WO2014126289A1

WO2014126289A1 - Vehicle radar and method for operating same

Info

Publication number: WO2014126289A1
Application number: PCT/KR2013/001986
Authority: WO
Inventors: 김충환; 박찬용
Original assignee: 우리로광통신 주식회사
Priority date: 2013-02-15
Filing date: 2013-03-12
Publication date: 2014-08-21
Also published as: KR101463142B1; KR20140102986A

Abstract

A vehicle radar includes: a download link control data reception unit for receiving download link control data from a mobile communications system so as to obtain a first synchronization with a first period and a second synchronization with a second period, the second period being included in the first period and formed by uniformly and minutely dividing the first period; a signal control unit for minutely dividing the second period into time slots of a fundamental unit on the basis of the first and the second synchronization to select at least one of the time slots of the fundamental unit as an exclusive time slot of an individual radar itself for outputting a transmission pulse; a transmission unit for repeatedly transmitting the transmission pulse in the exclusive time slot according to the control of the signal control unit; and a reception unit for receiving the reflected pulse coming back from a reflection body reflecting the transmission pulse.

Description

Vehicle Radar and Its Operation Method

The present invention relates to a vehicle radar and a method of operating the same, and more particularly, to a vehicle radar using a narrow band pulse and a method of operating the same.

Heavy equipment is much larger than ordinary vehicles and has a relatively wide range of blind spots. In the case of heavy equipment, accidents such as life accidents, vehicle collisions, and building collisions occur most frequently due to blind spots and neglect of observation.

According to the 2007 National Institute of Occupational Safety & Health (NIOSH) investigating the types of accidents for construction dump trucks, 68% of all construction dump truck accidents were reverse accidents. [1]

In Korea, the number of industrial accidents reported by the Korea Occupational Safety and Health Agency showed that the number of deaths in construction industry in 2006 was 609, accounting for 24.4% of all industries, an increase of about 23% from the previous year. In addition, the number of deaths from facilities and machinery, including heavy construction equipment, was 78, accounting for 16.6% of the deaths in the construction industry. Excavators, cranes, and forklifts with many accidents among construction heavy equipment were surveyed from 2004 to 2006. The most common accidents among excavators were 34 excavators, 33 cranes, and 4 forklifts. The most common type of excavator accidents was stenosis and coiling (41.5%), followed by falling and flying 23.4%, and collision and contact with 13.8%.

In order to minimize the damage to human life and property caused by heavy equipment, the need for a rear detection sensor that can be used for heavy equipment has emerged.

Among the rear sensing sensors, ultrasonic sensors are most widely used in general passenger cars. However, since the ultrasonic sensor has a very large signal attenuation due to mud and dust, the malfunction rate of the ultrasonic sensor is too high to be used as a sensor for heavy equipment used in a poor environment where mud and dust exist.

In addition, some heavy equipment is equipped with a rear detection camera for the purpose of preventing an accident, the use of the rear detection camera can be detected only by the driver's attention entirely, there is a problem that the accident rate varies depending on the condition of the driver.

Therefore, it is necessary to develop a sensor that can guarantee its performance even in a harsh environment such as a construction site, and automatically detect an accident risk and notify a driver immediately.

The technical problem to be solved by the present invention is to provide a vehicle radar and its operation method is guaranteed in the harsh environment.

The vehicle radar according to an embodiment of the present invention receives a downlink control data of a mobile communication system and performs a first period having a first period and a second period in which the first period is uniformly subdivided in the first period. A downlink control data receiver for acquiring a second synchronization having a second synchronization, and subdividing the second period into a time slot of a basic unit based on the first synchronization and the second synchronization and at least one of the time slots of the basic unit A signal controller which selects an exclusive radar own exclusive time slot for output of the transmit pulse, a transmitter which repeatedly outputs the transmit pulse in the exclusive time slot under the control of the signal controller, and the transmit pulse is a reflector It includes a receiver for receiving the reflected pulse reflected back to the.

The mobile communication system is a 3GPP WCDMA mobile communication system, and the downlink control data is transmitted through a broadcast channel (BCH), system information transmitted through a synchronization channel (SCH), a synchronization signal transmitted through a SCH (Common Pilot Channel), and a common pilot channel (CPICH). And a pilot signal to be transmitted, and the downlink control data receiver may acquire the first sync and the second sync using the system information, the sync signal, and the pilot signal.

The signal controller may set the size of the time slot of the basic unit to the size of the second period corresponding to the second period.

The signal controller may set the size of the time slot of the basic unit by subdividing the second period by using an internal clock signal of the radar.

The signal controller may detect at least one unused time slot among a plurality of time slots by receiving a transmission pulse output from an adjacent vehicle radar through the receiver.

The signal controller may select the exclusive time slot from the at least one unused time slot.

The signal controller may deactivate a radar function when a predetermined radius is approached near a radio astronomy site (RAS) from a position signal of a global positioning system (GPS).

The apparatus may further include a signal synthesizer configured to generate a local oscillator (LO) signal and supply it to the transmitter, and convert the LO signal into a quadrature signal.

The transmitter may include a pulse time generator for generating a baseband pulse signal, a low pass filter for removing noise from the baseband pulse signal, and an RF (radio) signal for the baseband pulse signal using the LO signal. It may include a DSB mixer (DoubleSideband mixer) up-converting to a frequency signal.

The transmitter may further include a transmission frequency band pass filter that removes noise from the RF signal.

The transmitter may further include a power amplifier amplifying the RF signal and outputting the RF signal as the transmission pulse through a transmission antenna.

The transmitter further includes an instantaneous peak power meter for measuring an instantaneous peak power of the transmission pulse and delivering a measurement value to the pulse time generator, wherein the pulse time generator is configured to determine the baseband pulse signal based on the measurement value. The maximum amplitude can be adjusted.

The receiving unit may be driven by a low noise amplifier for preventing a drop in signal-to-noise ratio caused by noise of the reflected pulse, a reception frequency band pass filter for removing noise from the reflected pulse amplified by the low noise amplifier, and the quad signal to receive the received signal. It may include a receiving quad mixer for down-converting the reflected pulse passed through the frequency band pass filter to a baseband quad base signal.

The receiver may further include a baseband filter that removes out-of-band noise from the baseband quad base signal.

The receiver may further include a programmable or variable gain amplifier (P / VGA) for converting the baseband quad base signal into an analog received signal having a reference voltage.

The receiver may further include an analog memory configured to sample, hold and temporarily store the baseband quad base signal corresponding to a time programmed by the pulse time generator.

The pulse time generator may output a triangular waveform having a minimum FWHM satisfying a specification of a short range radar (SRR) in a 24 GHz narrow band.

The pulse time generator may output a triangular waveform having a minimum FWHM that satisfies a short range radar (SRR) specification in a 77 GHz narrow band.

According to another aspect of the present invention, there is provided a method of operating a vehicle radar, obtaining time synchronization having a period by receiving control data of a mobile communication system, and setting the period of the time synchronization to a plurality of equally divided time slots. Outputting a transmission pulse through at least one of the plurality of time slots, receiving a reflection pulse in which the transmission pulse is reflected by a reflector, and processing the reflection pulse to calculate a distance to the reflector It includes a step.

The proposed vehicle radar is guaranteed in the harsh environment such as construction site.

Even if a plurality of vehicle radars are operated nearby, the detection performance of the vehicle radar can be improved by minimizing interference between the plurality of vehicle radars.

1 illustrates a vehicle radar system using a mobile communication system according to an embodiment of the present invention.

2 illustrates a time synchronization acquisition method and a method of outputting a transmission pulse in a time division multiplexing method according to an embodiment of the present invention.

3 shows a configuration of a vehicle radar according to an embodiment of the present invention.

4 is a graph showing an example of a baseband pulse signal, which is a waveform of a sine half wave.

5 is a graph illustrating an example of a transmission signal in which the baseband pulse signal of FIG. 4 is frequency up-converted into a radio frequency (RF) by a transmitter of the present invention.

FIG. 6 is a graph illustrating an example of an output waveform of an I port outputted from a P / VGA after a transmission signal of FIG. 5 is restored to a baseband signal at a receiver of the present invention.

FIG. 7 is a graph illustrating an example of an output waveform of a Q port output from P / VGA under the same condition as in FIG. 6.

8 is a graph illustrating an example of a (I ² + Q ² ) waveform in the P / VGA of FIGS. 6 and 7.

FIG. 9 is a graph illustrating a result of calculating a transmission power ratio within an occupied bandwidth for transmission power according to FWHM for a sine half wave, a triangle waveform, and a Gaussian waveform.

10 is a flowchart illustrating a method of operating a vehicle radar according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In addition, in various embodiments, components having the same configuration will be representatively described in the first embodiment using the same reference numerals, and in other embodiments, only the configuration different from the first embodiment will be described. .

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and like reference numerals designate like elements throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

Referring to FIG. 1, a mobile communication system includes a code division multiple access (CDMA) system, a wideband code division multiple access (WCDMA) system, a time division multiple access (TDMA) system, a frequency division multiple access (FDMA) system, and an IMT2000 (International). Mobile Telecommunication in the year 2000 system, Global System for Mobile communication (GSM) system, Long Term Evolution (LTE) system, and the like.

Here, it is assumed that the example mobile communication system is a WCDMA system of 3GPP (3rd Generation Generation Partnership Project), which is one of the most widely serviced methods, but the proposed vehicle radar system is not limited thereto. Since time synchronization is an essential element for demodulating digital data, various mobile communication systems can be used.

Acquiring a synchronization signal using a mobile communication system is not the only method. Although a specific operation example is omitted, for example, when using a European 24 GHz narrowband (NB) vehicle radar, the occupied band is used from 24.05 GHz to 24.25 GHz, but in the European advanced countries France, Germany, Russia, etc. The RAS (Radio Astronomy Site) has been operated for a long time to communicate with alien life. They use the 23.6-24 GHz band, where the RAS's extra-large antenna faces the sky but must receive extremely weak signals. Therefore, in the area of several kilometers to more than 10 kilometers, depending on the scale of the center of RAS, the unwanted emission of wireless devices using adjacent bands is more strictly defined than the general standard, the maximum amount of interference power causing interference to the RAS band. [3] Wireless devices that do not satisfy this cannot be used within the RAS radius. In this case, a GPS (Global Positioning System) is required, and a GPS-equipped radar can obtain a synchronization time from the GPS.

The mobile communication system includes a base station 10 and a terminal 20. The base station 10 generally refers to a fixed station communicating with the terminal 20, and may be referred to by other terms such as an evolvedNodeB (eNB), a base transceiver system (BTS), and an access point. The terminal 20 may be fixed or mobile, and may be called by other terms such as a user equipment (UE), a mobile station (MS), a user terminal (UT), a subscriber station (SS), a wireless device, and the like. .

There may be one or more cells in the base station 10. The base station 10 transmits and receives control data and user data with one or more terminals 20 located in its cell. Control data transmitted from the base station 10 to the terminal 20 may be transmitted through a broadcast channel (BCH), a synchronous channel (SCH), a common pilot channel (CPICH), and the like.

The BCH is a downlink control channel for the base station 10 to broadcast system information of the mobile communication system. Downlink means transmission from the base station 10 to the terminal 20.

The SCH is a downlink control channel for transmitting a synchronization signal from the base station 10 to the terminal 20. The synchronization signal transmitted through the SCH includes information about the base station 10, pilot transmission power, pilot phase offset, and the like.

The CPICH is a downlink channel for transmitting a pilot signal, which is an unmodulated direct sequence spread spectrum signal, in the base station 10. The CPICH allows the terminal 20 to capture the timing of the downlink channel and provides a reference phase for coherent modulation.

The vehicle radar system includes a vehicle radar (100 in FIG. 3) attached to the base station 10 and the vehicle 30 of the mobile communication system. The vehicle 30 may refer to heavy equipment that runs on a construction site. A plurality of heavy equipment 30 may be operated at the construction site, and the vehicle radar 100 attached to each heavy equipment 30 receives time control by receiving control data transmitted from the base station 10. That is, the vehicle radar 100 may receive system information, a synchronization signal, a pilot signal, and the like through the BCH, SCH, and CPICH, and may use this to obtain output synchronization of a transmission pulse. The plurality of vehicle radars 100 output transmission pulses in a time division multiplex based on the obtained time synchronization so that interference does not occur between each other.

Hereinafter, a method in which the plurality of vehicle radars 100 acquires time synchronization and outputs transmission pulses in a time division multiplexing system will be described with reference to FIG. 2.

Referring to FIG. 2, a super frame of the mobile communication system includes a plurality of frames. Herein, it is assumed that the super frame has a size of 80 ms, and 8 frames (# 0 to # 7) of the 10 ms size are included in the super frame.

According to the type of mobile communication system, the frame may have various hierarchical structures and sizes, and the proposed vehicle radar 100 may receive and use various transmission signals according to the frame hierarchical structure and size of the mobile communication system. will be.

Super frames are assigned a super frame header at the forefront of time. The super frame header may include a broadcast channel (BCH). System information and information on a plurality of frames are transmitted through the BCH. Since the control data through the BCH is broadcasted at intervals of 80 ms corresponding to the size of the super frame, the control data through the BCH may be received to obtain synchronization in units of 80 ms.

Each of the plurality of frames is assigned a frame header at the forefront in time. The frame header may include a SCH (Synchronous Channel). The SCH transmits a synchronization signal including information about the base station, pilot transmission power, pilot phase offset, and the like. A common pilot channel (CPICH) for transmitting a pilot signal may be included in a frame header or a frame. The pilot signal on the CPICH can be correctly received using the synchronization signal on the SCH. Since the synchronization signal through the SCH and the pilot signal through the CPICH are transmitted at 10 ms intervals corresponding to the size of the frame, the synchronization signal through the SCH and the pilot signal through the CPICH may be received to obtain synchronization in units of 10 ms.

As such, the vehicle radar 100 receives the downlink control data of the mobile communication system to perform a first synchronization having a first period (80 ms) and a second synchronization having a second period (10 ms) included in the first period. Can be obtained.

The vehicle radar 100 may divide the first period into a plurality of time slots based on the first synchronization and the second synchronization. For example, the vehicle radar 100 may set eight second periods included in the first period to eight time slots for outputting a transmission pulse. The specific vehicle radar 100 selects at least one of eight time slots as a time slot for outputting a transmission pulse. The vehicle radar 100 outputs a transmission pulse through the selected time slot. At this time, the vehicle radar selects a time slot in which no other vehicle radar outputs the transmission pulse from the eight time slots and outputs the transmission pulse.

For example, when the first vehicle radar outputs a transmission pulse during a 0 time slot corresponding to frame # 0, the second vehicle radar outputs a transmission pulse during a first time slot corresponding to frame # 1. The second vehicle radar repeatedly outputs a transmission pulse through the first time slot at intervals of a first period (80 ms). Accordingly, the second vehicle radar can prevent the interference with the transmission pulse of the first vehicle radar.

That is, a plurality of vehicle radars may be operated in a time division multiple manner in which different time slots are allocated to the plurality of vehicle radars during the first period, and the plurality of vehicle radars output transmission pulses through time slots allocated only to the plurality of vehicle radars. .

Hereinafter, the specific structure of the vehicle radar which can output a transmission pulse by time division multiplexing system is demonstrated.

Referring to FIG. 3, the vehicle radar 100 includes a downlink control data receiver 110, a signal controller 120, a transmitter 130, a receiver 140, and a signal synthesizer 150.

The downlink control data receiver 110 receives downlink control data of the mobile communication system to obtain synchronization. The downlink control data receiver 110 may be configured in the same manner as the receiver of the terminal 10 of the WCDMA system.

The downlink control data receiver 110 includes an RF unit 111, a demapper 112, and a baseband demodulator 113.

The RF unit 111 receives and transmits a radio signal transmitted from the base station 10 to the demapper 112.

The demapper 112 forms a symbol represented by a position on a signal constellation as encoded data according to a modulation scheme. The modulation scheme is not limited, and may be mPhase Shift Keying (mPSK) or mQuadrature Amplitude Modulation (mQAM). For example, mPSK may be BPSK, QPSK or 8PSK. mQAM may be 16QAM, 64QAM or 256QAM. The baseband demodulator 113 restores the encoded data to the original data.

The baseband demodulator 113 may detect the control data through the BCH in the reconstructed data to obtain synchronization in units of 80 ms. The baseband demodulator 113 may acquire synchronization in units of 10ms by detecting a synchronization signal through the SCH and a pilot signal through the CPICH from the reconstructed data. The baseband demodulator 113 transmits the synchronization information in units of 80 ms and 10 ms to the controller 121.

The signal controller 120 controls the overall functions of the vehicle radar 100. The signal controller 120 controls the output of the transmission pulse of the transmitter 130 and the overall time and time, and calculates the distance from the reflector using the reflection pulse received by the receiver 140.

The signal controller 120 includes a controller 121, an external interface 122, and an analog to digital converter (ADC) 123.

The controller 121 sets a plurality of time slots for outputting a transmission pulse based on synchronization of an 80 ms period and a 10 ms period. The controller 121 may set the time slot to a size of 10 ms in response to a 10 ms period. Alternatively, the controller 121 may set the time slot to be smaller than the size of 10 ms by subdividing the 10 ms period.

The controller 121 selects at least one of a plurality of time slots as a time slot for outputting a transmission pulse. At this time, the control unit 121 receives at least one unused time slot among a plurality of time slots by receiving a transmission pulse output from an adjacent vehicle radar through the receiver 140, and time slot for outputting a transmission pulse among the unused time slots. Can be selected. The controller 121 controls the transmitter 130 to output a transmission pulse through the selected time slot.

The controller 121 may communicate with an external terminal or a display through the external interface 122. The external interface 122 provides a communication interface between the external terminal or the display and the controller 121.

The ADC 123 converts the analog received signal stored in the analog memory 145 into a digital signal and transmits the digital signal to the controller 121.

The transmitter 130 outputs a transmission pulse under the control of the controller 121.

The transmitter 130 includes a pulse time generator 131, a low pass filter 132, a double sideband mixer 133, a transmitter radiofrequency bandpass filter 134, a power amplifier 135, and Instantaneous peak power detector 136.

The pulse time generator 131 generates a baseband pulse signal under the control of the controller 121. The baseband pulse signal may be generated as a sine half wave, a triangular waveform, and a Gaussian waveform. The pulse time generator 131 is a triangular waveform that has the shortest FWHM time while satisfying the regulation compared to the sine half wave or Gaussian pulse in consideration of narrowband occupied bandwidth (FWHM) specification. Can be generated as a baseband pulse signal. Here, FWHM means that the smaller the value, the better the spatial resolution.

For example, the pulse time generator 131 may output a triangular waveform having a minimum FWHM satisfying the specification [5] of short range radar (SRR) in a 24 GHz narrow band. The pulse time generator 131 may output a triangular waveform having a minimum FWHM that satisfies the SRR specification [9] in the 77 GHz narrow band.

The baseband pulse signal is passed to the low pass filter 132, which removes unwanted signals and noise from the baseband pulse signal.

The baseband pulse signal passing through the low pass filter 132 is transmitted to the DSB mixer 133.

The DSB mixer 133 up-converts the baseband pulse signal to a radio frequency (RF) signal using a local oscillator (LO) signal.

The transmit frequency band pass filter 134 removes unwanted signals and noise from the upconverted RF signal.

The power amplifier 135 amplifies the RF signal passing through the transmission frequency band pass filter 134 and outputs it as a transmission pulse through the transmission antenna.

The instantaneous peak power meter 136 measures the instantaneous peak power of the transmit pulse to control the transmit power. The value measured by the instantaneous peak power meter 136 is transmitted to the pulse time generator 131, and based on the measured value, the pulse time generator 131 adjusts the maximum amplitude and the FWHM of the baseband pulse signal according to the narrow band radio regulation. Can be adjusted.

The receiver 140 receives a reflected pulse in which the transmission pulse is reflected by the reflector and returned.

The receiver 140 includes a low noise amplifier (LNA) 141, a reception frequency band pass filter 142, a receiver quadrature mixer 143, a baseband filter 144, and a P / VGA ( programmable or variable gain amplifier 145 and analog memory 146.

The low noise amplifier 141 amplifies the signal by minimizing the reduction of the signal-to-noise ratio caused by the noise of the reflected pulse received through the receiving antenna.

The receive frequency band pass filter 142 removes noise from the amplified reflected pulses.

The receiving quad mixer 143 is driven by a quad LO signal transmitted from the signal synthesizing unit 150 to down convert the reflected pulse into a baseband quad base signal.

Baseband filter 144 removes noise from the baseband quad base signal.

P / VGA 145 converts the baseband quad base signal to an analog quad receive signal with a reference voltage. The P / VGA 145 may amplify a weak baseband quad base signal of less than 1V to adjust the signal to about 1V, or reduce the baseband quad base signal larger than 1V to adjust to a signal of about 1V.

The analog memory 146 samples and holds the analog received signal by the reflected pulse and stores it instantaneously corresponding to the time programmed by the pulse time generator 131.

When the storage of the analog reception signal is completed in the analog memory 146, the analog reception signal is converted into a digital signal through the ADC 123, and the controller 121 sequentially reads the digital signal to store data and distances from the reflector. To calculate.

The signal synthesizer 150 generates a local oscillator (LO) signal and supplies it to the DSB mixer 133 to drive the DSB mixer 133. The signal synthesizer 150 converts the LO signal into a quad signal and supplies the converted quad signal to the reception quad mixer 143 to drive the reception quad mixer 143.

Although the transmission antenna and the reception antenna are illustrated as separate bistatic radars, the vehicle radar 100 may be implemented as a monostatic radar operating as a single antenna for transmitting and receiving. At this time, the monostatic radar is provided with an isolator (isolator), the transmission signal is leaked to the low noise amplifier 141 of the receiver 140, the receiver 140 is saturated, the proximity signal according to the time to recover to the normal state after saturation It can minimize the phenomenon that becomes impossible to detect.

In addition, the vehicle radar 100 may include a GPS device (not shown) that acquires absolute time using GPS in place of the downlink control data receiver 110, and the signal controller 120 may provide an absolute time. The first period and the second period can be set. The signal controller 120 may deactivate the radar function when approaching a predetermined radius near the radio astronomy site (RAS) from the position signal of the GPS.

Now, the transmission and reception waveforms of the vehicle radar 100 described above will be described with reference to FIGS. 4 to 8. 4 is a graph showing an example of a baseband pulse signal, which is a waveform of a sine half wave. 5 is a graph illustrating an example of a transmission signal in which the baseband pulse signal of FIG. 4 is frequency up-converted into a radio frequency (RF) by a transmitter of the present invention. FIG. 6 is a graph illustrating an example of an output waveform of an I port outputted from a P / VGA after a transmission signal of FIG. 5 is restored to a baseband signal at a receiving end of the present invention. FIG. 7 is a graph illustrating an example of an output waveform of a Q port output from P / VGA under the same condition as in FIG. 6. 8 is a graph illustrating an example of a (I ² + Q ² ) waveform in the P / VGA of FIGS. 6 and 7.

Referring to FIG. 4, a sine halfwave is output as a baseband pulse signal. That is, the pulse time generator 131 may output a sine half wave as a baseband pulse signal. It is a unipolar half wave with a frequency of 40 MHz, with a waveform of 12.5 ns duration.

Referring to FIG. 5, as the LO (local oscillator) signal is supplied at 1 GHz from the signal synthesis unit 150, the baseband pulse signal, which is a sine half wave, is modulated by the LO signal by the DSB mixer 133 and output as an RF frequency signal. It is an example. The time from the start to the end of the RF frequency signal is 12.5 ns, indicating that the baseband is the envelope of the entire waveform. According to the repetitive output of the transmission pulse, the RF frequency signal is repeatedly output at a predetermined delay interval. Here, the first RF frequency signal out_delay1 and the second RF frequency signal out_delay2 are illustrated.

6 to 8, when looking at the output waveforms of the I port and the Q port output from the P / VGA 145, it can be seen that the output waveform is not constant according to the delay times delay1 and delay2. The delay time delay1 and delay2 are proportional to the distance from which the transmission pulse is reflected by the reflector and returned. However, looking at the (I ² + Q ² ) waveform, we can see that the waveform, such as the transmit baseband pulse signal, is restored. As the delay time delay1 and delay2 change, the reception time of the reflected pulse is also delayed to the same value as the delay time.

Therefore, the proposed vehicle radar 100 may calculate the distance to the reflector by using the delay information on the time axis of the peak of the baseband pulse signal and the calibration information measured from the reflector having a known distance. The calculation is as follows.

Equation 1

Where R is the distance between the reflector and the radar, c is the speed of light propagation in the air, and τ is the reflected time.

The proposed vehicle radar 100 may be a narrow band pulse radar using a licensed 24 GHz narrow band frequency for the vehicle radar. The most suitable waveforms for narrowband pulse radars should be the sharpest, with the smallest full width half maximum (FWHM). To find the most suitable waveform for narrowband pulse radar, we analyzed the ratio of OccupiedBandwidth Spectral Power according to FWHM for sine half wave, triangle wave and Gaussian wave. The relevant narrowband regulation requires that the integrated power in the 24.05 to 24.25 GHz band, which is occupied by the integrated power in the 24 to 24.3 GHz band, exceed 99%.

FIG. 9 is a graph illustrating a result of calculating occupied bandwidth spectrum according to FWHM for a sine half wave, a triangular waveform, and a Gaussian waveform.

Referring to FIG. 9, when the FWHM value over 99% of the occupied band spectral power ratio according to the FWHM is calculated in 0.5 ns units, the triangular waveform is 6.5 ns, the Gaussian waveform is 7 ns, and the sine half wave is 7.5 ns. That is, it can be seen that the occupied spectrum of the FWHM has the best triangular waveform. The 6W FWHM is 90cm, which is calculated by converting R in Equation 1 to ΔR and τ to FWHM, and then to the spatial resolution equation. The minimum theoretical value of the spatial resolution below is nearly 75cm. It can be seen.

Equation 2

Where BW is the bandwidth and 200MHz on a 24GHz narrowband radar.

In this case, the maximum output power value is 2.3dB for the Gaussian waveform and 1.2 sine halfwave for the triangle waveform. The triangular waveform can have the largest peak value, indicating that it is the best waveform in terms of pulse width and maximum output amplitude.

Hereinafter, a method of operating the vehicle radar 100 without causing interference between the plurality of vehicle radars 100 when the plurality of vehicle radars 100 is operated at the construction site will be described.

Referring to FIG. 10, the vehicle radar 100 receives control data transmitted from the base station 10 of the mobile communication system (S110). The control data includes system information transmitted through a broadcast channel (BCH), a synchronization signal transmitted through a SCH (synchronous channel), a pilot signal transmitted through a common pilot channel (CPICH), and the like.

The vehicle radar 100 obtains time synchronization by receiving control data (S120). The control data over the BCH may be broadcast at intervals of 80 ms, and the vehicle radar 100 may receive the control data over the BCH to obtain synchronization of an 80 ms period. The synchronization signal through the SCH may be transmitted at 10 ms intervals, and the vehicle radar 100 may receive the synchronization signal through the SCH to acquire synchronization with a 10 ms period.

That is, the vehicle radar 100 receives the first control data transmitted through the first downlink control channel of the mobile communication system to obtain a first synchronization of the first period, and the second downlink control channel of the mobile communication system. The second control of the second period may be obtained by receiving the second control data transmitted through the control unit. The second period may be included in the first period.

As the plurality of vehicle radars 100 obtain time synchronization from the same mobile communication system, the plurality of vehicle radars 100 may match output synchronization with each other.

The vehicle radar 100 sets a time slot after acquiring time synchronization (S130). The vehicle radar 100 may set a transmission time interval and a time slot according to a predetermined method based on the obtained time synchronization. For example, in response to the synchronization of the 80 ms period and the synchronization of the 10 ms period, a transmission time interval of 80 ms size including eight time slots of 10 ms size may be set. The transmission time interval refers to the interval at which the vehicle radar 100 outputs a transmission pulse, and the time slot refers to the time at which the transmission pulse is output. That is, the transmission pulse may be output through at least one of the plurality of time slots included in the transmission interval. The size of the time slot does not need to coincide with the second period, and the time slot may be set by further subdividing 10 ms based on the clock signal of the vehicle radar 100.

The vehicle radar 100 scans the set time slot (S140). The vehicle radar 100 detects a time slot used by another vehicle radar by receiving a transmission pulse output by another vehicle radar without outputting a transmission pulse. The period for scanning the time slot may be set to a time enough to detect a time slot being used by another radar over one transmission time interval.

If one time slot is 10ms, the transmission pulses output by the other vehicle radar are transmitted up to a maximum distance of 30 km for 10 ms, thereby detecting a time slot used by another vehicle radar operating within a 30 km radius. That is, the time slot used by another vehicle radar can be detected sufficiently only by receiving the transmission pulse which another vehicle radar outputs.

The vehicle radar 100 scans the time slot to determine whether there is an unused time slot (S150). When all of the plurality of time slots included in the transmission time interval are in use, the vehicle radar 100 performs time slot scanning again.

When at least one unused time slot is detected among a plurality of time slots included in the transmission time interval, the vehicle radar 100 selects a time slot to be used from the unused time slot (S160). For example, when the seventh time slot and the eighth time slot of the eight time slots included in the transmission time interval are not in use, the vehicle radar 100 may own one of the seventh time slot and the eighth time slot. You can choose to use this time slot.

The vehicle radar 100 outputs a transmission pulse through the selected time slot (S170). The vehicle radar 100 repeatedly outputs a transmission pulse for each time slot selected at a transmission time interval. The transmit pulse can have a 200 MHz bandwidth in the range of 24.05 to 24.25 GHz. The output transmission pulse is reflected by the reflector and returned to the vehicle radar 100.

The vehicle radar 100 receives a reflection pulse reflected by the reflector (S180).

The vehicle radar 100 processes the reflected pulse to calculate a distance from the reflector (S190).

Among the rear sensor, the ultrasonic sensor has a large attenuation of the signal due to the mud, dust, etc., so the malfunction rate is very high to be used as a sensor for heavy equipment used in a harsh environment in which mud, dust, etc. exist.

However, even if the radar case is contaminated with mud or dust on the radar case, the vehicle radar 100 hardly deteriorates its performance, so it is suitable as a sensor for heavy equipment used in construction sites.

Radar technology can be divided into CW (continuous wave) method and pulse method. CW radar includes frequency modulated CW (FMCW) radar, and pulsed radar includes ultrawideband (UWB) radar.

The FMCW radar is the most widely used radar with a good signal to noise ratio (SNR) in frequency resources with the same maximum transmit power and bandwidth. FMCW radars are used in various vehicles as long range radars (LRRs) for inter-vehicle auto maintenance and ACC (automatic cruise control) functions in conjunction with actuators in differential vehicles.

The transmit pulse of the FMCW radar is approximately hundreds of us to 10ms at a time, and the maximum time of 10ms is possible because a single transmission and signal processing of the reflected wave are possible with sufficient signal-to-noise ratio (SNR). Even if WCDMA synchronization is used, up to eight heavy-duty radars can be operated at a sufficient update rate of 10 or more times per second without interference at the same time.

For reference, in consideration of the safety of the human body, SNR = 16dB is usually based on a detection probability of more than 99% and a false detection probability requiring high reliability of 10 ^10. [4]

However, in the case of heavy equipment, the vehicle body may have a large and protruding portion, so the vehicle may act as a clutter. The FMCW radar is vulnerable to body clutter, so the body clutter signal is the closest signal and is usually made of metal with high reflectivity, so the signal is the largest, making it the largest signal while measuring the reflected signal. On the other hand, the reflected signal by the human body that requires the highest safety is very small compared to the body clutter signal because the reflectance is very small compared to the metal may cause a problem of inferior measurement sensitivity for human detection. That is, the FMCW radar has a mounting constraint that requires attention to clutter due to the reflection of the vehicle body, or a high performance frequency variable filter having a high quality factor (Q) of the receiver baseband that is not easy to implement in order to solve the hardware. Should be fitted.

Because UWB radar uses broadband, it has the advantage of good distance resolution, making it an essential radar for applications that require very good distance resolution such as pedestrian recognition and auto parking. The UWB radar transmits pulses for a short time as pulse radars, so there is no limitation in mounting due to differential reflection.

However, because UWB radar is broadband, it overlaps with the frequency bands used in other existing fields, so the maximum power constraint on the transmission is large in order to minimize interference with the existing radar.

According to the regulations of the US Federal Communications Commission (FCC) and the European Telecommunications Standards Institute, the UWB radar's instantaneous transmitting peak power is limited to 0 dBm / 50 MHz or less. The transmit power is limited to 41.3dBm / MHz.

On the other hand, the proposed vehicle radar 100 is a 24GHz narrowband radar with a maximum transmit power of 20dBm / 200MHz.

Comparing UWB radar with 24GHz narrowband radar, the output power of 24GHz UWB radar cannot be flat in the occupied frequency band, so the output power is calculated up to 10dBm / 500MHz or less for standard UWB impulse such as Gaussian and monopulse. Converted to In terms of the signal-to-noise ratio, UWB has a low value of about 1/25.

The best known way to increase the SNR of a radar is to coherently integrate multiple transmissions quickly. Repeated coherent Nc times increase the SNR by N times. The 24GHz narrowband radar that satisfies SNR = 16dB is calculated using the coherent integral radar equation (Equation 3) below. The 24GHz narrowband radar obtains Nc = 110. Therefore, for UWB, multiply by 25 to get Nc = 2750.

Equation 3

Where Ga is the antenna gain, P _Rx is the receive power, P _Tx is the transmit power, σ is the radar cross section, R is the reflector distance and N is the noise power. In the calculation, σ is 0.01 ~ 1m ² in the human body, and the geometric mean value 0.1m ² is used and R is 5m. [4]

In the case of 24GHz narrowband radar, the optimized triangular wave's FWHM is 6ns, so if you store the reflected wave's waveform in the receiving baseband analog memory at 1ns interval, the unit of distance is 15cm, which is more than the expected minimum resolution of 90cm. Samples & hold are required. In this case, the hardware can be realized in a small area using a moderately priced semiconductor process such as 0.13um CMOS. In order to configure the low cost to send and receive data once and process the data in the DSP (Digital Signal Processor), it is enough for about 10us. In this case, Nc = 110 times, 1.1ms is enough. It can be set as a shorter time such as 5ms, it can be seen that the number of simultaneous radar can be increased to 16, etc. than eight. Even if the signal processing takes time and exceeds the time allotted to itself, the DSP specification does not need to be very high because there is an additional slot time for other radars to transmit and receive until the next use.

In the case of 24 GHz wideband radar, Nc = 2750, so the same calculation as narrowband radar only takes 27.5ms to measure, so it can be seen that there is a problem in eliminating inter-radar interference by time division. The UWB radar requires a minimum bandwidth of 500 MHz or more, which translates into a 0.5 ns pulse for the FWHM. In this case, a sampling rate of at least 10 Gsps is required to achieve real time sampling to reduce data acquisition time. Currently, 1Gsps ADCs are too expensive to implement with ADCs with a 10Gsps sampling rate. In addition, if the S & H is configured in 0.1ns intervals in the above manner, the area problem is 610, and the price of the semiconductor process to be implemented is not economical. In addition, most of the methods for low cost hardware implementation and longer measurement cycles use noncoherent sensing methods. In this case, there is a loss that the increase rate of SNR becomes smaller for Nc which is the same as coherent integration due to noncoherent integration. In order to satisfy SNR = 16dB by noncoherent integration, it is difficult to reduce the measurement time because Nc should be over 100,000.

The phase code method is one of the methods commonly used to increase the SNR. This is one of the pulse compression methods that transmits a plurality of long pulses using the phase code. Barkercode, polyphase code, Costas code, etc., and peak in only a single pulse in autocorrelation can increase the SNR. The increase in SNR is proportional to the number of consecutive pulses, i.e. the number of codes. However, this method has a problem that the pulse radar itself cannot start receiving until the end of pulse transmission due to the leakage of the transmitted signal.If the number of pulse codes is increased too much, the minimum measurable distance is limited, so the number cannot be increased indefinitely. There is a disadvantage that the increase of the SNR is limited. As a result, UWB radars do not have a reasonable compromise between implementation cost and measurement time for time-sharing.

The multiplexing method is widely used as a method for multiple users simultaneously by minimizing interference in mobile communication. In addition to the above-described time division schemes, there are frequency domain multiple access (FDMA) or code division multiple access (CDMA), and orthogonal frequency domain multiplexer (OFDM) and code domain multiple access (CDMA) are typical. to be.

In the case of ITS (intelligent transportation system), not only radar for collision avoidance but also vehicle-to-vehicle communication are simultaneously required. Therefore, a multiplexing method capable of radar communication in the same manner has been studied. [7,8] When using radar, the spatial resolution is proportional to the inverse of the band used. Therefore, as shown in Equation 2, the widest bandwidth is used. Therefore, when the radar method is used, the time synchronization is very small, so it is very difficult to implement. For example, if 24 GHz narrow band is used as OFDM and CDMA radar, it is impossible to implement hardware because it needs to output, receive and process 200 MHz, which is a full band at the same time.

The proposed vehicle radar 100 is a narrow band pulse radar that uses a licensed 24 GHz narrowband frequency for vehicle radar. Since the number of pulse repetitions is lower than that of the UWB radar, the transmission and reception time of the pulse is short. . Therefore, a larger number of vehicle radars 100 may be operated in a space where interference may occur. In addition, since the vehicle radar 100 outputs a transmission pulse in a time division multiplexing manner, interference between the plurality of vehicle radars 100 may be avoided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The detailed description of the invention described with reference to the drawings referred to heretofore is merely exemplary of the invention, which has been used only for the purpose of illustrating the invention and is used to limit the scope of the invention as defined in the meaning or claims. It is not. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims

Downlink control data for receiving a downlink control data of the mobile communication system to obtain a first synchronization having a first period and a second synchronization included in the first period and a second period in which the first period is evenly divided. Receiving unit;

The second period is subdivided into time slots of a basic unit based on the first sync and the second sync, and at least one of time slots of the basic unit is an exclusive time of an individual radar itself for output of a transmission pulse. A signal controller to select a slot;

A transmitter for repeatedly outputting the transmission pulse in the exclusive time slot under the control of the signal controller; And

And a receiver configured to receive a reflected pulse in which the transmission pulse is reflected by a reflector and returned.
The method of claim 1,

The mobile communication system is a 3GPP WCDMA mobile communication system, and the downlink control data is transmitted through a broadcast channel (BCH), system information transmitted through a synchronization channel (SCH), a synchronization signal transmitted through a SCH (Common Pilot Channel), and a common pilot channel (CPICH). Includes a pilot signal transmitted,

The downlink control data receiving unit obtains the first synchronization and the second synchronization using the system information, the synchronization signal, and the pilot signal.
The method of claim 1,

The signal controller sets the size of the time slot of the basic unit to the size of the second period corresponding to the second period.
The method of claim 1,

The signal control unit uses the internal clock signal of the radar to subdivide the second period to set the size of the time slot of the basic unit.
The method of claim 1,

And the signal controller detects at least one unused time slot among a plurality of time slots by receiving a transmission pulse output from an adjacent vehicle radar through the receiver.
The method of claim 5,

And the signal controller selects the exclusive time slot from among the at least one unused time slot.
The method of claim 1,

The signal controller is a vehicle radar to deactivate the radar function when approaching a predetermined radius near the radio astronomy site (RAS) from the position signal of the Global Positioning System (GPS).
The method of claim 1,

And a signal synthesizer configured to generate a local oscillator (LO) signal and supply it to the transmitter, and convert the LO signal into a quadrature signal and supply the signal to the receiver.
The method of claim 8,

The transmitting unit,

A pulse time generator for generating a baseband pulse signal;

A low pass filter for removing noise from the baseband pulse signal; And

And a double sideband mixer (DSB mixer) for upconverting the baseband pulse signal to a radio frequency (RF) signal using the LO signal.
The method of claim 9,

The transmitting unit,

And a transmit frequency band pass filter for removing noise from the RF signal.
The method of claim 10,

The transmitting unit,

And a power amplifier for amplifying the RF signal and outputting the RF signal as the transmission pulse through a transmission antenna.
The method of claim 11, wherein

The transmitting unit,

The instantaneous peak power meter for measuring the instantaneous peak power of the transmit pulse to deliver a measurement value to the pulse time generator,

And the pulse time generator adjusts a maximum amplitude of the baseband pulse signal based on the measured value.
The method of claim 12,

The receiving unit,

A low noise amplifier which prevents the signal-to-noise ratio from being lowered due to the noise of the reflected pulses;

A reception frequency band pass filter for removing noise from the reflected pulses amplified by the low noise amplifier; And

And a receiving quad mixer driven by the quad signal to downconvert the reflected pulse passing through the receiving frequency band pass filter into a baseband quad base signal.
The method of claim 13,

The receiving unit,

And a baseband filter for removing out-of-band noise from the baseband quad base signal.
The method of claim 14,

The receiving unit,

And a programmable or variable gain amplifier (P / VGA) for converting the baseband quad base signal into an analog receive signal having a reference voltage.
The method of claim 15,

The receiving unit,

And an analog memory for sampling, holding and temporarily storing the baseband quad base signal corresponding to the time programmed by the pulse time generator.
The method according to any one of claims 9 to 16,

The pulse time generator is a vehicle radar for outputting a triangular waveform having a minimum FWHM that satisfies the specification of short range radar (SRR) in a 24GHz narrowband.
The method of claim 17,

The pulse time generator is a vehicle radar for outputting a triangular waveform having a minimum FWHM that satisfies the specification of short range radar (SRR) in the 77 GHz narrow band.
Receiving control data of a mobile communication system to obtain time synchronization having a period;

Setting the period of time synchronization to a plurality of equally divided time slots;

Outputting a transmission pulse through at least one of the plurality of time slots;

Receiving a reflection pulse in which the transmission pulse is reflected by a reflector and returned; And

Calculating a distance from the reflector by processing the reflected pulse.