Method and system for estimating the coding amount of satellite-to-ground quantum key distribution based on satellite cloud images

Abstract

The present invention proposes a coding amount estimation method and system for satellite-to-ground quantum key distribution based on satellite cloud images, wherein the satellite cloud images are analyzed to obtain the time-varying satellite-to-ground channel attenuation conditions that are consistent with the actual situation. Based on the actual satellite-to-ground channel attenuation conditions obtained by simulation and the actual background noise obtained by scanning the satellite orbit, the coding amount of any time period can be accurately estimated according to the coding formula through simulation calculation, so that the quantitative estimation of coding can be realized in satellite-to-ground quantum key distribution in accordance with the actual situation.

Description

Technical Field

[0001] The present invention relates to the field of quantum communication, and in particular to a method and system for estimating the coding amount of satellite-to-ground quantum key distribution based on satellite cloud images. Background Art

[0002] Quantum key distribution (QKD) uses quantum systems to prepare, transmit, receive and purify information to obtain secure symmetric keys that cannot be stolen by others in physical principles. This process ensures that the keys obtained by the communicating parties are completely consistent and that no third party can obtain any information about the keys.

[0003] The code generation capacity of quantum key distribution based on the BB84 protocol is generally estimated using preset parameters, that is, setting some fixed values, directly calculating the code generation rate per second according to the formula, and then multiplying it by the working time to get the code generation capacity. For example, in some existing technologies, the code generation rate at different distances is first obtained using fixed parameters, and then the code generation capacity within a certain period of time is obtained based on the actual system deployment.

[0004] For the prediction of satellite-ground coding conditions, the prior art generally uses weather websites to check the local weather conditions of the ground station to estimate whether it is appropriate to arrange the coding task, wherein the coding indicators cannot be quantified in advance.

[0005] The previous coding amount estimation method is only applicable to the fiber QKD system. Because the channel attenuation of the fiber QKD system is fixed, the coding rate is basically a fixed value. Therefore, in the traditional method, the coding rate can be directly calculated and then multiplied by the working time to get the total coding amount. However, for the satellite-to-ground free-space QKD system, the satellite is always flying around the earth in space. The relative distance between the satellite and the ground station and the channel environment are changing in real time, so the channel attenuation is also changing in real time. At the same time, the working time of the satellite-to-ground free-space QKD system is not fixed, and the satellite and the ground station need to be within the visual range of each other to communicate. Therefore, simply multiplying the coding rate and time cannot get the coding amount between each orbit between the satellite and the ground. And using the weather website to check the local weather conditions of the ground station cannot get the real meteorological data on the channel between the ground station and the satellite, such as the real situation of information such as the cloud cover above the ground station, and thus cannot get the quantitative index of coding. Summary of the invention

[0006] In view of the above-mentioned problems in the estimation of the amount of coding in satellite-to-ground quantum key distribution, the present invention proposes a method and system for estimating the amount of coding in satellite-to-ground quantum key distribution based on satellite cloud images, wherein the satellite cloud images are analyzed to obtain the time-varying satellite-to-ground channel attenuation conditions that are consistent with the actual situation. Based on the actual satellite-to-ground channel attenuation conditions obtained by simulation and the actual background noise obtained by scanning the satellite orbit, the amount of coding in any time period can be accurately estimated according to the coding formula through simulation calculation, so that the quantitative estimation of coding can be realized in satellite-to-ground quantum key distribution in accordance with the actual situation.

[0007] Specifically, one aspect of the present invention relates to a coding amount estimation method for satellite-to-ground quantum key distribution based on satellite cloud images, which includes a satellite orbit estimation step, a cloud image analysis step and a coding amount estimation step, wherein:

[0008] In the satellite orbit estimation step, the satellite orbit is estimated based on the ephemeris data;

[0009] In the cloud image analysis step, an original satellite cloud image of the cloud layer below the satellite orbit is obtained, and the cloud layer distribution and / or cloud top height of the cloud layer are calculated based on the visible light cloud image and the infrared light cloud image in the original satellite cloud image to calculate the atmospheric attenuation value of the satellite-to-ground free space channel; and

[0010] In the coding amount estimation step, the coding amount in a single key extraction process is estimated based on the atmospheric attenuation value of the satellite-to-ground free space channel.

[0011] Furthermore, in the cloud image analysis step, the atmospheric attenuation values ​​of the satellite-to-ground free space channel at multiple positions in the satellite orbit are calculated according to the cloud layer distribution and / or cloud top height, and the atmospheric attenuation values ​​of the satellite-to-ground free space channel at at least a part of the satellite orbit are obtained by fitting based on the atmospheric attenuation values ​​of the satellite-to-ground free space channel at the multiple positions. The fitting is achieved by interpolation and smoothing.

[0012] Furthermore, the coding amount estimation method of the present invention also includes the step of estimating a timetable for satellite-ground docking based on the atmospheric attenuation value of the satellite-ground free space channel and the ephemeris data.

[0013] Furthermore, the coding amount estimation method of the present invention also includes the step of scanning the satellite orbit to record the count of the single photon detector in the quantum key distribution device when there is no satellite signal input.

[0014] Furthermore, the coding amount estimation step is further configured to: based on the system noise at time T(i), the efficiency of the satellite-to-ground free space channel, and the system parameters, simulate and calculate part or all of the signal state gain Qu, the decoy state gain Qv, the signal state bit error rate Eu, the decoy state bit error rate Ev, the dark count rate Y0, and the dark count N0 at the time T(i), and simulate and calculate the signal state count in a time period i starting at the time T(i) and lasting for dT(i), wherein: T(i+1)=T(i)+dT(i), i is a natural number, T(1) is the starting time of the single key extraction process, and, in the time period i, the satellite-to-ground quantum key distribution All parameters in the transmission system remain unchanged and are consistent with the parameters at the starting time T(i) of the time period i; the signal state gain Qu is the probability that the transmitting end of the satellite-to-ground quantum key distribution sends a signal state with an average photon number of u and triggers the single-photon detector to respond, the decoy state gain Qv is the probability that the transmitting end sends a decoy state with an average photon number of v and triggers the single-photon detector to respond, the signal state bit error rate Eu is the bit error rate of the signal state with an average photon number of u, the decoy state bit error rate Ev is the bit error rate of the decoy state with an average photon number of v, Y0 is the probability that the transmitting end sends a vacuum state and triggers the dark count response of the single-photon detector, and N0 is the total count of dark counts;

[0015] Sum the signal state counts calculated by simulation in each time period i during the single key extraction process, and compare the sum of the signal state counts with a preset value M;

[0016] When the sum of the signal state counts is equal to or greater than the preset value M, the average values ​​of the signal state gain Qu, the signal state bit error rate Eu, Q1 and e1 of the single key extraction process are calculated, wherein Q1 is the probability that the transmitting end sends a single photon signal and triggers the single photon detector to respond, and e1 is the bit error rate of the single photon signal;

[0017] The amount of coding in the single key extraction process is estimated according to the average values ​​of the signal state gain Qu, the signal state bit error rate Eu, Q1 and e1.

[0018] Preferably, the dT(i) is set to the same value; and / or, the dT(i) is set to 1 second.

[0019] Furthermore, the coding amount estimation method of the present invention may also include the step of adding the coding amounts in all the single key extraction processes in a single track to obtain the coding amount of the single track.

[0020] Another aspect of the present invention relates to a coding amount estimation system for satellite-to-ground quantum key distribution based on satellite cloud images, which includes an optical-mechanical device, a quantum key distribution device, a host computer server and an intelligent analysis server, wherein:

[0021] The host computer server is configured to estimate the satellite orbit according to the ephemeris data, and drive the optical mechanical device to scan the satellite orbit;

[0022] The intelligent analysis server is configured to obtain an original satellite cloud image of the cloud layer below the satellite orbit, and calculate the cloud layer distribution and / or cloud top height of the cloud layer based on the visible light cloud image and the infrared light cloud image in the original satellite cloud image;

[0023] The host computer server is also configured to calculate the atmospheric attenuation value of the satellite-to-ground free space channel according to the cloud layer distribution and / or cloud top height, and to estimate the amount of coding in a single key extraction process based on the atmospheric attenuation value.

[0024] Preferably, the coding amount estimation system is configured to execute the above-mentioned coding amount estimation method proposed in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. It is obvious that the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1A An example of a raw satellite cloud image is shown;

[0028] Figure 1B It is shown that according to the present invention Figure 1A The original satellite cloud image is processed by the satellite cloud image;

[0029] Figure 2 A schematic diagram showing the composition of a coding amount estimation system for satellite-to-ground quantum key distribution based on satellite cloud images according to the present invention is shown;

[0030] Figure 3 A working principle diagram of a system and method for estimating the coding amount of satellite-to-ground quantum key distribution based on satellite cloud images according to the present invention is shown. DETAILED DESCRIPTION

[0031] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so as to fully convey the spirit of the present invention to those skilled in the art to which the present invention belongs. Therefore, the present invention is not limited to the embodiments disclosed herein.

[0032] According to the present invention, a coding amount estimation system for satellite-to-ground quantum key distribution based on satellite cloud images may include an optical-mechanical device, a quantum key distribution device, a host computer server and an intelligent analysis server.

[0033] Before the satellite-ground docking, the host server reads the ephemeris data and estimates the satellite orbit. In addition, the host server can also drive the optical machine device to scan the satellite orbit. At this time, the count of the single photon detector in the quantum key distribution device is the count when there is no satellite signal input, which is completely derived from the system's own noise (such as the internal noise of the telescope, the dark count of the detector) and environmental noise (such as the external environmental noise of the dome, the internal noise of the dome). Therefore, the count can be recorded to represent the actual system noise and used for accurate estimation of the channel coding rate (coding amount).

[0034] The intelligent analysis server can obtain the original satellite cloud image of the cloud layer below the satellite track, and the satellite cloud image may include a visible light cloud image and an infrared light cloud image. Therefore, the intelligent analysis server can obtain the cloud layer distribution and / or cloud top height of the cloud layer by analyzing the visible light cloud image and the infrared light cloud image in the original satellite cloud image.

[0035] At this time, the host server can calculate the atmospheric attenuation value of the channel on the satellite orbit according to the cloud distribution and cloud top height of the cloud layer below the satellite orbit. As an implementation method, the atmospheric attenuation values ​​of the satellite-to-ground free space channel at multiple positions in the satellite orbit can be calculated first, and then the atmospheric attenuation values ​​of the satellite-to-ground free space channel on part or the entire satellite orbit can be obtained by fitting. As an example, the above data can be fitted by means of interpolation, smoothing, etc.

[0036] Furthermore, the host server can also estimate the timetable allowing satellite-ground docking and the amount of coding based on the atmospheric attenuation value of the channel on the satellite orbit in combination with the ephemeris data.

[0037] Figure 1A The cloud image released by the meteorological satellite and obtained according to the present invention is shown, which includes the cloud image of the cloud layer below the quantum satellite orbit. Figure 1B A cloud diagram after data processing according to the present invention is shown, wherein the solid line represents the time slots allowing docking, and the dotted line represents the time slots not allowing docking.

[0038] Based on the atmospheric attenuation value of the satellite-to-ground free space channel thus obtained, the efficiency of the channel can be determined, which is related to the atmospheric attenuation value of the channel, the geometric attenuation value (which can be related to parameters such as satellite divergence angle, satellite-to-ground distance, equivalent aperture of ground station, etc.), and the tracking efficiency (which can be related to parameters such as tracking jitter, pointing deviation, etc.). Combined with the preset system parameters (such as satellite transmission frequency, basis vector comparison efficiency, signal state, decoy state, vacuum state ratio, signal state light intensity u, decoy state light intensity v, error correction algorithm efficiency, security parameters, system duty cycle, etc.) and system noise (such as dome external environmental noise, dome internal noise, telescope internal noise, detector dark count, etc.), the channel coding rate that is consistent with the actual situation can be simulated and calculated. Therefore, the coding amount in a single key extraction, or even the coding amount of a single track, can be accurately estimated.

[0039] Next, we will combine Figure 3 The workflow and coding amount estimation method of the coding amount estimation system for satellite-to-ground quantum key distribution based on satellite cloud images of the present invention are described in detail to more clearly understand the working principle of the present invention.

[0040] In the estimation system and method of the present invention, before the satellite and the ground are docked, for example, the host computer server reads the ephemeris data to estimate the satellite orbit.

[0041] The intelligent analysis server obtains the original satellite cloud image of the cloud layer below the satellite track, which may include a visible light cloud image and an infrared light cloud image. The intelligent analysis server calculates the cloud layer distribution and cloud top height of the cloud layer based on the original satellite cloud image.

[0042] The host server calculates the atmospheric attenuation value of the channel on the satellite orbit according to the cloud distribution and cloud top height of the cloud layer below the satellite orbit. For example, the atmospheric attenuation value of the satellite-to-ground free space channel at multiple predetermined positions in the satellite orbit is first calculated, and then based on the atmospheric attenuation value of the channel at these positions, the atmospheric attenuation value of the channel on part or the entire satellite orbit is fitted through data processing methods such as interpolation and smoothing.

[0043] At the same time, when the host server estimates the satellite orbit based on the ephemeris data, it also drives the optical machine to scan the satellite orbit to record the count of the single photon detector in the quantum key distribution device. As mentioned above, at this time, the count of the single photon detector in the quantum key distribution device is the count when there is no satellite signal input, which is completely derived from the system's own noise (such as internal noise of the telescope, dark count of the detector) and environmental noise (such as external environmental noise of the dome, internal noise of the dome). Therefore, this count represents the actual system noise, which will be used for accurate estimation of the channel coding rate (coding amount).

[0044] Based on the calculated atmospheric attenuation value of the channel on the quantum satellite orbit, the host server can also combine the ephemeris data to estimate the timetable that allows satellite-to-ground docking. Therefore, the coding amount of a single quantum key distribution process or the coding amount of a single track can be estimated based on the satellite-to-ground docking timetable.

[0045] After obtaining the atmospheric attenuation value of the satellite-to-ground free space channel on the quantum satellite orbit, the host server can read the relevant parameters of the optical-mechanical equipment and the quantum key distribution equipment, calculate the tracking loss and geometric loss, etc. to determine the channel efficiency, and calculate the synchronization loss, optical device (telescope, detector) loss, etc. to determine the ground station efficiency. Thus, the system efficiency (total system loss) on the free space channel is obtained, and finally the system efficiency (total system loss) on any free space channel on the orbit is calculated. In other words, the system efficiency (total system loss) of the satellite when performing quantum key distribution at any time T on a single track can be determined, that is, the system efficiency (total system loss) of the channel may be different at different times during the satellite's orbital operation, which is consistent with the actual situation in satellite-to-ground quantum key distribution.

[0046] Therefore, based on the time-varying total system loss, the coding amount of the satellite-to-ground quantum key distribution at any time can be estimated according to the coding algorithm, and then the total coding amount of the single track can be determined. Compared with the prior art method of directly calculating the coding rate according to the formula by preset values ​​to obtain the coding amount, in the present invention, since the coding amount is estimated based on the system efficiency and system noise that are consistent with the actual situation, the obtained coding amount is more accurate and can well meet the needs of satellite-to-ground quantum key distribution.

[0047] The following will further illustrate the process of estimating the amount of code generated in the quantum key distribution process by taking into account the system efficiency (total system loss) of the satellite-to-ground free space channel obtained based on satellite cloud images.

[0048] Continue to see Figure 3 , assuming that the starting time of a single key extraction process is T(1)=T1, time T(i+1)=T(i)+dT(i), i is a natural number, wherein, within a time period i starting from time T(i) and lasting for dT(i), each parameter in the satellite-to-ground quantum key distribution system remains unchanged and is consistent with the parameters at the starting time T(i) of the time period i.

[0049] Therefore, the atmospheric attenuation value or total system loss of the channel at time T(i) can be obtained from the channel state on the fitted orbit. Then, the signal state gain Qu, the decoy state gain Qv, the signal state bit error rate Eu, the decoy state bit error rate Ev, the dark count rate Y0, and the dark count N0 at time T(i) are simulated and calculated using the system noise at time T(i), the total system loss of the channel, and the system parameters preset in the quantum key distribution protocol. Among them, the signal state gain Qu is the probability that Alice sends a signal state with an average photon number (i.e., light intensity) of u and triggers the response of Bob's detector, the spoof state gain Qv is the probability that Alice sends a spoof state with an average photon number (i.e., light intensity) of v and triggers the response of Bob's detector, the signal state bit error rate Eu is the bit error rate of the signal state with an average photon number of u, the spoof state bit error rate Ev is the bit error rate of the spoof state with an average photon number of v, Y0 is the probability that the transmitter sends a vacuum state and triggers the dark count response of the single-photon detector, i.e., the dark count rate; N0 is the total count of dark counts.

[0050] The count of signal states within time period i is further calculated by simulating the preset system parameters such as satellite transmission frequency F.

[0051] Similarly, the host server calculates the signal state counts in each time period i during the current single key extraction process, accumulates the signal state counts, and compares the current sum of the signal state counts with the preset value M. Parameter M is a preset count target value for a single key extraction.

[0052] When the sum of the signal state counts is greater than or equal to the preset value M, the average values ​​of the signal state gain Qu, signal state bit error rate Eu, Q1 and e1 in the current single key extraction are calculated based on the sum of the signal state counts, where Q1 is the probability that Alice sends a single photon signal and triggers Bob's detector response, and e1 is the bit error rate of the single photon signal.

[0053] Therefore, the coding amount in the current single key extraction process can be estimated through the coding formula according to the average values ​​of the signal state gain Qu, the signal state bit error rate Eu, Q1 and e1 in the current single key extraction process.

[0054] In addition, the moment when the current signal state count is greater than or equal to the preset value M is used as the end moment of the current single key extraction process. Accordingly, the next moment after the current single key extraction process can be used as the start moment of a new single key extraction process, and the new single key extraction process can be re-executed, and the specific steps are the same as before.

[0055] Those skilled in the art will appreciate that the coding amount of a single track can be estimated by adding up the coding amounts extracted by all key extraction processes performed in a single track.

[0056] In one embodiment of the present invention, dT(i) may be set to have the same size. As a preferred example, dT(i) may be set to 1 second.

[0057] In the present invention, by using satellite cloud images, ephemeris data and real equipment to evaluate the real-time changing satellite-to-ground free space channel in a real quantum key distribution environment, the real situation of the satellite-to-ground quantum key process is effectively simulated; and, when estimating the amount of code in a single quantum key distribution process, based on the simulation data consistent with the real situation, the gain, bit error rate and other parameters of the channel are calculated in time periods and the counting data of the signal and the error in each time period are obtained, thereby obtaining the total counting data of the signal and the error in the single quantum key distribution process, and then calculating the average value of the gain, bit error rate and other parameters of the channel in the single quantum key distribution process based on the total counting data, and finally estimating the amount of code in the single quantum key distribution process based on these average values, and thus the amount of code in the single track can be further obtained. Compared with the traditional estimation method of directly calculating the code rate and then directly multiplying the time to estimate the amount of code, the estimation system and method proposed by the present invention conform to the actual environment and key generation process of the satellite-to-ground quantum key distribution process, and the coding amount estimation data provided by it is more accurate.

[0058] Although the present invention has been described above through specific embodiments in conjunction with the accompanying drawings, those skilled in the art will readily recognize that the above embodiments are merely exemplary and are used to illustrate the principles of the present invention, and do not limit the scope of the present invention. Those skilled in the art may make various combinations, modifications and equivalent substitutions to the above embodiments without departing from the spirit and scope of the present invention.

Claims

1. A coding amount estimation method for satellite-to-ground quantum key distribution based on satellite cloud images, comprising a satellite orbit estimation step, a cloud image analysis step and a coding amount estimation step, wherein: In the satellite orbit estimation step, the satellite orbit is estimated based on the ephemeris data; In the cloud image analysis step, an original satellite cloud image of the cloud layer below the satellite orbit is obtained, and the cloud layer distribution and / or cloud top height of the cloud layer are calculated based on the visible light cloud image and the infrared light cloud image in the original satellite cloud image to calculate the atmospheric attenuation value of the satellite-to-ground free space channel; and In the coding amount estimation step, the coding amount in a single key extraction process is estimated based on the atmospheric attenuation value of the satellite-to-ground free space channel; In the cloud map analysis step, the atmospheric attenuation values ​​of the satellite-to-earth free space channel at multiple positions in the satellite orbit are calculated according to the cloud layer distribution and / or cloud top height, and the atmospheric attenuation values ​​of the satellite-to-earth free space channel at least a part of the satellite orbit are obtained by fitting based on the atmospheric attenuation values ​​of the satellite-to-earth free space channel at the multiple positions.

2. The coding amount estimation method according to claim 1, wherein: The fitting is achieved by interpolation and smoothing.

3. The method for estimating the amount of coding as described in claim 1 further comprises the step of estimating a timetable for satellite-to-ground docking based on the atmospheric attenuation value of the satellite-to-ground free space channel and the ephemeris data.

4. The coding amount estimation method as described in claim 1 also includes the step of scanning the satellite orbit to record the count of the single photon detector in the quantum key distribution device when there is no satellite signal input.

5. The method for estimating the amount of coding as claimed in claim 4, wherein: The coding amount estimation step is further configured as follows: Determining the efficiency of the satellite-to-ground free space channel based on the atmospheric attenuation value of the satellite-to-ground free space channel; determining system noise based on counts of the single photon detector when there is no satellite signal input; Determine system parameters based on quantum key distribution protocol; The coding amount is estimated based on the efficiency of the satellite-to-ground free space channel, the system noise and the system parameters.

6. The method for estimating the amount of coding as claimed in claim 5, wherein: The coding amount estimation step is further configured as follows: Based on the system noise at time T(i), the efficiency of the satellite-to-ground free space channel, and the system parameters, the signal state gain Qu, the decoy state gain Qv, the signal state bit error rate Eu, the decoy state bit error rate Ev, the dark count rate Y0, and the dark count N0 at the time T(i) are simulated and calculated, and the signal state count in a time period i starting at the time T(i) and lasting for dT(i) is simulated and calculated, wherein: T(i+1)=T(i)+dT(i), i is a natural number, T(1) is the starting time of the single key extraction process, and, within the time period i, all parameters in the satellite-to-ground quantum key distribution system remain unchanged and are consistent with the parameters at the starting time T(i) of the time period i; the signal state gain Qu is the probability that the transmitting end of the satellite-to-ground quantum key distribution sends a signal state with an average photon number of u and triggers the single-photon detector to respond, the decoy state gain Qv is the probability that the transmitting end sends a decoy state with an average photon number of v and triggers the single-photon detector to respond, the signal state bit error rate Eu is the bit error rate of the signal state with an average photon number of u, the decoy state bit error rate Ev is the bit error rate of the decoy state with an average photon number of v, Y0 is the probability that the transmitting end sends a vacuum state and triggers the dark count response of the single-photon detector, and N0 is the total count of dark counts; Sum the signal state counts calculated by simulation in each time period i during the single key extraction process, and compare the sum of the signal state counts with a preset value M; When the sum of the signal state counts is equal to or greater than the preset value M, the average values ​​of the signal state gain Qu, the signal state bit error rate Eu, Q1 and e1 of the single key extraction process are calculated, wherein Q1 is the probability that the transmitting end sends a single photon signal and triggers the single photon detector to respond, and e1 is the bit error rate of the single photon signal; The amount of coding in the single key extraction process is estimated according to the average values ​​of the signal state gain Qu, the signal state bit error rate Eu, Q1 and e1.

7. The method for estimating the amount of coding as claimed in claim 6, wherein: The dT(i) is set to the same value; and / or, the dT(i) is set to 1 second.

8. The method for estimating the amount of coding as described in claim 6 further comprises the step of adding the amounts of coding in all the single key extraction processes in a single track to obtain the amount of coding of the single track.

9. A coding amount estimation system for satellite-to-ground quantum key distribution based on satellite cloud images, which includes optical-mechanical equipment, quantum key distribution equipment, a host computer server and an intelligent analysis server, wherein: The host computer server is configured to estimate the satellite orbit according to the ephemeris data, and drive the optical mechanical device to scan the satellite orbit; The intelligent analysis server is configured to obtain an original satellite cloud image of the cloud layer below the satellite orbit, and calculate the cloud layer distribution and / or cloud top height of the cloud layer based on the visible light cloud image and the infrared light cloud image in the original satellite cloud image; The host computer server is also configured to calculate the atmospheric attenuation value of the satellite-to-ground free space channel according to the cloud layer distribution and / or cloud top height, and to estimate the amount of coding in a single key extraction process based on the atmospheric attenuation value.

10. The coding amount estimation system according to claim 9, which is configured to execute the coding amount estimation method according to any one of claims 1-8.

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