A method for calibrating WiFi frequency offset under high temperature environment for a driving recorder

Abstract

The application discloses a WiFi frequency offset calibration method for a driving recorder in a high-temperature environment, which comprises the following steps: collecting the equipment temperature in real time and determining the high-temperature working condition classification; constructing a high-temperature temperature-frequency offset compensation model special for the driving recorder; and performing differential adaptive calibration based on the working condition classification, wherein, according to the temperature working condition level determined in real time, a corresponding calibration strategy is matched, the calibration accuracy and the equipment computing power consumption are taken into account, the frequency offset accuracy is checked, and residual error correction is performed. The application is used to solve the communication abnormality problem caused by the WiFi crystal oscillator drift and the radio frequency offset deviation of the driving recorder in the vehicle high-temperature closed environment, can be adapted to all vehicle driving recorders equipped with 2.4G / 5G dual-frequency WiFi transmission functions, and can be simultaneously extended to be applied to the radio frequency calibration scene of similar vehicle high-temperature wireless terminal equipment such as a vehicle rearview mirror recorder and a vehicle monitoring terminal.

Description

Technical Field

[0001] This application belongs to the field of vehicle wireless communication technology, specifically relating to a WiFi frequency offset calibration method for dashcams in high-temperature environments. Background Technology

[0002] As a core device for in-vehicle safety and evidence collection, dashcams are generally equipped with WiFi wireless transmission modules to enable core functions such as mobile phone connectivity, video projection, wireless download of recorded files, and remote device upgrades. The stability of WiFi communication directly determines the user experience and the effectiveness of the evidence collection function. Dashcams typically operate in the inside of the vehicle's windshield, a closed, heat-accumulating space without active cooling structures, making the ambient temperature highly susceptible to external weather conditions.

[0003] Current dashcam WiFi calibration technologies all employ a single, fixed calibration scheme at room temperature. This means that the device's WiFi RF frequency offset calibration is completed at a normal room temperature of 25℃, and fixed compensation parameters are then fixed. These parameters are used for frequency correction throughout the device's lifecycle after it leaves the factory. This scheme is only suitable for normal operating environments ranging from 0℃ to 40℃. At room temperature, the device's crystal oscillator and RF chip performance are stable, with small frequency offset errors, which can meet basic communication requirements.

[0004] However, in-vehicle scenarios involve extreme high-temperature conditions. After a vehicle is exposed to the sun in summer, the temperature of the dashcam can quickly rise to 60℃~85℃, far exceeding the standard operating temperature range of WiFi devices. Existing technologies have many core defects in high-temperature environments, as follows: 1. High-temperature component characteristic drift renders fixed calibration parameters completely ineffective. The passive crystal oscillator, RF PLL phase-locked loop, and load capacitor of the dashcam's WiFi module are all temperature-sensitive components. In high-temperature environments, they experience nonlinear resonant frequency drift, with the frequency deviation increasing as the temperature rises. Traditional fixed calibration parameters cannot dynamically adjust to temperature changes, resulting in a significant deviation of the actual WiFi carrier frequency from the standard channel frequency at high temperatures. The frequency deviation can reach up to ±50kHz in the 2.4GHz band and ±25kHz in the 5GHz band, far exceeding industry-permitted frequency deviation thresholds.

[0005] 2. Lack of temperature-graded compensation mechanism, resulting in poor adaptability to high and low temperature operating conditions. Existing technology does not differentiate between normal temperature, high temperature, and ultra-high temperature operating conditions, nor does it establish a corresponding compensation relationship between temperature and frequency deviation. It cannot perform targeted calibration and optimization for extreme high-temperature scenarios in vehicles ranging from 60℃ to 85℃, leading to continuous accumulation of frequency errors at high temperatures that cannot be corrected automatically.

[0006] 3. The calibration mode is singular and cannot achieve dynamic closed-loop correction. Traditional calibration is only a one-time static calibration at the factory, and there is no real-time calibration or iterative correction mechanism during the high-temperature operation of the equipment later. As the equipment ages under high temperature for a long time, the parameters of the crystal oscillator and RF circuit will continue to deviate, and the error of the fixed calibration parameters will continue to amplify, eventually leading to WiFi communication failure.

[0007] 4. Excessive frequency offset can cause multiple communication failures, affecting the core functions of the device. High temperature and excessive frequency offset can directly lead to deterioration of WiFi signal EVM phase noise, severe fluctuations in RSSI signal, and channel demodulation failure. This can result in problems such as mobile phone pairing failure, video transmission lag, wireless disconnection, and interrupted file downloads. In severe cases, it can prevent the dashcam from exporting evidence videos, rendering the device useless. Summary of the Invention

[0008] To address the shortcomings or deficiencies of the existing technologies, this application aims to provide a precise WiFi frequency offset calibration technology for dashcams in high-temperature heat accumulation scenarios. This technology primarily solves communication anomalies caused by WiFi crystal oscillator drift and excessive RF frequency offset in high-temperature, enclosed in-vehicle environments. It is compatible with all in-vehicle dashcam devices equipped with 2.4G / 5G dual-band WiFi transmission capabilities and can also be extended to RF frequency calibration scenarios for similar in-vehicle high-temperature wireless terminal devices such as rearview mirror dashcams and in-vehicle monitoring terminals.

[0009] To solve the above-mentioned technical problems, this application provides the following technical solution: This application proposes a WiFi frequency offset calibration method for dashcams in high-temperature environments, including: Real-time equipment temperature acquisition and high-temperature condition classification; Construct a high-temperature-frequency offset compensation model specifically for dashcams; Differentiated adaptive calibration based on operating condition classification, wherein the corresponding calibration strategy is matched according to the temperature operating condition level determined in real time, taking into account both calibration accuracy and equipment computing power consumption. Frequency offset accuracy verification and residual error correction.

[0010] Further, optionally, it also includes: long-term aging iterative optimization and parameter fixation and update steps.

[0011] Further optionally, the above-mentioned real-time acquisition of device temperature and high-temperature condition classification also includes: embedding a high-precision NTC temperature sensor in the WiFi radio frequency chip and crystal core heating area of ​​the dashcam, setting an ultra-high sampling period of 10ms~50ms, and acquiring the core working temperature T of the device body in real time.

[0012] Further optionally, it also includes: pre-setting three temperature thresholds based on the actual working conditions of the vehicle to accurately divide the working scenarios, including normal temperature conditions T≤45℃, high temperature conditions 45℃<T≤70℃, and ultra-high temperature conditions 70℃<T≤85℃.

[0013] Optionally, the above-mentioned construction of a dedicated high-temperature temperature-frequency offset compensation model for dashcams also includes: for the sealed heat accumulation characteristics of dashcams, a gradient high-temperature calibration test is completed using a high and low temperature test chamber, traversing the entire high-temperature range of 45℃ to 85℃ with a gradient of 5℃, and after being kept at a constant temperature for 30 minutes to ensure the temperature of the device is balanced, the actual frequency offset drift of the WiFi 2.4G and 5G full channels at each temperature point is accurately collected using a spectrum analyzer.

[0014] Further optionally, it also includes: based on the massive amount of collected measured data, establishing a temperature-frequency offset nonlinear mapping relationship through a polynomial fitting algorithm, generating a high-temperature compensation LUT lookup table, and solidifying the crystal oscillator compensation value and AFC register correction value corresponding to each temperature into the RF parameter partition of the device firmware to form a dedicated vehicle-mounted high-temperature compensation model.

[0015] Further, optionally, the above-mentioned differentiated adaptive calibration based on operating conditions also includes: enabling a basic low-frequency calibration mode under normal temperature conditions, retaining the factory normal temperature calibration parameters, reducing the computing power consumption of the equipment, and meeting the daily normal temperature usage requirements.

[0016] Further optionally, the above-mentioned differential adaptive calibration based on operating condition classification also includes: under high temperature operating conditions, starting the intermediate frequency dynamic calibration mode, shortening the calibration cycle to 20ms, retrieving the corresponding temperature compensation parameters from the LUT lookup table in real time, pre-correcting the initial frequency offset of the radio frequency, and simultaneously fine-tuning the carrier frequency through the AFC automatic frequency control algorithm to successively offset the high temperature linear frequency offset error.

[0017] Further optionally, the above-mentioned differentiated adaptive calibration based on operating condition classification also includes: under ultra-high temperature operating conditions, starting high-frequency forced calibration + clutter filtering mode, compressing the calibration cycle to 10ms, and simultaneously enabling the radio frequency signal filtering algorithm to filter vehicle-mounted high-temperature electromagnetic interference and frequency offset clutter interference, and accurately correcting nonlinear large frequency offset.

[0018] Optionally, the above-mentioned frequency offset accuracy verification and residual error correction also include: after each calibration, the device detects the three core indicators of the WiFi channel actual frequency offset value, RSSI signal strength, and EVM phase noise in real time, and verifies them against the vehicle high temperature calibration standard: the frequency offset of the 2.4G band ≤ ±15KHz and the frequency offset of the 5G band ≤ ±8KHz are qualified; if the indicators exceed the tolerance, a second iteration calibration is automatically triggered to cyclically correct the residual frequency offset error until all parameters meet the standard.

[0019] Compared with the prior art, this application has the following technical effects: This application employs a technical solution involving temperature grading determination, temperature-frequency offset model matching, dynamic closed-loop calibration, and iterative parameter optimization to achieve precise correction of WiFi frequency offset in the extreme high-temperature range of 60℃ to 85℃ for vehicles. This keeps the frequency offset under all high and low temperature operating conditions within the industry standard range, completely solving the problem of abnormal WiFi communication in dashcams at high temperatures and ensuring the continuous and stable operation of the device's wireless transmission function. Attached Figure Description

[0020] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This application includes a flowchart of a WiFi frequency offset calibration method for a dashcam under high-temperature conditions, according to an embodiment of the present application. Figure 2 An embodiment of this application and a line graph showing the variation of 2.4G frequency offset with temperature under conventional room temperature fixed calibration; Figure 3 An embodiment of this application and a line graph showing the change of 5G frequency offset with temperature under conventional room temperature fixed calibration; Figure 4 This application presents an embodiment of a clock error calibration method that compares to a conventional fixed-calibration clock error versus temperature. Figure 5 A bar chart comparing the frequency offset of key high-temperature points with a conventional room-temperature fixed calibration in one embodiment of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Example 1 like Figure 1 As shown, a WiFi frequency offset calibration method for dashcams in high-temperature environments includes the following steps: S1: Real-time equipment temperature acquisition and high-temperature condition classification: A high-precision NTC temperature sensor is built into the WiFi RF chip and the core heat-generating area of ​​the crystal oscillator in the dashcam. The sampling period is set to 10ms to 50ms to collect the core operating temperature T of the device body in real time. Combined with the actual vehicle operating conditions, three temperature thresholds are preset to divide the working scenario into normal temperature conditions (T≤45℃), high temperature conditions (45℃<T≤70℃), and ultra-high temperature conditions (70℃<T≤85℃). The device's current temperature level is determined in real time, providing data basis for differentiated calibration.

[0023] S2: Construct a high-temperature-frequency offset compensation model specifically for dashcams: To address the heat accumulation characteristics of the dashcam in a sealed environment, gradient high-temperature calibration tests were conducted in a high and low temperature test chamber, traversing the entire high-temperature range from 45℃ to 85℃ in 5℃ increments. Each temperature point was kept at a constant temperature for 30 minutes to ensure internal temperature equilibrium. Then, the actual frequency offset drift of all WiFi 2.4G and 5G channels at each temperature was accurately collected using a spectrum analyzer. Based on the massive amount of measured data collected, a polynomial fitting algorithm was used to establish a nonlinear mapping relationship between temperature and frequency offset, generating a high-temperature compensation LUT lookup table. The crystal oscillator compensation value and AFC register correction value corresponding to each temperature were then fixed into the RF parameter partition of the device firmware, forming a dedicated in-vehicle high-temperature compensation model.

[0024] S3: Differentiated adaptive calibration based on operating condition classification: Match the corresponding calibration strategy according to the real-time temperature operating condition level, taking into account both calibration accuracy and equipment computing power consumption. When the system is determined to be operating under normal temperature conditions (T≤45℃), the basic low-frequency calibration mode is activated to retain the factory normal temperature calibration parameters, reduce the computing power consumption of the equipment, and meet the daily normal temperature usage requirements. When the operating condition is determined to be high temperature (45℃<T≤70℃), the intermediate frequency dynamic calibration mode is activated, the calibration cycle is shortened to 20ms, the compensation parameters corresponding to the temperature in the LUT lookup table are retrieved in real time to pre-correct the initial frequency offset of the radio frequency, and the AFC automatic frequency control algorithm is run simultaneously to fine-tune the carrier frequency, thereby successively offsetting the linear frequency offset error caused by high temperature. When the system is determined to be operating under ultra-high temperature conditions (70℃<T≤85℃), the high-frequency forced calibration and noise filtering mode is activated, compressing the calibration cycle to 10ms. At the same time, the radio frequency signal filtering algorithm is enabled to effectively suppress electromagnetic interference and frequency deviation noise in the high-temperature environment of the vehicle, accurately correct nonlinear large frequency deviation, and strictly control the frequency deviation error under extreme high temperature conditions.

[0025] S4: Frequency offset accuracy verification and residual error correction: After each calibration is completed, the device detects three core indicators of the WiFi channel in real time: the actual frequency offset value, RSSI signal strength, and EVM phase noise, and performs verification against the vehicle-mounted high-temperature calibration standards: it is deemed qualified if the frequency offset in the 2.4G band does not exceed ±15KHz and the frequency offset in the 5G band does not exceed ±8KHz; if any indicator exceeds the limit, a secondary iterative calibration is automatically triggered, and the calibration and detection processes are executed cyclically until all parameters meet the standard requirements.

[0026] S5: Long-term aging iterative optimization and parameter solidification update: During the daily use of the device, the calibration data and frequency offset performance under high-temperature working conditions are continuously recorded, and the parameters of the temperature-frequency offset compensation model are automatically optimized and updated every 30 days to adapt to the aging drift of the crystal oscillator and radio frequency devices caused by long-term high-temperature operation, so as to ensure the long-term effectiveness and accuracy of the calibration model.

[0027] Further, as shown in Figures 2 to 5 , verified by actual measurement, after continuous power-on operation for 72 hours under the extreme high-temperature working condition of 85°C, this method enables the frequency offset of the dashcam in the WiFi 2.4G band to be stably maintained within ±12KHz, and the frequency offset in the 5G band to be stably maintained within ±6KHz. There are no phenomena such as WiFi disconnection, transmission stutter or pairing failure throughout the process, and the success rate of wireless video transmission reaches 100%, which fully meets the reliable communication requirements in the vehicle-mounted high-temperature environment.

[0028] Compared with the existing traditional normal-temperature fixed calibration technology, the present application has significant technical advantages and practical value. After multiple high and low temperature actual measurement verifications, the following core technical effects can be achieved: 1) The frequency offset under all high-temperature working conditions is precisely controllable. The WiFi frequency offset in the 2.4GHz band of the dashcam within the entire high-temperature range of 45°C to 85°C can be stably controlled at ≤±15KHz, and the frequency offset in the 5GHz band can be stably controlled at ≤±8KHz, which fully meets the WiFi communication industry standards and completely solves the problem of excessive high-temperature frequency offset.

[0029] 2) The high-temperature communication stability is greatly improved. Under the extreme high-temperature working condition of 85°C, the WiFi packet loss rate of the device is reduced from more than 15% of the traditional solution to less than 1%, the RSSI signal fluctuation is controlled within the range of ±5dB, there are no faults such as disconnection, stutter and pairing failure, and the functions of wireless video transmission and file download are stable throughout the process.

[0030] 3) Adapt to the long-term aging use of the device. Through the dynamic iterative optimization mechanism, it can adaptively adjust the parameter drift caused by long-term high-temperature aging of devices. The device can still maintain accurate high-temperature calibration capability after being used for more than 3 years, avoiding the problem of continuous deterioration of frequency offset in the later stage of the traditional solution, and greatly extending the stable service life of the device.

[0031] 4) Balancing accuracy and device computing power. Through a temperature-graded calibration strategy, the calibration frequency is reduced and device computing power is saved at room temperature, while calibration accuracy is improved at high temperature. Without increasing hardware costs, the performance of in-vehicle high-temperature WiFi communication is maximized, resulting in excellent cost performance and adaptability.

[0032] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. The preferred embodiments have been described in detail. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application, and all such modifications and substitutions should be covered within the scope of the claims of this application.

Claims

1. A method for WiFi frequency offset calibration in high-temperature environments for vehicle dashcams, characterized in that, include: Real-time equipment temperature acquisition and high-temperature condition classification; Construct a high-temperature-frequency offset compensation model specifically for dashcams; Differentiated adaptive calibration based on operating condition classification, wherein the corresponding calibration strategy is matched according to the temperature operating condition level determined in real time, taking into account both calibration accuracy and equipment computing power consumption; Frequency offset accuracy verification and residual error correction.

2. The WiFi frequency offset calibration method for a vehicle dashcam under high temperature conditions according to claim 1, characterized in that, Also includes: Long-term aging iterative optimization and parameter solidification update steps.

3. The WiFi frequency offset calibration method for a vehicle dashcam under high temperature conditions according to claim 1, characterized in that, The above-mentioned real-time acquisition of device temperature and high-temperature operating condition classification also includes: embedding a high-precision NTC temperature sensor in the WiFi radio frequency chip and crystal core heating area of ​​the dashcam, setting an ultra-high sampling period of 10ms~50ms, and acquiring the core operating temperature T of the device body in real time.

4. The WiFi frequency offset calibration method for a vehicle dashcam under high temperature conditions according to claim 3, characterized in that, Also includes: Based on the actual working conditions of the vehicle, three temperature thresholds are preset to accurately divide the working scenarios. Among them, the normal temperature working conditions are T≤45℃, the high temperature working conditions are 45℃<T≤70℃, and the ultra-high temperature working conditions are 70℃<T≤85℃.

5. The WiFi frequency offset calibration method for a vehicle dashcam under high temperature conditions according to claim 1, characterized in that, The above-mentioned construction of a high-temperature-frequency offset compensation model for dashcams also includes: for the sealed heat accumulation characteristics of dashcams, gradient high-temperature calibration tests are completed through a high and low temperature test chamber. The test covers the entire high-temperature range of 45℃ to 85℃ with a gradient of 5℃. After the device is kept at a constant temperature for 30 minutes to ensure temperature equilibrium, the actual frequency offset drift of the WiFi 2.4G and 5G full channels at each temperature point is accurately collected using a spectrum analyzer.

6. The WiFi frequency offset calibration method for a vehicle dashcam under high temperature conditions according to claim 5, characterized in that, It also includes: based on the massive amount of measured data collected, a nonlinear mapping relationship between temperature and frequency offset is established through a polynomial fitting algorithm, a high-temperature compensation LUT lookup table is generated, and the crystal oscillator compensation value and AFC register correction value corresponding to each temperature are solidified into the RF parameter partition of the device firmware to form a dedicated vehicle-mounted high-temperature compensation model.

7. The WiFi frequency offset calibration method for a vehicle dashcam under high temperature conditions according to claim 6, characterized in that, The aforementioned differentiated adaptive calibration based on operating conditions also includes: enabling a basic low-frequency calibration mode under normal temperature conditions, retaining the factory normal temperature calibration parameters, reducing the computing power consumption of the equipment, and meeting the daily normal temperature usage requirements.

8. The WiFi frequency offset calibration method for a vehicle dashcam under high temperature conditions according to claim 6, characterized in that, The aforementioned differential adaptive calibration based on operating conditions also includes: under high-temperature conditions, starting the intermediate frequency dynamic calibration mode, shortening the calibration cycle to 20ms, retrieving the corresponding temperature compensation parameters from the LUT lookup table in real time, pre-correcting the initial frequency offset of the radio frequency, and simultaneously fine-tuning the carrier frequency through the AFC automatic frequency control algorithm to successively offset the high-temperature linear frequency offset error.

9. The WiFi frequency offset calibration method for a vehicle dashcam under high temperature conditions according to claim 6, characterized in that, The aforementioned differentiated adaptive calibration based on operating conditions also includes: under ultra-high temperature conditions, starting high-frequency forced calibration + clutter filtering mode, compressing the calibration cycle to 10ms, and simultaneously enabling the radio frequency signal filtering algorithm to filter vehicle-mounted high-temperature electromagnetic interference and frequency offset clutter interference, and accurately correcting nonlinear large frequency offset.

10. The WiFi frequency offset calibration method for a vehicle dashcam under high temperature conditions according to any one of claims 1 to 9, characterized in that, The frequency offset accuracy verification and residual error correction mentioned above also include: after each calibration, the device detects the actual frequency offset value of the WiFi channel, RSSI signal strength, and EVM phase noise in real time, and verifies them against the vehicle high temperature calibration standard: the frequency offset of the 2.4G band ≤ ±15KHz and the frequency offset of the 5G band ≤ ±8KHz are qualified; if the indicators are out of tolerance, a second iteration calibration is automatically triggered to cyclically correct the residual frequency offset error until all parameters meet the standard.

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