Automatic gain control system and method for a wideband satellite receiver

Abstract

The present application relates to the technical field of satellite, and particularly provides an automatic gain control system and method of a wideband satellite receiver, aiming at solving the problem of how to better meet the variable symbol rate forward channel receiving requirement of the satellite receiver. To this end, the present application performs analog automatic gain control on the received signal in the first automatic gain control loop, so that the power level of the received signal is adjusted to a first setting value; after the received signal obtains a wideband sampling signal through a digital-analog converter, the wideband sampling signal is subjected to down-conversion processing through a down-conversion module to obtain a down-converted digital signal; the second automatic gain control loop performs digital automatic gain control on the down-converted digital signal, so that the power level is adjusted to a second setting value; and the adjusted down-converted digital signal is sent to baseband demodulation, which can effectively utilize the dynamic range of analog-digital conversion, support the variable symbol rate forward channel receiving requirement, and improve the flexibility of forward channel bandwidth allocation.

Description

Technical Field

[0001] This invention relates to the field of satellite technology, specifically providing an automatic gain control system and method for a broadband satellite receiver. Background Technology

[0002] With the commercialization of high-throughput satellites, greater bandwidth resources are available, and more service channels can be flexibly allocated. Wideband satellite receivers need to match this flexible bandwidth allocation requirement, supporting symbol rate variations over a wide range, from tens to hundreds of megabits per second. This places high demands on the dynamic range of satellite receivers. On the one hand, wideband sampling by the ADC (Analog-to-Digital Converter) is required, maximizing the utilization of the ADC's dynamic range through wideband gain control. On the other hand, the forward channel bandwidth allocation is flexible, necessitating corresponding gain control based on the allocated channel bandwidth.

[0003] Accordingly, there is a need in the field for a new automatic gain control scheme to solve the above problems. Summary of the Invention

[0004] To overcome the above-mentioned shortcomings, this invention is proposed to provide a solution, or at least a partial solution, to the problem of how to better meet the variable symbol rate forward channel reception requirements of satellite receivers.

[0005] In a first aspect, the present invention provides an automatic gain control system for a broadband satellite receiver, the system comprising a first automatic gain control loop, an analog-to-digital converter, a down-conversion module, and a second automatic gain control loop;

[0006] The first automatic gain control loop is used to perform analog automatic gain control on the received signal so that the power level of the received signal reaches a preset first setting value;

[0007] The analog-to-digital converter is used to perform analog-to-digital conversion on the received signal after analog gain control to obtain a broadband sampled digital signal;

[0008] The down-conversion module is used to perform down-conversion processing on the broadband sampled digital signal to obtain a down-converted digital signal;

[0009] The second automatic gain control loop is used to perform digital automatic gain control on the down-converted digital signal so that the power level of the down-converted digital signal reaches a preset second setting value, thereby obtaining a baseband signal for demodulation.

[0010] In one technical solution of the above-mentioned automatic gain control system, the first automatic gain control loop includes a first power detection submodule and an analog gain adjustment submodule;

[0011] The first power detection submodule is used to perform power detection on the broadband sampled data signal to obtain the power level of the broadband sampled digital signal;

[0012] The analog gain adjustment submodule is used to obtain an analog gain based on the power level and the first reference level, so as to adjust the received signal to the first set value according to the analog gain;

[0013] The first reference level is obtained based on the peak-to-average power ratio of the broadband sampled digital signal.

[0014] In one technical solution of the above-mentioned automatic gain control system, the analog gain adjustment submodule includes a first gain acquisition unit, a first error control unit, and a first gain adjustment unit;

[0015] The first gain acquisition unit is used to acquire a first logarithmic gain based on the power level and the first reference level;

[0016] The first error control unit is used to perform error control based on the first logarithmic gain to obtain the analog gain;

[0017] The first gain adjustment unit is used to adjust the received signal to the first set value according to the analog gain.

[0018] In one technical solution of the above-mentioned automatic gain control system, the first gain acquisition unit includes a first linear gain acquisition subunit and a first logarithmic gain acquisition subunit;

[0019] The first linear gain acquisition subunit is used to divide the power level and the first reference level to obtain the first linear gain;

[0020] The first logarithmic gain acquisition subunit is configured to convert the first linear gain into the first logarithmic gain based on a preset logarithmic gain range and a preset step size; and / or,

[0021] The first error control unit includes a first error limiting subunit and a first loop filter;

[0022] The first error limiting subunit is used to limit the range of the first logarithmic gain in order to reduce the oscillation of the first logarithmic gain;

[0023] The first loop filter is used to perform integral filtering based on the first logarithmic gain of the previous order to obtain the first logarithmic gain of the current order; and / or,

[0024] The first gain adjustment unit includes a variable gain amplifier;

[0025] The variable gain amplifier is used to adjust the variable gain according to the analog gain, so that the received signal is adjusted to the first set value.

[0026] In one technical solution of the above-mentioned automatic gain control system, the second gain control loop includes a second power detection submodule and a digital gain adjustment submodule;

[0027] The second power detection submodule is used to perform power detection on the down-converted digital signal to obtain the power level of the down-converted signal;

[0028] The digital gain adjustment submodule is used to obtain a digital gain based on the power level and the second reference level, and adjust the power level of the down-converted digital signal to a preset second setting value based on the digital gain, so as to obtain the baseband signal for demodulation.

[0029] The second reference level is obtained based on the peak-to-average power ratio of the down-converted digital signal.

[0030] In one technical solution of the above-mentioned automatic gain control system, the digital gain adjustment submodule includes a second gain acquisition unit, a second error control unit, and a second gain adjustment unit;

[0031] The second gain acquisition unit is used to acquire a second logarithmic gain based on the power level and the second reference level;

[0032] The second error control unit is used to perform error control based on the second logarithmic gain and obtain the digital gain;

[0033] The second gain adjustment unit is used to adjust the power level of the down-converted digital signal to the second set value according to the digital gain.

[0034] In one technical solution of the above-mentioned automatic gain control system, the second gain acquisition unit includes a second linear gain acquisition subunit and a second logarithmic gain acquisition subunit;

[0035] The second linear acquisition subunit is used to divide the power level by the second reference level to obtain the second linear gain;

[0036] The second logarithmic gain acquisition subunit is used to convert the second linear gain into the second logarithmic gain based on a preset logarithmic gain range and a preset step size; and / or,

[0037] The second error control unit includes a second error limiting subunit and a second loop filter;

[0038] The second error limiting subunit is used to limit the range of the second logarithmic gain in order to reduce the oscillation of the second logarithmic gain;

[0039] The second loop filter is used to perform integral filtering based on the second logarithmic gain and the digital gain of the previous order to obtain the digital gain of the current order; and / or,

[0040] The second gain adjustment unit includes a logarithmic-to-linear gain subunit and a second multiplier;

[0041] The logarithmic-to-linear gain subunit is used to reverse the digital gain according to the logarithmic gain range and the step size to obtain the final linear gain.

[0042] The second multiplier is used to multiply the final linear gain with the down-converted digital signal, thereby adjusting the power level of the down-converted digital signal to the second set value.

[0043] In one technical solution of the above-mentioned automatic gain control system, the down-conversion module includes a digital oscillator and a digital down-conversion submodule;

[0044] The digital oscillator is used to shift the broadband sampled digital signal to the baseband signal frequency;

[0045] The digital down-conversion submodule is used to perform downsampling filtering on the frequency-shifted broadband sampled digital signal to obtain the down-converted digital signal; and / or,

[0046] The analog automatic gain control uses open-loop gain control and / or closed-loop gain control.

[0047] The digital automatic gain control uses open-loop gain control and / or closed-loop gain control.

[0048] In one technical solution of the above-mentioned automatic gain control system, the analog automatic gain control and / or the digital automatic gain control use open-loop gain control when performing initial control.

[0049] The open-loop gain control is performed according to the following formula:

[0050] gain(0) = round(err) dB / step)·step

[0051] Where gain(0) is the initial open-loop gain, err dB For logarithmic gain, step is the preset step size; and / or,

[0052] The analog automatic gain control and / or the digital automatic gain control perform initial control followed by closed-loop gain control;

[0053] The closed-loop gain control is performed according to the following formula:

[0054] gain(n+1)=gain(n)+err dB ·α

[0055] Where gain(n+1) is the (n+1)th order closed-loop gain, gain(n) is the nth order closed-loop gain, and α is the loop scaling factor.

[0056] In a second aspect, the present invention provides an automatic gain control method for a broadband satellite receiver, the method being based on the automatic gain control system described in any of the above-described automatic gain control system technical solutions; the method comprising:

[0057] The first automatic gain control loop performs analog automatic gain control on the received signal to adjust the power level of the received signal to a preset first setting value.

[0058] The analog-to-digital converter is used to perform analog-to-digital conversion on the received signal after analog gain control in order to obtain a broadband sampled digital signal.

[0059] The broadband sampling signal is down-converted by the down-conversion module to obtain a down-converted digital signal.

[0060] The down-converted digital signal is subjected to digital automatic gain control through the second automatic gain control loop, so that the power level of the down-converted digital signal reaches a preset second setting value, thereby obtaining a baseband signal for demodulation.

[0061] The above-described technical solutions of the present invention have at least one or more of the following beneficial effects:

[0062] In implementing the technical solution of this invention, the automatic gain control system includes two automatic gain control loops. In the first automatic gain control loop, analog automatic gain control is performed on the received signal to adjust the power level of the received signal to a preset first setting value. After the received signal obtains a broadband sampling signal through a digital-to-analog converter, it undergoes down-conversion processing through a down-conversion module to obtain a down-converted digital signal. The second automatic gain control loop performs digital automatic gain control on the down-converted digital signal to adjust the power level of the down-converted digital signal to a second setting value. The adjusted down-converted digital signal is then sent to baseband demodulation. Through the above configuration, this invention can effectively utilize the dynamic range of analog-to-digital conversion. Furthermore, since the power detection points and sampling rates of the two automatic gain control loops are different, different power detection strategies and different loop bandwidth configurations can be adopted, supporting the forward channel reception requirements with variable symbol rates and improving the flexibility of forward channel bandwidth allocation. Attached Figure Description

[0063] The disclosure of this invention will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0064] Figure 1 This is a schematic diagram of the main structure of the automatic gain control system of a broadband satellite receiver according to an embodiment of the present invention;

[0065] Figure 2 This is a schematic diagram of the main components of a forward communication system;

[0066] Figure 3 This is a schematic diagram of the main components of a first automatic gain control loop according to an embodiment of the present invention;

[0067] Figure 4 This is a schematic diagram illustrating power detection of a broadband sampled signal according to one embodiment of the present invention;

[0068] Figure 5 This is a schematic diagram of quantization level generation according to one embodiment of the present invention;

[0069] Figure 6 This is a schematic diagram showing the correspondence between a first reference level and a quantization level according to an embodiment of the present invention;

[0070] Figure 7 This is a schematic diagram showing the correspondence between the first linear gain and the first logarithmic gain according to one embodiment of the present invention;

[0071] Figure 8 This is a schematic diagram of a method for reducing oscillations in the first logarithmic gain according to an embodiment of the present invention;

[0072] Figure 9 This is a schematic diagram of the main components of a first loop filter according to an embodiment of the present invention;

[0073] Figure 10 This is a schematic diagram of the main components of a downconverter module according to one embodiment of the present invention;

[0074] Figure 11 This is a schematic diagram of a method for frequency selectivity of a broadband satellite receiver according to an embodiment of the present invention.

[0075] Figure 12 This is a schematic diagram of the main components of a second automatic gain control loop according to an embodiment of the present invention;

[0076] Figure 13 This is a control simulation diagram of an example first automatic gain control loop according to an embodiment of the present invention;

[0077] Figure 14 Is only used Figure 13 A schematic diagram of baseband signal demodulation in the first automatic gain control loop of the circuit.

[0078] Figure 15 This is a control simulation diagram of the second automatic gain control loop according to an embodiment of the present invention;

[0079] Figure 16 Is used simultaneously Figure 13 The first automatic gain control loop and Figure 15 A schematic diagram of baseband signal demodulation in the second automatic gain control loop;

[0080] Figure 17 This is a schematic flowchart of the main steps of an automatic gain control method for a broadband satellite receiver according to an embodiment of the present invention.

[0081] List of reference numerals :

[0082] 11: First automatic gain control loop; 111: First power detection submodule; 112: Analog gain adjustment submodule; 12: Analog-to-digital converter; 13: Down-conversion module; 131: Digital oscillator; 132: Digital down-conversion submodule; 14: Second automatic gain control loop; 141: Second power detection submodule; 142: Digital gain adjustment submodule. Detailed Implementation

[0083] Some embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0084] In the description of this invention, "module" and "processor" can include hardware, software, or a combination of both. A module can include hardware circuitry, various suitable sensors, communication ports, memory, and may also include software components, such as program code, or a combination of software and hardware. A processor can be a central processing unit, microprocessor, image processor, digital signal processor, or any other suitable processor. The processor has data and / or signal processing capabilities. The processor can be implemented in software, in hardware, or a combination of both. Non-transitory computer-readable storage media includes any suitable medium capable of storing program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc. The term "A and / or B" means all possible combinations of A and B, such as only A, only B, or A and B. The terms "at least one A or B" or "at least one of A and B" have a similar meaning to "A and / or B" and can include only A, only B, or A and B. The singular terms "a" or "this" can also include plural forms.

[0085] See appendix Figure 2 , Figure 2 This is a schematic diagram of the main components of a forward communication system. For example... Figure 2 As shown, the network side transmits data forward and through the local area network (LAN) to higher layers. After baseband transmission processing, intermediate frequency (IF) transmission processing, and radio frequency (RF) processing, the wireless signal is transmitted from the wireless channel. The receiver receives the wireless signal, processes it through RF, and sends it to the IF channel. The IF receiving section amplifies the signal to a set reference level through gain control, and then sends it to the baseband receiving section after frequency shifting and filtering. The baseband receiving section demodulates the data and transmits the result to the higher layers on the terminal side.

[0086] See appendix Figure 1 , Figure 1 This is a schematic block diagram of the main structure of the automatic gain control system of a broadband satellite receiver according to an embodiment of the present invention. Figure 1 As shown, the automatic gain control system in this embodiment of the invention may include a first automatic gain control loop 11, an analog-to-digital converter 12, a down-conversion module 13, and a second automatic gain control loop 14.

[0087] In this embodiment, the first automatic gain control loop 11 can be used to perform analog automatic gain control on the received signal, so that the power level of the received signal reaches a preset first setting value. The analog-to-digital converter 12 can be used to perform analog-to-digital conversion on the received signal after analog gain control to obtain a wideband sampled digital signal. The down-conversion module 13 can be used to down-convert the wideband sampled digital signal to obtain a down-converted digital signal. The second automatic gain control loop 14 can be used to perform digital automatic gain control on the down-converted digital signal, so that the power level of the down-converted digital signal reaches a preset second setting value, thereby obtaining a baseband signal for demodulation.

[0088] Through the above configuration, the automatic gain control system of this embodiment includes two automatic gain control loops. In the first automatic gain control loop 11, analog automatic gain control is performed on the received signal to adjust the power level of the received signal to a preset first setting value. After the received signal obtains a broadband sampling signal through a digital-to-analog converter, it undergoes down-conversion processing through a down-conversion module 13 to obtain a down-converted digital signal. The second automatic gain control loop 14 performs digital automatic gain control on the down-converted digital signal to adjust the power level of the down-converted digital signal to a second setting value. The adjusted down-converted digital signal is then sent to baseband demodulation. Through the above configuration, this embodiment of the invention can effectively utilize the dynamic range of analog-to-digital conversion. Furthermore, since the power detection points and sampling rates of the two automatic gain control loops are different, different power detection strategies and different loop bandwidth configurations can be adopted, supporting the forward channel reception requirements with variable symbol rates and improving the flexibility of forward channel bandwidth allocation.

[0089] The following is in conjunction with the appendix Figure 3 To be continued Figure 12 The first automatic gain control loop 11, the analog-to-digital converter 12, the down-conversion module 13, and the second automatic gain control loop 14 will be further described.

[0090] In one embodiment of the present invention, see appendix. Figure 3 , Figure 3 This is a schematic diagram of the main components of a first automatic gain control loop according to an embodiment of the present invention. Figure 3 As shown, the first automatic gain control loop 11 may include a first power detection submodule 111 and an analog gain adjustment submodule 112. The first power detection submodule 111 can be used to detect the power of the broadband sampled data signal to obtain the power level of the broadband sampled digital signal. The analog gain adjustment submodule 112 can be used to obtain an analog gain based on the power level and a first reference level, so as to adjust the received signal to a first set value according to the analog gain. The first reference level is obtained based on the peak-to-average power ratio of the broadband sampled digital signal.

[0091] In this embodiment, for high-throughput satellites, which can support larger bandwidths and flexible channel bandwidth allocation, the broadband satellite receiver needs to support symbol rate variations over a wide range, from tens of megabits to hundreds of megabits. Therefore, the broadband satellite receiver needs to perform broadband sampling via the analog-to-digital converter 12 (ADC) and fully utilize the ADC's dynamic range. Figure 3 The first automatic gain control loop 11 controls the gain of the received signal.

[0092] In one embodiment, the first power detection submodule 111 can perform power detection on the broadband sampled signal using a downsampling method. See Appendix [link to appendix]. Figure 4 , Figure 4 This is a schematic diagram illustrating power detection of a broadband sampled signal according to one embodiment of the present invention. Figure 4 As shown, since the sampling rate of broadband sampling signals can reach GHz, direct power detection requires significant overhead. Therefore, downsampling can be used for power detection, with intervals between sampling points (…). Figure 4 Power detection is performed using the AGC1 power detection window, which can effectively reduce computational overhead and resource consumption. Here, AGC1 corresponds to the first automatic gain control loop 11, and AGC stands for Automatic Generation Control.

[0093] In one implementation, see Appendix Figure 5 and attached Figure 6 , Figure 5 This is a schematic diagram of quantization level generation according to one embodiment of the present invention; Figure 6 This is a schematic diagram illustrating the correspondence between a first reference level and a quantization level according to one embodiment of the present invention. Different first reference level settings in the first automatic gain control loop 11 correspond to different power levels after Mbit quantization. Figure 5 As shown, the received signal's gain amplitude is controlled by the first reference level of AGC1 (first automatic gain control loop 11), and then sent to baseband processing after M-bit quantization. Here, M bits represent the bit width used by the hardware SOC of the broadband satellite receiver, and the first automatic gain control loop 11 matches it by setting the first reference level. Figure 6As shown, the number of bits reserved for peak quantization of the wideband sampled digital signal is a < b. If the reserved number of bits a does not result in quantization saturation loss, then setting the first reference level 1 is more appropriate than setting the first reference level 2. In practical applications, the first reference level can be set according to the PAPR (Peak to Average Power Ratio) statistical characteristics of the wideband sampled digital signal. By setting an appropriate first reference level, it is possible to ensure that the M-bit quantized signal maintains a small quantization error and can express a high SNR (Signal-to-Noise Ratio).

[0094] In one embodiment, the analog gain adjustment submodule 112 may include a first gain acquisition unit, a first error control unit, and a first gain adjustment unit. The first gain acquisition unit can be used to acquire a first logarithmic gain based on a power level and a first reference level. The first error control unit can be used to perform error control based on the first logarithmic gain to obtain an analog gain. The first gain adjustment unit can be used to adjust the received signal to a first set value based on the analog gain.

[0095] In one embodiment, the first gain acquisition unit may include a first linear gain acquisition subunit and a first logarithmic gain acquisition subunit. The first linear gain acquisition subunit may be used to divide the power level by a first reference level to obtain a first linear gain. The first logarithmic gain acquisition subunit may be used to convert the first linear gain into a first logarithmic gain based on a preset logarithmic gain range and a preset step size.

[0096] In this embodiment, such as Figure 3 As shown, the first line gain acquisition subunit is... Figure 3 The function corresponding to the division sign in the code is to divide the power level obtained by power detection by the AGC1 reference level (first reference level) to obtain the first linear gain.

[0097] The first logarithmic gain acquisition subunit corresponds to Figure 3 The linear-to-dB function in the middle converts the first linear gain to the first logarithmic gain.

[0098] See appendix Figure 7 , Figure 7 This is a schematic diagram illustrating the correspondence between the first linear gain and the first logarithmic gain according to one embodiment of the present invention. Figure 7 As shown, the logarithmic gain range can be preset, such as -15dB to 15dB, and the step size can be preset, such as 0.25dB. Then the first linear gain a0, a1, ..., a... 120 According to Figure 7 The correspondence shown is converted into the first logarithmic gain.

[0099] In one embodiment, the first error control unit may include a first error limiting subunit and a first loop filter. The first error limiting subunit may be used to limit the range of the first logarithmic gain to reduce oscillations in the first logarithmic gain. The first loop filter may be used to perform integral filtering based on the first logarithmic gain and the analog gain of the previous order to obtain the analog gain of the current order.

[0100] In this embodiment, such as Figure 3 As shown, the first error limit corresponds to Figure 3 The error limiting function in the first logarithmic gain acquisition subunit limits the range of the first logarithmic gain (error) output.

[0101] Please refer to the appendix. Figure 8 , Figure 8 This is a schematic diagram of a method for reducing the oscillation of the first logarithmic gain according to an embodiment of the present invention. It can be achieved through... Figure 8 The method described herein limits the range of the first logarithmic gain. Specifically, a dead zone is set to prevent the first logarithmic gain from frequently fluctuating between -0.25dB, 0dB, and 0.25dB when converting from the first linear gain to the first logarithmic gain. To avoid oscillations in the first logarithmic gain, an oscillation dead zone can be set so that the first logarithmic gain satisfies the relationship shown in formula (1):

[0102] err dB =0,if|err dB |<0.5 (1)

[0103] Among them, err dB This is the first logarithmic gain.

[0104] For the first logarithmic gain within 0.25dB, the first logarithmic gain can be set directly to 0 and not included in the subsequent loop accumulation. For the first logarithmic gain exceeding 0.25dB, it will be included in the subsequent loop accumulation.

[0105] like Figure 3 As shown, the first loop filter corresponds to Figure 3 The loop function in the diagram, and its specific structure, can be found in the appendix. Figure 9 , Figure 9 This is a schematic diagram of the main components of a first loop filter according to an embodiment of the present invention. Figure 9 As shown, an integrator (Z) can be added after the first logarithmic gain and the previous-order analog gain. -1 This is used to implement integral filtering, thereby obtaining the analog gain of the current order. Its specific expression is shown in formula (2):

[0106] errloop (n+1)=err loop (n)+α·err (2)

[0107] Among them, err loop (n+1) represents the analog gain of the current order, err loop (n) represents the previous analog gain, α is the scaling factor, and err is the first logarithmic gain.

[0108] Since the power variation of the received signal is relatively stable, the above-mentioned first-order loop filter can make the system have good stability.

[0109] In one embodiment, the first gain adjustment unit may include a variable gain amplifier. The variable gain amplifier can be used to perform variable gain adjustment based on analog gain, such that the received signal is adjusted to a first set value.

[0110] In this embodiment, such as Figure 3 As shown, the variable gain amplifier is Figure 3 The VGA (Variable Gain Amplifier) ​​adjusts the power level of the received signal to a first set value based on the analog AGC gain (analog gain), thereby adjusting the power level of the ADC (analog-to-digital converter 12) to the first set value.

[0111] In one embodiment of the present invention, the down-conversion module 13 may include a digital oscillator 131 and a digital down-conversion submodule 132. The digital oscillator 131 can be used to shift the frequency of the broadband sampled digital signal to the baseband signal frequency. The digital down-conversion submodule 132 can be used to perform downsampling filtering on the frequency-shifted broadband sampled digital signal to obtain the down-converted digital signal.

[0112] In this embodiment, please refer to the appendix. Figure 10 , Figure 10 This is a schematic diagram of the main structural components of a downconverter module according to one embodiment of the present invention. Figure 10 As shown, the digital oscillator 131 (Numerically Controlled Oscillator) shifts the intermediate frequency broadband sampling signal to the baseband, and the digital downconverter submodule 132 (DDC) reduces the high sampling rate of the ADC to 2x the baseband processing rate.

[0113] See appendix Figure 11 , Figure 11 This is a schematic diagram of a frequency selectivity method for a broadband satellite receiver according to one embodiment of the present invention. Figure 11As shown, in the received broadband sampled signal, the specified channel is extracted using a down-conversion method. Figure 11 Channel 2) is sent to the second automatic gain control loop 14 (AGC2).

[0114] In one embodiment of the present invention, the second gain control loop may include a second power detection submodule 141 and a digital gain adjustment submodule 142. The second power detection submodule 141 can be used to detect the power of the down-converted digital signal to obtain its power level. The digital gain adjustment submodule 142 can be used to obtain a digital gain based on the power level and a second reference level, and adjust the power level of the down-converted digital signal to a preset second setting value according to the digital gain to obtain a baseband signal for demodulation. The second reference level is obtained based on the peak-to-average power ratio of the down-converted digital signal.

[0115] In this embodiment, the forward channel bandwidth allocation is flexible and requires gain control based on the corresponding channel bandwidth allocation, with digital gain control performed in the second automatic gain control loop 14. See Appendix [link to appendix]. Figure 12 , Figure 12 This is a schematic diagram of the main components of a second automatic gain control loop according to one embodiment of the present invention. Figure 12 As shown, the input of the second power detection submodule 141 corresponds to the output signal of the downconversion module 13. After processing by the downconversion module 13, the sample rate is twice the baseband symbol rate, and power detection can be performed using the method shown in formula (3):

[0116] P(n) = I 2 (n)+Q 2 (n) (3)

[0117] Where P is the power level of the down-converted signal, I is the real part of the vector signal corresponding to the down-converted signal, and Q is the imaginary part of the vector signal corresponding to the down-converted signal.

[0118] A suitable second reference level can be obtained based on the peak-to-average power ratio of the down-converted digital signal.

[0119] In one embodiment, the digital gain adjustment submodule 142 may include a second gain acquisition unit, a second error control unit, and a second gain adjustment unit. The second gain acquisition unit may be used to acquire a second logarithmic gain based on a power level and a second reference level. The second error control unit may be used to perform error control based on the second logarithmic gain to acquire the digital gain. The second gain adjustment unit may be used to adjust the power level of the down-converted digital signal to a second set value based on the digital gain.

[0120] In this embodiment, such as Figure 12As shown, the second gain acquisition unit includes a second linear gain acquisition subunit and a second logarithmic gain acquisition subunit. The second linear acquisition subunit can be used to compare the power level with a second reference level ( Figure 12 Divide the AGC2 reference level in the equation to obtain the second linear gain, which corresponds to... Figure 12 The division function in the code. The second logarithmic gain acquisition subunit can be used to convert the second linear gain into a second logarithmic gain based on a preset logarithmic gain range and a preset step, which corresponds to... Figure 12 The linear-to-dB conversion function is described. The implementation methods of the second linear gain acquisition subunit and the second logarithmic gain acquisition subunit are the same as those of the first linear gain acquisition subunit and the first logarithmic gain acquisition subunit, respectively. These implementation methods can be referenced.

[0121] The second error control unit may include a second error limiting subunit and a second loop filter. The second error limiting subunit can be used to limit the range of the second logarithmic gain to reduce oscillations in the second logarithmic gain, which corresponds to... Figure 12 The error limiting function is included. The second loop filter can be used for integral filtering based on the second logarithmic gain and the previous order's digital gain to obtain the current order's digital gain, which corresponds to... Figure 12 The loop function is described. The second error limiting subunit and the second loop filter are implemented in the same way as the first error limiting subunit and the first loop filter, and can be referenced to their implementation methods.

[0122] The second gain adjustment unit may include a logarithmic-to-linear gain subunit and a second multiplier. The logarithmic-to-linear gain subunit can be used to inversely transform the digital gain according to the logarithmic gain range and step size to obtain the final linear gain. Figure 12 The digital AGC gain in the data corresponds to... Figure 12 The dB-to-linear conversion function is included. The second multiplier can be used to multiply the final linear gain by the down-converted digital signal, thereby adjusting the power level of the down-converted digital signal to a second set value, which corresponds to... Figure 12 The multiplication function in [the code]. The logarithmic-to-linear gain subunit can be based on [the function of the multiplication sign]. Figure 7 The directional lookup table is performed as shown, thereby obtaining the final linear gain based on the second logarithmic gain. And through... Figure 12 The second multiplier in Figure 12 The multiplication function in the code adjusts the power level of the downconverted signal to the second set value based on the digital AGC gain (final linear gain).

[0123] In one implementation, analog automatic gain control can use either open-loop or closed-loop gain control; digital automatic gain control can also use either open-loop or closed-loop gain control. Combining open-loop and closed-loop control improves the response speed of the automatic gain control system while ensuring steady-state error.

[0124] In one implementation, open-loop gain control can be used during initial control, according to the following formula (4):

[0125] gain(0) = round(err) dB / step)·step (4)

[0126] Where gain(0) is the initial open-loop gain, err dB For logarithmic gain, step is the preset step size.

[0127] Closed-loop gain control can be used after initial control, according to the following formula (5):

[0128] gain(n+1)=gain(n)+err dB ·α (5)

[0129] Where gain(n+1) is the (n+1)th order closed-loop gain, gain(n) is the nth order closed-loop gain, and α is the loop scaling factor.

[0130] In one implementation, step can be a 0.25 dB increment; α can take values ​​of 1 / 4, 1 / 8, ...

[0131] See Appendix for an example. Figure 13 and attached Figure 14 , Figure 13 This is a control simulation diagram of an example first automatic gain control loop according to an embodiment of the present invention; Figure 14 Is only used Figure 13 The diagram shows the baseband signal demodulation during AGC1 (first automatic gain control loop 11). Figure 13 As shown, in this example, only the first automatic gain control loop 11 is used to adjust the gain of the intermediate frequency signal. The baseband signal after the DDC (downconversion module 13) is not adjusted by the second automatic gain control loop 14, resulting in a mismatch between the amplitude and the quantization of the baseband signal.

[0132] Specifically, the simulation parameters for the first automatic gain control loop 11 are:

[0133] ADC sampling rate: 2GHz;

[0134] Power detection downsampling rate: 8;

[0135] The proportionality coefficient α of the loop is 0.25;

[0136] Sample detection length: 1024.

[0137] When the intermediate frequency input signal (received signal) is low, AGC1 adjusts the gain to bring its amplitude to the set value. For example... Figure 13 As shown in (a), AGC1 uses 1 / 8 downsampling power to detect the power level of the intermediate frequency input signal as -6dB; correspondingly, as Figure 13 As shown in (b), the AGC1 control gain is compensated by 6dB.

[0138] like Figure 14 As shown, the link simulation only uses AGC1. When the gain adjustment result of AGC1 does not match the baseband signal amplitude, it affects the demodulation performance of the receiving link.

[0139] In another example, see Appendix Figure 15 and attached Figure 16 , Figure 15 This is a control simulation diagram of the second automatic gain control loop according to an embodiment of the present invention; Figure 16 Is used simultaneously Figure 13 The first automatic gain control loop 11 and Figure 15 The diagram illustrates baseband signal demodulation in the second automatic gain control loop 14. In this example, a hybrid gain control system using AGC1 (first automatic gain control loop 11) and AGC2 (second automatic gain control loop 14) is employed. AGC1 performs gain control on the analog intermediate frequency signal, while AGC2 performs gain control on the down-converted baseband signal (down-converted digital signal).

[0140] The simulation parameters for AGC1 are the same as in the previous example. The gain control results can be found in the appendix. Figure 13 .

[0141] AGC2 simulation parameters:

[0142] The proportionality coefficient α of the loop is 0.5;

[0143] Sample detection length: 1024.

[0144] When the intermediate frequency input signal (received signal) is low, AGC1 first adjusts the gain to make the signal amplitude before the ADC reach the first set value. Simultaneously, AGC2 detects the signal power after the downconverter module 13DDC, such as... Figure 15 As shown in (a), AGC2 detects that the input power of the down-converted digital signal after DDC is 18dB. Correspondingly, as Figure 15As shown in (b), the AGC2 control gain decreases by -18dB.

[0145] like Figure 16 The image shows a link simulation of a hybrid AGC including AGC1 and AGC2. Figure 14 In comparison, increasing the -18dB attenuation of AGC2 makes the amplitude of the signal after DDC match that of the baseband signal. The results show that the gain adjustment of the dual AGC loop including AGC1 and AGC2 does not affect the demodulation performance of the receiving link in steady state.

[0146] Furthermore, the present invention also provides an automatic gain control method for a broadband satellite receiver.

[0147] See appendix Figure 17 , Figure 17 This is a schematic flowchart illustrating the main steps of an automatic gain control method according to an embodiment of the present invention. Figure 17 As shown, the automatic gain control method in this embodiment of the invention is based on the automatic gain control system in the above-described automatic gain control system embodiment. The automatic gain control method includes the following steps S101 to S104:

[0148] Step S101: The received signal is subjected to analog automatic gain control through the first automatic gain control loop to adjust the power level of the received signal to a preset first setting value.

[0149] Step S102: The received signal after analog gain control is converted to digital using an analog-to-digital converter to obtain a broadband sampled digital signal.

[0150] Step S103: The broadband sampling signal is down-converted by the down-conversion module to obtain a down-converted digital signal.

[0151] Step S104: The down-converted digital signal is subjected to digital automatic gain control through the second automatic gain control loop, so that the power level of the down-converted digital signal reaches the preset second setting value, thereby obtaining the baseband signal for demodulation.

[0152] Through steps S101 to S104 described above, this embodiment of the invention can perform analog automatic gain control on the received signal in the first automatic gain control loop, adjusting the power level of the received signal to a preset first setting value. After the received signal obtains a wideband sampling signal through a digital-to-analog converter, it undergoes down-conversion processing through a down-conversion module to obtain a down-converted digital signal. The second automatic gain control loop performs digital automatic gain control on the down-converted digital signal, adjusting the power level of the down-converted digital signal to a second setting value. The adjusted down-converted digital signal is then sent to baseband demodulation. Through the above configuration, this embodiment of the invention can effectively utilize the dynamic range of analog-to-digital conversion. Furthermore, since the power detection points and sampling rates of the two automatic gain control loops are different, different power detection strategies and different loop bandwidth configurations can be adopted, supporting the forward channel reception requirements with variable symbol rates and improving the flexibility of forward channel bandwidth allocation.

[0153] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effects of the present invention, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of the present invention.

[0154] Those skilled in the art will understand that all or part of the processes in the method of the above embodiment of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium can include any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content included in the computer-readable storage medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0155] Furthermore, it should be understood that since the various modules are only provided to illustrate the functional units of the device of the present invention, the physical devices corresponding to these modules may be the processor itself, or a part of the processor's software, hardware, or a combination of software and hardware. Therefore, the number of modules shown in the figures is merely illustrative.

[0156] Those skilled in the art will understand that the various modules in the device can be adaptively split or combined. Such splitting or combining of specific modules will not cause the technical solution to deviate from the principles of the present invention; therefore, the technical solutions after splitting or combining will fall within the protection scope of the present invention.

[0157] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. An automatic gain control system for a broadband satellite receiver, characterized in that, The system includes a first automatic gain control loop, an analog-to-digital converter, a down-conversion module, and a second automatic gain control loop. The first automatic gain control loop is used to perform analog automatic gain control on the received signal so that the power level of the received signal reaches a preset first setting value; The analog-to-digital converter is used to perform analog-to-digital conversion on the received signal after analog gain control to obtain a broadband sampled digital signal; The down-conversion module is used to perform down-conversion processing on the broadband sampled digital signal to obtain a down-converted digital signal; The second automatic gain control loop is used to perform digital automatic gain control on the down-converted digital signal so that the power level of the down-converted digital signal reaches a preset second setting value, thereby obtaining a baseband signal for demodulation; The first automatic gain control loop includes a first power detection submodule and an analog gain adjustment submodule; The first power detection submodule is used to perform power detection on the broadband sampled data signal to obtain the power level of the broadband sampled digital signal; The first power detection submodule uses downsampling to detect the power of the broadband sampled signal; The analog gain adjustment submodule is used to obtain an analog gain based on the power level and a first reference level, so as to adjust the received signal to the first set value according to the analog gain; wherein, the first reference level is obtained based on the peak-to-average power ratio of the broadband sampled digital signal; different first reference level settings of the first automatic gain control loop correspond to different power levels after M-bit quantization; the received signal controls the gain amplitude through the first reference level of the first automatic gain control loop, and then sends it to the baseband processing after M-bit quantization; wherein, M bits is the bit width used by the hardware SOC of the broadband satellite receiver, and the first automatic gain control loop is matched with M bits through the setting of the first reference level; The second automatic gain control loop includes a second power detection submodule and a digital gain adjustment submodule; The second power detection submodule is used to perform power detection on the down-converted digital signal to obtain the power level of the down-converted digital signal; The digital gain adjustment submodule is used to obtain a digital gain based on the power level and the second reference level, and adjust the power level of the down-converted digital signal to a preset second setting value based on the digital gain, so as to obtain the baseband signal for demodulation. The second reference level is obtained based on the peak-to-average power ratio of the down-converted digital signal.

2. The automatic gain control system according to claim 1, characterized in that, The analog gain adjustment submodule includes a first gain acquisition unit, a first error control unit, and a first gain adjustment unit; The first gain acquisition unit is used to acquire a first logarithmic gain based on the power level and the first reference level; The first error control unit is used to perform error control based on the first logarithmic gain to obtain the analog gain; The first gain adjustment unit is used to adjust the received signal to the first set value according to the analog gain.

3. The automatic gain control system according to claim 2, characterized in that, The first gain acquisition unit includes a first linear gain acquisition subunit and a first logarithmic gain acquisition subunit; The first linear gain acquisition subunit is used to divide the power level and the first reference level to obtain the first linear gain; The first logarithmic gain acquisition subunit is configured to convert the first linear gain into the first logarithmic gain based on a preset logarithmic gain range and a preset step size; and / or, The first error control unit includes a first error limiting subunit and a first loop filter; The first error limiting subunit is used to limit the range of the first logarithmic gain in order to reduce the oscillation of the first logarithmic gain; The first loop filter is used to perform integral filtering based on the first logarithmic gain and the analog gain of the previous order to obtain the analog gain of the current order; and / or, The first gain adjustment unit includes a variable gain amplifier; The variable gain amplifier is used to adjust the variable gain according to the analog gain, so that the received signal is adjusted to the first set value.

4. The automatic gain control system according to claim 1, characterized in that, The digital gain adjustment submodule includes a second gain acquisition unit, a second error control unit, and a second gain adjustment unit. The second gain acquisition unit is used to acquire a second logarithmic gain based on the power level and the second reference level; The second error control unit is used to perform error control based on the second logarithmic gain and obtain the digital gain; The second gain adjustment unit is used to adjust the power level of the down-converted digital signal to the second set value according to the digital gain.

5. The automatic gain control system according to claim 4, characterized in that, The second gain acquisition unit includes a second linear gain acquisition subunit and a second logarithmic gain acquisition subunit; The second linear gain acquisition subunit is used to divide the power level by the second reference level to obtain the second linear gain; The second logarithmic gain acquisition subunit is used to convert the second linear gain into the second logarithmic gain based on a preset logarithmic gain range and a preset step size; and / or, The second error control unit includes a second error limiting subunit and a second loop filter; The second error limiting subunit is used to limit the range of the second logarithmic gain in order to reduce the oscillation of the second logarithmic gain; The second loop filter is used to perform integral filtering based on the second logarithmic gain and the digital gain of the previous order to obtain the digital gain of the current order; and / or, The second gain adjustment unit includes a logarithmic-to-linear gain subunit and a second multiplier; The logarithmic-to-linear gain subunit is used to reverse the digital gain according to the logarithmic gain range and the step size to obtain the final linear gain. The second multiplier is used to multiply the final linear gain with the down-converted digital signal, thereby adjusting the power level of the down-converted digital signal to the second set value.

6. The automatic gain control system according to claim 1, characterized in that, The downconversion module includes a digital oscillator and a digital downconversion submodule; The digital oscillator is used to shift the broadband sampled digital signal to the baseband signal frequency; The digital down-conversion submodule is used to perform downsampling filtering on the frequency-shifted broadband sampled digital signal to obtain the down-converted digital signal; and / or, The analog automatic gain control uses open-loop gain control and / or closed-loop gain control. The digital automatic gain control uses open-loop gain control and / or closed-loop gain control.

7. The automatic gain control system according to claim 6, characterized in that, The analog automatic gain control and / or the digital automatic gain control use open-loop gain control during initial control. The open-loop gain control is performed according to the following formula: in, This is the initial open-loop gain. For logarithmic gain, step is the preset step size; and / or, The analog automatic gain control and / or the digital automatic gain control perform initial control followed by closed-loop gain control; The closed-loop gain control is performed according to the following formula: in, For the (n+1)th order closed-loop gain, This represents the nth-order closed-loop gain. This is the proportional coefficient of the loop.

8. An automatic gain control method for a broadband satellite receiver, characterized in that, The method is based on the automatic gain control system according to any one of claims 1 to 7; the method includes: The first automatic gain control loop performs analog automatic gain control on the received signal to adjust the power level of the received signal to a preset first setting value. The analog-to-digital converter is used to perform analog-to-digital conversion on the received signal after analog gain control in order to obtain a broadband sampled digital signal. The broadband sampling signal is down-converted by the down-conversion module to obtain a down-converted digital signal. The down-converted digital signal is subjected to digital automatic gain control through the second automatic gain control loop, so that the power level of the down-converted digital signal reaches a preset second setting value, thereby obtaining a baseband signal for demodulation.

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