CN212569123U

CN212569123U - Resonant frequency correction device, electronic equipment and reversing radar alarm and distance measurement system

Info

Publication number: CN212569123U
Application number: CN202022192344.0U
Authority: CN
Inventors: 张文荣; 包旭鹤; 陆健; 罗鹏; 孙建刚
Original assignee: Shanghai Sinomcu Microelectronics Co ltd
Current assignee: Shanghai Sinomcu Microelectronics Co ltd
Priority date: 2020-09-29
Filing date: 2020-09-29
Publication date: 2021-02-19
Anticipated expiration: 2030-09-29

Abstract

The utility model relates to a resonant frequency correcting unit, electronic equipment, radar warning and ranging system of backing a car, the device includes: the device comprises a band-pass sampling module, a down-conversion filtering module and a frequency deviation detection module. Through above device, the embodiment of the utility model provides a can carry out band-pass sampling filtering to the ultrasonic signal who receives, obtain complex baseband signal, carry out the frequency deviation to complex baseband signal and detect, obtain the first carrier frequency deviation of complex baseband signal, and utilize first carrier frequency deviation and complex baseband signal to confirm the second carrier frequency deviation, and utilize ultrasonic transmitter's the resonant frequency of predetermineeing transmitting frequency and second carrier frequency deviation and confirming ultrasonic transmitter, in order to carry out frequency correction to ultrasonic transmitter, rectify through the actual resonant frequency to ultrasonic transmitter, can solve the frequency drift problem, in order to improve emission efficiency, reduce the influence of carrier frequency deviation, thereby improve the range finding precision.

Description

Resonant frequency correction device, electronic equipment and reversing radar alarm and distance measurement system

Technical Field

The utility model relates to a measure technical field, especially relate to a resonant frequency correcting unit, electronic equipment, radar alarm and ranging system backs a car.

Background

The ultrasonic distance measurement is a non-contact detection technology, is not influenced by light, the color of a measured object and the like, is more sanitary compared with other instruments, is more resistant to severe environments such as moisture, dust, high temperature, corrosive gas and the like, and has the characteristics of less maintenance, no pollution, high reliability, long service life and the like. Therefore, the ultrasonic distance measurement in the air has wide application under special environment, and the distance accuracy can be calibrated on line in different environments. The ultrasonic detection is often relatively rapid and convenient, the calculation is simple, the real-time control is easy to realize, and the industrial practical index requirement can be met in the aspect of measurement precision.

The ultrasonic sensor is generally self-transmitting and self-receiving, but due to cost, the frequency temperature of a crystal oscillator used by a peripheral circuit is poor, which causes great changes of carrier frequencies at the receiving moment and the transmitting moment, and a receiving circuit utilizing the related art causes great distortion of a demodulated envelope, thereby seriously affecting the ranging accuracy.

SUMMERY OF THE UTILITY MODEL

Technical problem

In view of this, the technical problem to be solved by the present invention is how to improve the precision of ultrasonic distance measurement.

Solution scheme

In order to solve the above technical problem, according to the utility model discloses an embodiment provides a resonant frequency correcting unit, the device includes:

the device comprises a band-pass sampling module, a frequency conversion module and a frequency conversion module, wherein the band-pass sampling module is used for performing band-pass sampling on a received ultrasonic signal to obtain a sampling signal, and the ultrasonic signal is generated by an ultrasonic transmitter configured to be at a preset transmitting frequency;

the down-conversion filtering module is electrically connected with the band-pass sampling module and is used for performing quadrature down-conversion processing on the sampling signal to obtain a complex bandpass signal and filtering the complex bandpass signal to obtain a complex baseband signal;

the frequency offset detection module is electrically connected to the down-conversion filtering module and is used for performing frequency offset detection on the complex baseband signal to obtain a first carrier frequency offset of the complex baseband signal and determining a second carrier frequency offset by using the first carrier frequency offset and the complex baseband signal;

and the frequency correction module is electrically connected to the frequency offset detection module and is used for determining the resonant frequency of the ultrasonic transmitter by using the preset transmitting frequency of the ultrasonic transmitter and the second carrier frequency offset so as to correct the frequency of the ultrasonic transmitter.

For the above apparatus, in one possible implementation, the down-conversion filtering module includes:

the down-conversion unit is used for carrying out quadrature down-conversion processing on the sampling signal to obtain the complex bandpass signal;

and the low-pass filtering unit is electrically connected with the down-conversion unit and is used for filtering the complex bandpass signal to obtain the complex baseband signal.

For the above apparatus, in a possible implementation, the frequency offset detection module includes:

a differential phase demodulation unit, configured to perform differential phase demodulation processing on the complex baseband signal to obtain the first carrier frequency offset;

the oscillation unit is electrically connected with the differential phase demodulation unit and the loop filter unit and is used for obtaining an oscillation signal according to the output of the loop filter unit and the first carrier frequency offset;

the multiplication unit is electrically connected with the oscillation unit and is used for multiplying the oscillation signal and the complex baseband signal to obtain a multiplication signal;

and the loop filtering unit is electrically connected to the multiplying unit and is used for performing loop filtering on the multiplication signal to obtain the second carrier frequency offset.

For the above apparatus, in a possible implementation manner, the performing loop filtering on the multiplication signal to obtain the second carrier frequency offset includes:

acquiring an imaginary part signal of the multiplication signal to obtain a phase error signal;

and performing loop filtering on the phase error signal to obtain the second carrier frequency offset.

For the above apparatus, in a possible implementation, the differential phase detection unit includes:

the phase demodulation subunit is used for performing phase demodulation processing on the complex baseband signal to obtain a phase signal;

and the differential subunit is electrically connected to the phase demodulation subunit and is configured to perform differential processing on the phase signal to obtain the first carrier frequency offset.

For the above apparatus, in one possible implementation, the frequency correction module includes:

the frequency determining unit is used for determining the resonant frequency of the ultrasonic transmitter by using the preset transmitting frequency of the ultrasonic transmitter and the second carrier frequency offset;

and the frequency correction unit is electrically connected with the frequency determination unit and is used for configuring the center frequency of the ultrasonic signal transmitted by the ultrasonic transmitter by using the determined resonance frequency.

According to the utility model discloses an on the other hand, provided an electronic equipment, electronic equipment includes:

the resonance frequency correction device.

According to the utility model discloses an on the other hand, a radar alarm system backs a car, system electronic equipment.

According to the utility model discloses a further aspect provides a ranging system, the system includes:

an ultrasonic transmitter for generating an ultrasonic signal using a preset transmission frequency configured;

the resonance frequency correction device is used for determining the resonance frequency of the ultrasonic transmitter by using the ultrasonic signal so as to carry out frequency correction on the ultrasonic transmitter;

the ultrasonic transmitter is also used for generating a ranging ultrasonic signal after frequency correction;

and the distance measuring device is used for receiving the distance measuring ultrasonic signal so as to determine the distance according to the distance measuring ultrasonic signal.

Advantageous effects

Through the device, the embodiment of the utility model can carry out band-pass sampling on the received ultrasonic signals to obtain sampling signals, carrying out quadrature down-conversion processing on the sampling signal to obtain a complex bandpass signal, filtering the complex bandpass signal to obtain a complex baseband signal, performing frequency offset detection on the complex baseband signal to obtain a first carrier frequency offset of the complex baseband signal, determining a second carrier frequency offset by using the first carrier frequency offset and the complex baseband signal, and determining a resonant frequency of the ultrasonic transmitter by using a preset transmitting frequency of the ultrasonic transmitter and the second carrier frequency offset, to perform a frequency correction of the ultrasonic transmitter, by correcting the actual resonance frequency of the ultrasonic transmitter, the problem of frequency drift can be solved, so that the transmitting efficiency is improved, the influence of carrier frequency offset is reduced, and the ranging precision is improved.

Other features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the present invention and, together with the description, serve to explain the principles of the invention.

Fig. 1 shows a schematic diagram of an ultrasonic distance measurement principle according to an embodiment of the present invention.

Fig. 2 shows a schematic diagram of a resonant frequency correction device according to an embodiment of the present invention.

Fig. 3 shows a schematic diagram of a resonant frequency correction device according to an embodiment of the present invention.

Detailed Description

Various exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present invention.

The backing radar alarm system used in backing the car is commonly called backing radar. When the automobile backs, the ultrasonic wave radar of backing a car adopts the ultrasonic ranging principle to survey the distance of automobile afterbody from the barrier, and when the automobile afterbody detected the barrier, the radar of backing a car just real-time dynamic display was from the distance of barrier, when reaching the safety warning value of setting for, the radar of backing a car sends the chimes of doom immediately to warn the driver, supplementary driver safety is backed a car. Most automobiles are now equipped with a reversing radar.

The reversing radar adopts an ultrasonic generator (ultrasonic transducer) to transmit ultrasonic waves, and utilizes an ultrasonic sensor to receive the ultrasonic waves so as to measure distance, and the ultrasonic generator and the ultrasonic sensor can be integrated in the same equipment or can be arranged separately.

The ultrasonic ranging method is exemplarily described below.

Referring to fig. 1, fig. 1 is a schematic diagram illustrating an ultrasonic distance measurement principle according to an embodiment of the present invention.

As shown in fig. 1, in the ultrasonic ranging, an ultrasonic transmitter transmits ultrasonic waves in a certain direction, timing is started at the same time as the transmission time, the ultrasonic waves propagate in the air and return immediately when hitting an obstacle in the process, and the ultrasonic receiver stops timing immediately when receiving reflected waves. The propagation speed of the ultrasonic wave in the air is 340m/s, and the distance(s) of the transmitting point from the obstacle can be calculated according to the time t recorded by the timer, namely: and s is 340 t/2.

Since ultrasonic waves are a kind of sound waves, the sound velocity V is related to temperature. In use, the ultrasonic velocity can be approximated as being substantially constant during propagation if the propagation medium temperature does not vary much. If the requirement on the distance measurement precision is high, the measurement result is subjected to numerical correction by a temperature compensation method. After the sound velocity is determined, the distance can be obtained by measuring the round-trip time of the ultrasonic wave.

From FIG. 1, it can be seen that:

H＝S*cosθ (1)

θ＝arctg(L/H) (2)

wherein, S represents the length of the ultrasonic wave reaching the obstacle, L represents half of the distance between the ultrasonic transmitter and the ultrasonic receiver, H represents the distance to be measured, and theta represents the included angle between H and L.

The distance of ultrasonic propagation is:

2S＝vt (3)

where v represents the propagation velocity of the ultrasonic wave in the medium, and t represents the time required for the ultrasonic wave to travel from transmission to reception.

Substituting the formula (2) and the formula (3) into the formula (1) to obtain:

since the propagation velocity V of the ultrasonic wave is constant at a certain temperature (for example, when the temperature T is 30 degrees, V is 349m/s), when the distance H to be measured is much greater than L, equation (4) becomes:

H＝1/2vt (5)

thus, by the above formula, the measured distance H can be derived.

The resonant frequency of the ultrasonic transmitter (e.g., ultrasonic transducer) is f0, so the transmitted ultrasonic signal can be considered as an amplitude modulated signal with a center frequency of f 0. The envelope of the amplitude-modulated signal depends on the device characteristics of the ultrasonic transmitter.

The resonant frequency of the ultrasonic transmitter is a very important parameter, but the resonant frequency shifts due to factors such as ambient temperature and aging of components, and the shift of the resonant frequency reduces the transmitting efficiency of the ultrasonic transmitter, resulting in reduction of the effective detection distance. When there is a large carrier frequency offset at the transmitting and receiving ends, the accuracy of ranging is seriously affected.

For solving the above problem, the embodiment of the utility model provides a resonant frequency correcting unit is proposed, can realize rectifying ultrasonic emitter's frequency, improve emission efficiency, reduce the influence of carrier wave frequency deviation to improve the range finding precision.

Referring to fig. 2, fig. 2 is a schematic diagram illustrating a resonant frequency calibration apparatus according to an embodiment of the present invention.

In one example, the apparatus may be applied in an electronic device to enable frequency correction of an ultrasonic transmitter disposed in the electronic device.

In one example, an electronic device, also referred to as a User Equipment (UE), a Mobile Station (MS), a Mobile Terminal (MT), etc., is a device that provides voice and/or data connectivity to a user, such as a handheld device with wireless connectivity, a vehicle-mounted device, etc. Currently, some examples of terminals are: a mobile phone (mobile phone), a tablet computer, a notebook computer, a palm top computer, a Mobile Internet Device (MID), a wearable device, a Virtual Reality (VR) device, an Augmented Reality (AR) device, a wireless terminal in industrial control (industrial control), a wireless terminal in unmanned driving (self), a wireless terminal in remote surgery (remote medical supply), a wireless terminal in smart grid (smart grid), a wireless terminal in transportation safety (transportation safety), a wireless terminal in city (smart city), a wireless terminal in smart home (smart home), a wireless terminal in vehicle networking, and the like.

In one example, the apparatus or electronics may be provided in a reverse radar warning system to effect frequency correction of the ultrasonic transmitter in reverse.

In one example, the reverse radar warning system may be provided in various mobile devices, such as an automobile.

As shown in fig. 2, the apparatus includes:

a band-pass sampling module 10, configured to perform band-pass sampling on a received ultrasonic signal to obtain a sampled signal, where the ultrasonic signal is generated by an ultrasonic transmitter configured to a preset transmission frequency;

the down-conversion filtering module 20 is electrically connected to the band-pass sampling module 10, and is configured to perform quadrature down-conversion processing on the sampled signal to obtain a complex bandpass signal, and filter the complex bandpass signal to obtain a complex baseband signal;

a frequency offset detection module 30, electrically connected to the down-conversion filtering module 20, configured to perform frequency offset detection on the complex baseband signal to obtain a first carrier frequency offset of the complex baseband signal, and determine a second carrier frequency offset by using the first carrier frequency offset and the complex baseband signal;

a frequency correction module 40, electrically connected to the frequency offset detection module 30, configured to determine a resonant frequency of the ultrasonic transmitter by using a preset transmission frequency of the ultrasonic transmitter and the second carrier frequency offset, so as to perform frequency correction on the ultrasonic transmitter.

It should be noted that, in the resonant frequency correction device provided in the embodiments of the present invention, each module may be implemented by a digital circuit.

In one possible embodiment, the band pass sampling module may include an analog-to-digital converter (ADC) through which band pass sampling of the ultrasound signal may be achieved.

In one example, the analog-to-digital converter may be arranged to operate in Sigma-Delta mode.

The embodiment of the utility model provides a through setting up analog to digital converter into sigma-delta mode, can be so that quantization noise minimizing, the signal rate after carrying out the band-pass sampling to the ultrasonic signal received is far greater than envelope signal's bandwidth.

Of course, in other embodiments, the bandpass sampling module may also be implemented by other devices or hardware circuits, which is not limited by the present invention.

Referring to fig. 3, fig. 3 is a schematic diagram illustrating a resonant frequency calibration apparatus according to an embodiment of the present invention.

In one possible implementation, as shown in fig. 3, the down-conversion filtering module 20 may include:

a down-conversion unit 210, configured to perform quadrature down-conversion processing on the sampling signal to obtain the complex bandpass signal;

the low-pass filtering unit 220 is electrically connected to the down-conversion unit 210, and is configured to filter the complex bandpass signal to obtain the complex baseband signal.

In an example, the down-conversion unit 210 may be implemented by a frequency converter in the related art, or may be implemented by a dedicated hardware circuit or a digital circuit, and the embodiment of the present invention is not limited to the specific implementation manner of the down-conversion unit.

In one example, the down-conversion unit 210 may down-convert the center frequency of the sampling signal to 0, thereby obtaining the complex bandpass signal.

In one example, the low pass filtering unit 220 may include a low pass filter to low pass filter the complex bandpass signal.

Through down frequency conversion filtering module, the embodiment of the utility model provides a can carry out down frequency conversion and filtering to the sampling signal of band-pass sampling module output and handle to obtain compound baseband signal.

In one possible implementation, as shown in fig. 3, the frequency offset detection module 30 may include:

a differential phase demodulation unit 310, configured to perform differential phase demodulation processing on the complex baseband signal to obtain the first carrier frequency offset;

the oscillating unit 320 is electrically connected to the differential phase detection unit 310 and the loop filter unit 340, and configured to obtain an oscillating signal according to the output of the loop filter unit 340 and the first carrier frequency offset;

the multiplication unit 330, electrically connected to the oscillation unit 320, is configured to multiply the oscillation signal and the complex baseband signal to obtain a multiplication signal;

the loop filtering unit 340 is electrically connected to the multiplying unit 330, and configured to perform loop filtering on the multiplication signal to obtain the second carrier frequency offset.

In a possible implementation, the differential phase detection unit 310 may include:

In one example, the phase detection subunit may include a phase detection circuit, and the phase detection circuit may perform an arc tangent calculation on the complex baseband signal to obtain a phase signal in the complex baseband signal.

In one example, the differential subunit may include a differential circuit, and the differential circuit may perform a differential operation on the phase signal to obtain the first carrier frequency offset of the phase signal.

In one example, the oscillation unit 320 may include an oscillator, such as a digital oscillator.

In one example, the multiplication unit 330 may include a multiplier.

In one example, the loop filtering unit 340 may include a loop filter.

The oscillation unit, the multiplication unit and the loop filter unit can be realized by special hardware circuits.

In a possible implementation manner, the performing loop filtering on the multiplication signal to obtain the second carrier frequency offset may include:

The embodiment of the utility model provides a confirm first carrier frequency offset through difference phase demodulation unit, the oscillating unit utilizes the output of loop filter unit and first carrier frequency offset to produce oscillating signal and export the multiplication unit, the multiplication unit multiplies oscillating signal and complex baseband signal and obtains multiplication signal after, exports the loop filter unit, the imaginary part signal of multiplication signal is got to the loop filter unit, contain phase error information in the imaginary part signal, can obtain the carrier frequency offset after the loop filter.

In one example, in an initialization stage, the oscillating unit may generate an oscillating signal using the first carrier frequency offset as an initial input frequency.

In one example, when the initialization of the oscillation unit is completed, the multiplication unit and the loop filter unit may work normally, and the oscillation unit may generate the oscillation signal by using the loop filter unit.

Through frequency deviation detection module, the embodiment of the utility model provides a can track the frequency deviation of complex baseband signal, confirm the second frequency deviation signal of complex baseband signal.

In one possible implementation, as shown in fig. 3, the frequency correction module 40 may include:

a frequency determining unit 410, configured to determine a resonant frequency of the ultrasonic transmitter by using a preset transmitting frequency of the ultrasonic transmitter and the second carrier frequency offset;

and a frequency correction unit 420 electrically connected to the frequency determination unit 410 for configuring a center frequency of the ultrasonic signal emitted from the ultrasonic emitter by using the determined resonance frequency.

In one example, the frequency determination unit 410 may include an addition circuit, such as an adder, and the frequency determination unit may add the preset transmission frequency of the ultrasonic transmitter and the second carrier frequency offset to determine the resonant frequency of the ultrasonic transmitter.

In one example, the frequency correction unit may include a frequency correction circuit to implement the configuration of the center frequency of the ultrasonic signal.

In one example, the ultrasonic transmitter transmits a signal, and the two phases are divided into a forced response phase and a free response phase. The forced response phase is controlled by an electrical signal applied to the ultrasonic transmitter. The signal center frequency at this stage depends on the frequency of the electrical signal. The free response phase is the free response of the ultrasonic transmitter after the electrical signal is over. The utility model discloses utilize above device, can detect ultrasonic emitter's resonant frequency accurately, have that check-out time is fast and characteristics that the precision is high.

The embodiment of the utility model provides an utilize full digital circuit to remove the resonant frequency who estimates the transducer, estimate ultrasonic emitter's resonant frequency back, adjust the resonant frequency that obtains for the estimation to ultrasonic emitter transmit signal's central frequency to obtain higher emission efficiency. This allows the effect of carrier frequency offset to be negligible in the receiving circuit. Meanwhile, the accuracy of distance measurement can be improved due to the high consistency of the transmitting frequency and the resonant frequency.

The reversing radar warning system may be provided in various mobile devices, such as a car.

In an example, the distance measuring device can be realized through a hardware circuit, the embodiment of the present invention does not limit the specific implementation manner of the distance measuring device, for example, the peak value of the second carrier frequency offset is detected by the peak value detection circuit in the frequency correction device, and the purpose of distance measurement can be realized by using peak value distance measurement or other manners, and the person skilled in the art can realize the distance measuring device through the correlation technique.

In this way, the embodiment of the utility model provides a can realize the correction to the center frequency of the ultrasonic transmitter in the system to utilize the ultrasonic transmitter after the correction to carry out the range finding.

The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A resonance frequency correction apparatus, characterized in that the apparatus comprises:

2. The apparatus of claim 1, wherein the down-conversion filtering module comprises:

3. The apparatus of claim 1, wherein the frequency offset detection module comprises:

4. The apparatus of claim 3, wherein the differential phase detection unit comprises:

5. The apparatus of claim 1, wherein the frequency correction module comprises:

6. An electronic device, characterized in that the electronic device comprises:

a resonant frequency correction device as claimed in any one of claims 1 to 5.

7. A reversing radar warning system, characterized in that it comprises an electronic device according to claim 6.

8. A ranging system, the system comprising:

the resonance frequency correction apparatus according to any one of claims 1 to 5, for determining a resonance frequency of the ultrasonic transmitter using the ultrasonic signal to perform frequency correction on the ultrasonic transmitter;