Satellite-borne AIS (Automatic Identification System) receiver design method capable of receiving multiple messages

Abstract

The invention provides a satellite-borne AIS receiver and a design method thereof, and relates to the field of satellite communication. The satellite-borne AIS receiver comprises a radio frequency receiving link used for receiving an AIS message signal; the power divider is used for averagely dividing the AIS message signal into a first path of signal and a second path of signal according to power; the first attenuator is used for attenuating the first path of signals; the first analog-to-digital quantizer is used for performing analog-to-digital conversion on the first path of signal and outputting a first digital signal; the second attenuator is used for attenuating the second path of signal; the second analog-to-digital quantizer is used for performing analog-to-digital conversion on the second path of signal and outputting a second digital signal; the saturation detector is used for detecting whether the first digital signal is saturated or not, and if yes, sending the first digital signal to the demodulator; otherwise, the second digital signal is sent to the demodulator; and the demodulator is used for demodulating the first digital signal or the second digital signal. According to the invention, the power requirement for receiving multiple AIS messages is met.

Description

Technical Field

[0001] The present invention relates to the field of satellite communications, and in particular to a design method for a satellite-borne AIS receiver capable of receiving multiple messages. Background Art

[0002] The satellite-borne AIS receiver receives and demodulates AIS messages sent by ground ships, obtains the identity, position, speed, heading and other information of the ground ships, and implements tracking, search and rescue and other regulatory measures for ground ships in a wide area.

[0003] Compared with ship-borne or shore-based AIS message receiving technology, satellite-borne AIS receiving technology has wide-area characteristics and is not restricted by the rules for sending and receiving messages in ground AIS cells. It can receive multiple messages from different AIS cells at the same time.

[0004] The existing satellite-borne AIS reception technology for receiving multiple AIS messages mainly focuses on the research of algorithms for separating multiple AIS messages through signal characteristic demodulation, and the research of design methods for separately receiving signals from different areas by combining AIS antenna design and multi-channel reception technology.

[0005] However, the existing satellite-borne AIS reception technology for receiving multiple AIS messages has the following shortcomings:

[0006] 1. In on-orbit applications, nearshore or in areas with dense shipping traffic, satellite-borne AIS receivers often experience power saturation. Existing methods are unable to demodulate messages in these situations. Existing methods do not explain the correlation between this phenomenon and the reception of multiple messages.

[0007] 2. The prior art does not elaborate on the design indicators, sensitivity and dynamic range of satellite-borne AIS receivers that meet the requirements for receiving multiple AIS messages.

[0008] 3. AIS signals are bursty and have short message durations. Due to the power saturation of satellite-borne AIS receivers, automatic gain adjustment is not suitable for reception. The prior art does not provide a design method for a satellite-borne AIS receiver with high sensitivity and a large dynamic range that can receive multiple AIS messages.

[0009] Chinese patent publication number CN 115327981 A discloses an FPGA-based satellite-borne AIS signal receiver capable of simultaneously receiving AIS signals from multiple different ship AIS devices. However, it does not disclose how to meet the power requirements for receiving multiple AIS messages. Summary of the Invention

[0010] In order to solve the technical problems existing in the above-mentioned prior art, the object of the present invention is to provide a satellite-borne AIS receiver and a design method thereof, which can meet the power requirements for receiving multiple AIS messages.

[0011] To achieve the above-mentioned object, the present invention provides a method for designing a satellite-borne AIS receiver capable of receiving multiple messages. The satellite-borne AIS receiver includes:

[0012] A radio frequency receiving link is used to receive AIS message signals and down-convert the AIS message signals;

[0013] A power splitter is used to divide the down-converted AIS message signal into a first signal and a second signal according to average power;

[0014] A first attenuator, configured to attenuate the first signal using a preset first attenuation value;

[0015] The first attenuation value is preconfigured in the first attenuator;

[0016] A first analog quantizer, configured to perform analog-to-digital conversion on the attenuated first signal and output a first digital signal;

[0017] A second attenuator, configured to attenuate the second signal by a preset second attenuation value;

[0018] The second attenuation value is preconfigured in the second attenuator;

[0019] A second analog quantizer, configured to perform analog-to-digital conversion on the attenuated second signal and output a second digital signal;

[0020] a saturation detector, configured to detect whether the first digital signal is saturated, and if the first digital signal is not saturated, send the first digital signal to the demodulator; otherwise, send the second digital signal to the demodulator;

[0021] The demodulator is used to demodulate the first digital signal or the second digital signal to obtain a demodulated AIS message.

[0022] According to a technical solution of the present invention, the specific steps for designing the above-mentioned satellite-borne AIS receiver are as follows:

[0023] S01. Calculate the receiving sensitivity of a single AIS message;

[0024] S02. Establishing a power layering model for simultaneously receiving multiple AIS messages;

[0025] S03. Calculate the maximum received power of a single message for each cell in each layer according to the received power layer model of step S02.

[0026] S04. Obtain the number of cells within the coverage area of the satellite-borne AIS receiver;

[0027] The cell is the maximum time slot conflict-free area for sending AIS messages, and each cell sends at most one AIS message;

[0028] S05. Calculate the dynamic range of multiple message reception of the satellite-borne AIS receiver based on the number of cells within the coverage area, the maximum receiving power of a single message in each cell, and the receiving sensitivity;

[0029] S06. Associating the multiple message receiving dynamic ranges with the expected number of quantization bits of the expected analog quantizer to calculate the expected number of quantization bits;

[0030] S07: selecting two identical actual analog quantizers as a first analog quantizer and a second analog quantizer based on the expected number of quantization bits;

[0031] S08. Calculate the required gain of the radio frequency receiving link based on the actual quantization bit number of the actual analog-to-digital quantizer, the reference voltage of the actual analog-to-digital quantizer, and the attenuation of the power divider;

[0032] S09. Calculate a first attenuation value based on the receiver noise floor power;

[0033] S10. Setting a second attenuation value based on the first attenuation value so that the second digital signal is not saturated at the maximum received power;

[0034] Complete the design of satellite-borne AIS receiver.

[0035] According to a technical solution of the present invention, the number of cells within the coverage area of a satellite-borne AIS receiver is obtained. The specific process is as follows:

[0036] The number of cells in each layer is calculated based on the radius of the Earth, the number of layers in the power layering model, the satellite orbit altitude where the onboard AIS receiver is located, and the cell diameter;

[0037] The innermost layer in the power layer model is layer 0, the outermost layer is layer M, and the layer between layer 0 and layer M is layer n; and n = 1, 2, 3...n max , M=n max +1;

[0038] The 0th layer is a circular cell with the sub-satellite point of the satellite carrying the onboard AIS receiver as the center and D / 2 as the radius; where D is the maximum time slot collision-free distance of the AIS message;

[0039] The nth layer includes a plurality of circular cells with a radius of D / 2, and the distance between the center of the cell and the sub-satellite point is n×D;

[0040] The Mth layer includes a plurality of circular cells with a radius of D / 2, and the distance between the center of the cell and the sub-satellite point is M×D;

[0041] The sum of the number of cells in all layers is taken as the number of cells within the coverage area of the satellite-borne AIS receiver.

[0042] According to a technical solution of the present invention, the dynamic range of multiple message reception of a satellite-borne AIS receiver is calculated based on the number of cells within the coverage area, the maximum receive power of a single message in each cell, and the receive sensitivity. The process is as follows:

[0043] Based on the satellite orbit altitude of the onboard AIS receiver, the radius of the Earth, the distance between each cell and the onboard AIS receiver, the path loss corresponding to each cell, the maximum AIS message transmission power, and the AIS message transmission frequency, the maximum receiving power of a single message in each cell is calculated.

[0044] Based on the number of cells on each layer and the maximum received power of a single message in the cells on the corresponding layer, the maximum received power of multiple messages on each layer is calculated;

[0045] The sum of the maximum receiving powers of multiple messages in all layers is used as the upper limit of the dynamic range of receiving multiple messages, and the receiving sensitivity is used as the lower limit of the dynamic range of receiving multiple messages to obtain the dynamic range of receiving multiple messages.

[0046] According to a technical solution of the present invention, the dynamic range of receiving multiple messages is associated with the expected number of quantization bits of the expected modulus quantizer, and the expected number of quantization bits is calculated. The process is as follows:

[0047] The dynamic range of the desired quantizer is set to at least cover the sum of the dynamic ranges of multiple message receptions, the minimum demodulation signal-to-noise ratio, and the receiver noise floor power, and an inequality is constructed; in the inequality, the dynamic range of the desired quantizer is greater than the sum of the dynamic ranges of multiple message receptions, the minimum demodulation signal-to-noise ratio, and the receiver noise floor power;

[0048] The expected number of quantization bits is substituted into the inequality to obtain the expected number of quantization bits.

[0049] According to a technical solution of the present invention, the actual number of quantization bits is smaller than the expected number of quantization bits.

[0050] According to a technical solution of the present invention, the first attenuation value is configured as:

[0051] Make the digital signal quantization power corresponding to the receiving sensitivity equal to the sum of the minimum demodulation signal-to-noise ratio and the receiver noise floor power.

[0052] According to a technical solution of the present invention, the second attenuation value is configured as:

[0053] The setting of the second attenuator is adjusted so that the second digital signal is not saturated at the maximum received power; and when the first digital signal is just saturated, the strength of the second digital signal is greater than the minimum demodulation signal-to-noise ratio.

[0054] The present invention also provides an electronic device, comprising: one or more processors, one or more memories, and one or more computer programs; wherein the processor is connected to the memory, and the one or more computer programs are stored in the memory. When the electronic device is running, the processor executes the one or more computer programs stored in the memory, so that the electronic device executes the above-mentioned method for designing a satellite-borne AIS receiver that meets the requirements for receiving multiple messages.

[0055] The present invention also provides a computer-readable storage medium for storing computer instructions. When the computer instructions are executed by a processor, the above-mentioned method for designing a satellite-borne AIS receiver that meets the requirements for receiving multiple messages is implemented.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] The present invention provides a satellite-borne AIS receiver and a design method thereof, which have the advantages of:

[0058] (1) Based on the power coverage rules of ship AIS messages, this method establishes a power layering model for receiving multiple AIS messages. This model provides theoretical support for the design requirement analysis and indicator demonstration of satellite-borne AIS reception.

[0059] (2) Based on the establishment of a power layering model for multiple AIS messages, this method provides a calculation method for the above two key indicators, providing a calculation method for determining the indicators of satellite-borne AIS receivers that meet the requirements of receiving multiple AIS messages.

[0060] (3) Based on the design constraints of low-cost and high-reliability satellite payloads, this method is designed to split the signal power into two paths, and AD quantize it into a digital signal after attenuation in each path. This overcomes the contradiction between the low-cost quantizer with a low bit number and the large dynamic range, and provides a solution for the design of a high-sensitivity and large dynamic range satellite-borne AIS receiver. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0062] Figure 1A flowchart schematically illustrates a method for designing a satellite-borne AIS receiver capable of receiving multiple messages according to an embodiment of the present invention;

[0063] Figure 2 Schematically showing a principle diagram of a power hierarchical model in a design method for a satellite-borne AIS receiver capable of receiving multiple messages according to an embodiment of the present invention;

[0064] Figure 3 A schematic diagram illustrating a principle of calculating the distance between a cell and a satellite-borne AIS receiver in a method for designing a satellite-borne AIS receiver capable of receiving multiple messages according to an embodiment of the present invention;

[0065] Figure 4 The figure schematically shows the structure of a satellite-borne AIS receiver according to one embodiment of the present invention. DETAILED DESCRIPTION

[0066] The description of the embodiments in this specification should be combined with the corresponding drawings, which should be considered a complete part of this specification. In the drawings, the shapes and thicknesses of the embodiments may be exaggerated and indicated for simplicity or convenience. Furthermore, the various structural components in the drawings will be described separately. It is worth noting that components not shown in the drawings or not described in words are known to those of ordinary skill in the art.

[0067] The description of the embodiments herein and any references to directions and orientations are for ease of description only and are not to be construed as limiting the scope of the present invention. The following description of the preferred embodiments may involve combinations of features, which may exist independently or in combination. The present invention is not specifically limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0068] like Figures 1 to 4 As shown, a satellite-borne AIS receiver of the present invention includes:

[0069] RF receiving link 1, used to receive AIS message signals and down-convert the AIS message signals;

[0070] A power splitter 2 is used to divide the down-converted AIS message signal into a first signal and a second signal according to the average power;

[0071] A first attenuator 3, configured to attenuate the first signal using a preset first attenuation value;

[0072] The first attenuation value is pre-configured in the first attenuator 3;

[0073] A first analog quantizer 4 is used to perform analog-to-digital conversion on the attenuated first signal and output a first digital signal;

[0074] The second attenuator 5 is used to attenuate the second signal by a preset second attenuation value;

[0075] The second attenuation value is pre-configured in the second attenuator 5;

[0076] A second analog quantizer 6, configured to perform analog-to-digital conversion on the attenuated second signal and output a second digital signal;

[0077] a saturation detector 7 for detecting whether the first digital signal is saturated, and sending the first digital signal to the demodulator 8 if the first digital signal is not saturated; otherwise, sending the second digital signal to the demodulator 8;

[0078] The demodulator 8 is configured to demodulate the first digital signal or the second digital signal to obtain a demodulated AIS message.

[0079] In this embodiment, the embodiment adopts Figure 4 In the satellite-borne AIS receiver design shown in FIG, AIS message signals are down-converted to intermediate frequency signals via RF receive link 1. A power divider 2 splits the intermediate frequency signals into two paths. Each path is connected to a first attenuator 3 / second attenuator 5 before being fed into a q-bit AD quantizer chip (a first analog-to-quantizer 4 / second analog-to-quantizer 6). After sampling, two digital signals are obtained. When a saturation detector 7 detects that the first digital signal is not saturated, a demodulator 8 uses the first digital signal to demodulate the message. When the first digital signal is saturated, the demodulator 8 uses the second digital signal to demodulate the message.

[0080] The present invention provides a method for designing a satellite-borne AIS receiver capable of receiving multiple messages, which is used to design the above-mentioned satellite-borne AIS receiver. The specific steps are as follows:

[0081] S01. Calculate the receiving sensitivity and maximum receiving power of a single AIS message. According to the electromagnetic wave propagation theory, the receiving sensitivity P of the satellite-borne AIS receiver for receiving a single AIS message is derived. MinRec_dB and the maximum received power P MaxRec_dB The calculation expression of .

[0082] S02. Establish a power hierarchical model for receiving multiple AIS messages simultaneously. Based on the rules for sending ship AIS messages, a power hierarchical model for receiving multiple AIS messages on board is established within the satellite coverage area, and an expression for the receiving power of multiple AIS messages is given.

[0083] S03. Calculate the maximum received power of a single message for each cell in each layer based on the received power layer model of step (S02) and the maximum received power of a single AIS message given in step (S01);

[0084] S04. Calculate the number of cells in each layer according to the receiving power layer model in step (2) to obtain the number of cells within the coverage of the satellite-borne AIS receiver (p0, p n and p M );

[0085] The cell is the maximum time slot conflict-free area for sending AIS messages, and each cell can send at most one AIS message;

[0086] S05, according to the number of cells within the coverage area (p0, p n and p M ), the maximum receiving power of a single message in each cell (P MaxRec_0_dB 、P MaxRec_n_dB and P MaxRec_M_dB ), and receiving sensitivity (P MinRec_dB ), calculate the dynamic range of multiple messages received by the satellite-borne AIS receiver (P DynMulti_dB );

[0087] S06, receiving multiple messages in the dynamic range (P DynMulti_dB ) is associated with the expected number of quantization bits of the expected modulus quantizer to calculate the expected number of quantization bits (m);

[0088] S07, selecting two identical actual analog quantizers as the first analog quantizer 4 and the second analog quantizer 6 based on the expected number of quantization bits (m);

[0089] S08, based on the actual quantization bit number (q) of the actual analog quantizer, the reference voltage (V ref ), the attenuation of power divider 2 (L Pdiv ) Calculate the required gain of the RF receiving chain 1;

[0090] S09. Calculate a first attenuation value based on the receiver noise floor power;

[0091] S10. Setting a second attenuation value based on the first attenuation value so that the second digital signal is not saturated at maximum received power;

[0092] Complete the design of satellite-borne AIS receiver.

[0093] In this implementation, a design method for a satellite-borne AIS receiver capable of receiving multiple messages is proposed. The specific design process and principles of the satellite-borne AIS receiver are as follows:

[0094] (1) Calculate the receiving sensitivity and maximum receiving power of a single AIS message. Based on the electromagnetic wave propagation theory, derive the calculation expressions of the receiving sensitivity and maximum receiving power of a satellite-borne AIS receiver receiving a single AIS message.

[0095] (1.1) Calculate the receiving sensitivity of a single AIS message:

[0096] When a single ship on the ground sends an AIS message, it is transmitted as an electromagnetic wave to the satellite-borne AIS antenna. The antenna converts the electromagnetic wave into an electrical signal that is then transmitted to the satellite-borne AIS receiver. During this process, the relationship between the transmit power of a single ship on the ground and the receive power of the satellite-borne AIS receiver is as follows.

[0097] The power of the AIS message sent by a single ship on the ground is P Tra , propagating in free space, the power density at any point is Among them, G Tra is the transmit antenna gain, G Tra = 1. The power received by the satellite-borne AIS receiver is P Rec =P Des A Rec .

[0098] Among them, A Rec is the effective area of the receiving antenna, G Rec is the receiving antenna gain, G Rec =1. The receiving power of the satellite-borne AIS receiver can be expressed as:

[0099]

[0100] Among them, P Tra is the AIS message transmission power of the ground ship, λ is the wavelength of the electromagnetic wave, and R is the transmission distance.

[0101] The AIS message carrier uses the VHF frequency band, and the attenuation of this frequency band by gases in the atmosphere is negligible. The transmission path attenuation L is:

[0102]

[0103] To facilitate calculation, the above formula is converted into a form with dB as the unit, and the wavelength of the electromagnetic wave is converted into a form expressed as carrier frequency, which is:

[0104]

[0105] Among them, L dB is the path loss dB value, R km is the transmission path value in km, f MHz is the transmission frequency in MHz.

[0106] The maximum value of the transmission path is the maximum distance R between the satellite and the ground ship. Max ,have:

[0107]

[0108] Among them, R E is the radius of the Earth, H is the altitude of the satellite orbit. The minimum value of the transmission path is the distance H from the satellite to the sub-satellite point.

[0109] The receiving sensitivity of a single AIS message, that is, the minimum receiving power P MinRec_dB for:

[0110]

[0111] Among them, P MinRec_dB is the receiving sensitivity of a single AIS message, P MinTra_dB is the minimum transmit power, R Max_km is the maximum transmission distance in km, f MHz is the signal frequency in MHz, R Max is the maximum transmission distance, R E is the radius of the Earth, and H is the altitude of the satellite orbit.

[0112] (1.2) Calculate the maximum receiving power of a single AIS message:

[0113] The maximum receiving power of a single AIS message is:

[0114] P MaxRec_dB =P MaxTra_dB -32.45-20logH km -20logf MHz

[0115] Among them, P MaxRec_dB is the maximum receiving power of a single AIS message, P MaxTra_dB is the maximum transmit power, f MHz is the signal frequency in MHz, and the minimum transmission distance is the satellite orbit height H in km. km .

[0116] (2) A power stratification model for receiving multiple AIS messages simultaneously is established. According to the sending rules of ship AIS messages, a power stratification model for the receiving power of multiple AIS messages on board is established within the satellite coverage area, and the receiving power expression of multiple AIS messages is given.

[0117] AIS messages sent by ground-based vessels follow time slots only within a certain range: 40 nautical miles (approximately 72 kilometers). Within this range, there is no time slot conflict between ground-based vessels sending and receiving AIS messages. This area is called a cell. Satellite-based AIS receiving systems have a range far exceeding 72 kilometers, so they can receive multiple AIS messages simultaneously.

[0118] The multiple AIS messages received at the same time come from multiple cells within the satellite coverage area. Figure 2 The figure shows a schematic diagram of multiple cells within the satellite coverage area. The small circle in the center is the cell with a diameter of 72 kilometers, centered at the sub-satellite point. This is also the cell closest to the satellite and is defined as the Layer 0 cell. Outside the Layer 0 cells are the Layer 1 cells, with the center of the Layer 1 cells being 72 kilometers away from the sub-satellite point. Outside the Layer 1 cells are the Layer 2 cells, with the center of the Layer 2 cells being 144 kilometers away from the sub-satellite point. Similarly, the distance between the center of the nth layer cell and the sub-satellite point is Dn. D is the cell diameter, 72 kilometers. At the edge of the satellite coverage area are the Layer M cells, which are also the cells farthest from the satellite.

[0119] The innermost layer in the power layer model is layer 0, the outermost layer is layer M, and the layer between layer 0 and layer M is layer n; and n = 1, 2, 3...n max , M=n max +1;

[0120] Layer 0 is a circular cell with the sub-satellite point of the satellite carrying the onboard AIS receiver as the center and a radius of D / 2. Here, D is the maximum time slot collision-free distance of the AIS message.

[0121] The nth layer includes multiple circular cells with a radius of D / 2, and the distance between the center of the cell and the sub-satellite point is n×D;

[0122] The Mth layer includes multiple circular cells with a radius of D / 2, and the distance between the center of the cell and the sub-satellite point is M×D;

[0123] According to the above-mentioned AIS cell layering method, the satellite-borne AIS receiving system receives AIS messages from cells in different layers with different receiving powers. Multiple AIS messages received may come from multiple messages from different cells in the same layer, or from multiple messages from cells in different layers. The total receiving power is the sum of the powers of AIS messages from multiple cells in different layers. The receiving power P of the satellite-borne AIS receiver receiving multiple AIS messages is MultiRec for:

[0124] P MultiRec =k0P Rec_0 +k1P Rec_1 +k2P Rec_2 +...+k n P Rec_n +...+k M P Rec_M

[0125] Among them, P Rec_0 、P Rec_1 、P Rec_2 、P Rec_n 、PRec_M are the receiving powers of AIS messages of cells at layer 0, layer 1, layer 2, layer n and layer M respectively. n 、k M The number of AIS messages received by cells at layer 0, layer 1, layer 2, layer n, and layer M respectively. The minimum value is 0 and the maximum value is the number of cells at that layer.

[0126] (3) Based on the receiving power layer model in step (2) and the maximum receiving power of a single AIS message given in step (1), calculate the maximum receiving power of a single message in each AIS cell layer.

[0127] (3.1) Calculate the maximum receiving power of a single AIS message in the 0th layer cell:

[0128] The distance between the ship and the satellite in the 0th layer cell is R 0_km =H km , obtained from step (1), the maximum receiving power P for receiving the layer 0 message MaxRec_0_dB for:

[0129] P MaxRec_0_dB =P MaxTra_dB -32.45-20log H km -20log f MHz

[0130] Among them, P MaxTra_dB is the maximum transmission power of the ship AIS message in dB, H km is the satellite orbit altitude in km, f MHz The frequency of ship AIS message transmission in MHz.

[0131] (3.2) Calculate the maximum receiving power of a single AIS message in the nth cell:

[0132] The distance between the center point of each cell and the satellite is taken as the typical value R of the cell transmission distance. n ,like Figure 3 As shown, the geocentric angle between the center point of the cell on the nth layer and the sub-satellite point is θ n , The maximum value of the geocentric angle is Corresponding to the geocentric angle of the Mth layer cell, it can be concluded that the maximum value of n is n Max for:

[0133]

[0134] Among them, [*] is the rounding function, R E is the radius of the earth, H is the satellite orbit height, and D is the cell diameter.

[0135] The distance R from the center of the cell in the nth layer to the satellite n for:

[0136]

[0137] Among them, R E is the radius of the Earth, and H is the altitude of the satellite orbit.

[0138] From step (1), it can be concluded that the transmission attenuation L of the AIS message sent by the ship in the nth cell to the satellite is n_dB for:

[0139] L n_dB =32.45+20logR n_km +20logf MHz

[0140] It can be concluded that the maximum receiving power P of a single AIS message in the nth layer cell is MaxRec_n_dB for:

[0141]

[0142] Among them, P MaxTra_dB R is the maximum transmission power of the ship's AIS message in dB. n_km is the AIS message transmission distance in km, R n θ is the AIS message transmission distance. n is the geocentric angle, [*] is the rounding function, R E is the radius of the earth, H is the satellite orbit height, and D is the cell diameter.

[0143] (3.3) Calculate the maximum receiving power of a single AIS message in the Mth layer cell:

[0144] The Mth layer cell is the farthest cell from the satellite, and the message transmission distance is R Max , obtained from step (1), The maximum receiving power P for receiving messages at layer M MaxRec_M_dB for:

[0145]

[0146] P MaxTra_dB is the maximum transmission power of the ship AIS message in dB, R Max is the maximum transmission distance between the satellite and the ship, R Max_km is the maximum transmission distance in km, f MHz is the transmit frequency in MHz.

[0147] (4) Calculate the number of cells in each layer according to the receiving power layer model in step (2) and obtain the number of cells within the coverage range of the satellite-borne AIS receiver (p0, p n and p M );

[0148] (4.1) Calculate the number of cells in layer 0:

[0149] The 0th layer cell is a cell centered at the sub-satellite point, and the number is 1. The number of 0th layer cells p0 is 1.

[0150] (4.2) Calculate the number of cells in the nth layer:

[0151] like Figure 2 As shown, the sub-satellite point is point O, and the center point of any cell in the first layer is selected as point A. The line connecting the center points of all cells in the first layer intersects the cell at point B. In the spherical triangle OAB, the arc length of the OA segment is the cell diameter D, the arc length of the OB segment is the cell diameter D, and the arc length of the AB segment is the cell radius. Angle AOB is

[0152]

[0153] The number of cells in the first layer, p1, is:

[0154]

[0155] Similarly, the arc length of the OA arc segment of any n-th layer cell is nD, the arc length of the OB arc segment is nD, and the arc length of the AB arc segment is the cell radius. The number of cells in the nth layer p n for:

[0156]

[0157] From step (3.2), the maximum value of n is

[0158] To sum up, calculate the number of cells p in the nth layer n The expression is:

[0159]

[0160] Among them, [*] is the rounding function, R E is the radius of the earth, H is the satellite orbit height, and D is the cell diameter.

[0161] (4.3) Calculate the number of cells in the Mth layer:

[0162] The Mth layer cell is the farthest cell from the satellite. Some areas of this layer of cells are within the satellite coverage, while some areas are beyond the satellite coverage. The same as the derivation in step (3.2), the arc length of the arc segment OA between the center point of this layer of cells and the sub-satellite point is n max D+D, the arc length of OB is n max D+D, the length of the AB arc is the radius of the cell The expression p for calculating the number of cells in the Mth layer is obtained M for:

[0163]

[0164] Among them, [*] is the rounding function, R E is the radius of the earth, H is the satellite orbit height, and D is the cell diameter.

[0165] (5) According to the number of cells within the coverage area (p0, p n and p M ), the maximum receiving power of a single message in each cell (P MaxRec_0_dB 、P MaxRec_n_dB and P MaxRec_M_dB ), and receiving sensitivity (P MinRec_dB ), calculate the dynamic range of multiple messages received by the satellite-borne AIS receiver (P DynMulti_dB );

[0166] The dynamic range for receiving multiple AIS messages is the difference between the maximum and minimum received power values, where the minimum received power value is the minimum received power value for a single AIS message, as described in step (1). The maximum received power value must take into account the power of all AIS cells within the satellite coverage area transmitting messages at their maximum transmit power and receiving the messages simultaneously. That is, the sum of the maximum received powers of all messages within the satellite coverage area is the maximum received power value.

[0167] According to the receiving power layer model in step (2), the maximum receiving power of all cells can be expressed as follows: the maximum receiving power of a single message in each layer of cells is multiplied by the number of cells in each layer to obtain the maximum power sum of each layer of cells, and the maximum power sum of each layer of cells is superimposed to obtain the maximum receiving power sum of all cells. Therefore, the maximum receiving power P MaxMultiRec for:

[0168]

[0169] Among them, P MaxRec_0 is the maximum receiving power of a single message at layer 0, P MaxRec_n is the maximum receiving power of a single message at layer n, P MaxRec_M is the receiving power of a single message at layer M. p0, p n、p M is the number of cells at layer 0, layer n, and layer M. Substituting the maximum receiving power of a single message at layer 0, layer n, and layer M and the number of cells obtained in step (3) into the above formula, the maximum receiving power is:

[0170]

[0171] Subtract the maximum value of the above received power from the minimum value of the received power obtained in step (1) to obtain the dynamic range P for receiving multiple AIS messages. DynMulti_dB for:

[0172]

[0173] P MaxRec_0_dB =P TraMax_dB -32.45-20logH km -20logf MHz

[0174] P MaxRec_n_dB =P TraMax_dB -32.45-20log R n_km -20log f MHz

[0175] P MaxRec_M_dB =P TraMax_dB -32.45-20logR Max_km -20logf MHz

[0176]

[0177] Among them, P MaxTra_dB is the maximum transmission power of the ship AIS message in dB, [*] is the rounding function, R E is the radius of the earth, H is the satellite orbit height, D is the cell diameter, f MHz is the transmit frequency in MHz.

[0178] (6) The dynamic range of receiving multiple messages (P DynMulti_dB ) is associated with the expected number of quantization bits of the expected modulus quantizer to calculate the expected number of quantization bits (m);

[0179] (6.1) Establish the relationship between the number of bits of AD quantizer and its dynamic range:

[0180] The AIS message signal enters the satellite-borne AIS receiver through the AIS antenna, and is down-converted to an intermediate frequency signal through a radio frequency link consisting of a filter, low-noise amplifier, amplifier, mixer, etc. The intermediate frequency signal is sampled and quantized from analog to digital using AD sampling, and the digital signal is sent to the signal processing chip to demodulate the AIS message.

[0181] The first bit of the AD quantizer represents the sign bit of the signal, and the number of quantization bits that can represent the signal amplitude is m-1 bits. The signal amplitude A is 2 (m-1) The signal power is The maximum signal power in dB is the dynamic range of the AD quantizer. From this, it can be concluded that the number of bits m of the AD quantizer and the dynamic range P of the digital signal it represents are DigDyn_dB The relationship between them is:

[0182]

[0183] (6.2) Analyze the factors that determine the dynamic range of the AD quantizer:

[0184] The noise floor characteristics of the satellite-borne AIS receiver are a part that needs to be paid attention to in the design of the satellite-borne AIS receiver. The dynamic range of the AD quantizer should not only reflect the dynamic range of the AIS message reception, but also reflect the characteristics of the noise floor of the satellite-borne AIS receiver. Therefore, the dynamic range of the AD quantizer must be greater than the sum of the dynamic range of the AIS message reception, the minimum demodulation signal-to-noise ratio, and the noise floor power of the receiver. Among them, the dynamic range of the AIS message reception has been described in detail in step (5). The following analyzes the impact of the other two factors on the determination of the dynamic range of the AD quantizer.

[0185] The minimum demodulation signal-to-noise ratio is related to the demodulation method of the AIS message. The modulation method of the AIS message is GMSK modulation, and the matched filter method is usually used for demodulation. The demodulation bit error rate p e The relationship with the signal-to-noise ratio Q is:

[0186]

[0187] where erfc(*) is the complementary error function.

[0188] The length of each message ranges from 1 to 5 time slots, with each time slot containing 256 bits. The first 12 bits of the message are protection and synchronization bits. Using the above bit error rate formula, the variation trend of the message demodulation probability with the signal-to-noise ratio and message length is calculated, as shown in Table 1.

[0189] Table 1 Trend of message demodulation probability with SNR

[0190] 1 time slot 2 time slots 3 time slots 4 time slots 5 time slots SNR / dB Bit Error Rate 244 bits 500 bits 756 bits 1012 bits 1268 bits 6 2.388E-03 0.558 0.303 0.164 0.089 0.048 7 7.727E-04 0.828 0.679 0.557 0.457 0.375 8 1.909E-04 0.954 0.909 0.866 0.824 0.785 9 3.363E-05 0.992 0.983 0.975 0.967 0.958 10 3.872E-06 0.999 0.998 0.997 0.996 0.995 11 2.613E-07 1.000 1.000 1.000 1.000 1.000

[0191] As can be seen from Table 1, the signal-to-noise ratio QdB When the demodulation probability is 10dB, the message demodulation probability can reach more than 99%. Therefore, the minimum demodulation signal-to-noise ratio is determined to be Q Min_dB =10dB.

[0192] The receiver noise floor power characterizes the thermal noise characteristics of the internal link of the satellite-borne AIS receiver and the noise characteristics of the AIS antenna. Typically, the noise floor of a satellite-borne AIS receiver exhibits the fluctuating characteristics of Gaussian white noise. The noise can be appropriately attenuated using the first attenuator 3 before entering the AD quantizer. However, to understand the noise floor characteristics, at least a 3-bit AD quantization amplitude is required. The minimum value of the receiver noise floor power after AD quantization is:

[0193] N Min_dB =20log2 3 =18dB

[0194] In summary, the factors that influence the dynamic range of the AD quantizer include: the dynamic range of the AIS message reception, the minimum demodulation signal-to-noise ratio, and the receiver noise floor power. Furthermore, the dynamic range of the AD quantizer must be greater than the sum of the AIS message reception dynamic range, the receiver noise floor power, and the minimum demodulation signal-to-noise ratio. That is:

[0195] P DigDyn_dB >P DynMulti_dB +Q Min_dB +N Min_dB

[0196] Substituting the minimum demodulation signal-to-noise ratio and the receiver noise floor power into the above formula, we can find that the dynamic range of the AD quantizer must meet the following conditions:

[0197] P DigDyn_dB >P DynMulti_dB +28

[0198] (6.3) Relationship between the receiving dynamic range and the number of AD quantizer bits (expected number of quantization bits):

[0199] Substituting the correlation between the number of AD quantizer bits and its dynamic range described in step (6.1) into the conditions that the AD quantizer dynamic range must meet described in step (6.2), the relationship between the AIS message reception dynamic range and the number of AD quantizer bits is obtained as follows:

[0200] 6m-9>P DynMulti_dB +28

[0201] Where m is the number of AD quantizer bits, P DynMulti_dB Dynamic range for receiving multiple AIS messages.

[0202] The minimum value of m can be obtained through the above formula, which is the minimum value of the desired quantization bits.

[0203] (7) Based on the expected number of quantization bits (m), two identical actual analog quantizers are selected as the first analog quantizer 4 and the second analog quantizer 6; the number of bits of the actual analog quantizer is less than the expected number of quantization bits. This design satisfies the requirements of a high-sensitivity, large-dynamic-range satellite-borne AIS receiver that can receive multiple AIS messages.

[0204] (8) Based on the actual number of quantization bits (q) of the actual analog quantizer, the reference voltage of the actual analog quantizer (V ref ), the attenuation of power divider 2 (L Pdiv ) Calculate the required gain of the RF receiving chain 1;

[0205] The following describes in detail the design method of the RF link gain and the first attenuator 3 .

[0206] In this embodiment, the digital signal corresponding to the sensitivity (minimum received power) is 28dB, and the AD sampling analog amplitude A corresponding to the sensitivity is obtained as follows:

[0207]

[0208] Before entering AD, the gain of RF receiving link 1 is the AD sampling analog power corresponding to the sensitivity minus the attenuation of the power divider minus the receiving sensitivity, that is:

[0209]

[0210] Among them, V ref It is the reference voltage of AD quantizer. Pdiv is the attenuation of power divider 2, P Min_dB is the receiving sensitivity obtained in step (1.1).

[0211] (9) Calculating a first attenuation value based on the receiver noise floor power;

[0212] The first attenuator 3 is set to adjust the setting of the first attenuator 3 so that the power noise floor of the satellite-borne AIS receiver is attenuated to about 18 dB, occupying 3 quantization bits. Then, the digital signal quantization power corresponding to the receiving sensitivity is 28 dB.

[0213] (10) setting a second attenuation value based on the first attenuation value so that the second digital signal is not saturated at the maximum received power;

[0214] The second attenuator 5 is set to adjust the setting of the second attenuator 5 so that the second digital signal is not saturated at the maximum receiving power, and when the first digital signal is just saturated, the second digital signal cannot be too small and must be greater than 10dB (minimum demodulation signal-to-noise ratio) so that the message can be demodulated normally.

[0215] This embodiment further illustrates the design of the AIS receiver in steps (1) to (10):

[0216] Based on the maximum and minimum ship transmit powers specified in Recommendation ITU-R M.1371-5 (Technical Characteristics of the Automatic Identification System using Time Division Multiple Access in the VHF Maritime Mobile Band, 2014 Edition), and using the calculation method for the AD quantizer dynamic range given in step (4.3), the number of quantization bits required for the AD quantizer dynamic range (the expected number of quantization bits) is calculated. This number will exceed the number of quantization bits (the actual number of quantization bits) currently used in orbital spaceborne AIS receivers. This is one of the reasons why the received power of spaceborne AIS often saturates when currently in orbit.

[0217] Currently, most on-orbit AIS receivers use 10-bit or 12-bit AD quantizer chips. To avoid the on-orbit risks associated with using newer, higher-bit AD quantizer chips, and considering the high cost of higher-bit AD quantizers, this embodiment still uses currently commonly used lower-bit AD quantizer chips (actual number of quantization bits). The following design is adopted to achieve a wide dynamic range for receiving AIS message signals with burst characteristics while ensuring high sensitivity, thereby meeting the requirements for on-orbit reception and demodulation of multiple AIS messages.

[0218] In the design method of a satellite-borne AIS receiver capable of receiving multiple messages, the first attenuation value is configured as follows:

[0219] Make the digital signal quantization power corresponding to the receiving sensitivity equal to the sum of the minimum demodulation signal-to-noise ratio and the receiver noise floor power.

[0220] In this embodiment, the sum of the minimum demodulation signal-to-noise ratio and the receiver noise floor power is 28 dB, and the digital signal quantization power corresponding to the receiving sensitivity is 28 dB.

[0221] In the design method of a satellite-borne AIS receiver capable of receiving multiple messages, the second attenuation value is configured as follows:

[0222] The setting of the second attenuator is adjusted so that the second digital signal is not saturated at the maximum received power; and when the first digital signal is just saturated, the power of the second digital signal is greater than the minimum demodulation signal-to-noise ratio.

[0223] In this implementation, according to Recommendation ITU-R M.1371-5 (Technical Characteristics of the Automatic Identification System using Time Division Multiple Access in the VHF Maritime Mobile Band, 2014 Edition), the minimum ship transmit power is 1W and the maximum is 12.5W. This is based on an orbital altitude of 1000km.

[0224] According to the calculation method of AIS message receiving sensitivity given in step (1.1), the AIS message receiving sensitivity is calculated to be -115dBmW.

[0225] According to the calculation method of the maximum receiving power of multiple AIS messages given in steps (3)-(5), as shown in Table 2, the maximum receiving power is -64dBmW. The receiving dynamic range of the AIS message is 51dB.

[0226] Table 2 Calculation of the maximum power of multiple AIS messages received based on the power layering model

[0227]

[0228]

[0229]

[0230] According to the calculation method of the AD quantizer dynamic range given in step (6), it is concluded that the AD quantizer dynamic range must be greater than 79dB (51dB+28dB).

[0231] According to the calculation method of the AD quantizer bit number given in step (6), it is found that the AD expected quantizer bit number that satisfies the AD quantizer dynamic range greater than 79dB is at least 15 bits.

[0232] According to the design method of the satellite-borne AIS receiver that meets the requirements of receiving multiple messages given in steps (7)-(10), a 10-bit AD quantizer chip is selected for the satellite-borne AIS receiver design, with a reference voltage of 1V, a power divider attenuation of 3dB, and a satellite-borne AIS receiver link gain of 116dB. The first attenuator 3 is appropriately adjusted so that the quantization power corresponding to the receiving sensitivity is 28dB. The setting of the second attenuator is adjusted so that the second digital signal is not saturated at the maximum receiving power, and when the first digital signal is just saturated, the power of the second digital signal cannot be too small (the power must be greater than the minimum demodulation signal-to-noise ratio, 10dB) so as to affect the message demodulation. In this example, the second attenuator 5-first attenuator 3=30dB, which meets the adjustment constraints of the above-mentioned second attenuator. As shown in Table 3, the amplitude and quantization bit number of the first digital signal and the second digital signal are listed from the receiving sensitivity (minimum receiving power) -115dBmW to the maximum receiving power -64dBmW.

[0233] Table 3 Satellite-borne AIS receiver design

[0234]

[0235]

[0236] According to one aspect of the present invention, an electronic device is provided, comprising: one or more processors, one or more memories, and one or more computer programs; wherein the processor is connected to the memory, and the one or more computer programs are stored in the memory. When the electronic device is running, the processor executes the one or more computer programs stored in the memory, so that the electronic device implements the method for designing a satellite-borne AIS receiver capable of receiving multiple messages as described in the above technical solution.

[0237] According to one aspect of the present invention, a computer-readable storage medium is provided for storing computer instructions. When the computer instructions are executed by a processor, the method for designing a satellite-borne AIS receiver capable of receiving multiple messages as described in the above technical solution is implemented.

[0238] Computer-readable storage media may include any medium capable of storing or transmitting information. Examples of computer-readable storage media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, and the like. The code segments may be downloaded via a computer network such as the Internet, an intranet, and the like.

[0239] The present invention provides a method and system for designing a satellite-borne AIS receiver that meets the requirements for receiving multiple messages. The satellite-borne AIS receiver includes: a radio frequency receiving link for receiving AIS message signals; a power splitter for dividing the AIS message signals into a first signal and a second signal according to power averages; a first attenuator for attenuating the first signal; a first analog-to-digital converter for performing analog-to-digital conversion on the first signal and outputting a first digital signal; a second attenuator for attenuating the second signal; a second analog-to-digital converter for performing analog-to-digital conversion on the second signal and outputting a second digital signal; a saturation detector for detecting whether the first digital signal is saturated, and if so, sending the first digital signal to a demodulator; otherwise, sending the second digital signal to the demodulator; and a demodulator for demodulating the first digital signal or the second digital signal. The present invention meets the power requirements for receiving multiple AIS messages.

[0240] Furthermore, it should be noted that the present invention may be provided as a method, apparatus, or computer program product. Thus, embodiments of the present invention may take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of the present invention may take the form of a computer program product embodied on one or more computer-usable storage media containing computer-usable program code.

[0241] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the process in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0242] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, so that a series of operation steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for implementing the process in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0243] It should also be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or terminal device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or terminal device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or terminal device comprising the element.

[0244] Finally, it should be noted that the above is a preferred embodiment of the present invention. It should be noted that although the preferred embodiment of the present invention has been described, it is clear that those skilled in the art, once they understand the basic inventive concept of the present invention, can make various improvements and modifications without departing from the principles of the present invention. Such improvements and modifications should also be considered as within the scope of protection of the present invention. Therefore, the appended claims are intended to be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the embodiments of the present invention.

Claims

1. A design method for a satellite-borne AIS receiver capable of receiving multiple messages, characterized in that: The satellite-borne AIS receiver comprises: A radio frequency receiving link (1) is used to receive an AIS message signal and down-convert the AIS message signal; A power splitter (2) is used for evenly dividing the down-converted AIS message signal into a first signal and a second signal according to power; A first attenuator (3) is used to attenuate the first signal using a preset first attenuation value; The first attenuation value is pre-configured in the first attenuator (3); A first analog quantizer (4) is used to perform analog-to-digital conversion on the attenuated first signal and output a first digital signal; A second attenuator (5) is used to attenuate the second signal using a preset second attenuation value; The second attenuation value is pre-configured in the second attenuator (5); A second analog quantizer (6) is used for performing analog-to-digital conversion on the attenuated second signal and outputting a second digital signal; a saturation detector (7) for detecting whether the first digital signal is saturated, and sending the first digital signal to a demodulator (8) if the first digital signal is not saturated; otherwise, sending a second digital signal to the demodulator (8); The demodulator (8) is used for demodulating the first digital signal or the second digital signal to obtain a demodulated AIS message.

2. The method for designing a satellite-borne AIS receiver capable of receiving multiple messages according to claim 1, wherein: The specific steps for designing the satellite-borne AIS receiver are as follows: S01. Calculate the receiving sensitivity of a single AIS message; S02. Establishing a power layering model for simultaneously receiving multiple AIS messages; S03. Calculate the maximum received power of a single message for each cell in each layer according to the received power layer model of step S02. S04. Obtain the number of cells within the coverage area of the satellite-borne AIS receiver; The cell is the maximum time slot conflict-free area for sending AIS messages, and each cell sends at most one AIS message; S05. Calculate the dynamic range of multiple message reception of the satellite-borne AIS receiver based on the number of cells within the coverage area, the maximum receiving power of a single message in each cell, and the receiving sensitivity; S06. Associating the multiple message receiving dynamic ranges with the expected number of quantization bits of the expected analog quantizer to calculate the expected number of quantization bits; S07, selecting two identical actual analog quantizers as a first analog quantizer (4) and a second analog quantizer (6) based on the expected number of quantization bits; S08, calculating and obtaining the gain of the required radio frequency receiving link (1) based on the actual quantization bit number of the actual analog-to-digital quantizer, the reference voltage of the actual analog-to-digital quantizer, and the attenuation of the power divider (2); S09. Calculate a first attenuation value based on the receiver noise floor power; S10. Setting a second attenuation value based on the first attenuation value so that the second digital signal is not saturated at the maximum received power; Complete the design of satellite-borne AIS receiver.

3. The method for designing a satellite-borne AIS receiver capable of receiving multiple messages according to claim 2, wherein: Get the number of cells within the coverage area of the satellite-borne AIS receiver. The specific process is as follows: The number of cells in each layer is calculated based on the radius of the Earth, the number of layers in the power layering model, the satellite orbit altitude where the onboard AIS receiver is located, and the cell diameter; The innermost layer in the power layer model is layer 0, the outermost layer is layer M, and the layer between layer 0 and layer M is layer n; and n = 1, 2, 3...n max , M=n max +1; The 0th layer is a circular cell with the sub-satellite point of the satellite carrying the onboard AIS receiver as the center and D / 2 as the radius; where D is the maximum time slot collision-free distance of the AIS message; The nth layer includes a plurality of circular cells with a radius of D / 2, and the distance between the center of the cell and the sub-satellite point is n×D; The Mth layer includes a plurality of circular cells with a radius of D / 2, and the distance between the center of the cell and the sub-satellite point is M×D; The sum of the number of cells in all layers is taken as the number of cells within the coverage area of the satellite-borne AIS receiver.

4. The method for designing a satellite-borne AIS receiver capable of receiving multiple messages according to claim 2 or 3, wherein: The dynamic range of multiple message reception of the satellite-borne AIS receiver is calculated based on the number of cells within the coverage area, the maximum receive power of a single message in each cell, and the receive sensitivity. The process is as follows: Based on the satellite orbit altitude of the onboard AIS receiver, the radius of the Earth, the distance between each cell and the onboard AIS receiver, the path loss corresponding to each cell, the maximum AIS message transmission power, and the AIS message transmission frequency, the maximum receiving power of a single message in each cell is calculated. Based on the number of cells on each layer and the maximum received power of a single message in the cells on the corresponding layer, the maximum received power of multiple messages on each layer is calculated; The sum of the maximum receiving powers of multiple messages in all layers is used as the upper limit of the dynamic range of receiving multiple messages, and the receiving sensitivity is used as the lower limit of the dynamic range of receiving multiple messages to obtain the dynamic range of receiving multiple messages.

5. The method for designing a satellite-borne AIS receiver capable of receiving multiple messages according to claim 4, wherein: The dynamic range of receiving multiple messages is associated with the expected number of quantization bits of the expected modulus quantizer, and the expected number of quantization bits is calculated as follows: The dynamic range of the desired quantizer is set to at least cover the sum of the dynamic ranges of multiple message receptions, the minimum demodulation signal-to-noise ratio, and the receiver noise floor power, and an inequality is constructed; in the inequality, the dynamic range of the desired quantizer is greater than the sum of the dynamic ranges of multiple message receptions, the minimum demodulation signal-to-noise ratio, and the receiver noise floor power; The expected number of quantization bits is substituted into the inequality to obtain the expected number of quantization bits.

6. The method for designing a satellite-borne AIS receiver capable of receiving multiple messages according to claim 5, wherein: The actual number of quantization bits is smaller than the expected number of quantization bits.

7. The method for designing a satellite-borne AIS receiver capable of receiving multiple messages according to any one of claims 2, 3, 5 or 6, wherein: The first attenuation value is configured as: Make the digital signal quantization power corresponding to the receiving sensitivity equal to the sum of the minimum demodulation signal-to-noise ratio and the receiver noise floor power.

8. The method for designing a satellite-borne AIS receiver capable of receiving multiple messages according to claim 7, wherein: The second attenuation value is configured as follows: adjusting the setting of the second attenuator so that the second digital signal is not saturated at the maximum received power; and when the first digital signal is just saturated, the strength of the second digital signal is greater than the minimum demodulation signal-to-noise ratio.

9. An electronic device, characterized in that: include: One or more processors, one or more memories, and one or more computer programs; wherein the processor is connected to the memory, and the one or more computer programs are stored in the memory; when the electronic device is running, the processor executes the one or more computer programs stored in the memory, so that the electronic device executes the method for designing a satellite-borne AIS receiver that meets the requirements for receiving multiple messages as described in any one of claims 2 to 8.

10. A computer-readable storage medium, characterized in that The device is used to store computer instructions, which, when executed by a processor, implement the method for designing a satellite-borne AIS receiver capable of receiving multiple messages according to any one of claims 2 to 8.

Images