the frequency modulated continuous wave receiver, the fractional correlator comprises: a fractional Fourier modulation transformer arranged for generating a fractional Fourier modulation signal based on fractional
Fourier transforming the narrow band modulation signal; and a processing block arranged for providing a/the correlation signal based on processing the fractional
Fourier modulation signal for application in the fractional correlator, more specifically when on the embodiment above and mentioned in claim 2, the fractional Fourier mixer.
This embodiment advantageously provides an implementation for generating the correlation signal.
In an embodiment of the frequency modulated continuous wave receiver, the digitizer comprises: a low pass filter arranged for providing a filtered mixed received signal based on low pass filtering the mixed received signal; and an analogue to digital converter arranged for providing the digitized mixed received signal based on the filtered mixed received signal. This embodiment details the digitizer and provides an implementation of the digitizer.
In an embodiment of the frequency modulated continuous wave receiver, the wide band continuous wave chirp has a wide bandwidth; the narrow band modulation signal has a narrow bandwidth; and the wide bandwidth relative to the narrow bandwidth is at least 2 times, preferably at least 4 times, more preferably at least 8 times, more preferably at least 16 times, more preferably at least 32 times, most preferably at least 40 times, as wide. This embodiment advantageously provides a reference for narrow and wide band signals relative to each other.
In an embodiment of the frequency modulated continuous wave receiver, the wide band continuous wave chirp has a/the wide bandwidth based on the filters and/or is below 10 GHz, preferably 4 GHz, more preferably 1 GHz; and the narrow band modulation signal has a/the narrow bandwidth below one, preferably a half, more preferably a quarter, of the sampling frequency fs the digitizer. This embodiment advantageously provides a reference for narrow and wide band signals in absolute terms.
In an embodiment of the frequency modulated continuous wave receiver, the narrow band modulation signal comprises an identification signal. The identification signal advantageously allows to identify the frequency modulated continuous wave from other frequency modulated continuous waves. This identification signal is typically advantageous in a MIMO application of the receiver.
In an embodiment of the frequency modulated continuous wave receiver, the frequency modulated continuous wave receiver is a linear frequency modulation receiver advantageously simplifying the implementation and/or structure of the receiver.
In an embodiment of the frequency modulated continuous wave receiver, the frequency modulated continuous wave receiver is a phase-modulated frequency modulated continuous wave receiver or an OFDM continuous wave receiver or any other information carrying waveform. Both modulations are examples of suitable modulations schemes for this type of receiver. The phase-modulated frequency modulated continuous wave provides the further advantage that the side lobs and/or bandwidth are limited. The phase-modulated frequency modulated continuous wave further provides the advantage of an improved peak-to-average power ratio (PAPR).
In an embodiment of the frequency modulated continuous wave receiver, mixing the narrow band modulation signal and the wide band continuous wave chirp is advantageously based on phase modulating the wide band continuous wave chirp based on the narrow band modulation signal. In an embodiment of the frequency modulated continuous wave receiver, the time delay and the beat frequency advantageously have a linear relation. In an embodiment of the frequency modulated continuous wave receiver, the receiver comprises an receiving antenna arranged for advantageously providing the frequency modulated continuous wave to the antenna input. In an embodiment of the frequency modulated continuous wave receiver, the narrow band modulation signal advantageously encodes an identifier, preferably a unique identifier, for identifying the frequency modulated continuous wave. The unique identifier advantageously allows to identify the frequency modulated continuous wave from other frequency modulated continuous waves. This unique identifier is typically advantageous in a MIMO application of the receiver.
In an embodiment of the frequency modulated continuous wave receiver, the wide band continuous wave chirp has a bandwidth in the range of 1 MHz — 10
GHz, preferably 5 MHz — 5 GHz, more preferably 10 MHz — 1 GHz. In an embodiment of the frequency modulated continuous wave receiver, the wide band continuous wave chirp has a length in the range of 1 us — 200 ms, preferably 5 us — 100 ms, more preferably 7 us — 5 ms, most preferably 10 us — 1 ms. In an embodiment of the frequency modulated continuous wave receiver, the wide band continuous wave chirp has a carrier frequency in the range of 1 — 300 GHz; preferably 2 — 200 GHz, more preferably 3 — 100 GHz, most preferably 3 — 84 GHz. In an embodiment of the frequency modulated continuous wave receiver, the digitizer has a sample frequency inthe range of 1 — 400 MHz, preferably 3 — 100 MHz, more preferably 5 — 80 MHz, most preferably 10 — 40 MHz.
In an embodiment of the frequency modulated continuous wave transmitter, the signal generator generates the narrow band modulation signal based on encoding an identifier, preferably a unique identifier, for identifying the frequency modulated continuous wave. The unique identifier advantageously allows to identify the frequency modulated continuous wave from other frequency modulated continuous waves. This unique identifier is typically advantageous in a MIMO application of the transmitter.
Furthermore, the unique identifier advantageously allows realization of joint communication and/or joint sensing.
In an embodiment of the frequency modulated continuous wave transmitter, the transmitter comprises: a fractional Fourier modulation transformer arranged for generating a fractional Fourier modulation signal based on fractional Fourier transforming the narrow band modulation signal; and a processing block arranged for providing a correlation signal based on processing the fractional Fourier modulation signal for application in a frequency modulated continuous wave receiver. This embodiment advantageously provides an implementation for generating the correlation signal.
In a further embodiment of the frequency modulated continuous wave transmitter, the transmitter comprises a memory for storing the correlation signal or a constituent part of the correlation signal which is precalculated. The memory advantageously allows to reuse precalculated data, more specifically the memory and the pre-calculating reduce energy usage of the transmitter and/or the accompanying receiver, response time of the accompanying receiver and/or a processor load, if a processor is part of the transmitter and/or the accompanying receiver or at least partly implementing the transmitter and/or the accompanying receiver.
In an embodiment of the frequency modulated continuous wave transmitter, the wide band continuous wave chirp has a bandwidth in the range of 1 MHz — 10
GHz, preferably 5 MHz — 5 GHz, more preferably 10 MHz — 1 GHz. In an embodiment of the frequency modulated continuous wave transmitter, the wide band continuous wave chirp has a length in the range of 1 us — 200 ms, preferably 5 us — 100 ms, more preferably 7 us — 5 ms, most preferably 10 us — 1 ms. In an embodiment of the frequency modulated continuous wave transmitter, the wide band continuous wave chirp has a carrier frequency in the range of 1 — 300 GHz; preferably 2 — 200 GHz, more preferably 3 — 100 GHz, most preferably 3 — 84 GHz. In an embodiment of the frequency modulated continuous wave transmitter, the digitizer has a sample frequency in the range of 1 — 400 MHz, preferably 3 — 100 MHz, more preferably 5 — 80 MHz, most preferably 10 — 40 MHz.
In an embodiment of the frequency modulated continuous wave transceiver, the one or more frequency modulated continuous wave transmitters is at least two frequency modulated continuous wave transmitters; the at least two frequency modulated continuous wave transmitters depend on any of the mentioned embodiment comprising an identifier; the respective identifiers of the at least two frequency modulated continuous wave transmitters are different; and the one or more frequency modulated continuous wave receivers are arranged for receiving from the at least two frequency modulated continuous wave transmitters. The identifier advantageously allows to identify the frequency modulated continuous wave from other frequency modulated continuous waves. This identifier is typically advantageous in a MIMO application as mentioned in this embodiment.
In an embodiment of the frequency modulated continuous wave transceiver, the one or more frequency modulated continuous wave receivers is at least two frequency modulated continuous wave receivers; and the at least two frequency modulated continuous wave receivers depend on any of the mentioned embodiment comprising an identification signal. The identification signal advantageously allows to identify the frequency modulated continuous wave from other frequency modulated continuous waves. This identification signal is typically advantageous in a MIMO application as mentioned in this embodiment.
In an embodiment of the frequency modulated continuous wave range finder, the range finder is advantageously arranged for use in automotive, surveillance, meteorology, and/or meteorological applications.
In an embodiment of the method, determining comprises: generating a received fractional Fourier signal based on fractional Fourier transforming the digitized mixed received signal; providing a mixed fractional Fourier signal based on mixing the received fractional Fourier signal and a correlation signal based on the narrow band modulation signal; and providing the range profile signal based on inverse Fourier transforming the mixed fractional Fourier signal. This embodiment advantageously provides an implementation of the fractional correlator.
In an embodiment of the method, the fractional Fourier transformer transforms over an angle ¢ based on one or more predetermined parameters, such as one or more predetermined parameters of the frequency modulated continuous wave and/or the receiver, preferably only one or more predetermined frequency modulated continuous wave and/or receiver parameters, more preferably an oversampling factor yr, a bandwidth of the frequency modulated continuous wave B, and/or a sample frequency fs. Differently formulated, in an embodiment, the fractional Fourier transformer transforms over an angle ¢, wherein angle ¢ is independent of the path traversed by the frequency modulated continuous wave. As the angle ¢ is independent of the path traversed by the frequency modulated continuous wave, the angle ¢ may advantageously be a design parameter instead of a parameter that needs adjustment during operation or use. The angle ¢ may advantageously be selected or set in advance such that the method for receiving may be adapted also in advance to the selected or set angle op. The adaptation may advantageously comprise pre-calculating data or intermediate values used in the method for receiving, such as the correlation signal.
In an embodiment of the method, the method comprises storing the correlation signal or a constituent part of the correlation signal which is precalculated.
The storing advantageously allows to reuse precalculated data, more specifically the storing and the pre-calculating reduce energy usage of the method for receiving, response time of the method for receiving and/or a processor load, if a processor is part of implementing the method for receiving or at least partly implementing the method for receiving.
In an embodiment of the method, providing a digitized mixed received signal comprises: configuring a filter for providing a filtered mixed received signal based on low pass filtering the mixed received signal; and/or configuring an analogue to digital converter for providing the digitized mixed received signal based on the filtered mixed received signal. This embodiment advantageously provides an implementation for controlling a digitizer and/or hardware or software involved in digitizing the mixed received signal.
In an embodiment of the method, the narrow band modulation signal is an identification signal. The identification signal advantageously allows to identify the frequency modulated continuous wave from other frequency modulated continuous waves. This identification signal is typically advantageous in a MIMO application as mentioned in this embodiment.
In an embodiment of the method, generating a narrow band modulation signal generates the narrow band modulation signal based on encoding an identifier, preferably a unique identifier, for identifying the frequency modulated continuous wave.
The unique identifier advantageously allows to identify the frequency modulated continuous wave from other frequency modulated continuous waves. This unique identifier is typically advantageous in a MIMO application of the transmitter.
In an embodiment of the method, the method comprises: generating a fractional Fourier modulation signal based on fractional Fourier transforming the narrow band modulation signal; and providing a correlation signal based on processing the fractional Fourier modulation signal for application in a frequency modulated continuous wave receiver. This embodiment advantageously provides an implementation for generating the correlation signal. In a further embodiment of the method, the method comprises storing the correlation signal or a constituent part of the correlation signal which is precalculated.
In an embodiment of the method, the one or more instances of the transmitting method for transmitting a frequency modulated continuous wave is at least two instances of the transmitting method; the at least two instances of the transmitting method depend on an embodiment of the transmitter comprising an identifier; the respective identifiers of the at least two instances of the transmitting method are different; and the one or more instances of the receiving method are arranged for receiving from the at least two instances of the transmitting methods.
In an embodiment of the method, the one or more instances of receiving method is at least two instances of receiving methods; and the at least two receiving methods depend on an embodiment of the receiver comprising an identifier.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be apparent from and elucidated further with reference to the embodiments described by way of example in the following description and with reference to the accompanying drawings, in which:
Figure 1 schematically shows a time-frequency representation of the received signal and its relation to the FrFT angle ¢;
Figure 1b schematically shows a time-frequency representation of the received and the correlation signals after transforming them by the FrFT with angle 9;
Figure 2 schematically shows an FRFT transceiver structure for modulated FMCW waveforms;
Figure 3 schematically shows (a) an GMSK modulation signal m(t); (b)
Received signal s(t); (c) FrFT of the modulation signal M72* 9 (p}; (d) FrFT of the received signal S72* 9 (p); (e) Product of FrFTs S™2* ¢(p)(M™2* ?(p))*: (f) Range profile as the result of fractional correlation (11);
Figure 4 schematically shows an estimated range profile of a point like target with three considered receiver structures: (a) narrow-band modulation, Bm / fs = 1/64; (b) wide-band modulation, Bm / fs = 1/4;
Figure 5 schematically shows an SNR loss vs the normalized bandwidth of the modulation signal m(t);
Figure 6 schematically shows an SNR loss as the function of the target range: (a) narrow-band modulation, Bm/ fs = 1/16; (b) wide-band modulation, Bm / fs = 1/4, (C) Bm / fs = 1/2;
Figure 7 schematically shows the computational complexity of three considered receiver structures;
Figure 8 schematically shows an embodiment of the method of the receiver; and
Figure 9 schematically shows an embodiment of a computer program product, computer readable medium and/or non-transitory computer readable storage medium according to the invention.
The figures are purely diagrammatic and not drawn to scale. In the figures, elements which correspond to elements already described may have the same reference numerals.
LIST OF REFERENCE NUMERALS
FrFT transceiver received antenna signal wide band continuous wave chirp mixed received signal digitized mixed received signal correlation signal narrow band modulation signal fractional correlator range profile signal fractional Fourier receiver transformer received fractional Fourier signal fractional Fourier mixer mixed fractional Fourier signal signal generators chirp generator signal generator mixed transmission signal antenna output 0 method for receiving a frequency modulated continuous wave providing digitized mixed received signal determining range profile signal 1000 computer program product 1010 computer readable medium 1020 computer readable code
DETAILED DESCRIPTION OF THE FIGURES
Modification of a linearly frequency modulated (LFM) waveform by applying a (multi-carrier) phase modulation to it is an emerging technology for automotive radars. It allows combining the low sampling requirements of LFM signals and waveform diversity of information-carrying waveforms, which is a strongly required element for efficient realization of radar (self)-interference mitigation and joint communication and sensing.
A novel receiver structure, based on Fractional Fourier Transform (FrFT) is proposed, which demonstrates an improved performance over the state-of-the-art solutions for moderate-to-large bandwidth of the information-carrying waveforms with a minor increase in the computational complexity.
SIGNAL MODEL AND MATCHED FILTER RECEIVER
Signal model
Assume the radar transmits a wideband LFM chirp modulated with a narrow-band modulation signal mt): where fc stands for the carrier frequency of the radar, B = B/T is the chirp rate, B and T are the bandwidth and the duration of the chirp respectively. Moreover, we assume that the bandwidth of m(t) is much smaller that of the chirp Bm<<B.
The signal from (1) impinges on a target at range ro moving with a constant radial velocity vo towards or away from the radar. The reflected signal is received by the radar with the time delay: ee 2, | ~ ig
Told) = — {rg + vol] = Ta + —4 {2}
N O attenuated proportionally to the target RCS and two-way propagation of the way by the complex coefficient ao. Hereinafter, we incorporate all the constant terms of signal processing into ag with no loss of generality. The signal impinging the receiver becomes:
WE \ On Ee Fy LE] + wn 3 > ‚0 FF anmif—Te}-e FE etait 0), where fp = 2vofc/c and we used (1-2vo)/c = 1 considering that in a typical scenario velocities vo << c. Applying the stretch processing on receive (also called dechirping or deramping), which consists of multiplication of the received signal with the transmitted chirp and filtering out high frequency components, results in: = gm (t — To} el Tee} {4} ze gm it — To) ele, ; °
It comprises of two main components: the delayed modulated signal and the beat frequency. The second item is standard for dechipring of LFM signals. It also comprises Doppler frequency shift due to target motion, which is typically negligible compared to the frequency resolution of the beat signal after applying FFT to it, i.e. fp <<fs/N, where fs is the sampling frequency of the beat signal and N is the number of fast-time samples.
Signal processing - filter bank
The form of (4) can be alternatively interpreted if we denote fun = BTo as a virtual Doppler frequency shift, which is significantly (about two orders of magnitude) larger than the typical for automotive radar Doppler frequency shift fp in (4). In this formulation it resembles a conventional response of a waveform m(t) with the time delay To and Doppler frequency shift fvo. This representation resembles the reception of a general waveform m(t) with a large Doppler shift. In this case, the optimal receiver in white noise may be a matched filter for each range-Doppler hypothesis. It can be realized either via a search over all possible range-Doppler hypothesis or via performing Doppler processing prior to range compression. Due to the explicit relation between the parameters couple fv = BTo, one-dimensional search over the parameter
Tis needed. Thus, the receiver calculates for each T:
Wr) = / stim” {f= 1) oI gy {3) *
Modern radars perform baseband signal processing digitally, after the received beat signal is sampled by ADC at the sampling frequency fs and stored in vector s € CM: 8 = gm (nf fs — Tp) ed STE nij {67 where t = nffs, n=0,..., N-1.
The reference signal in the integral (5) for the fixed T can be given via a
Hadamard product of two vectors a(t) © m(T): alr) = ot Dewan fa i
CL | {7} mir} =mn/fe—r}. n=0,..., N-1; a(t), m(1) € CN",
Stacking the steering vectors of beat signal and delayed modulation signal as columns in matrices A = [a(To), ...., a(Tr)] and M = m(T1o), ..., m(TR)] respectively, with
N; being the predefined number of range cells, it is possible to write the convolution (5) via a vector product: : y=(AoM"s (8)
This receiver structure may be called compensated stretch processing. The compensation referred in the name of the algorithm realizes the proper shift of the reference modulation signal for each range hypothesis, realized here via matrix M. The filter bank realization of the compensated stretch processing leads to the computational complexity of DFT O(N?).
Waveform analysis and design
The key block of the receiver (5) (or its digital counterpart (8)) correlates the received signal with the time delay and frequency shifted template. That is equivalent to calculating the cross correlation of s(t) and m(t) along the diagonal line in the time delay / Doppler shift domain.
If we further expand (5), considering target Doppler frequency shift as in (4), we get:
UT) = org / {t= rp) mn’ (tT) el BT fot gy = 69 / mt ym (FAL) edt Ean) Ve = 0g Xn (A+, (BA, — fp) ) (9) where t' = t - To, Ar = 1 - To and Xm(T, fo) defines the ambiguity function of the waveform m(t). It implies that the range response of the proposed processing is determined by the diagonal cut of the ambiguity function X(T, fp). This can be alternatively interpreted as a shear of the ambiguity function of the waveform m(t) being modulated by a chirp.
Another consequence of (9) is that the (phase) modulation schemes, optimized for low range sidelobes, e.g Barker, Frank or Zadoff-Chu phase codes, would not preserve this property if they are used to modulate a chirp (1).
FRACTIONAL CORRELATION RECEIVER
In a conventional radar signal processing, the time delay (range) and signal frequency shift (Doppler) are typically estimated separately and independent of each other: range via the correlation of the received signal with the replica and Doppler frequency via Fourier transform over slow-time - both with a computational complexity of FFT. The former exploits the fact that correlation in time transforms into a simple multiplication operations in the frequency domain: tram {ft —-7)= / slijm’ (t- Tidj] (10) where *® denotes correlation, F-®2{+} is the inverse Fourier transform (the reason for this superscript will be explained shortly); S(f) and M(f) are the Fourier transforms of s(t) and m(t) respectively.
So, the objective is to develop an efficient algorithm to calculate the cross- correlation along the diagonal line in the time delay / Doppler shift domain (5) with the computational complexity of FFT. That can be done using the theory of the fractional
Fourier transform (FrFT) and fractional correlation.
With the use of FrFT, the definition (10) can be extended for calculating the cross-correlation along any line in the Doppler-delay plane: ry z= sl) B mt — 7} where the operators se and F¢{+} denotes fractional correlation and the fractional Fourier transform associated with angle ¢, measured anti-clockwise from the time axis, such that F™2{} and F"™2{-} correspond to the Fourier transform and inverse
Fourier transform respectively. Moreover, we denote by S¥(p)=F%{s(t)} and
M®(p)=F®%{m(t)} the ¢-th fractional Fourier transform (FrFT) of s(t) and m(t) and p is the argument in this FrFT domain.
The fractional Fourier transform (FrFT) of s(t) is defined for angle ¢ as:
Sp) = VI = cot geit? oo / sel cote tates gy. ' (12)
Time-frequency representation of the modulation signal m(t) and that of the received signal (4) are presented in Fig. 1. It can be seen that the range information of the target is fully described by the radial displacement p at the angle 9.
The displacement of the signal time-frequency representation by p, ¢ in polar coordinated corresponds to: where we used the notation & = ei27(902/2)cos 9 sing ag for the FrFT of s(t) it can be substituted into the constant term of the received signal ap with no loss of generality. Given the property (13) of FrFT and comparing it to (4), the relation of the
FrFT parameters to the waveform and radar parameters can be found via: fio COR = =
Pr SIE = Fo where yr is the oversampling factor for range processing. It should be also noted that depending on the sign of the analytical signal in (1) and also on the choice of up/down chirp, the beat frequency can have a negative sign. That should be taken in the account at the output of IQ demodulation. Furthermore, the angle of FrFT is fully determined by the parameters of the radar according to the ratio of scales in relative frequency shift (B1/fs) to relative time delay of the signal (1/T) and thus: { Br, À Ve p= arctan (=) . (15) \ J #
The range of the target depends linearly on the parameter po: pa = elan) = VE, {16} and can be directly scaled to the range axis.
The FrFT receiver or transceiver structure or architecture is presented in
Fig. 2. An important component of the receiver is the fractional correlation block, which realizes (11).
It is assumed that fractional correlation block operates with the sampled signals. The discrete version of the FrFT (12) can be derived from the discrete Fourier transform by the eigenvalue decomposition of the transformation matrix and maintain most of the properties of the continuous FrFT. It approximates well the continuous fractional Fourier transform for large number of samples.
A faster way to compute an approximation of the continuous fractional
Fourier transform exploits the fact that FrFT can be rewritten via a convolution in between two chirp multiplications, which need to be sampled at twice the original sampling rate. The computational complexity of such implementation is O(N log2 (N)), being determined by the realization of the convolution via FFT. This algorithm provides the advantage of low computation load and high accuracy made.
It should be noted that digital calculation of FrFT assumed that the signal is approximately confined to the interval [-T/2, T/2] in time and to the interval [fs/2, fs/2] in frequency. While the former is easy to satisfy be shifting the time axes of Rx signal s(t) and replica m(t) by -T/2, the latter results in folding the signal in FrFT domain for ft > fs/2. To avoid frequency folding, we propose to transmit the modulated signal m(t) with a frequency offset As = fs/2 + B/2, where Bm is the bandwidth of modulation sequence, which insures that the sampled received is time-frequency shifted version of the reference one for ranges: re Yo = Bm)? wo =] an where Ar = ¢/(2B). The modulation of FMCW therefore leads to the degradation of the maximum detectable range by the factor (fs - Bm)/fs. Note, that the discussion above assumes the IQ receiver structure; if sampling only | channel, both signals should belong to the interval [0, fs/2] and thus the frequency offset should be set to Ar= Bn/2.
SIMULATIONS
Consider the waveform with chirp bandwidth B = 200 MHz, chirp duration T = 12.8 us operating at carrier f. = 77 GHz and the sampling frequency of the beat signal is fs = 20 MHz. With thus setup, the maximum range of FMCW is Rmax = 192 m.
The signal m(t) is Gaussian minimum shift keying (GMSK) modulated waveform with the time-bandwidth product of GMSK equal to 0.3 and N=64 chips, which corresponds to the modulation signal bandwidth of Bm = fs/4 = 5 MHz. For the range processing, we consider range oversampling y: = 2, which according to (15) gives ¢ = arctan(20) = 1.52. To demonstrate the principle of the FrFT receiver, we assume a noise-free scenario with a single stationary point-like target located at ro =60 m from the radar.
Principles of FRFT receiver/transceiver
The signal representation at all the stages of the fractional correlation (11) is plotted in Fig. 3. Here, we did not apply frequency shift of the modulation signal,
described at the end of the previous section, for better visibility (there is no difference in applying this shift or not for a target at ro = Rmax/2). It can be seen that despite the time and frequency shift between the received s(t) and the reference m(t) signals (Fig. 3, a, b), it vanishes in their FrFT representations (Fig. 3,c, d). As a result, their product has a wide and uniform spectrum (Fig. 3,e), which leads to a narrow peak in the reconstructed range profile (Fig. 3,f).
We further compare the performance of the FrFT receiver to that of the filter bank approach or architectureand to that of the group delay receiver (Fig. 4).
Simulation results demonstrate that all three receivers have comparable range response for small bandwidth of modulation signal Bm/ fs = 1/64 (Fig. 4,a), but for larger bandwidth of m(t) the performance of group delay receiver or receiver architecture degrades significantly compared to that of filter bank and FrFT approaches or architectures (Fig. 4,b shows the result for Bm / fs = 1/4). The performance of FrFT receiver is similar to that of the filter bank, being different only in the implementation and related to it computational complexity, as we mentioned above.
SNR loss
To better demonstrate the limit of applicability the group delay receiver, we compare Fig. 5 the SNR loss as the function of the code bandwidth Bm / fs normalized by fs. Similarly to the above, we considered a noise-free scenario with a single target present in the scene at the range ro = 60 + wr m, where wr € [-2.5Ar, 2.5Ar], models an offset from the defined range grid with a step 0.125Ar.
The plots in Fig. 5 show the average (solid line), the best-case and the worst-case (dashed lines) SNR loss for three considered receivers. It can be seen that all three receivers behave similarly for a small code bandwidth, having about 1 dB straddle loss. For large code bandwidth Bm / fs = 1/8, the matched filter and the FrFT receiver keep having small straddle loss, while the group delay filter leads to a significant (over 10 dB) SNR loss, which is also seen via defocusing of the main lobe of the range response in Fig. 4, b. This performance degradation of the group delay receiver for large bandwidth of the modulation signal m(t) imposes an additional constraint on the choice of the modulation sequence m(t). Finally, it should be noticed that for Bm / fs = 1 all the receivers have degraded performance for observing the target at ro = 60, because a part of the modulated signal spectrum is being rejected by the low pass filter of the receiver.
The bandwidth of the modulation signal has an impact on the maximum detectable target range. We investigate this behaviour via simulations in Fig. 6 for three values of the normalized bandwidth of the modulation signal: Bm / fs = 1/16 (Fig. 6, a), Bm/ fs = 1/4 (Fig. 6, b) and Bn / fs = 1/2 (Fig. 6, c). The range axes in Fig. 6 are similar to that in Fig. 4, up to the normalization by a scalar Rmax. It can be seen, that a small bandwidth of the modulation B (Fig. 6, a) has almost no impact on the maximum detectable range of the target, while in case of significant modulation bandwidth Bm, SNR loss rapidly increases for r 2 0.8Rmaxwhen Bm / fs = 1/4 and for r 2 0.6Rmax when Bn / fs = 1/2. These values slightly exceed the criteria defined in (17), while the latter still gives a reasonable estimation of the maximum range for applying dechirping receiver with a modulated LFM waveform.
Computational complexity
Further, we compared the average over 100 trials execution time of each of the three receivers as the function of fast-time samples per chirp (Fig. 7). In this simulation we used two different implementations of FrFT.
The results in Fig. 7 show that the slope of FrFT and group delay receivers follows the trend O(N log: (N)) and the matched filter complexity grows according to
O(N2). Two implementations of FrFT have slightly different execution time. For moderate to large number of samples per chirp, the FrFR receiver has over one order of magnitude gain in computational time. The group delay receiver brings the execution time even lower, but its performance for long code sequences is unsatisfactory, as explained above.
CONCLUSION
The new receiver structure for the modulated LFM waveform can be realized in hardware or software. We demonstrated that matched filter processing of this waveform corresponds to calculating the cross-correlation along a diagonal line in the delay-Doppler plane - called Fractional correlation, which can be efficiently implemented via the Fractional Fourier Transform (FrFT). FrFT receiver is introduced and its improved performance over the state-of-the art techniques is demonstrated for moderate-to-large bandwidth of the applied to chirp modulation. It is computationally more efficient and more accurate for target detection than a traditional receiver based on a group delay filter. The larger the receive signal bandwidth is, the higher the performance advantage of the receiver proposed over a traditional receiver is.Figure 1a schematically shows a time-frequency representation of the received signal and its relation to the FrFT angle ¢. On the horizontal axis, time is shown. On the vertical axis, frequency is shown.
Figure 1b schematically shows a time-frequency representation of the received signal and the correlation signal after transforming them by the FrFT angle og.
Figure 1b is closely related to figure 1a. The time-frequency representation of the signals are shown converted and/or rotated to visually show an interpretation of the fractional Fourier transformation over an angle ¢. This conversion and/or rotation visually shows the linear relationship for the time delay and the beat frequency and their relation to the argument in Fractional domain p.
Figure 2 schematically shows an FRFT transceiver structure or architecture for modulated FMCW waveforms. The transceiver comprises a transmitter and a receiver. The receiver may be viewed as comprising the blocks in the lower data path.
The transmitter and receiver may share the signal generators. Alternatively, one of the transmitter and receiver may comprise one or more of the signal generators providing the generated signal to the other. The signal generators are the chirp generator 210 generating the wide band continuous wave chirp, and the signal generator 220 generating the narrow band modulation signal. The transmitter may comprise the antenna output 240 and the transmitter mixer 230.
The signal representation at all the stages of the fractional correlation is plotted in Fig. 3. Here, we did not apply frequency shift of the modulation signal, described at the end of the previous section, for better visibility (there is no difference in applying this shift or not for a target at ro =< Rmax/2). It can be seen that despite the time and frequency shift between the received s(t) and the reference m(t) signals (Fig. 3, a, b), it vanishes in their FrFT representations (Fig. 3,c, d). As a result, their product has a wide and uniform spectrum (Fig. 3,e), which leads to a narrow peak in the reconstructed range profile (Fig. 3,f).
Figure 4 schematically shows an estimated range profile of a point like target with three considered receiver structures: (a) narrow-band modulation, Bm / fs = 1/64; (b) wide-band modulation, Bm / fs = 1/4. On the horizontal axis, the range is in metres. On the vertical axis, the signal strength is in dB. The FRFT architecture is shown as a solid line, the matched filter architecture of the prior art is shown as a dashed line, and the group delay architecture of the prior art is shown as a dashed dotted line.
Figure 5 schematically shows an SNR loss vs the normalized bandwidth of the modulation signal m(t). On the vertical axis, the SNR loss is in dB. The FRFT architecture is shown as a solid line with crosses, the matched filter architecture of the prior art is shown as a solid line circles, and the group delay architecture of the prior art is shown as a solid line with diamonds. The minimum and maximum for each architecture is shown as dashed dotted line around the respective solid lines. It is further noted that the FRFT and matched filter architectures almost coincide in this figure.
Figure 6 schematically shows an SNR loss as the function of the target range: (a) narrow-band modulation, Bm/ fs = 1/16; (b) wide-band modulation, Bm / fs = 1/4, (c) Bm / fs = 1/2. The FRFT architecture is shown as a solid blue line, the matched filter architecture of the prior art is shown as a solid red line, and the group delay architecture of the prior art is shown as a solid green line. The minimum and maximum for each architecture is shown as dashed dotted line around the respective solid lines.
It is further noted for Figure 6a that the FRFT, matched filter, and group delay architectures almost coincide in this figure. It is further noted for Figure 6b that the
FRFT, and matched filter architectures almost coincide and that the group delay architecture is below the other two architectures in this figure. It is further noted for
Figure Sc that the FRFT, and matched filter architectures almost coincide and that the group delay architecture is below the other two architectures in this figure.
Figure 7 schematically shows the computational complexity of three considered receiver structures. On the horizontal axis, the number of samples per chirp. On the vertical axis, the average execution time in seconds. A first embodiment of a FRFT architecture is shown as a solid line with circles. A second embodiment of a
FRFT architecture is shown as a solid line with crosses. The matched filter architecture of the prior art is shown as a dashed line with diamonds. The group delay architecture of the prior art is shown as a dashed dotted line with triangles.
Figures 6 show that the FRFT architecture provides a comparable performance to the matched filter architecture in comparison tests, while the group delay architecture provides considerable lower performance. Figure 7 shows that different FRFT architecture implementations have lower execution times compared to a matched filter architecture. Figure 7 shows further that the different FRFT architecture implementations have a longer average execution time compared to a group delay architecture. The combination of figures 6 and 7 show that the FRFT architecture for the receiver, transmitter and the transceiver provide best or almost best performance while having considerable lower average execution times for providing this performance. Hence, the FRFT architecture provides an optimal balance in performance and average execution time.
Figure 8 schematically shows an embodiment of the method of the receiver 900. The method is for receiving a frequency modulated continuous wave.
The method comprises providing 910 a digitized mixed received signal based on digitizing the mixed received signal. The mixed received signal is based on receiving an antenna signal and providing a mixed received signal. The antenna signal is typically from a receiving antenna arranged for receiving a frequency modulated continuous wave. The mixed received signal is in turn based on mixing the received antenna signal of the antenna and a wide band continuous wave chirp.
The method further comprises determining 920 a range profile signal indicative of the path length traversed by the frequency modulated continuous wave.
The range profile signal is based on correlating in a fractional Fourier transform domain with a narrow band modulation signal . The range profile signal is further based on fractional Fourier transforming the digitized mixed received signal. A correlation signal is based on the narrow band modulation signal. The frequency modulated continuous wave is based on mixing the wide band continuous wave chirp with the narrow band modulation signal.
It is noted that one or more of the methods mentioned in the description or claims may be computer implemented or on a processor typically coupled to hardware for performing the invention disclosed in the claims. It is further noted that the terms structure and architecture are used interchangeable in the description. It is also noted that although figure 2 shows a transceiver architecture, some references are made as receiver typically focussing in that passage on the receiver performance of the transceiver.
Figure © schematically shows an embodiment of a computer program product 1000, computer readable medium 1010 and/or non-transitory computer readable storage medium comprising computer readable code 1020 according to the invention. The video recording assembly may comprise a part, such as the carrier frame, arranged on a user. The video recording assembly may comprise another part, not arranged on a user. The part not arranged on the user typically may comprise a processing unit for processing the video stream from the video recording assembly.
The part not arranged on the user may be typed as an external part, server and/or smartbox. In another embodiments, the video processing unit may be arranged to the carrier frame.
It will also be clear that the above description and drawings are included to illustrate some embodiments of the invention, and not to limit the scope of protection.
Starting from this disclosure, many more embodiments will be evident to a skilled person without departing from the scope of the invention as set forth in the appended claims. These embodiments are within the scope of protection and the essence of this invention and are obvious combinations of prior art techniques and the disclosure of this patent. Devices functionally forming separate devices may be integrated in a single physical device.
The term “substantially” herein, such as in “substantially all emission” or in “substantially consists”, will be understood by the person skilled in the art. The term “substantially” may also include embodiments with “entirely”, “completely”, “all”, etc.
Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term “substantially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” also includes embodiments wherein the term “comprises” means “consists of”.
The term "functionally” will be understood by, and be clear to, a person skilled in the art. The term “substantially” as well as “functionally” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective functionally may also be removed. When used, for instance in “functionally parallel’, a skilled person will understand that the adjective “functionally” includes the term substantially as explained above. Functionally in particular is to be understood to include a configuration of features that allows these features to function as if the adjective “functionally” was not present. The term “functionally” is intended to cover variations in the feature to which it refers, and which variations are such that in the functional use of the feature, possibly in combination with other features it relates to in the invention, that combination of features is able to operate or function. For instance, if an antenna is functionally coupled or functionally connected to a communication device, received electromagnetic signals that are receives by the antenna can be used by the communication device. The word “functionally” as for instance used in “functionally parallel” is used to cover exactly parallel, but also the embodiments that are covered by the word “substantially” explained above. For instance, “functionally parallel’ relates to embodiments that in operation function as if the parts are for instance parallel. This covers embodiments for which it is clear to a skilled person that it operates within its intended field of use as if it were parallel.
Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements.
The devices or apparatus herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and “to include”, and its conjugations does not exclude the presence of elements or steps other than those stated in a claim.
Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an." The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.
The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device or apparatus claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
The invention further applies to an apparatus or device comprising one or more of the characterising features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterising features described in the description and/or shown in the attached drawings.
It will be appreciated that the invention also applies to computer programs, particularly computer programs on or in a carrier, adapted to put the invention into practice. The program may be in the form of a source code, a code intermediate source and an object code such as in a partially compiled form, or in any other form suitable for use in the implementation of the method according to the invention. It will also be appreciated that such a program may have many different architectural designs. For example, a program code implementing the functionality of the method or system according to the invention may be sub-divided into one or more sub-routines.
Many different ways of distributing the functionality among these sub-routines will be apparent to the skilled person. The sub-routines may be stored together in one executable file to form a self-contained program. Such an executable file may comprise computer-executable instructions, for example, processor instructions and/or interpreter instructions (e.g. Java interpreter instructions). Alternatively, one or more or all of the sub-routines may be stored in at least one external library file and linked with a main program either statically or dynamically, e.g. at run-time. The main program contains at least one call to at least one of the sub-routines. The sub-routines may also comprise function calls to each other. An embodiment relating to a computer program product comprises computer-executable instructions corresponding to each processing stage of at least one of the methods set forth herein. These instructions may be sub- divided into sub-routines and/or stored in one or more files that may be linked statically or dynamically. Another embodiment relating to a computer program product comprises computer-executable instructions corresponding to each means of at least one of the systems and/or products set forth herein. These instructions may be sub- divided into sub-routines and/or stored in one or more files that may be linked statically or dynamically.
The carrier of a computer program may be any entity or device capable of carrying the program. For example, the carrier may include a data storage, such as a
ROM, for example, a CD ROM or a semiconductor ROM, or a magnetic recording medium, for example, a hard disk. Furthermore, the carrier may be a transmissible carrier such as an electric or optical signal, which may be conveyed via electric or optical cable or by radio or other means. When the program is embodied in such a signal, the carrier may be constituted by such a cable or other device or means.
Alternatively, the carrier may be an integrated circuit in which the program is embedded, the integrated circuit being adapted to perform, or used in the performance of, the relevant method.
The various aspects discussed in this patent can be combined in order to provide additional advantages. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. Furthermore, some of the features can form the basis for one or more divisional applications. Furthermore, the methods mentioned may be implementable and executable on a computer.
EMBODIMENTS
1. Frequency modulated continuous wave receiver, comprising: - an antenna input (110) arranged for receiving an antenna signal from a receiving antenna arranged for receiving a frequency modulated continuous wave; - a receiver mixer (120) arranged for providing a mixed received signal (125) based on mixing the received antenna signal (115) of the antenna and a wide band continuous wave chirp (116); - a digitizer (130) arranged for providing a digitized mixed received signal (135) based on digitizing the mixed received signal; and - a fractional correlator (140) arranged for determining a range profile signal (145) indicative of the path length traversed by the frequency modulated continuous wave, wherein the range profile signal is based on correlating in a fractional Fourier transform domain the digitized mixed received signal with a narrow band modulation signal (137); and wherein the frequency modulated continuous wave is based on mixing the wide band continuous wave chirp with the narrow band modulation signal. 2. Frequency modulated continuous wave receiver according to the preceding claim, wherein the fractional correlator comprises: - a fractional Fourier receiver transformer (150) arranged for generating a received fractional Fourier signal (155) based on fractional Fourier transforming the digitized mixed received signal; - a fractional Fourier mixer (160) arranged for providing a mixed fractional
Fourier signal (165) based on mixing the received fractional Fourier signal and a correlation signal (137) based on the narrow band modulation signal; and - an inverse Fourier transformer (170) arranged for providing the range profile signal based on inverse Fourier transforming the mixed fractional Fourier signal. 3. Frequency modulated continuous wave receiver according to the preceding claim, wherein the fractional Fourier transformer transforms over an angle ¢ based on one or more predetermined parameters, such as one or more predetermined parameters of the frequency modulated continuous wave and/or the receiver, preferably only one or more predetermined frequency modulated continuous wave and/or receiver parameters, more preferably an oversampling factor y;, a bandwidth of the frequency modulated continuous wave B, and/or a sample frequency fs. 4. Frequency modulated continuous wave receiver according to any of the preceding claims 2-3, wherein the correlation signal or a constituent part of the correlation signal is precalculated; and wherein the receiver comprises a memory for storing the precalculated correlation signal or a precalculated constituent part of the correlation signal.
5. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein the fractional correlator comprises: - a fractional Fourier modulation transformer (180) arranged for generating a fractional Fourier modulation signal (185) based on fractional Fourier transforming the narrow band modulation signal; and - a processing block (190) arranged for providing a/the correlation signal based on processing the fractional Fourier modulation signal for application in the fractional correlator, more specifically when depending on claim 2, the fractional Fourier mixer. 6. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein the digitizer comprises: - a low pass filter arranged for providing a filtered mixed received signal based on low pass filtering the mixed received signal; and - an analogue to digital converter arranged for providing the digitized mixed received signal based on the filtered mixed received signal. 7. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein the wide band continuous wave chirp has a wide bandwidth; wherein the narrow band modulation signal has a narrow bandwidth; and wherein the wide bandwidth relative to the narrow bandwidth is at least 2 times, preferably at least 4 times, more preferably at least 8 times, more preferably at least 16 times, more preferably at least 32 times, most preferably at least 40 times, as wide.
8. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein the wide band continuous wave chirp has a/the wide bandwidth based on the filters and/or is below 10 GHz, preferably 4 GHz, more preferably 1 GHz; and wherein the narrow band modulation signal has a/the narrow bandwidth below one, preferably a half, more preferably a quarter, of the sampling frequency fs the digitizer. 9. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein the narrow band modulation signal comprises an identification signal. 10. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein the frequency modulated continuous wave receiver is a linear frequency modulation receiver. 11. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein the frequency modulated continuous wave receiver is a phase-modulated frequency modulated continuous wave receiver or an OFDM continuous wave receiver or any other information carrying waveform. 12. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein mixing the narrow band modulation signal and the wide band continuous wave chirp is based on phase modulating the wide band continuous wave chirp based on the narrow band modulation signal. 13. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein the time delay and the beat frequency have a linear relation. 14. Frequency modulated continuous wave receiver according to any of the preceding claims, comprising an receiving antenna arranged for providing the frequency modulated continuous wave to the antenna input.
15. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein the narrow band modulation signal encodes an identifier, preferably a unique identifier, for identifying the frequency modulated continuous wave. 16. Frequency modulated continuous wave receiver according to any of the preceding claims, wherein the wide band continuous wave chirp has a bandwidth in the range of 1
MHz — 10 GHz, preferably 5 MHz — 5 GHz, more preferably 10 MHz — 1 GHz; wherein the wide band continuous wave chirp has a length in the range of 1 us —200 ms, preferably 5 us — 100 ms, more preferably 7 us — 5 ms, most preferably 10
Us — 1 ms; wherein the wide band continuous wave chirp has a carrier frequency in the range of 1 — 300 GHz; preferably 2 — 200 GHz, more preferably 3 — 100 GHz, most preferably 3 — 84 GHz; and wherein the digitizer has a sample frequency in the range of 1 — 400 MHz, preferably 3 — 100 MHz, more preferably 5 — 80 MHz, most preferably 10 — 40 MHz. 17. Frequency modulated continuous wave transmitter, comprising: - a chirp generator (210) arranged for generating a wide band continuous wave chirp (116); - a signal generator (220) arranged for generating a narrow band modulation signal (137); - a transmitter mixer (230) arranged for providing a mixed transmission signal (235) based on mixing the wide band continuous wave chirp and the narrow band modulation signal; and - an antenna output (240) arranged for providing an antenna signal to a transmitting antenna based on the mixed transmission signal for the transmitting antenna transmitting a frequency modulated continuous wave. 18. Frequency modulated continuous wave transmitter according to the preceding claim, wherein the signal generator generates the narrow band modulation signal based on encoding an identifier, preferably a unique identifier, for identifying the frequency modulated continuous wave.
19. Frequency modulated continuous wave transmitter according to any of the preceding claims 17-18, comprising: - a fractional Fourier modulation transformer arranged for generating a fractional
Fourier modulation signal based on fractional Fourier transforming the narrow band modulation signal; and - a processing block arranged for providing a correlation signal based on processing the fractional Fourier modulation signal for application in a frequency modulated continuous wave receiver. 20. Frequency modulated continuous wave transmitter according to the preceding claim, comprising a memory for storing the correlation signal or a constituent part of the correlation signal which is precalculated. 21. Frequency modulated continuous wave transmitter according to any of the preceding claims, wherein the wide band continuous wave chirp has a bandwidth in the range of 1
MHz — 10 GHz, preferably 5 MHz — 5 GHz, more preferably 10 MHz — 1 GHz; wherein the wide band continuous wave chirp has a length in the range of 1 us —200ms, preferably 5 us — 100 ms, more preferably 7 us — 5 ms, most preferably 10
Us — 1 MS; wherein the wide band continuous wave chirp has a carrier frequency in the range of 1 — 300 GHz; preferably 2 — 200 GHz, more preferably 3 — 100 GHz, most preferably 3 — 84 GHz; and wherein the digitizer has a sample frequency in the range of 1 — 400 MHz, preferably 3 — 100 MHz, more preferably 5 — 80 MHz, most preferably 10 — 40 MHz. 22. Frequency modulated continuous wave transceiver, comprising: - one or more frequency modulated continuous wave receivers according to any of the claims 1-16; and - one or more frequency modulated continuous wave transmitters according to any of the claims 17-21.
23. Frequency modulated continuous wave transceiver according to the preceding claim,
wherein the one or more frequency modulated continuous wave transmitters is at least two frequency modulated continuous wave transmitters;
wherein the at least two frequency modulated continuous wave transmitters depend on claim 18;
wherein the respective identifiers of the at least two frequency modulated continuous wave transmitters are different; and wherein the one or more frequency modulated continuous wave receivers are arranged for receiving from the at least two frequency modulated continuous wave transmitters.
24. Frequency modulated continuous wave transceiver according to the preceding claim,
wherein the one or more frequency modulated continuous wave receivers is at least two frequency modulated continuous wave receivers; and wherein the at least two frequency modulated continuous wave receivers depend on claim 9.
25. Range finder comprising a frequency modulated continuous wave transceiver according to any of the claims 22-24, arranged as radar, preferably MIMO radar, or sonar, preferably MIMO sonar.
26. Range finder according to any of the preceding claims 24-25, wherein the range finder is arranged for use in automotive, surveillance, meteorology, and/or meteorological applications.
27. Method for receiving a frequency modulated continuous wave, comprising: - providing (910) a digitized mixed received signal based on digitizing the mixed received signal which is based on:
- receiving an antenna signal from a receiving antenna arranged for receiving a frequency modulated continuous wave; and - providing a mixed received signal based on mixing the received antenna signal of the antenna and a wide band continuous wave chirp; and
- determining (920) a range profile signal indicative of the path length traversed by the frequency modulated continuous wave, wherein the range profile signal is based on correlating in a fractional Fourier transform domain the digitized mixed received signal with a narrow band modulation signal; and wherein the frequency modulated continuous wave is based on mixing the wide band continuous wave chirp with the narrow band modulation signal. 28. Method according to the preceding claim, wherein determining comprises: - generating a received fractional Fourier signal based on fractional Fourier transforming the digitized mixed received signal;
- providing a mixed fractional Fourier signal based on mixing the received fractional Fourier signal and a correlation signal based on the narrow band modulation signal; and
- providing the range profile signal based on inverse Fourier transforming the mixed fractional Fourier signal. 29. Method according to the preceding claim, wherein the fractional Fourier transformer transforms over an angle ¢ based on one or more predetermined parameters, such as one or more predetermined parameters of the frequency modulated continuous wave and/or the receiver, preferably only one or more predetermined frequency modulated continuous wave and/or receiver parameters, more preferably an oversampling factor yr, a bandwidth of the frequency modulated continuous wave B, and/or a sample frequency fs.
30. Method according to any of the preceding claims 28-29, comprising storing the correlation signal or a constituent part of the correlation signal which is precalculated. 31. Method according to any of the preceding claims 27-30, wherein providing a digitized mixed received signal comprises:
- configuring a filter for providing a filtered mixed received signal based on low pass filtering the mixed received signal; and/or
- configuring an analogue to digital converter for providing the digitized mixed received signal based on the filtered mixed received signal.
32. Method according to any of the preceding claims 27-31, wherein the narrow band modulation signal is an identification signal. 33. Method for transmitting a frequency modulated continuous wave, comprising: - configuring a chirp generator for generating a wide band continuous wave chirp; and
- configuring a signal generator for generating a narrow band modulation signal;
wherein the configuring steps are performed for:
- providing a mixed transmission signal based on mixing the wide band continuous wave chirp and the narrow band modulation signal; and
- providing an antenna signal to a transmitting antenna based on the mixed transmission signal for the transmitting antenna transmitting a frequency modulated continuous wave.
34. Method according to the preceding claim, wherein generating a narrow band modulation signal generates the narrow band modulation signal based on encoding an identifier, preferably a unique identifier, for identifying the frequency modulated continuous wave.
35. Method according to any of the preceding claims 33-34, comprising:
- generating a fractional Fourier modulation signal based on fractional Fourier transforming the narrow band modulation signal; and
- providing a correlation signal based on processing the fractional Fourier modulation signal for application in a frequency modulated continuous wave receiver.
36. Method according to the preceding claim, comprising storing the correlation signal or a constituent part of the correlation signal which is precalculated.
37. Method for a frequency modulated continuous wave transceiver, comprising:
- one or more instances of the receiving method according to any of the claims 27-32; and
- one or more instances of the transmitting method according to any of the claims 33-36.
38. Method according to the preceding claim, wherein the one or more instances of the transmitting method for transmitting a frequency modulated continuous wave is at least two instances of the transmitting method; wherein the at least two instances of the transmitting method depend on claim 34; wherein the respective identifiers of the at least two instances of the transmitting method are different; and wherein the one or more instances of the receiving method are arranged for receiving from the at least two instances of the transmitting methods. 39. Method according to the preceding claim, wherein the one or more instances of receiving method is at least two instances of receiving methods; and wherein the at least two receiving methods depend on claim 32. 40. Computer program product (1000) comprising instructions which, when the program is executed by a suitable processor, cause the processor to carry out any of the methods of claim 27-39.

Claims (40)

CONCLUSIESCONCLUSIONS 1. Frequentiegemoduleerde continuegolfontvanger, omvattende: - een antenne-ingang (110) ingericht voor het ontvangen van een antennesignaal van een ontvangantenne ingericht voor het ontvangen van een frequentiegemoduleerde continue golf; - een ontvangermixer (120) ingericht voor het leveren van een gemengd ontvangen signaal (125) gebaseerd op het mengen van het ontvangen antennesignaal (115) van de antenne en een breedbandige continuegolfchirp (116); - een digitaliseerder (130) ingericht voor het verschaffen van een gedigitaliseerd gemengd ontvangen signaal (135) op basis van het digitaliseren van het gemengde ontvangen signaal; en - een fractionele correlator (140) ingericht voor het bepalen van een afstandprofielsignaal (145) dat indicatief is voor de padlengte die wordt doorlopen door de frequentiegemoduleerde continue golf, waarbij het afstandprofielsignaal is gebaseerd op het correleren in het fractionele Fourier domein van het gedigitaliseerde gemengde ontvangen signaal met een smalbandig modulatiesignaal (137); en waarbij de frequentiegemoduleerde continue golf is gebaseerd op het mengen van de breedbandige continuegolfchirp met het smalbandige modulatiesignaal.A frequency modulated continuous wave receiver, comprising: - an antenna input (110) arranged to receive an antenna signal from a receiving antenna adapted to receive a frequency modulated continuous wave; - a receiver mixer (120) configured to provide a mixed received signal (125) based on mixing the received antenna signal (115) from the antenna and a broadband continuous wave chirp (116); - a digitizer (130) configured to provide a digitized mixed received signal (135) based on digitizing the mixed received signal; and - a fractional correlator (140) arranged to determine a distance profile signal (145) indicative of the path length traversed by the frequency modulated continuous wave, the distance profile signal being based on correlating in the fractional Fourier domain of the digitized mixed received signal with a narrowband modulation signal (137); and wherein the frequency modulated continuous wave is based on mixing the broadband continuous wave chirp with the narrowband modulation signal. 2. Frequentiegemoduleerde continuegolfontvanger volgens de voorgaande conclusie, waarbij de fractionele correlator omvat: - een fractionele Fourier-ontvangertransformator (150) die is ingericht voor het genereren van een ontvangen fractioneel Fourier-signaal (155) op basis van het fractioneel Fourier-transformeren van het gedigitaliseerde gemengde ontvangen signaal; - een fractionele Fourier-mixer (160) ingericht voor het verschaffen van een gemengd fractioneel Fourier-signaal (165) gebaseerd op het mengen van het ontvangen fractionele Fourier-signaal en een correlatiesignaal gebaseerd op het smalbandige modulatiesignaal (137); en - een inverse Fourier-transformator (170) die is ingericht voor het verschaffen van het afstandprofielsignaal op basis van het inverse Fourier-transformeren van het gemengde fractionele Fourier-signaal.A frequency modulated continuous wave receiver according to the preceding claim, wherein the fractional correlator comprises: - a fractional Fourier receiver transformer (150) arranged to generate a received fractional Fourier signal (155) based on the fractional Fourier transform of the digitized mixed received signal; - a fractional Fourier mixer (160) configured to provide a mixed fractional Fourier signal (165) based on mixing the received fractional Fourier signal and a correlation signal based on the narrowband modulation signal (137); and - an inverse Fourier transformer (170) arranged to provide the range profile signal based on inverse Fourier transforming the mixed fractional Fourier signal. 3. Frequentiegemoduleerde continuegolfontvanger volgens de voorgaande conclusie, waarbij de fractionele Fourier-transformator transformeert over een hoek ¢ op basis van een of meer vooraf bepaalde parameters, zoals een of meer vooraf bepaalde parameters van de frequentiegemoduleerde continue golf en/of de ontvanger, bij voorkeur slechts één of meer vooraf bepaalde frequentiegemoduleerde continuegolf- en/of ontvangerparameters, bij verdere voorkeur een overbemonsteringsfactor yr, een bandbreedte van de frequentiegemoduleerde continue golf B, en/of een bemonsteringsfrequentie fs.3. Frequency modulated continuous wave receiver according to the preceding claim, wherein the fractional Fourier transformer transforms over an angle ¢ based on one or more predetermined parameters, such as one or more predetermined parameters of the frequency modulated continuous wave and/or the receiver, preferably only one or more predetermined frequency modulated continuous wave and/or receiver parameters, further preferably an oversampling factor yr, a bandwidth of the frequency modulated continuous wave B, and/or a sampling frequency fs. 4. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij het correlatiesignaal of een bestanddeel van het correlatiesignaal vooraf is berekend; en waarbij de ontvanger een geheugen omvat voor het opslaan van het vooraf berekende correlatiesignaal of een vooraf berekend bestanddeel van het correlatiesignaal.4. Frequency modulated continuous wave receiver according to any one of the preceding claims, wherein the correlation signal or a component of the correlation signal has been calculated in advance; and wherein the receiver comprises a memory for storing the pre-computed correlation signal or a pre-computed component of the correlation signal. 5. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij de fractionele correlator omvat: - een fractionele Fourier-modulatietransformator (180) ingericht voor het genereren van een fractioneel Fourier-modulatiesignaal (185) gebaseerd op het fractioneel Fourier-transformeren van het smalbandige modulatiesignaal; en - een verwerkingsblok (190) ingericht voor het verschaffen van een/het correlatiesignaal op basis van het verwerken van het fractionele Fourier- modulatiesignaal voor toepassing in de fractionele correlator, meer in het bijzonder wanneer afhankelijk van conclusie 2, de fractionele Fourier-mixer.A frequency modulated continuous wave receiver according to any one of the preceding claims, wherein the fractional correlator comprises: - a fractional Fourier modulation transformer (180) arranged to generate a fractional Fourier modulation signal (185) based on fractional Fourier transforming the narrowband modulation signal ; and - a processing block (190) arranged to provide a correlation signal based on processing the fractional Fourier modulation signal for use in the fractional correlator, more particularly when dependent on claim 2, the fractional Fourier mixer. 6. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij de digitaliseerder omvat: - een laagdoorlaatfilter ingericht voor het verschaffen van een gefilterd gemengd ontvangen signaal op basis van het laagdoorlaatfilteren van het gemengd ontvangen signaal; en - een analoog naar digitaal omzetter ingericht voor het leveren van het gedigitaliseerde gemengde ontvangen signaal op basis van het gefilterde gemengde ontvangen signaal.6. Frequency modulated continuous wave receiver according to any one of the preceding claims, wherein the digitizer comprises: - a low-pass filter arranged to provide a filtered mixed received signal based on low-pass filtering of the mixed received signal; and - an analog to digital converter arranged to provide the digitized mixed received signal on the basis of the filtered mixed received signal. 7. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij de breedband continuegolfchirp een brede bandbreedte heeft; waarbij het smalbandige modulatiesignaal een smalle bandbreedte heeft; en waarbij de brede bandbreedte ten opzichte van de smalle bandbreedte ten minste 2 keer, bij voorkeur ten minste 4 keer, met meer voorkeur ten minste 8 keer, met meer voorkeur ten minste 16 keer, met meer voorkeur ten minste 32 keer, met de meeste voorkeur ten minste 40 is keer, zo breed is.7. Frequency modulated continuous wave receiver according to any one of the preceding claims, wherein the broadband continuous wave chirp has a wide bandwidth; wherein the narrowband modulation signal has a narrow bandwidth; and wherein the wide bandwidth relative to the narrow bandwidth is at least 2 times, preferably at least 4 times, more preferably at least 8 times, more preferably at least 16 times, more preferably at least 32 times, most preferably preferably at least 40 times, so wide. 8. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij de breedband continuegolfchirp een/de brede bandbreedte heeft gebaseerd op de filters en/of lager is dan 10 GHz, bij voorkeur 4 GHz, bij verdere voorkeur 1 GHz; en waarbij het smalbandige modulatiesignaal een/de smalle bandbreedte heeft van minder dan een, bij voorkeur de helft, bij verdere voorkeur een kwart, van de bemonsteringsfrequentie fs van de digitaliseerder.8. Frequency modulated continuous wave receiver according to any one of the preceding claims, wherein the broadband continuous wave chirp has a wide bandwidth based on the filters and/or is lower than 10 GHz, preferably 4 GHz, further preferably 1 GHz; and wherein the narrowband modulation signal has a narrow bandwidth of less than one, preferably half, further preferably one quarter, of the sampling frequency fs of the digitizer. 9. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij het smalbandige modulatiesignaal een identificatiesignaal omvat.9. Frequency-modulated continuous wave receiver according to any of the preceding claims, wherein the narrowband modulation signal comprises an identification signal. 10. Frequentie-gemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij de frequentiegemoduleerde continuegolfontvanger een lineaire frequentiemodulatie-ontvanger is.10. Frequency-modulated continuous-wave receiver according to any one of the preceding claims, wherein the frequency-modulated continuous-wave receiver is a linear frequency modulation receiver. 11. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij de frequentiegemoduleerde continuegolfontvanger een fasegemoduleerde frequentiegemoduleerde continuegolfontvanger of een OFDM continuegolfontvanger of elke ander informatie dragende golfvorm is.11. Frequency-modulated continuous-wave receiver according to any one of the preceding claims, wherein the frequency-modulated continuous-wave receiver is a phase-modulated frequency-modulated continuous-wave receiver or an OFDM continuous-wave receiver or any other information-carrying waveform. 12. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij het mengen van het smalbandige modulatiesignaal en de breedband continuegolfchirp is gebaseerd op fasemodulatie van de breedband continuegolfchirp gebaseerd op het smalbandige modulatiesignaal.A frequency modulated continuous wave receiver according to any one of the preceding claims, wherein the mixing of the narrowband modulation signal and the broadband continuous wave chirp is based on phase modulation of the broadband continuous wave chirp based on the narrowband modulation signal. 13. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij de tijdvertraging en de zwevingsfrequentie een lineaire relatie hebben.13. Frequency modulated continuous wave receiver according to any one of the preceding claims, wherein the time delay and the beat frequency have a linear relationship. 14. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, omvattende een ontvangstantenne die is ingericht voor het leveren van de frequentiegemoduleerde continue golf aan de antenne-ingang.14. Frequency-modulated continuous wave receiver according to any of the preceding claims, comprising a receiving antenna that is adapted to supply the frequency-modulated continuous wave to the antenna input. 15. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij het smalbandige modulatiesignaal een identificatie codeert, bij voorkeur een unieke identificatie, voor het identificeren van de frequentiegemoduleerde continue golf.15. Frequency-modulated continuous wave receiver according to any one of the preceding claims, wherein the narrowband modulation signal encodes an identification, preferably a unique identification, for identifying the frequency-modulated continuous wave. 16. Frequentiegemoduleerde continuegolfontvanger volgens een van de voorgaande conclusies, waarbij de breedband continuegolfchirp een bandbreedte heeft in het bereik van 1 MHz - 10 GHz, bij voorkeur 5 MHz - 5 GHz, met meer voorkeur 10 MHz - 1 GHz; waarbij de breedband continuegolfchirp een lengte heeft in het bereik van 1 us — 200 ms, bij voorkeur 5 Hs — 100 ms, bij verdere voorkeur 7 us — 5 ms, bij hoogste voorkeur 10 Hs — 1 ms; waarbij de breedband continuegolfchirp een draaggolffrequentie heeft in het bereik van 1 - 300 GHz; bij voorkeur 2 — 200 GHz, bij verdere voorkeur 3 — 100 GHz, bij hoogste voorkeur 3 — 84 GHz; en waarbij de digitaliseerder een bemonsteringsfrequentie heeft in het bereik van 1 -400 MHz, bij voorkeur 3 - 100 MHz, bij verdere voorkeur 5 - 80 MHz, bij hoogste voorkeur 10 - 40 MHz.A frequency modulated continuous wave receiver according to any one of the preceding claims, wherein the broadband continuous wave chirp has a bandwidth in the range of 1 MHz - 10 GHz, preferably 5 MHz - 5 GHz, more preferably 10 MHz - 1 GHz; wherein the broadband continuous wave chirp has a length in the range of 1 µs - 200 ms, preferably 5 µs - 100 ms, further preferably 7 µs - 5 ms, most preferably 10 Hs - 1 ms; wherein the broadband continuous wave chirp has a carrier frequency in the range 1 - 300 GHz; preferably 2 - 200 GHz, further preferably 3 - 100 GHz, most preferably 3 - 84 GHz; and wherein the digitizer has a sampling frequency in the range of 1 - 400 MHz, preferably 3 - 100 MHz, further preferably 5 - 80 MHz, most preferably 10 - 40 MHz. 17. Frequentiegemoduleerde continuegolfzender, omvattende: - een chirpgenerator (210) die is ingericht voor het genereren van een breedbandige continuegolfchirp (116); - een signaalgenerator (220) ingericht voor het genereren van een smalbandig modulatiesignaal (137); - een zendermixer (230) ingericht voor het verschaffen van een gemengd transmissiesignaal (235) gebaseerd op het mengen van de breedband continuegolfchirp en het smalbandige modulatiesignaal; en - een antenne-uitgang (240) die is ingericht voor het leveren van een antennesignaal aan een zendantenne op basis van het gemengde zendsignaal voor de zendantenne die een frequentiegemoduleerde continue golf uitzendt.A frequency modulated continuous wave transmitter, comprising: - a chirp generator (210) adapted to generate a broadband continuous wave chirp (116); - a signal generator (220) adapted to generate a narrowband modulation signal (137); - a transmitter mixer (230) configured to provide a mixed transmission signal (235) based on mixing the broadband continuous wave chirp and the narrowband modulation signal; and - an antenna output (240) arranged to supply an antenna signal to a transmitting antenna based on the mixed transmitting signal for the transmitting antenna that transmits a frequency-modulated continuous wave. 18. Frequentiegemoduleerde continuegolfzender volgens de voorgaande conclusie, waarbij de signaalgenerator het smalbandige modulatiesignaal genereert op basis van het coderen van een identificatie, bij voorkeur een unieke identificatie, voor het identificeren van de frequentiegemoduleerde continue golf.18. Frequency modulated continuous wave transmitter according to the preceding claim, wherein the signal generator generates the narrowband modulation signal on the basis of encoding an identification, preferably a unique identification, for identifying the frequency modulated continuous wave. 19. Frequentiegemoduleerde continuegolfzender volgens een van de voorgaande conclusies 17-18, omvattende: - een fractionele Fourier-modulatietransformator ingericht voor het genereren van een fractioneel Fourier-modulatiesignaal op basis van het fractioneel Fourier- transformeren van het smalbandige modulatiesignaal; en - een verwerkingsblok dat is ingericht voor het verschaffen van een correlatiesignaal op basis van het verwerken van het fractionele Fourier- modulatiesignaal voor toepassing in een frequentiegemoduleerde continue golfontvanger.19. Frequency-modulated continuous wave transmitter according to any of the preceding claims 17-18, comprising: - a fractional Fourier modulation transformer arranged for generating a fractional Fourier modulation signal based on the fractional Fourier transform of the narrowband modulation signal; and - a processing block adapted to provide a correlation signal based on processing the fractional Fourier modulation signal for use in a frequency-modulated continuous wave receiver. 20. Frequentiegemoduleerde continugolfzender volgens de voorgaande conclusie, omvattende een geheugen voor het opslaan van het correlatiesignaal of een bestanddeel van het correlatiesignaal dat vooraf is berekend.20. Frequency modulated continuous wave transmitter according to the preceding claim, comprising a memory for storing the correlation signal or a component of the correlation signal that has been calculated in advance. 21. Frequentiegemoduleerde continuegolfzender volgens een van de voorgaande conclusies, waarbij de breedband continuegolfchirp een bandbreedte heeft in het bereik van 1 MHz - 10 GHz, bij voorkeur 5 MHz - 5 GHz, bij verdere voorkeur 10 MHz - 1 GHz; waarbij de breedband continuegolfchirp een lengte heeft in het bereik van 1 us21. Frequency modulated continuous wave transmitter according to any of the preceding claims, wherein the broadband continuous wave chirp has a bandwidth in the range of 1 MHz - 10 GHz, preferably 5 MHz - 5 GHz, further preferably 10 MHz - 1 GHz; wherein the broadband continuous wave chirp has a length in the range of 1 µs — 200 ms, bij voorkeur 5 Hs — 100 ms, bij verdere voorkeur 7 us — 5 ms, bij hoogste voorkeur 10 HS — 1 ms; waarbij de breedband continuegolfchirp een draaggolffrequentie heeft in het bereik van 1 - 300 GHz; bij voorkeur 2 — 200 GHz, bij verdere voorkeur 3 — 100 GHz, bij hoogste voorkeur 3 — 84 GHz; en waarbij de digitaliseerder een bemonsteringsfrequentie heeft in het bereik van 1 - 400 MHz, bij voorkeur 3 - 100 MHz, bij verdere voorkeur 5 - 80 MHz, bij hoogste voorkeur 10 - 40 MHz.— 200 ms, preferably 5 Hs — 100 ms, further preferably 7 us — 5 ms, most preferably 10 HS — 1 ms; wherein the broadband continuous wave chirp has a carrier frequency in the range 1 - 300 GHz; preferably 2 - 200 GHz, further preferably 3 - 100 GHz, most preferably 3 - 84 GHz; and wherein the digitizer has a sampling frequency in the range of 1 - 400 MHz, preferably 3 - 100 MHz, further preferably 5 - 80 MHz, most preferably 10 - 40 MHz. 22. Frequentiegemoduleerde continuegolfzendontvanger, omvattende: - een of meer frequentiegemoduleerde continue golfontvangers volgens een van de conclusies 1-18; en - een of meer frequentiegemoduleerde continue golfzenders volgens een van de conclusies 17-21.22. Frequency-modulated continuous-wave transceiver, comprising: - one or more frequency-modulated continuous-wave receivers according to any of the claims 1-18; and - one or more frequency-modulated continuous wave transmitters according to any one of claims 17-21. 23. Frequentiegemoduleerde continuegolfzendontvanger volgens de voorgaande conclusie, waarbij de één of meer frequentiegemoduleerde continue golfzenders ten minste twee frequentiegemoduleerde continuegolfzenders zijn; waarbij de ten minste twee frequentiegemoduleerde continue golfzenders afhankelijk zijn van conclusie 18; waarbij de respectieve identificaties van de ten minste twee frequentiegemoduleerde continue golfzenders verschillend zijn; en waarbij de één of meer frequentiegemoduleerde continue-golfontvangers zijn ingericht voor het ontvangen van de ten minste twee frequentiegemoduleerde continue-golfzenders.A frequency-modulated continuous-wave transceiver according to the preceding claim, wherein the one or more frequency-modulated continuous-wave transmitters are at least two frequency-modulated continuous-wave transmitters; wherein the at least two frequency modulated continuous wave transmitters are dependent on claim 18; wherein the respective identifications of the at least two frequency modulated continuous wave transmitters are different; and wherein the one or more frequency-modulated continuous-wave receivers are arranged to receive the at least two frequency-modulated continuous-wave transmitters. 24. Frequentiegemoduleerde continuegolfzendontvanger volgens de voorgaande conclusie, waarbij de één of meer frequentiegemoduleerde continuegolfontvangers ten minste twee frequentiegemoduleerde continuegolfontvangers zijn; en waarbij de ten minste twee frequentiegemoduleerde continuegolfontvangers afhankelijk zijn van conclusie 9.A frequency-modulated continuous-wave transceiver according to the preceding claim, wherein the one or more frequency-modulated continuous-wave receivers are at least two frequency-modulated continuous-wave receivers; and wherein the at least two frequency modulated continuous wave receivers depend on claim 9. 25. Afstandsmeter omvattende een frequentiegemoduleerde continuegolfzendontvanger volgens een van de conclusies 22-24, opgesteld als radar, bij voorkeur MIMO-radar, of sonar, bij voorkeur MIMO-sonar.25. Rangefinder comprising a frequency-modulated continuous wave transceiver according to any one of claims 22-24, arranged as radar, preferably MIMO radar, or sonar, preferably MIMO sonar. 26. Afstandsmeter volgens een van de voorgaande conclusies 24-25, waarbij de afstandsmeter is ingericht voor gebruik in automobiel-, bewakings-, meteorologie- en/of meteorologische toepassingen.26. Distance meter according to any of the preceding claims 24-25, wherein the distance meter is designed for use in automotive, surveillance, meteorology and/or meteorological applications. 27. Werkwijze voor het ontvangen van een frequentiegemoduleerde continue golf, omvattende: - het verschaffen (910) van een gedigitaliseerd gemengd ontvangen signaal op basis van het digitaliseren van het gemengde ontvangen signaal dat is gebaseerd op: - het ontvangen van een antennesignaal van een ontvangantenne die is ingericht voor het ontvangen van een frequentiegemoduleerde continue golf; en - het verschaffen van een gemengd ontvangen signaal op basis van het mengen van het ontvangen antennesignaal van de antenne en een breedbandige continuegolfchirp ; en - het bepalen (920) van een afstandprofielsignaal dat indicatief is voor de padlengte die wordt doorlopen door de frequentiegemoduleerde continue golf, waarbij het afstandprofielsignaal is gebaseerd op het correleren in het fractionele Fourier domein van het gedigitaliseerde gemengde ontvangen signaal met een smalbandig modulatiesignaal; en waarbij de frequentiegemoduleerde continue golf is gebaseerd op het mengen van de breedbandige continuegolfchirp met het smalbandige modulatiesignaal.27. Method of receiving a frequency modulated continuous wave, comprising: - providing (910) a digitized mixed received signal based on digitizing the mixed received signal based on: - receiving an antenna signal from a receiving antenna which is adapted to receive a frequency-modulated continuous wave; and - providing a mixed received signal based on mixing the received antenna signal from the antenna and a broadband continuous wave chirp; and - determining (920) a range profile signal indicative of the path length traversed by the frequency modulated continuous wave, the range profile signal being based on correlating in the fractional Fourier domain the digitized mixed received signal with a narrowband modulation signal; and wherein the frequency modulated continuous wave is based on mixing the broadband continuous wave chirp with the narrowband modulation signal. 28. Werkwijze volgens de voorgaande conclusie, waarbij het bepalen omvat: - het genereren van een ontvangen fractioneel Fourier-signaal op basis van het fractioneel Fourier-transformeren van het gedigitaliseerde gemengde ontvangen signaal; - het verschaffen van een gemengd fractioneel Fourier-signaal op basis van het mengen van het ontvangen fractionele Fourier-signaal en een correlatiesignaal gebaseerd op het smalbandige modulatiesignaal; en - het verschaffen van het afstandprofielsignaal op basis van inverse Fourier- transformatie van het gemengde fractionele Fourier-signaal.A method according to the preceding claim, wherein the determining comprises: - generating a received fractional Fourier signal based on fractional Fourier transforming the digitized mixed received signal; - providing a mixed fractional Fourier signal based on mixing the received fractional Fourier signal and a correlation signal based on the narrowband modulation signal; and - providing the range profile signal based on inverse Fourier transform of the mixed fractional Fourier signal. 29. Werkwijze volgens de voorgaande conclusie, waarbij de fractionele Fourier- transformator over een hoek ¢@ transformeert op basis van één of meer vooraf bepaalde parameters, zoals één of meer vooraf bepaalde parameters van de frequentiegemoduleerde continue golf en/of de ontvanger, bij voorkeur slechts één of meer vooraf bepaalde frequentiegemoduleerde continuegolf- en/of ontvangerparameters, bij verdere voorkeur een overbemonsteringsfactor yr, een bandbreedte van de frequentiegemoduleerde continue golf B, en/of een bemonsteringsfrequentie fs.29. Method according to the preceding claim, wherein the fractional Fourier transformer transforms over an angle ¢@ based on one or more predetermined parameters, such as one or more predetermined parameters of the frequency modulated continuous wave and/or the receiver, preferably only one or more predetermined frequency modulated continuous wave and/or receiver parameters, further preferably an oversampling factor yr, a bandwidth of the frequency modulated continuous wave B, and/or a sampling frequency fs. 30. Werkwijze volgens een van de voorgaande conclusies 28-29, omvattende het opslaan van het correlatiesignaal of een bestanddeel van het correlatiesignaal dat vooraf is berekend.30. Method according to any of the preceding claims 28-29, comprising storing the correlation signal or a component of the correlation signal that has been calculated in advance. 31. Werkwijze volgens een van de voorgaande conclusies 27-30, waarbij het verschaffen van een gedigitaliseerd gemengd ontvangen signaal omvat: - het configureren van een filter voor het verschaffen van een gefilterd gemengd ontvangen signaal op basis van laagdoorlaatfiltering van het gemengde ontvangen signaal; en/of - het configureren van een analoog naar digitaal omzetter voor het leveren van het gedigitaliseerde gemengde ontvangen signaal op basis van het gefilterde gemengde ontvangen signaal.A method according to any one of the preceding claims 27-30, wherein providing a digitized mixed received signal comprises: - configuring a filter for providing a filtered mixed received signal based on low-pass filtering of the mixed received signal; and/or - configuring an analog to digital converter to provide the digitized mixed received signal based on the filtered mixed received signal. 32. Werkwijze volgens een van de voorgaande conclusies 27-31, waarbij het smalbandige modulatiesignaal een identificatiesignaal omvat.32. Method according to any of the preceding claims 27-31, wherein the narrowband modulation signal comprises an identification signal. 33. Werkwijze voor het uitzenden van een frequentiegemoduleerde continue golf, omvattende: - het configureren van een chirpgenerator voor het genereren van een breedbandige continuegolfchirp; en - het configureren van een signaalgenerator voor het genereren van een smalbandig modulatiesignaal; waarbij de configuratiestappen worden uitgevoerd voor: - het verschaffen van een gemengd transmissiesignaal op basis van het mengen van de breedband continuegolfchirp en het smalbandige modulatiesignaal; en - het verschaffen van een antennesignaal aan een zendantenne op basis van het gemengde zendsignaal voor de zendantenne die een frequentiegemoduleerde continue golf uitzendt.33. Method for transmitting a frequency modulated continuous wave, comprising: - configuring a chirp generator to generate a broadband continuous wave chirp; and - configuring a signal generator for generating a narrowband modulation signal; wherein the configuration steps are performed to: - provide a mixed transmission signal based on mixing the broadband continuous wave chirp and the narrowband modulation signal; and - providing an antenna signal to a transmitting antenna based on the mixed transmitting signal for the transmitting antenna that transmits a frequency modulated continuous wave. 34. Werkwijze volgens de voorgaande conclusie, waarbij het genereren van een smalbandig modulatiesignaal het smalbandige modulatiesignaal genereert op basis van het coderen van een identificatie, bij voorkeur een unieke identificatie, voor het identificeren van de frequentiegemoduleerde continue golf.A method according to the preceding claim, wherein generating a narrow-band modulation signal generates the narrow-band modulation signal on the basis of encoding an identification, preferably a unique identification, for identifying the frequency-modulated continuous wave. 35. Werkwijze volgens een van de voorgaande conclusies 33-34, omvattende: - het genereren van een fractioneel Fourier-modulatiesignaal op basis van het fractioneel Fourier-transformeren van het smalbandige modulatiesignaal; en - het verschaffen van een correlatiesignaal op basis van het verwerken van het fractionele Fourier-modulatiesignaal voor toepassing in een frequentiegemoduleerde continue golfontvanger.35. Method according to any of the preceding claims 33-34, comprising: - generating a fractional Fourier modulation signal based on the fractional Fourier transform of the narrowband modulation signal; and - providing a correlation signal based on processing the fractional Fourier modulation signal for use in a frequency modulated continuous wave receiver. 36. Werkwijze volgens de voorgaande conclusie, omvattende het opslaan van het correlatiesignaal of een bestanddeel van het correlatiesignaal dat vooraf is berekend.A method according to the preceding claim, comprising storing the correlation signal or a component of the correlation signal that has been calculated in advance. 37. Werkwijze voor een frequentiegemoduleerde continue golfzendontvanger, omvattende: - een of meer gevallen van de ontvangstwerkwijze volgens een van de conclusies 27-32; en - een of meer gevallen van de verzendwerkwijze volgens een van de conclusies 33-36.A method for a frequency-modulated continuous wave transceiver, comprising: - one or more cases of the reception method according to any one of claims 27-32; and - one or more cases of the shipping method according to any of claims 33-36. 38. Werkwijze volgens de voorgaande conclusie, waarbij de één of meer instanties van de verzendwerkwijze voor het verzenden van een frequentiegemoduleerde continue golf ten minste twee instanties van de verzendwerkwijze zijn; waarbij de ten minste twee instanties van de verzendwerkwijze afhankelijk zijn van conclusie 34; waarbij de respectieve identificaties van de ten minste twee instanties van de verzendwerkwijze verschillend zijn; en waarbij de een of meer instanties van de ontvangstwerkwijze zijn ingericht voor het ontvangen van de ten minste twee instanties van de verzendwerkwijzen.The method of the preceding claim, wherein the one or more instances of the transmission method for transmitting a frequency modulated continuous wave are at least two instances of the transmission method; wherein the at least two instances of the transmission method depend on claim 34; wherein the respective identifiers of the at least two instances of the shipping method are different; and wherein the one or more instances of the receiving method are arranged to receive the at least two instances of the sending methods. 39. Werkwijze volgens de voorgaande conclusie, waarbij de één of meer gevallen van ontvangstwerkwijze ten minste twee gevallen van ontvangstwerkwijzen zijn; en waarbij de ten minste twee ontvangstwerkwijzen afhankelijk zijn van conclusieA method according to the preceding claim, wherein the one or more receiving method cases are at least two receiving method cases; and wherein the at least two reception methods are dependent on conclusion 32.32. 40. Computerprogrammaproduct (1000) dat instructies omvat die, wanneer het programma wordt uitgevoerd door een geschikte processor, ervoor zorgen dat de processor een van de werkwijzen van conclusie 27-39 uitvoert.A computer program product (1000) comprising instructions that, when the program is executed by an appropriate processor, causes the processor to perform any of the methods of claims 27-39.
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