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] This application relates to the field of SPAD technology, and more specifically, to a SPAD-based remote ranging system. Background Technology

[0002] DTOF devices, or direct time-of-flight depth measurement chips, are an advanced chip technology used for three-dimensional depth sensing.

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

[0004] The core component of a DTOF device is a single-photon avalanche diode (SPAD). A SPAD is a highly sensitive optoelectronic device that generates an avalanche effect upon receiving a single photon, thereby triggering an electrical signal. DTOF devices utilize the high sensitivity of SPADs to detect weak light pulse signals, achieving high-precision distance measurement.

[0005] Traditional infrared remote control signal demodulation typically employs a photodiode-based demodulation scheme. Implementing infrared remote control in a DTOF device usually requires adding an additional photosensitive device to receive the infrared remote control signal. Utility Model Content

[0006] The purpose of this application is to provide a SPAD-based remote control ranging system to solve the problem that existing DTOF devices typically require additional photosensitive devices to receive infrared remote control signals.

[0007] This application provides a SPAD-based remote ranging system, comprising: a controller, and a receiving device connected to the controller;

[0008] The receiving device includes: 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 input signals and output sensing signals; the ranging signal processing module is used to obtain depth information based on the sensing signals; the remote control signal processing module is used to obtain demodulated signals based on the sensing signals.

[0010] The controller is used for:

[0011] Set to ranging mode and control the SPAD to output sensing signals to the ranging signal processing module;

[0012] Alternatively, it can be set to remote control mode and the SPAD can be controlled to output sensing signals to the remote control signal processing module.

[0013] In the above technical solution, the system integrates a SPAD array, a ranging signal processing module, and a remote control signal processing module, achieving simultaneous depth measurement and infrared remote control signal reception in a single device. Because the system uses a single SPAD-based receiver to process both depth measurement and infrared remote control signals, it avoids the complexity of adding additional photosensitive devices as required in traditional solutions. This simplifies system design and reduces production and maintenance costs. The SPAD array, as the core component of the system, possesses high sensitivity, capable of generating effective electrical signal output even 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 system reliability and accuracy. The system uses a controller to flexibly switch between ranging and remote control modes, allowing users to select the appropriate mode according to their actual needs, thus meeting the requirements of different application scenarios.

[0014] In some optional implementations, 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 light pulse signals.

[0016] In the above technical solution, the light source emitting device emits light pulse signals, which are used to measure the time of flight.

[0017] In some optional implementations, when the remote 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.

[0018] In ranging mode, the controller first controls the light source emitting device to emit a series of light pulse signals. The frequency, pulse width, and intensity of the light pulse signals can be adjusted according to specific ranging requirements and the characteristics of the target object. When the light pulse signal illuminates the target object, some photons are reflected back and received by the SPAD array. Each SPAD unit in the SPAD array is a highly sensitive photosensor. When it receives a photon, it undergoes an avalanche multiplication effect, generating an electrical signal (i.e., a sensing signal). These sensing signals contain information about the time the light pulse arrives at the SPAD array, which is crucial 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 digital time signals, generate histograms, and parse out the depth information in the histograms.

[0022] In the above technical solution, when the SPAD array receives photons and generates a sensing signal (an analog electrical signal), this signal is input to the TDC module. The TDC module contains a high-precision time measurement circuit capable of accurately recording the arrival time of the sensing signal. By comparing it with a known reference time (such as the emission time of a light pulse), the TDC module can calculate the flight time of the light pulse and convert it into a digital time signal. The histogram processing module first counts each digital time signal and then distributes these signals into different time bins according to the different time intervals. Over time, the count in each time bin gradually increases, forming a histogram of time distribution. Since the propagation speed of a light pulse in air is constant (i.e., the speed of light), the counts in different time bins actually represent the number of reflected photons at different distances. By analyzing the shape and peak positions of the histogram, the histogram processing module can determine the depth information of the target object. Specifically, the peak positions in the histogram typically correspond to the distance to the target object, while the width and shape of the peaks provide information about the surface roughness and reflectivity of the target object.

[0023] In some optional embodiments, it further includes: a remote control transmitting device; the remote control transmitting device includes: a signal generation module and a modulation transmission module;

[0024] The signal generation module is used to generate control signals according to user instructions;

[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 a user issues a command through an input device (such as a button, touchscreen, or voice recognition system), the command is input to the signal generation module. The signal generation module contains one or more processors or microcontrollers to parse the user command and generate 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 this modulated infrared signal. Because infrared signals have good penetration and directionality, they can be accurately received by the receiving part of the remote control ranging system at a relatively long distance.

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

[0028] In the above technical solution, when the modulated signal emitted by the remote control transmitter arrives at the remote control ranging system, the SPAD array, acting as the system's receiving part, begins to operate. Each SPAD unit in the SPAD array is a highly sensitive photodetector capable of receiving the modulated signal on the infrared carrier. Since the modulated signal propagates in the form of photons, when these photons are received by the SPAD unit, they trigger an avalanche multiplication effect, thereby generating an electrical signal (i.e., a sensing signal). This sensing signal contains information about the modulated signal, namely 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 sensed signal to obtain the modulated recovery signal;

[0031] The infrared signal demodulation module is used to demodulate the modulated recovery signal to obtain the 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 the modulation recovery signal. This process helps to remove noise and interference from the signal and improve signal quality. The infrared signal demodulation module further demodulates the modulation recovery signal to obtain the control signal. This demodulation process can accurately restore the original infrared remote control signal, ensuring 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 simultaneously starts the timer, and performs continuous processing according to the following logic:

[0035] If no new pulse is received within the set time, the modulation recovery signal is determined to be at the first level.

[0036] If more than a set number of pulses are received continuously within a set time, the modulation recovery signal is determined to be at the second level.

[0037] If more than a set number of pulses are received continuously within a set time period and no pulses are received in the next set time period, then the pulse end time of the modulation recovery signal is determined.

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

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

[0040] In some optional implementations, the controller is also configured to enter a ranging mode when it receives a ranging command; and exit the ranging mode and enter a remote control mode after the ranging is completed. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 A schematic diagram of a SPAD-based remote ranging system provided in an embodiment of this application;

[0043] Figure 2 This is a schematic diagram of the remote control signal processing flow provided in the embodiments of this application;

[0044] Figure 3 The waveform diagram is shown in the modulation and demodulation process provided in the embodiment of this application.

[0045] Icons: 1-Light source emitting device, 2-Controller, 3-Receiver, 31-SPAD array, 32-Range 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 generation module, 42-Modulation transmitting module. Detailed Implementation

[0046] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0047] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a SPAD-based remote ranging system provided in an embodiment of this 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, a ranging signal processing module 32 and a remote control signal processing module 33 connected to the SPAD array 31.

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

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

[0051] In a SPAD-based remote ranging system, the ranging and remote control functions cannot be used simultaneously because the SPAD array 31 will interfere with each other if it receives both ranging and remote control signals at the same time. Therefore, the system is manually switched between ranging and remote control modes. For example, the system defaults to remote control mode. When controller 2 receives a ranging command, it enters ranging mode; after ranging is completed, it exits ranging mode and enters remote control mode. Alternatively, the system defaults to ranging mode. When controller 2 receives a remote control command, it enters remote control mode; after the remote control process is completed, it exits remote control mode and enters ranging mode.

[0052] In remote control mode, the system can perform infrared communication. It can also learn infrared codes and store the obtained modulation codes.

[0053] In this embodiment, the system integrates a SPAD array 31, a ranging signal processing module 32, and a remote control signal processing module 33, achieving simultaneous depth measurement and infrared remote control signal reception in a single device. Because the system uses a single SPAD-based receiving device 3 to simultaneously process depth measurement and infrared remote control signals, it avoids the complexity of adding additional photosensitive devices as required in traditional solutions. This simplifies system design and reduces production and maintenance costs. The SPAD array 31, as the core component of the system, possesses high sensitivity, capable of generating effective electrical signal output even 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 system reliability and accuracy. The system uses a controller 2 to flexibly switch between ranging and remote control modes, allowing users to select the appropriate mode according to their actual needs, thus meeting the requirements of different application scenarios.

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

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

[0056] In some optional implementations, when the remote ranging system is in 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 ranging mode, controller 2 first controls the light source emitting device 1 to emit a series of light pulse signals. The frequency, pulse width, and intensity of the light pulse signals can be adjusted according to specific ranging requirements and the characteristics of the target object. When the light pulse signals illuminate the target object, some photons are reflected back and received by the SPAD array 31. Each SPAD unit in the SPAD array 31 is a highly sensitive photodetector. When it receives photons, it undergoes an avalanche multiplication effect, generating an electrical signal (i.e., a sensing signal). These sensing signals contain the time information of the light pulses arriving at the SPAD array 31, which is crucial 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 sensed signal into a digital time signal;

[0060] The histogram processing module is used to perform statistics and classification on digital time signals, generate histograms, and parse out the depth information in the histograms.

[0061] In this embodiment, when the SPAD array 31 receives photons and generates a sensing signal (an analog electrical signal), this signal is input to the TDC module. The TDC module contains a high-precision time measurement circuit capable of accurately recording the arrival time of the sensing signal. By comparing it with a known reference time (such as the emission time of a light pulse), the TDC module can calculate the flight time of the light pulse and convert it into a digital time signal. The histogram processing module first counts each digital time signal and then distributes these signals into different time bins according to the different time intervals. Over time, the count in each time bin gradually increases, forming a histogram of time distribution. Since the propagation speed of a light pulse in air is constant (i.e., the speed of light), the counts in different time bins actually represent the number of reflected photons at different distances. By analyzing the shape and peak positions of the histogram, the histogram processing module can determine the depth information of the target object. Specifically, the peak positions in the histogram typically correspond to the distance to the target object, while the width and shape of the peaks provide information about the surface roughness and reflectivity of the target object.

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

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

[0064] Signal generation module 41 is used to generate control signals according to user instructions;

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

[0066] In this embodiment, when a user issues a command through an input device (such as a button, touchscreen, or voice recognition system), the command is input to the signal generation module 41. The signal generation module 41 internally contains one or more processors or microcontrollers 2, used to parse the user command and generate 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 internally 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 this modulated infrared signal. Because infrared signals have good penetration and directionality, they can be accurately received by the receiving part of the remote ranging system at a relatively long distance.

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

[0068] In this embodiment, when the modulated signal emitted by the remote control transmitter 4 arrives at the remote control ranging system, the SPAD array 31, acting as the receiving part of the system, begins to operate. Each SPAD unit in the SPAD array 31 is a highly sensitive photodetector capable of receiving the modulated signal on the infrared carrier. Since the modulated signal propagates in the form of photons, when these photons are received by the SPAD units, they trigger an avalanche multiplication effect, thereby generating an electrical signal (i.e., a sensing signal). This sensing signal contains information about the modulated signal, namely, 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] Infrared signal sampling module 331 is used to downsample and filter the sensed signal to obtain the modulated recovery signal;

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

[0072] In this embodiment, the infrared signal sampling module 331 downsamples and filters the sensing signal output by the SPAD array 31 to obtain a modulated recovery signal. This process helps remove noise and interference from the signal, improving signal quality. The infrared signal demodulation module 332 further demodulates the modulated recovery signal to obtain a control signal. This demodulation process accurately restores the original infrared remote control signal, ensuring that the system can correctly respond to remote control commands.

[0073] In some alternative implementations, the infrared signal sampling module 331 employs logic circuitry including a counter and a timer;

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

[0075] If no new pulse is received within the set time, the modulation recovery signal is determined to be at the first level.

[0076] If more than a set number of pulses are received continuously within a set time, the modulation recovery signal is determined to be at the second level.

[0077] If more than a set number of pulses are received continuously within a set time period and no pulses are received in the next set time period, then the pulse end time of the modulation recovery signal is determined.

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

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

[0080] Specifically, the modulation process of the remote control transmitter 4 and the demodulation process of the receiver 3, such as... Figure 3 As shown.

[0081] The specific modulation process includes:

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

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

[0084] The demodulation process includes:

[0085] SPAD array 31 samples infrared signals and outputs high-frequency pulses; using infrared signal sampling module 331, the sampling output of SPAD array 31 is downsampled and filtered to recover the PPM signal; the recovered PPM signal is then digitally processed to demodulate the original input signal.

[0086] The downsampling filter is designed using a counter. To suppress noise output from the SPAD caused by self-triggering and ambient light noise, a lower threshold for the counter and a timer are introduced. When a SPAD output pulse is received, the counter starts counting pulses and simultaneously starts the timer. The specific logic level of the PPM signal is determined as follows:

[0087] Within a specified time, such as 1 microsecond for timer, if no new SPAD output pulse is received, it is assumed that no infrared signal has been received and the corresponding logic high level is output.

[0088] Within a specified time period, for example, 1 microsecond for the timer, if a new SPAD pulse arrives, the counter increments by 1 and the timer is reset. If the counter value exceeds the lower limit of the counter threshold, it is considered that an infrared signal has been received, and the corresponding logic low level is output. If the counter value exceeds the counter threshold but no SPAD pulse signal is received in the next timing period, it is considered that the infrared signal has ended, identified as the pulse end moment, which is the falling edge.

[0089] The above process is used to recover the PPM signal. After the PPM signal is recovered, the signal intervals with and without carrier waves are identified, and finally the original input signal is demodulated from the PPM signal.

[0090] It should be clarified that in this embodiment, the low level of the PPM modulation output corresponds to infrared emission; however, in other embodiments, the high level of the PPM modulation output can also correspond to infrared emission.

[0091] In this embodiment, the SPAD sampling frequency is approximately 40MHz, the infrared modulation signal frequency is approximately tens of kHz, and the original input signal is approximately several hundred Hz. Because the SPAD array can sample at high frequencies, it can more accurately capture the pulses of the infrared signal, which is particularly important for demodulating signals using modulation methods such as PPM (Pulse Position Modulation).

[0092] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0093] Furthermore, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

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

[0095] In this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, without necessarily requiring or implying any such actual relationship or order between these entities or operations.

[0096] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A SPAD-based remote ranging system, characterized in that, include: A controller, and a receiving device connected to the controller; The receiving device includes: 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 input signals and output sensing signals; the ranging signal processing module is used to obtain depth information based on the sensing signals; the remote control signal processing module is used to obtain demodulated signals based on the sensing signals. The controller is used for: Set to ranging mode and control the SPAD to output sensing signals to the ranging signal processing module; Alternatively, it can be set to remote control mode and the SPAD can be controlled to output sensing signals to the remote control signal processing module.

2. The remote ranging system as described in 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 light pulse signals.

3. The remote ranging system as described in claim 2, characterized in that, When the remote 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 ranging system as described in 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 digital time signals, generate histograms, and parse out the depth information in the histograms.

5. The remote ranging system as described in claim 1, characterized in that, Also includes: Remote control transmitting device; The remote control transmitting device includes: a signal generation module and a modulation transmission module; The signal generation module is used to generate control signals according to user instructions; 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 ranging system as described in claim 5, characterized in that, When the remote ranging system is in remote control mode, the SPAD array receives the modulation signal transmitted by the remote control transmitter and outputs the sensing signal to the remote control signal processing module.

7. The remote ranging system as described in 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 sensed signal to obtain the modulated recovery signal; The infrared signal demodulation module is used to demodulate the modulated recovery signal to obtain the control signal.

8. The remote ranging system as described in 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 simultaneously starts the timer, and performs continuous processing according to the following logic: If no new pulse is received within the set time, the modulation recovery signal is determined to be at the first level. If more than a set number of pulses are received continuously within a set time, the modulation recovery signal is determined to be at the second level. If more than a set number of pulses are received continuously within a set time period and no pulses are received in the next set time period, then the pulse end time of the modulation recovery signal is determined.

9. The remote ranging system as described in claim 7, characterized in that, The infrared signal demodulation module is also used to: identify signal intervals with carrier waves and signal intervals without carrier waves, remove the carrier wave from the signal intervals with carrier waves, and obtain control signals.

10. The remote ranging system as described in claim 1, characterized in that, The controller is also used to enter the ranging mode when it receives a ranging command; and to exit the ranging mode and enter the remote control mode after the ranging is completed.

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