Remote control ranging system based on SPAD

Abstract

According to the SPAD-based remote control distance measurement system provided by the invention, the SPAD array, the distance measurement signal processing module and the remote control signal processing module are integrated, so that the functions of simultaneously completing depth measurement and infrared remote control signal receiving in a single device are realized; the system adopts a single receiving device based on the SPAD to process depth measurement and infrared remote control signals at the same time, so that the complexity of additionally adding a photosensitive device in the traditional scheme is avoided, the system design is simplified, and the production and maintenance cost is reduced. The SPAD array serves as a core component of the system, has the characteristic of high sensitivity, and can generate effective electric signal output when receiving weak optical signals, so that the system can perform accurate depth measurement and infrared remote control signal receiving under various illumination conditions, and the reliability and accuracy of the system are improved.

Description

Technical Field

[0001] The present application relates to the field of SPAD technology, and in particular to a remote control ranging system based on SPAD. Background Art

[0002] The DTOF device, or direct Time-of-Flight depth measurement chip, is an advanced chip technology used for three-dimensional depth perception.

[0003] The DTOF device obtains distance information by measuring the flight time of the light pulse from emission to reception. It emits a light pulse to the object to be measured and receives the reflected light pulse. By calculating the time difference between the two light pulses, the depth or distance of the object to be measured can be accurately calculated.

[0004] The core device of the DTOF device is the Single Photon Avalanche Diode (SPAD). SPAD is a highly sensitive optoelectronic device that can produce an avalanche effect when receiving a single photon, thereby triggering an electrical signal. The DTOF device uses the high sensitivity of SPAD to detect weak optical pulse signals and achieve high-precision distance measurement.

[0005] Traditional infrared remote control signal demodulation usually adopts a demodulation scheme based on photodiodes. To implement infrared remote control in a DTOF device, it is usually necessary to add additional photosensitive devices to receive infrared remote control signals. Summary of the invention

[0006] The purpose of the embodiments of the present application is to provide a remote control ranging system based on SPAD to solve the problem that in order to realize infrared remote control in the existing DTOF device, it is usually necessary to add additional photosensitive devices to realize the reception of infrared remote control signals.

[0007] A remote control ranging system based on SPAD provided in an embodiment of the present application includes: a controller, and a receiving device connected to the controller;

[0008] The receiving device comprises: a SPAD array, and a ranging signal processing module and a remote control signal processing module connected to the SPAD array;

[0009] The SPAD array is used to receive an input signal and output a sensing signal; the ranging signal processing module is used to obtain depth information according to the sensing signal; the remote control signal processing module is used to obtain a demodulated signal according to the sensing signal;

[0010] The controller is used to:

[0011] Setting the ranging mode to control the SPAD to output a sensing signal to the ranging signal processing module;

[0012] Or, set to remote control mode, and control the SPAD to output a sensing signal to the remote control signal processing module.

[0013] In the above technical solution, the system integrates the SPAD array, the ranging signal processing module and the remote control signal processing module to realize the functions of depth measurement and infrared remote control signal reception in a single device. Since the system uses a single receiving device based on SPAD to simultaneously process depth measurement and infrared remote control signals, it avoids the complexity of the traditional solution that requires additional photosensitive devices, which not only simplifies the system design, but also reduces production and maintenance costs. As the core component of the system, the SPAD array has high sensitivity and can generate effective electrical signal output when receiving weak light signals. This enables the system to perform accurate depth measurement and infrared remote control signal reception under various lighting conditions, improving the reliability and accuracy of the system. The system uses a controller to realize flexible switching between ranging mode and remote control mode. Users can select the corresponding mode according to actual needs to meet the needs of different application scenarios.

[0014] In some optional embodiments, it further includes: a light source emitting device connected to the controller;

[0015] The controller is also used to control the light source emitting device to emit a light pulse signal.

[0016] In the above technical solution, the light source emitting device emits a light pulse signal, and the light pulse signal is used to measure the flight time.

[0017] In some optional embodiments, when the remote control ranging system is in the ranging mode, the SPAD array receives photons emitted by the light source emitting device and outputs a sensing signal to the ranging signal processing module.

[0018] In the ranging mode, the controller first controls the light source emitting device to emit a series of light pulse signals. Parameters such as the frequency, pulse width and intensity of the light pulse signal can be adjusted according to the specific ranging requirements and the characteristics of the target object. When the light pulse signal is irradiated on the target object, some photons will be reflected back and received by the SPAD array. Each SPAD unit in the SPAD array is a highly sensitive light detector. When a photon is received, it undergoes an avalanche multiplication effect and generates an electrical signal (ie, a sensing signal). These sensing signals contain the time information of the light pulse arriving at the SPAD array, which is the key data for ranging.

[0019] In some optional implementations, the ranging signal processing module includes: a TDC module and a histogram processing module;

[0020] The TDC module is used to convert the sensing signal into a digital time signal;

[0021] The histogram processing module is used to perform statistics and classification on the digital time signal, generate a histogram, and parse out the depth information in the histogram.

[0022] In the above technical solution, when the SPAD array receives photons and generates a sensing signal (which is an analog electrical signal), the signal is input to the TDC module. The TDC module contains a high-precision time measurement circuit that can accurately record the time point when the sensing signal arrives. By comparing with a known reference time point (such as the emission time of the light pulse), the TDC module can calculate the flight time of the light pulse and convert it into a time signal in digital format. The histogram processing module first counts each digital time signal, and then distributes these signals to different time buckets (bins) according to different time intervals. As time goes by, the counts in each time bucket will gradually increase, forming a histogram of time distribution. Since the propagation speed of the light pulse in the air is constant (i.e., the speed of light), the counts in different time buckets actually represent the number of reflected photons at different distances. By analyzing the shape and peak position of the histogram, the histogram processing module can determine the depth information of the target object. Specifically, the peak position in the histogram usually corresponds to the distance of the target object, while the width and shape of the peak provide information about the surface roughness and reflectivity of the target object.

[0023] In some optional implementations, the system further includes: a remote control transmitting device; the remote control transmitting device includes: a signal generating module and a modulation transmitting module;

[0024] The signal generating module is used to generate a control signal according to a user instruction;

[0025] The modulation and transmission module is used to modulate the control signal onto an infrared carrier and transmit the modulated signal via infrared.

[0026] In the above technical solution, when the user issues an instruction through an input device (such as a button, a touch screen or a voice recognition system), the instruction is input into the signal generation module. The signal generation module contains one or more processors or microcontrollers for parsing user instructions and generating corresponding control signals. These control signals are then sent to the modulation and transmission module for further processing. The modulation and transmission module contains an infrared transmitter and a modulation circuit. The modulation circuit receives the control signal from the signal generation module and modulates it to a specific infrared carrier frequency. The infrared transmitter is responsible for transmitting the modulated infrared signal. Since the infrared signal has good penetration and directionality, it can be accurately received by the receiving part of the remote control ranging system at a long distance.

[0027] In some optional implementations, when the remote control ranging system is in remote control mode, the SPAD array receives a modulated signal transmitted by the remote control transmitting device, and outputs a sensing signal to the remote control signal processing module.

[0028] In the above technical solution, when the modulated signal emitted by the remote control transmitting device reaches the remote control ranging system, the SPAD array starts working as the receiving part of the system. Each SPAD unit in the SPAD array is a highly sensitive light detector that can receive the modulated signal on the infrared carrier. Since the modulated signal is transmitted in the form of photons, when these photons are received by the SPAD unit, they trigger the avalanche multiplication effect, thereby generating an electrical signal (i.e., a sensing signal). This sensing signal contains the information of the modulated signal, i.e., the remote control command sent by the user.

[0029] In some optional implementations, the remote control signal processing module includes: an infrared signal sampling module and an infrared signal demodulation module;

[0030] The infrared signal sampling module is used to downsample and filter the sensing signal to obtain a modulated recovery signal;

[0031] The infrared signal demodulation module is used to demodulate the modulated recovery signal to obtain a control signal.

[0032] In the above technical solution, the infrared signal sampling module can downsample and filter the sensing signal output by the SPAD array to obtain a modulated recovery signal. This process helps to remove noise and interference in the signal and improve the quality of the signal. The infrared signal demodulation module further demodulates the modulated recovery signal to obtain a control signal. This demodulation process can accurately restore the original infrared remote control signal to ensure that the system can correctly respond to remote control commands.

[0033] In some optional implementations, the infrared signal sampling module includes a counter and a timer;

[0034] When the infrared signal sampling module receives a pulse, the counter starts counting pulses and starts the timer at the same time, and performs continuous processing according to the following logic:

[0035] If no new pulse is received within the set time, determining that the modulation recovery signal is at the first level;

[0036] When pulses greater than a set number are continuously received within a set time, it is determined that the modulation recovery signal is at a second level;

[0037] If pulses greater than the set number are continuously received within the set time and no pulses are received within the next set time, it is determined as the pulse end time of the modulation recovery signal.

[0038] In the above technical solution, through the cooperation of the counter and the timer, the infrared signal sampling module can accurately identify and process the received infrared pulse signal.

[0039] In some optional implementations, the infrared signal demodulation module is further used to: identify a signal interval with a carrier and a signal interval without a carrier, and remove the carrier from the signal interval with a carrier to obtain a control signal.

[0040] In some optional implementations, the controller is further configured to enter a distance measurement mode upon receiving a distance measurement instruction; after the distance measurement is completed, exit the distance measurement mode and enter a remote control mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A schematic diagram of a remote control ranging system based on SPAD provided in an embodiment of the present application;

[0043] Figure 2 A schematic diagram of a remote control signal processing flow provided in an embodiment of the present application;

[0044] Figure 3 This is a waveform diagram of the modulation and demodulation process provided in an embodiment of the present application.

[0045] Icon: 1-light source transmitting device, 2-controller, 3-receiving device, 31-SPAD array, 32-ranging signal processing module, 33-remote control signal processing module, 331-infrared signal sampling module, 332-infrared signal demodulation module, 4-remote control transmitting device, 41-signal generating module, 42-modulation transmitting module. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0047] Please refer to Figure 1 , Figure 1 A schematic diagram of a SPAD-based remote control ranging system provided in an embodiment of the present application, the system includes: a controller 2, and a receiving device 3 connected to the controller 2.

[0048] The receiving device 3 includes: a SPAD array 31 , and a ranging signal processing module 32 and a remote control signal processing module 33 connected to the SPAD array 31 .

[0049] The SPAD array 31 is used to receive input signals and output sensing signals; the ranging signal processing module 32 is used to obtain depth information based on the sensing signals; and the remote control signal processing module 33 is used to obtain a demodulated signal based on the sensing signals.

[0050] The controller 2 is used to: set to the distance measurement mode, and control the SPAD to output the sensing signal to the distance measurement signal processing module 32; or, set to the remote control mode, and control the SPAD to output the sensing signal to the remote control signal processing module 33.

[0051] The remote control ranging system based on SPAD cannot use its ranging function and remote control function at the same time. The reason is that if the SPAD array 31 receives the ranging signal and the remote control signal at the same time, the two signals will interfere with each other. Therefore, the remote control ranging system is switched between the ranging mode and the remote control mode by manual switching. For example, the remote control ranging system works in the remote control mode by default. When the controller 2 receives the ranging instruction, it enters the ranging mode; after the ranging is completed, it exits the ranging mode and enters the remote control mode. For another example, the remote control ranging system works in the ranging mode by default. When the controller 2 receives the remote control instruction, it enters the remote control mode; after the remote control process is completed, it exits the remote control mode and enters the ranging mode.

[0052] In remote control mode, the system can perform infrared communication, infrared coding learning, and store the obtained modulation coding.

[0053] In the embodiment of the present application, the system realizes the functions of simultaneously completing depth measurement and infrared remote control signal reception in a single device by integrating the SPAD array 31, the ranging signal processing module 32 and the remote control signal processing module 33. Since the system adopts a single receiving device 3 based on SPAD to simultaneously process depth measurement and infrared remote control signals, the complexity of the traditional solution that requires additional photosensitive devices is avoided, which not only simplifies the system design, but also reduces production and maintenance costs. As the core component of the system, the SPAD array 31 has high sensitivity characteristics and can generate effective electrical signal output when receiving weak light signals. This enables the system to perform accurate depth measurement and infrared remote control signal reception under various lighting conditions, improving the reliability and accuracy of the system. The system realizes flexible switching between ranging mode and remote control mode through the controller 2, and users can select the corresponding mode according to actual needs to meet the needs of different application scenarios.

[0054] In some optional embodiments, it further includes: a light source emitting device 1 connected to a controller 2; the controller 2 is also used to control the light source emitting device 1 to emit a light pulse signal.

[0055] In the embodiment of the present application, the light source emitting device 1 emits a light pulse signal, and the light pulse signal is used to measure the flight time.

[0056] In some optional embodiments, when the remote control ranging system is in the ranging mode, the SPAD array 31 receives photons emitted by the light source emitting device 1 and outputs a sensing signal to the ranging signal processing module 32 .

[0057] In the ranging mode, the controller 2 first controls the light source emitting device 1 to emit a series of light pulse signals. Parameters such as the frequency, pulse width and intensity of the light pulse signal can be adjusted according to the specific ranging requirements and the characteristics of the target object. When the light pulse signal is irradiated onto the target object, some photons will be reflected back and received by the SPAD array 31. Each SPAD unit in the SPAD array 31 is a highly sensitive light detector. When a photon is received, it will experience an avalanche multiplication effect and generate an electrical signal (i.e., a sensing signal). These sensing signals contain the time information of the light pulse arriving at the SPAD array 31, which is the key data for ranging.

[0058] In some optional implementations, the ranging signal processing module 32 includes: a TDC module and a histogram processing module;

[0059] The TDC module is used to convert the sensing signal into a digital time signal;

[0060] The histogram processing module is used to count and classify the digital time signal, generate a histogram, and parse out the depth information in the histogram.

[0061] In the embodiment of the present application, when the SPAD array 31 receives a photon and generates a sensing signal (the signal is an analog electrical signal), the signal is input to the TDC module. The TDC module contains a high-precision time measurement circuit that can accurately record the time point when the sensing signal arrives. By comparing with a known reference time point (such as the emission time of the light pulse), the TDC module can calculate the flight time of the light pulse and convert it into a time signal in digital format. The histogram processing module first counts each digital time signal, and then distributes these signals to different time buckets (bins) according to different time intervals. As time goes by, the counts in each time bucket will gradually increase, forming a histogram of time distribution. Since the propagation speed of the light pulse in the air is constant (i.e., the speed of light), the counts in different time buckets actually represent the number of reflected photons at different distances. By analyzing the shape and peak position of the histogram, the histogram processing module can determine the depth information of the target object. Specifically, the peak position in the histogram usually corresponds to the distance of the target object, while the width and shape of the peak provide information about the surface roughness and reflectivity of the target object.

[0062] Please refer to Figure 2 , Figure 2 A schematic diagram of the remote control signal processing flow provided in an embodiment of the present application.

[0063] In some optional implementations, it further includes: a remote control transmitting device 4; the remote control transmitting device 4 includes: a signal generating module 41 and a modulation transmitting module 42;

[0064] The signal generating module 41 is used to generate a control signal according to a user instruction;

[0065] The modulation and transmission module 42 is used to modulate the control signal onto an infrared carrier and transmit the modulated signal via infrared.

[0066] In the embodiment of the present application, when a user issues an instruction through an input device (such as a button, a touch screen or a voice recognition system), the instruction is input into the signal generation module 41. The signal generation module 41 contains one or more processors or microcontrollers 2 for parsing user instructions and generating corresponding control signals. These control signals are then sent to the modulation and transmission module 42 for further processing. The modulation and transmission module 42 contains an infrared transmitter and a modulation circuit. The modulation circuit receives the control signal from the signal generation module 41 and modulates it to a specific infrared carrier frequency. The infrared transmitter is responsible for transmitting the modulated infrared signal. Since the infrared signal has good penetration and directivity, it can be accurately received by the receiving part of the remote control ranging system at a long distance.

[0067] In some optional implementations, when the remote control ranging system is in the remote control mode, the SPAD array 31 receives the modulated signal transmitted by the remote control transmitting device 4 and outputs the sensing signal to the remote control signal processing module 33 .

[0068] In the embodiment of the present application, when the modulated signal emitted by the remote control transmitting device 4 reaches the remote control ranging system, the SPAD array 31 starts working as the receiving part of the system. Each SPAD unit in the SPAD array 31 is a highly sensitive photodetector that can receive the modulated signal on the infrared carrier. Since the modulated signal is transmitted in the form of photons, when these photons are received by the SPAD unit, they trigger the avalanche multiplication effect, thereby generating an electrical signal (i.e., a sensing signal). This sensing signal contains the information of the modulated signal, i.e., the remote control command sent by the user.

[0069] In some optional implementations, the remote control signal processing module 33 includes: an infrared signal sampling module 331 and an infrared signal demodulation module 332;

[0070] The infrared signal sampling module 331 is used to downsample and filter the sensing signal to obtain a modulated recovery signal;

[0071] The infrared signal demodulation module 332 is used to demodulate the modulated recovery signal to obtain a control signal.

[0072] In the embodiment of the present application, the infrared signal sampling module 331 can downsample and filter the sensing signal output by the SPAD array 31 to obtain a modulated recovery signal. This process helps to remove noise and interference in the signal and improve the quality of the signal. The infrared signal demodulation module 332 further demodulates the modulated recovery signal to obtain a control signal. This demodulation process can accurately restore the original infrared remote control signal to ensure that the system can correctly respond to the remote control command.

[0073] In some optional implementations, the infrared signal sampling module 331 includes a counter and a timer;

[0074] When the infrared signal sampling module 331 receives a pulse, the counter starts counting the pulse and starts the timer at the same time, and performs continuous processing according to the following logic:

[0075] If no new pulse is received within the set time, determining that the modulation recovery signal is at the first level;

[0076] When pulses greater than a set number are continuously received within a set time, it is determined that the modulation recovery signal is at a second level;

[0077] If pulses greater than the set number are continuously received within the set time and no pulses are received within the next set time, it is determined as the pulse end time of the modulation recovery signal.

[0078] In the embodiment of the present application, through the cooperation of the counter and the timer, the infrared signal sampling module 331 can accurately identify and process the received infrared pulse signal.

[0079] In some optional implementations, the infrared signal demodulation module 332 is further used to: identify a signal interval with a carrier and a signal interval without a carrier, and remove the carrier from the signal interval with a carrier to obtain a control signal.

[0080] Specifically, the modulation process of the remote control transmitting device 4 and the demodulation process of the receiving device 3 are as follows: Figure 3 shown.

[0081] The specific modulation process includes:

[0082] Using PPM (Pulse Position Modulation) technology, the original signal input is modulated onto the carrier to obtain PPM modulated output.

[0083] The PPM modulation output drives the LED to emit an infrared signal. In this embodiment, the low level of the PPM modulation output corresponds to infrared light emission.

[0084] The demodulation process includes:

[0085] The SPAD array 31 samples the infrared signal and outputs a high-frequency pulse. The infrared signal sampling module 331 is used to downsample and filter the sampled output of the SPAD array 31 to restore the PPM signal, and the restored PPM signal is digitally processed to demodulate the original input signal.

[0086] Among them, the downsampling filter is designed with a counter. In order to suppress the noise output caused by self-triggering and ambient light noise triggering of SPAD, the counter threshold lower limit and timer are introduced. When the SPAD output pulse is received, the counter starts counting pulses and starts the timer at the same time. The logic level of the specific PPM signal is judged as follows:

[0087] If no new SPAD output pulse is received within a specified time, such as 1 microsecond, it is considered that no infrared signal is received and a corresponding logic high level is output.

[0088] Within the specified time, such as 1 microsecond for the timer, if a new SPAD pulse arrives, the counter increases by 1 and resets the timer. If the counter value exceeds the lower limit of the counter threshold, it is considered that the infrared signal is received and the corresponding logic low level is output. If the counter value exceeds the counter threshold but no SPAD pulse signal is received during the next timing period, it is considered that the infrared signal ends and is identified as the pulse end time, that is, the falling edge.

[0089] The above process is used to restore the PPM signal. After the PPM signal is restored, the signal interval with carrier and the signal interval without carrier are identified, and finally the original input signal is demodulated from the PPM signal.

[0090] It should be clear that, in the present embodiment, the low level of the PPM modulation output corresponds to infrared light emission; however, in other embodiments, the high level of the PPM modulation output may correspond to infrared light emission.

[0091] In this embodiment, the SPAD sampling frequency is about 40MHz, the infrared modulation signal frequency is about tens of KHz, and the original input signal is about hundreds of Hz. Since the SPAD array can sample at a high frequency, the pulse of the infrared signal can be captured more accurately, which is particularly important for signal demodulation of modulation methods such as PPM (pulse position modulation).

[0092] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0093] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0094] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0095] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0096] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A remote control ranging system based on SPAD, characterized in that: include: A controller, and a receiving device connected to the controller; The receiving device comprises: a SPAD array, and a ranging signal processing module and a remote control signal processing module connected to the SPAD array; The SPAD array is used to receive an input signal and output a sensing signal; the ranging signal processing module is used to obtain depth information according to the sensing signal; the remote control signal processing module is used to obtain a demodulated signal according to the sensing signal; The controller is used to: Setting the ranging mode to control the SPAD to output a sensing signal to the ranging signal processing module; Or, set to remote control mode, and control the SPAD to output a sensing signal to the remote control signal processing module.

2. The remote control ranging system according to claim 1, characterized in that: Also includes: A light source emitting device connected to the controller; The controller is also used to control the light source emitting device to emit a light pulse signal.

3. The remote control ranging system according to claim 2, characterized in that: When the remote control ranging system is in ranging mode, the SPAD array receives photons emitted by the light source emitting device and outputs a sensing signal to the ranging signal processing module.

4. The remote control ranging system according to claim 1, characterized in that: The ranging signal processing module includes: a TDC module and a histogram processing module; The TDC module is used to convert the sensing signal into a digital time signal; The histogram processing module is used to perform statistics and classification on the digital time signal, generate a histogram, and parse out the depth information in the histogram.

5. The remote control ranging system according to claim 1, characterized in that: Also includes: Remote control transmitting device; The remote control transmitting device comprises: a signal generating module and a modulation transmitting module; The signal generating module is used to generate a control signal according to a user instruction; The modulation and transmission module is used to modulate the control signal onto an infrared carrier and transmit the modulated signal via infrared.

6. The remote control ranging system according to claim 5, characterized in that: When the remote control ranging system is in the remote control mode, the SPAD array receives the modulated signal transmitted by the remote control transmitting device, and outputs a sensing signal to the remote control signal processing module.

7. The remote control ranging system according to claim 1, characterized in that: The remote control signal processing module includes: an infrared signal sampling module and an infrared signal demodulation module; The infrared signal sampling module is used to downsample and filter the sensing signal to obtain a modulated recovery signal; The infrared signal demodulation module is used to demodulate the modulated recovery signal to obtain a control signal.

8. The remote control ranging system according to claim 7, characterized in that: The infrared signal sampling module includes a counter and a timer; When the infrared signal sampling module receives a pulse, the counter starts counting pulses and starts the timer at the same time, and performs continuous processing according to the following logic: If no new pulse is received within the set time, determining that the modulation recovery signal is at the first level; When pulses greater than a set number are continuously received within a set time, it is determined that the modulation recovery signal is at a second level; If pulses greater than the set number are continuously received within the set time and no pulses are received within the next set time, it is determined as the pulse end time of the modulation recovery signal.

9. The remote control ranging system according to claim 7, characterized in that: The infrared signal demodulation module is also used to: identify a signal interval with a carrier and a signal interval without a carrier, and remove the carrier from the signal interval with a carrier to obtain a control signal.

10. The remote control ranging system according to claim 1, characterized in that: The controller is also used to enter the distance measurement mode when receiving the distance measurement instruction; after the distance measurement is completed, exit the distance measurement mode and enter the remote control mode.

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