CN214473923U - 24GHz millimeter wave radar device - Google Patents
24GHz millimeter wave radar device Download PDFInfo
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- CN214473923U CN214473923U CN202120258398.4U CN202120258398U CN214473923U CN 214473923 U CN214473923 U CN 214473923U CN 202120258398 U CN202120258398 U CN 202120258398U CN 214473923 U CN214473923 U CN 214473923U
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Abstract
The utility model discloses a 24GHz millimeter wave radar installations, the front end module sends echo signal to the singlechip, send amplifier group after passing through the wave filter simultaneously, select through analog switch group to be used for single-frequency continuous wave or frequency modulation continuous wave mode, amplifier group sends the singlechip to echo signal amplification back, the singlechip judges echo signal received from the front end module, select echo signal and voltage-controlled gain amplifier transmitting power that will receive, carry out the self-adaptation of level four intermediate frequency automatic gain and long distance short distance range finding; the single chip microcomputer sends a control signal to the analog switch group, and the analog switch group is controlled to select a working mode to switch the working mode under a single-frequency continuous wave or a frequency-modulated continuous wave. The utility model discloses simple structure, processing convenience, circuit design benefit reduce the electromagnetic wave lobe angle of front end module transmission, guarantee millimeter wave radar module's precision, it is big to have avoided ultrasonic radar angle of incidence, the relatively poor problem of directionality.
Description
Technical Field
The utility model belongs to microwave radar device field relates to a 24GHz millimeter wave radar device.
Background
In recent years, the informatization and intellectualization of the expressway have become the focus of traffic construction, and attract the attention of a plurality of enterprises. The radar is an important technology for human perception and detection at present and is also an important means for monitoring high-speed vehicles in China. The radar detects a target by using an electromagnetic wave through radio detection and ranging, emits the electromagnetic wave to irradiate the target and receives an echo of the electromagnetic wave, so that information related to the distance from the electromagnetic wave to the target and the like can be obtained. The radar technology not only has normal human visual recognition, but also has the capability of medium-distance and long-distance environmental perception. At present, the radar technology mainly comprises millimeter wave radar, laser radar, ultrasonic radar and the like.
The frequency range of the millimeter wave radar is 30GHz-300GHz, the wavelength is from 1cm to 1mm, the detection distance of the millimeter wave radar is long and can reach more than 200 meters, and the millimeter wave radar can be used for detecting whether a target exists or not, measuring distance, measuring speed and measuring direction. It has good angle resolution capability and can detect smaller objects. Meanwhile, the millimeter wave radar has extremely high penetration rate, can penetrate through illumination, rainfall, dust raising, fog or frost to accurately detect objects, can work in a completely black environment and can work all the day.
The millimeter wave radar mainly comprises a radar radio frequency front end, a signal processing system and a rear end algorithm. In the existing product, the patent licensing cost of the radar back-end algorithm accounts for about 50% of the cost, the radio frequency front-end accounts for about 40% of the cost, and the signal processing system accounts for about 10% of the cost.
The radio frequency front end obtains an intermediate frequency signal by transmitting and receiving millimeter waves, and extracts information such as distance, speed and the like from the intermediate frequency signal. Thus, the radio frequency front end directly determines the performance of the radar system. The signal processing system is also an important component of the radar, and extracts the intermediate frequency signal acquired from the radio frequency front end by embedding different signal processing algorithms to obtain specific type target information. The rear-end algorithm accounts for the highest proportion of the cost of the whole millimeter wave radar. For millimeter wave radar, domestic researchers propose a large number of algorithms from multiple angles of frequency domain, time domain and time frequency analysis, and the accuracy of an off-line experiment is high. However, the domestic radar products mainly adopt the frequency domain-based fast fourier transform and the improved algorithm thereof for analysis, the measurement precision and the application range have certain limitations, and foreign algorithms are strictly protected by patents and are very expensive.
Millimeter wave radar compares with laser radar: in essence, the laser radar and the millimeter wave radar both utilize echo imaging to construct and display a detected object, the laser radar is easily influenced by natural light or heat radiation, the laser radar is greatly weakened when the natural light is intense or in a radiation area, and the laser radar can obviously not well cope with a severe environment; and the laser radar has high manufacturing cost and higher requirements on the process level, and relatively speaking, the manufacturing cost of the millimeter wave radar is more suitable.
Compared with an ultrasonic radar: the ultrasonic radar has different transmission speeds under different weather conditions such as snow, rain and the like, and has a slow transmission speed, so that when a vehicle runs at a high speed, the ultrasonic radar can not follow the real-time change of a moving vehicle, and a large error is generated on a measurement result; the ultrasonic radar has large scattering angle and poor directivity, and when a long-distance target is measured, an echo signal is weak, so that the measurement precision is influenced; when a plurality of ultrasonic radars exist in the same area, there may be a problem of mutual interference between the radars.
The millimeter wave radar has moderate manufacturing cost, can effectively overcome the problem of severe environment, and does not have the problems of mutual interference and the like between radars.
SUMMERY OF THE UTILITY MODEL
In order to solve the above problems, the present invention aims to provide a radar module for 24GHz millimeter waves, which solves the problem of the prior art that the size of the radar module is large; the precision is not enough, and the measurement result is not accurate enough; the resolution is not high enough, and for small distances, the small changes of 1cm and 2cm cannot be accurately measured; the installation environment is not complete enough and the like.
The technical scheme of the utility model is that: a24 GHz millimeter wave radar device comprises an upper cover, a lower cover, self-tapping screws, a sealing ring, a rubber ring and a circuit board, wherein the upper cover and the lower cover are assembled through the self-tapping screws, the sealing ring is arranged in a groove of the lower cover, and the circuit board is clamped and fixed by the upper cover and the lower cover; the upper surface of the lower cover is provided with four positioning guide columns, the positioning guide columns are used for positioning the circuit board and the lower cover, and the rubber pads are arranged on the positioning guide columns;
the circuit board comprises a front-end module and a rear-end module, the front-end module comprises a front-end device, and the rear-end module comprises a single chip microcomputer, an amplifier group, a filter, a voltage follower, an analog switch group, a comparator, a complex programmable logic chip, an optical coupler, a power supply module, a reference voltage, a crystal oscillator and a memory; the front-end module sends echo signals to the single-chip microcomputer, meanwhile, the echo signals are filtered by the filter and then sent to the amplifier group, the analog switch group selects a mode for single-frequency continuous waves or frequency-modulated continuous waves, the amplifier group sends the amplified echo signals to the single-chip microcomputer, the single-chip microcomputer judges the echo signals received by the front-end module, the echo signals to be received and the voltage-controlled gain amplifier transmitting power are selected, and self-adaptation of four-level intermediate-frequency automatic gain and long-distance short-distance ranging is carried out; the singlechip sends a control signal to the analog switch group, and the analog switch group is controlled to select a working mode to switch the working mode under a single-frequency continuous wave or a frequency-modulated continuous wave;
the single chip microcomputer sends modulation voltage to the front-end module, the front-end module sends a frequency signal to the comparator after working, the frequency signal is collected by the complex programmable logic chip and then sent to the single chip microcomputer, and the single chip microcomputer compares the obtained frequency signal with the frequency which can be generated by the modulation voltage and carries out linear modulation frequency calibration;
the singlechip is connected with an external interface through an optical coupler; the crystal oscillator provides output frequencies of 30MHz and 150MHz to the single chip microcomputer and the complex programmable logic chip;
an external power supply is input into the power supply module, and the power supply module outputs voltage to supply power to the front-end module and the singlechip;
the reference voltage generates 3.0V voltage to the voltage follower, the voltage follower stably outputs the 3.0V reference voltage according to the reference voltage and external voltage, and the reference voltage is sent to the amplifier group, the single chip microcomputer and the front end module.
Preferably, the device also comprises a 485 interface output circuit which is connected with the singlechip.
Preferably, the memory is an SPI-FLASH.
Preferably, the front end module and the rear end module are welded by means of a ball grid array structure.
Preferably, the surface of the upper shell is provided with a hemispherical emission surface or a semi-cylindrical emission surface or a planar emission surface.
Preferably, the single chip microcomputer is STM32 series.
Preferably, the analog switch group comprises a first analog switch, a second analog switch and a third analog switch, which all comprise a GS4157 chip; the amplifier group comprises a secondary amplifier, a tertiary amplifier and a quaternary amplifier, which all comprise GS8051 chips;
the front-end module is used for simultaneously transmitting the echo signals to a PA7 pin of the singlechip and a secondary amplifier after primary amplification is carried out on the echo signals; the first-stage amplification echo signal sent to the second-stage amplifier is firstly sent to a pin A of the first analog switch, a pin PE11 of the single chip microcomputer controls the echo signal to be output from an output port B1 or a port B0 of the first analog switch, the output echo signal enters the input end of the filter, the output end of the filter sends the echo signal to a-IN pin of the second-stage amplifier after being filtered by the filter, the echo signal is amplified and then output from an OUT pin of the second-stage amplifier, and is simultaneously sent to the single chip microcomputer and the third-stage amplifier, and the second-stage amplification echo signal sent to the single chip microcomputer is filtered by the filter capacitor and then sent to a pin PC4 of the single chip microcomputer;
the second-stage amplification echo signal sent to the third-stage amplifier is firstly sent to a pin A of a second analog switch, a pin PE12 of the single chip microcomputer controls the echo signal to be output from an output port B1 or a port B0 of the second analog switch, the echo signal enters a pin-IN of the third-stage amplifier, the echo signal is amplified by the third-stage amplifier and then is output by an OUT pin of the third-stage amplifier, the echo signal is simultaneously sent to the single chip microcomputer and a fourth-stage amplifier, and the third-stage amplification echo signal sent to the single chip microcomputer is filtered by a filter capacitor and then is sent to a pin PA1 and a pin PA0 of the single chip microcomputer;
the three-level amplified echo signal sent to the four-level amplifier is firstly sent to a pin A of a third analog switch, a pin PE13 of the single chip microcomputer controls the echo signal to be output from an output port B1 or a port B0 of the third analog switch and enter a pin-IN of the four-level amplifier, the three-level amplified echo signal is amplified by the four-level amplifier and then is output from a pin OUT of the four-level amplifier, and the three-level amplified echo signal is filtered by a filter capacitor and then is sent to a pin PA3 and a pin PA2 of the single chip microcomputer; pins PA7, PC4, PA1, PA0, PA3 and PA2 of the singlechip respectively receive a primary amplification echo signal and a secondary amplification echo signal, are used for a tertiary amplification echo signal in a frequency modulation continuous wave mode, are used for a tertiary amplification echo signal in a single-frequency continuous wave mode, are used for a quaternary amplification echo signal in the frequency modulation continuous wave mode and are used for a quaternary amplification echo signal in the single-frequency continuous wave mode;
the single chip microcomputer judges whether intermediate frequency gain is needed or not according to an echo signal received by a PA7 pin, and selects a corresponding echo amplification signal; meanwhile, signals are sent to a VGA pin of the front-end module through a PA5 pin, the transmitting power of the front-end module is changed, and four-stage intermediate frequency automatic gain is carried out.
Preferably, echo signals output by a pin PA1 and a pin PA0 of the single chip microcomputer are respectively used in a frequency modulation continuous wave mode and a single-frequency continuous wave mode.
Preferably, echo signals output by a pin PA3 and a pin PA2 of the single chip microcomputer are respectively used in a frequency modulation continuous wave mode and a single-frequency continuous wave mode.
Preferably, the optical coupler comprises a PS2801-4 chip.
Compared with the prior art, the beneficial effects of the utility model include at least:
1. the upper cover and the lower cover of the shell are connected through the cross pan head self-tapping screw, so that the structure is simple and the connection is stable;
2. the sealing is carried out by arranging an O-shaped sealing ring and a round rubber pad between the equipment circuit board and the lower cover of the shell, so that the sealing performance of the radar module is ensured, and the normal work under severe environment can be coped with;
3. the upper cover of the shell is provided with two hemispheres, and the lens is made of polytetrafluoroethylene materials, so that the lobe angle of electromagnetic waves emitted by the front-end module can be reduced, the precision of the millimeter wave radar module is ensured, and the problems of large ultrasonic radar angle and poor directivity are solved;
4. the front-end module and the rear-end circuit board are connected in a BGA welding mode, so that the welding process can be simplified, and automatic welding is realized;
5. by optimizing the rear-end module, the problem of insufficient resolution of the millimeter wave radar module is improved.
Drawings
Fig. 1 is a schematic structural diagram of a 24GHz millimeter wave radar apparatus according to an embodiment of the present invention;
fig. 2 is a block diagram of a circuit board structure of a 24GHz millimeter wave radar apparatus according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a single chip microcomputer part of the 24GHz millimeter wave radar apparatus according to the embodiment of the present invention;
fig. 4 is a schematic circuit diagram of an amplifier group of a 24GHz millimeter wave radar apparatus according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an analog switch block and a filter circuit of a 24GHz millimeter wave radar apparatus according to an embodiment of the present invention;
fig. 6 is a schematic circuit diagram of a front-end module, a comparator and a voltage follower of a 24GHz millimeter wave radar apparatus according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a portion of a complex programmable logic chip of a 24GHz millimeter wave radar apparatus according to an embodiment of the present invention;
fig. 8 is a schematic circuit diagram of a power module of a 24GHz millimeter wave radar apparatus according to an embodiment of the present invention;
fig. 9 is a schematic diagram of an external connection part of a single chip microcomputer of the 24GHz millimeter wave radar apparatus according to the embodiment of the present invention;
fig. 10 is a schematic diagram of an optical coupler and a clock circuit of a 24GHz millimeter wave radar apparatus according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
On the contrary, the invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in order to provide a better understanding of the present invention to the public, certain specific details are set forth in the following detailed description of the invention. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
Referring to fig. 1, the utility model discloses a 24GHz millimeter wave radar installations's structural schematic diagram, the length of upper cover 2 is 72.5mm, and the width is 67.5mm, and the hole site diameter that is used for setting up self tapping screw 3 of cross pan head wherein is 3.2 mm. The upper cover 2 is provided with three emitting surfaces: hemisphere transmitting surface, semicylinder transmitting surface, plane transmitting surface, upper cover 2 and three kinds of transmitting surfaces are integrated into one piece, have avoided droing of upper cover 2 and transmitting surface, guarantee the leakproofness, can adapt to more adverse circumstances, and the material is polypropylene (PP) or Polytetrafluoroethylene (PTFE).
Referring to fig. 1, a specific embodiment of a hemispherical emission surface is shown: the radius of the hemisphere is 15mm, the center distance is 24.26mm, and the center thickness of the hemisphere is 14mm, so that the horizontal lobe width and the vertical lobe width of the electromagnetic wave emitted by the front end module 8 can be 25 degrees and 25 degrees respectively, the purpose of reducing the lobe width is achieved, and the problem of poor radar directivity is solved.
Semi-cylindrical transmitting surface: the surface of the upper cover 2 is a semi-cylindrical surface symmetrically separated from the diameter direction, the width of the semi-cylindrical surface is 54mm, the thickness of the semi-cylindrical surface is 14mm, and the diameter of a complete circle is 30mm, so that the horizontal lobe width and the vertical lobe width of the electromagnetic wave emitted by the front end module 8 can be 25 degrees and 60 degrees, the purpose of reducing the lobe width is achieved, and the problem of poor radar directivity is solved.
A planar emission surface: the thickness is 2.3mm, and the horizontal lobe width and the vertical lobe width of the electromagnetic wave emitted by the front-end module 8 are 60 degrees and 60 degrees respectively at this time.
The circuit board 6 and the circular rubber ring 5 are arranged on the positioning guide post of the lower cover 1, the rubber ring 5 is arranged between the circuit board 6 and the lower cover 1, and the rubber ring 5 is used as a cushion layer when the lower cover 1 and the upper cover 2 clamp and fix the circuit board 6.
When the emitting surface of the upper cover 2 is a hemisphere, the positioning guide post of the lower cover 1 ensures that the mounting position of the circuit board 6 is accurate, so that the centers of the receiving antenna array 82 and the emitting antenna array 81 of the front end module 8 in the circuit board 6 respectively face the centers of the two hemispheres, and the directivity of the emitted millimeter waves is ensured when the radar device samples. The front module 8 is 6mm away from the upper cover 2 at this time, and is a radar wavelength.
The O-shaped sealing ring 4 is arranged in a groove of the lower cover 1 and is clamped and fixed by the upper cover 2 and the lower cover 1, and the sealing performance of the whole device is ensured. The lower cover 2 has a length of 76mm and a width of 71 mm.
The outside of lower cover 2 is provided with three connecting hole, and the diameter of connecting hole is 11mm, selects the screw of suitable size to pass the connecting hole, can fix this device under wall or other environment to satisfy the use of radar installations under various environment.
The upper cover 2 and the lower cover 1 are fixedly connected by a cross pan head self-tapping screw 3, so that the processing difficulty is reduced.
The inner sides and the outer sides of the upper cover 2 and the lower cover 1 are provided with reinforcing ribs in a plurality of places, and the mode can ensure that the stability is good under the condition of not increasing the thickness and the weight.
The circuit board 6 includes a front end module 8 and a rear end module, the front end module 8 is a front end sensor of the model IMD2411A of the eight-feather science and technology ltd, and other circuits except the IMD2411A front end sensor in the circuit board 6 form the rear end module, including a single chip microcomputer 7, an amplifier group 9, a filter 10, a voltage follower 11, an analog switch group 71, a comparator 12, a CPLD chip (Complex Programmable Logic Device) 18, an optical coupler 13, a power module 14, a 485 interface output circuit, a reference voltage 16, a memory (SPI-FLASH)15 and a crystal oscillator 17.
In the circuit board 6, the front-end module 8 and the rear-end module are connected by BGA (Ball Grid Array) soldering.
The four-stage intermediate frequency automatic gain function is realized by a front-end module 8, a singlechip 7, a filter 10 and an amplifier group 9.
Referring to fig. 3-6, after the echo signal is subjected to primary amplification by the front-end module 8, the echo signal is simultaneously sent to the PA7 pin and the secondary amplifier of the single chip microcomputer 7 through the output pin IFQ _ AMP of the front-end module 8; the first-stage amplification echo signal sent to the second-stage amplifier is firstly sent to a pin A of a first analog switch U9, a pin PE11 of the singlechip 7 controls the output port of the first analog switch U9, namely the output port B1 or B0, the output echo signal enters the input end of a filter 10, the output end of the filter 10 sends the echo signal to a pin IN of a U1-GS8051 chip IN the second-stage amplifier after being filtered by the filter 10, the echo signal is amplified and then is output by a pin OUT of a U1-GS8051 chip of the second-stage amplifier and simultaneously sent to the singlechip 7 and a third-stage amplifier, and the second-stage amplification echo signal sent to the singlechip 7 is filtered by a pin C23 and then sent to a pin PC4 of the singlechip 7; the second-stage amplification echo signal sent to the third-stage amplifier is firstly sent to a pin A of a second analog switch U10, a pin PE12 of the singlechip 7 controls the echo signal to be output from an output port B1 or a port B0 of a second analog switch U10, the echo signal enters a pin-IN of a U3-GS8051 chip of the third-stage amplifier, the echo signal is amplified by the third-stage amplifier and then is output from an OUT pin of the U3-GS8051 chip, the echo signal is simultaneously sent to the singlechip 7 and a fourth-stage amplifier, the third-stage amplification echo signal sent to the singlechip 7 is filtered by C22 and C33 and then is sent to a pin PA1 and a pin PA0 of the singlechip 7, and the echo signals output by the two pins are respectively used for a continuous wave (FMCW) mode and a single-frequency Continuous Wave (CW) mode; the three-stage amplified echo signal sent to the four-stage amplifier is firstly sent to the pin a of the third analog switch U22, the pin PE13 of the single chip microcomputer 7 controls the echo signal to be output from the output port B1 or B0 of the third analog switch U22, and the echo signal enters the pin-IN of the U21-GS8051 chip IN the four-stage amplifier, the three-stage amplified echo signal is amplified by the four-stage amplifier and then output from the pin-OUT of the U21-GS8051 chip IN the four-stage amplifier, and the three-stage amplified echo signal is filtered by the pins C109 and C106 and then sent to the pin PA3 and the pin-PA 2 of the single chip microcomputer 7 (the echo signals output from the two pins are respectively used IN FMCW mode and CW mode). Therefore, the pins PA7, PC4, PA1, PA0, PA3, and PA2 of the single chip microcomputer 7 respectively receive the first-stage amplified echo signal, the second-stage amplified echo signal, the third-stage amplified echo signal in the FMCW mode, the third-stage amplified echo signal in the CW mode, the fourth-stage amplified echo signal in the FMCW mode, and the fourth-stage amplified echo signal in the CW mode. The single chip microcomputer 7 judges whether intermediate frequency gain is needed or not according to the echo signal received by the PA7 pin, and makes a judgment to select a proper echo amplification signal; meanwhile, a signal is sent to a VGA pin of the front-end module 8 through a PA5 pin, so that the transmitting power of the front-end module 8 is changed, and the four-stage intermediate-frequency automatic gain function is realized.
The CW/FMCW double-working-mode switching function is realized by the singlechip 7 and the analog switch group 71.
First analog switch U9: the echo signal is received by a pin A of a GS4157 chip of a first analog switch U9, the singlechip 7 sends a control signal to a pin S of the GS4157 chip through a pin PE11, the output of the first analog switch is controlled to be output by a pin B1 or a pin B0, and when the output is output by a pin B0, the echo signal is sent to a next-stage filter for filtering and then sent to a second-stage amplifier; when the signal is output from the pin B1, the signal is filtered by a capacitor C26 and then is sent to the input end of U3 in the secondary amplifier.
Second analog switch U10: the second-stage amplified echo signal is received by a pin A of a GS4157 chip of a second analog switch U10, the singlechip 7 sends a control signal to a pin S of the GS4157 chip through a pin PE12, the output of the second analog switch is controlled to be output by a pin B1 or a pin B0 of U10, and when the control signal is output by a pin B0, the echo signal is filtered and sent to a third-stage amplifier after being connected with a capacitor C10 in parallel through a capacitor C30; when the signal is output from a pin B1, a capacitor C31 is connected in parallel with a capacitor C10, and then the echo signal is filtered and sent to the input end of a U3 in the three-stage amplifier.
Third analog switch U22: the three-stage amplified echo signal is received by a pin A of a GS4157 chip of a third analog switch U22, the single chip microcomputer 7 sends a control signal to a pin S of the GS4157 chip through a pin PE13, the output of the third analog switch U22 is controlled to be output by a pin B1 or a pin B0, and when the output is output by a pin B0, the echo signal is filtered after being connected with a capacitor C110 in parallel through a capacitor C112 and then is sent to a four-stage amplifier; when the signal is output from the pin B1, the echo signal is filtered by the capacitor C113 after being connected with the capacitor C110 in parallel and then is sent to the input end of the U21 of the four-stage amplifier.
The long-distance and short-distance measurement self-adaptive function is realized by a front-end module 8, a singlechip 7, a filter 10 and an amplifier group 9.
After the echo signal is subjected to primary amplification by the front-end module 8, the echo signal is simultaneously sent to a PA7 pin and a secondary amplifier of the singlechip 7 through an output pin IFQ _ AMP of the front-end module 8; the first-stage amplification echo signal sent to the second-stage amplifier is firstly sent to a pin A of a first analog switch U9, a pin PE11 of the singlechip 7 controls the output port of the first analog switch U9, namely the output port B1 or B0, the output echo signal enters the input end of a filter 10, the output end of the filter 10 sends the echo signal to a pin-IN of a U1-GS8051 chip IN the second-stage amplifier after being filtered by the filter 10, the echo signal is amplified and then is output by a pin-OUT of a U1-GS8051 chip IN a circuit of the second-stage amplifier and simultaneously sent to the singlechip 7 and a third-stage amplifier, and the second-stage amplification echo signal sent to the singlechip 7 is sent to a pin PC4 of the singlechip 7 after being filtered by a pin C23; the second-stage amplification echo signal sent to the third-stage amplifier is firstly sent to a pin A of a second analog switch U10, a pin PE12 of the singlechip 7 controls the echo signal to be output from an output port B1 or a port B0 of a second analog switch U10, the echo signal enters a pin-IN of a U3-GS8051 chip IN the third-stage amplifier, the echo signal is amplified by the third-stage amplifier and then is output from a pin-OUT of a U3-GS8051 chip IN the third-stage amplifier, the echo signal is simultaneously sent to the singlechip 7 and the fourth-stage amplifier, and the third-stage amplification echo signal sent to the singlechip 7 is filtered by C22 and C33 and then is sent to a pin PA1 and a pin PA0 of the singlechip 7 (the echo signals output by the two pins are respectively used IN a CW FMCW mode and a CW mode); the three-stage amplified echo signal sent to the four-stage amplifier is firstly sent to the pin a of the third analog switch U22, the pin PE13 of the single chip microcomputer 7 controls the echo signal to be output from the output port B1 or B0 of the third analog switch U22, and the echo signal enters the pin-IN of the U21-GS8051 chip IN the four-stage amplifier, the three-stage amplified echo signal is amplified by the four-stage amplifier and then output from the pin-OUT of the U21-GS8051 chip IN the four-stage amplifier, and the three-stage amplified echo signal is filtered by the pins C109 and C106 and then sent to the pin PA3 and the pin-PA 2 of the single chip microcomputer 7 (the echo signals output from the two pins are respectively used IN FMCW mode and CW mode). Therefore, the pins PA7, PC4, PA1, PA0, PA3, and PA2 of the single chip microcomputer 7 respectively receive the first-stage amplified echo signal, the second-stage amplified echo signal, the third-stage amplified echo signal in the FMCW mode, the third-stage amplified echo signal in the CW mode, the fourth-stage amplified echo signal in the FMCW mode, and the fourth-stage amplified echo signal in the CW mode. The single chip microcomputer 7 judges whether intermediate frequency gain is needed or not according to the echo signal received by the PA7 pin, and makes a judgment to select a proper echo amplification signal; meanwhile, a signal is sent to a VGA pin of the front-end module 8 through a PA5 pin to change the transmitting power of the front-end module 8, so that the four-stage intermediate frequency automatic gain function is realized.
The linear modulation frequency calibration function is realized by the singlechip 7, the front-end module 8, the comparator 12 and the CPLD chip 18.
The single chip microcomputer 7 sends a modulation voltage signal to a VTUNE pin of the front-end module 8 through a PA4 pin, the front-end module 8 generates frequency according to the given modulation voltage signal, the frequency is divided by a frequency divider inside the front-end module 8, a frequency signal is output to an input end of a comparator 12 (comprising a U32MAX999 chip) through a DIV pin, the frequency signal is compared by the comparator 12 and then sent to a PL8A pin of a CPLD chip 18 from an output end, the CPLD chip 18 collects the frequency signal and then sends the frequency signal to the single chip microcomputer 7, and the single chip microcomputer 7 compares the actually received frequency signal with the frequency which can be generated by the modulation voltage, so that the linear modulation frequency calibration is realized. The function only needs to calibrate one point in the CW mode; in the FMCW mode, frequency linearity calibration is performed.
Referring to fig. 10, pins PD13, PD14, PA15 and PC6 of the single chip microcomputer 7 are connected to an optical coupler (Q1PS2801-4)13, outputs are GPIO1 and GPIO2, and the GPIO external interface is protected by the optical coupler 13.
The clock generator is input by a 25MHz crystal oscillator, and CLK0 and CLK1 pins of a U30 Si351A-B-GTR chip in the clock generator circuit respectively output 30MHz and 150MHz frequencies which are respectively provided for the singlechip 7 and the CPLD chip 18(U31 LCMXO2-1200HC-4TG 100I).
Referring to fig. 9, the PA10, PE3, PC13, and PA9 pins of the single chip microcomputer 7 are respectively connected to the RO, RE, DE, and DI pins of the U14-MAX3458 chip in the 485 circuit, and are connected to an external interface through the 485 circuit, and may be connected to an external serial interface or 485 interface. D12 and D13 in the 485 circuit are used for lightning protection of the circuit; d3, D10 and D11 are used for the antistatic function of the 485 circuit.
Referring to fig. 8, an external power supply is connected to the DC12V interface EMC protection circuit at the lower left corner of fig. 8, in the circuit, D8 is used for lightning protection, D9 is used for static protection, and L4 is used for removing impurities in an alternating current signal, and then the circuit is connected to the input end of the power module 14 through the output end of the circuit, and outputs 3.3V voltage to supply power to the circuit board 6 after being processed by the power module 14. The PA12 pin of the singlechip 7 outputs a control signal to an APM4953 chip of the U23 to control the power supply of the front-end module 8. The single chip microcomputer 7 receives the input voltage through the PC5 to realize monitoring of the input voltage.
Referring to fig. 6 and 9, the reference voltage 16(U2 REF3030AIDBZR) generates a voltage of 3.0V, and outputs the voltage to the IN + pin of the GS321 chip IN the voltage follower 11, and the voltage follower 11 makes the voltage follower stably output the voltage of 3.0V according to the reference voltage and the external voltage, and provides the voltage to the single chip 7, the amplifier circuit 9, and the VGA and VTUNE of the front-end module 8.
Voltage follower U28 in fig. 9: the VOUT port of a GS321 chip IN the voltage follower U28 outputs 3.0V voltage, the voltage is divided by R1 and R4, and then the divided voltage is filtered by C6 and output to the + IN end of a U1-GS8051 chip IN a secondary amplifier; the filtered signal is output to the + IN end of a U3-GS8051 chip IN the three-stage amplifier after being filtered by C25; the signal is filtered by the C111 and then output to the + IN end of a U21-GS8051 chip IN a four-stage amplifier; and outputs to the singlechip 7.
Voltage follower U18 in fig. 6: the VOUT port of the GS321 chip in the voltage follower U18 outputs a 3.0V voltage to the VTUNE pin of the front-end module 8.
Voltage follower U29: the VOUT port of the GS321 chip in the voltage follower U29 outputs a 3.0V voltage to the VGA pin of the front end module 8.
The memory 15 comprises a U5 and U12 GD25Q40H chip.
The power module 14 also includes a U19-TLV62130RGTR chip.
The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A24 GHz millimeter wave radar device is characterized by comprising an upper cover, a lower cover, self-tapping screws, a sealing ring, a rubber ring and a circuit board, wherein the upper cover and the lower cover are assembled through the self-tapping screws, the sealing ring is arranged in a groove of the lower cover, and the circuit board is clamped and fixed by the upper cover and the lower cover; the upper surface of the lower cover is provided with four positioning guide columns, the positioning guide columns are used for positioning the circuit board and the lower cover, and the rubber pads are arranged on the positioning guide columns;
the circuit board comprises a front-end module and a rear-end module, the front-end module comprises a front-end device, and the rear-end module comprises a single chip microcomputer, an amplifier group, a filter, a voltage follower, an analog switch group, a comparator, a complex programmable logic chip, an optical coupler, a power supply module, a reference voltage, a crystal oscillator and a memory; the front-end module sends echo signals to the single-chip microcomputer, meanwhile, the echo signals are filtered by the filter and then sent to the amplifier group, the analog switch group selects a mode for single-frequency continuous waves or frequency-modulated continuous waves, the amplifier group sends the amplified echo signals to the single-chip microcomputer, the single-chip microcomputer judges the echo signals received by the front-end module, the echo signals to be received and the voltage-controlled gain amplifier transmitting power are selected, and self-adaptation of four-level intermediate-frequency automatic gain and long-distance short-distance ranging is carried out; the singlechip sends a control signal to the analog switch group, and the analog switch group is controlled to select a working mode to switch the working mode under a single-frequency continuous wave or a frequency-modulated continuous wave;
the single chip microcomputer sends modulation voltage to the front-end module, the front-end module sends a frequency signal to the comparator after working, the frequency signal is collected by the complex programmable logic chip and then sent to the single chip microcomputer, and the single chip microcomputer compares the obtained frequency signal with the frequency which can be generated by the modulation voltage and carries out linear modulation frequency calibration;
the singlechip is connected with an external interface through an optical coupler; the crystal oscillator provides output frequencies of 30MHz and 150MHz to the single chip microcomputer and the complex programmable logic chip;
an external power supply is input into the power supply module, and the power supply module outputs voltage to supply power to the front-end module and the singlechip;
the reference voltage generates 3.0V voltage to the voltage follower, the voltage follower stably outputs the 3.0V reference voltage according to the reference voltage and external voltage, and the reference voltage is sent to the amplifier group, the single chip microcomputer and the front end module.
2. The device of claim 1, further comprising a 485 interface output circuit connected to the single chip.
3. The apparatus of claim 1, wherein the memory is SPI-FLASH.
4. The apparatus of claim 1, wherein the front end module and the back end module are soldered by way of a ball grid array structure.
5. The device of claim 1, wherein the surface of the upper cover is provided with a hemispherical emitting surface or a semi-cylindrical emitting surface or a planar emitting surface.
6. The apparatus of claim 1, wherein the single chip microcomputer is of the STM32 series.
7. The apparatus of claim 6, wherein the set of analog switches comprises a first analog switch, a second analog switch, and a third analog switch, each comprising a GS4157 chip; the amplifier group comprises a secondary amplifier, a tertiary amplifier and a quaternary amplifier, which all comprise GS8051 chips;
the front-end module is used for simultaneously transmitting the echo signals to a PA7 pin of the singlechip and a secondary amplifier after primary amplification is carried out on the echo signals; the first-stage amplification echo signal sent to the second-stage amplifier is firstly sent to a pin A of the first analog switch, a pin PE11 of the single chip microcomputer controls the echo signal to be output from an output port B1 or a port B0 of the first analog switch, the output echo signal enters the input end of the filter, the output end of the filter sends the echo signal to a-IN pin of the second-stage amplifier after being filtered by the filter, the echo signal is amplified and then output from an OUT pin of the second-stage amplifier, and is simultaneously sent to the single chip microcomputer and the third-stage amplifier, and the second-stage amplification echo signal sent to the single chip microcomputer is filtered by the filter capacitor and then sent to a pin PC4 of the single chip microcomputer;
the second-stage amplification echo signal sent to the third-stage amplifier is firstly sent to a pin A of a second analog switch, a pin PE12 of the single chip microcomputer controls the echo signal to be output from an output port B1 or a port B0 of the second analog switch, the echo signal enters a pin-IN of the third-stage amplifier, the echo signal is amplified by the third-stage amplifier and then is output by an OUT pin of the third-stage amplifier, the echo signal is simultaneously sent to the single chip microcomputer and a fourth-stage amplifier, and the third-stage amplification echo signal sent to the single chip microcomputer is filtered by a filter capacitor and then is sent to a pin PA1 and a pin PA0 of the single chip microcomputer;
the three-level amplified echo signal sent to the four-level amplifier is firstly sent to a pin A of a third analog switch, a pin PE13 of the single chip microcomputer controls the echo signal to be output from an output port B1 or a port B0 of the third analog switch and enter a pin-IN of the four-level amplifier, the three-level amplified echo signal is amplified by the four-level amplifier and then is output from a pin OUT of the four-level amplifier, and the three-level amplified echo signal is filtered by a filter capacitor and then is sent to a pin PA3 and a pin PA2 of the single chip microcomputer; pins PA7, PC4, PA1, PA0, PA3 and PA2 of the singlechip respectively receive a primary amplification echo signal and a secondary amplification echo signal, are used for a tertiary amplification echo signal in a frequency modulation continuous wave mode, are used for a tertiary amplification echo signal in a single-frequency continuous wave mode, are used for a quaternary amplification echo signal in the frequency modulation continuous wave mode and are used for a quaternary amplification echo signal in the single-frequency continuous wave mode;
the single chip microcomputer judges whether intermediate frequency gain is needed or not according to an echo signal received by a PA7 pin, and selects a corresponding echo amplification signal; meanwhile, signals are sent to a VGA pin of the front-end module through a PA5 pin, the transmitting power of the front-end module is changed, and four-stage intermediate frequency automatic gain is carried out.
8. The device of claim 7, wherein the echo signals output from the PA1 pin and the PA0 pin of the single chip microcomputer are respectively used for frequency modulated continuous wave and single frequency continuous wave modes.
9. The device of claim 7, wherein the echo signals output from the PA3 pin and the PA2 pin of the single chip microcomputer are respectively used for frequency modulated continuous wave and single frequency continuous wave modes.
10. The apparatus of claim 1, wherein the optical coupler comprises a PS2801-4 chip.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120258398.4U CN214473923U (en) | 2021-01-29 | 2021-01-29 | 24GHz millimeter wave radar device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120258398.4U CN214473923U (en) | 2021-01-29 | 2021-01-29 | 24GHz millimeter wave radar device |
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| CN214473923U true CN214473923U (en) | 2021-10-22 |
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