CN115276694A - Frequency hopping receiver and automatic gain control method thereof - Google Patents
Frequency hopping receiver and automatic gain control method thereof Download PDFInfo
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- CN115276694A CN115276694A CN202211072474.8A CN202211072474A CN115276694A CN 115276694 A CN115276694 A CN 115276694A CN 202211072474 A CN202211072474 A CN 202211072474A CN 115276694 A CN115276694 A CN 115276694A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/30—Circuits for homodyne or synchrodyne receivers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/715—Interference-related aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/30—Circuits for homodyne or synchrodyne receivers
- H04B2001/307—Circuits for homodyne or synchrodyne receivers using n-port mixer
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/715—Interference-related aspects
- H04B2001/7152—Interference-related aspects with means for suppressing interference
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a frequency hopping receiver and a gain automatic control method thereof, wherein the frequency hopping receiver comprises a frequency conversion band-pass filter, a first variable gain module, a second variable gain module, a third variable gain module, a first detector for detecting the signal power of the input end of the first variable gain module, a second detector for detecting the signal power of the input end of the second variable gain module, a third detector for detecting the signal power of the input end of the third variable gain module, a controller, a first intermediate frequency filter circuit, a second intermediate frequency filter circuit, a high-speed analog-to-digital converter, a multichannel analog-to-digital converter and a frequency source; the signal received by the antenna is electrically connected with the controller through the variable frequency band-pass filter, the first variable gain module, the first intermediate frequency filter circuit, the second variable gain module, the second intermediate frequency filter circuit and the third variable gain module in sequence; the controller adjusts the gains of the first variable gain module, the second variable gain module and the third variable gain module according to the received first voltage value, the received second voltage value and the received third voltage value, and automatic control of the receiving gain is achieved.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a frequency hopping receiver and an automatic gain control method thereof.
Background
The frequency hopping radio station is widely applied to important communication fields such as military and the like, the spatial electromagnetic wave is used as a transmission channel to remotely transmit an electric signal, the frequency fading effect is generated under the influence of factors such as distance, diffraction and fading, the signal intensity of frequency hopping carrier signals with different frequencies reaching a receiving end is discrete, the amplitude fluctuation is intense, and the normal demodulation of a receiver is influenced. In addition, the communication distances between the stations are different, and the received signal strengths of the receiving ends are also greatly different, which may cause performance degradation and abnormal reception of the receiver if no effective measures are taken. Therefore, an Automatic Gain Control (AGC) function is required to adjust in the receiver design.
In some published patent or technical literature libraries, the introduction of automatic gain control of a receiver is not few, most of the introduction is biased to refer to circuit architecture composition, specific control methods and strategies are lacked in the practical application scene of a frequency hopping radio station, the applicability is not high, and the defects are obvious. For example: a high-speed frequency hopping automatic gain control method, its low-speed synchronization and high-speed data communication signal adopt and divide the channel to receive, there are two apparent deficiencies: firstly, the hardware overhead cost is increased, and secondly, the low-speed synchronous receiving channel also has device saturation and signal distortion under the environment of a near-field large signal, so that the success rate of synchronization is reduced.
Disclosure of Invention
The invention aims to solve the problems of the defects and shortcomings of the prior art, provides a frequency hopping receiver and an automatic gain control method thereof, covers the practical application scene of a frequency hopping radio station, and improves the effectiveness and reliability of an automatic gain control circuit in the frequency hopping radio station on the basis of ensuring the response speed, the control precision and the dynamics.
In order to achieve the purpose of the invention, the technical scheme is as follows:
a frequency hopping receiver comprises a first detector, a second detector, a third detector, a first variable gain module, a second variable gain module, a third variable gain module, a multi-channel analog-to-digital converter, a controller, a variable frequency band-pass filter, a first intermediate frequency filter and a second intermediate frequency filter;
the variable-frequency band-pass filter, the first variable gain module, the first intermediate frequency filter, the second variable gain module, the second intermediate frequency filter, the third variable gain module and the controller are electrically connected in sequence;
the first detector is used for detecting the signal power intensity of the input end of the first variable gain module, a sampling detection point is arranged between the variable frequency band-pass filter and the first variable gain module, and the first detector converts the signal power intensity of the input end of the first variable gain module into a voltage value, namely a first voltage value;
the second detector is used for detecting the signal power intensity of the input end of the second variable gain module, the sampling detection point is arranged between the first intermediate frequency filter and the second variable gain module, and the second detector converts the signal power intensity of the input end of the second variable gain module into a voltage value which is called a second voltage value;
the third detector is used for detecting the signal power intensity at the input end of the third variable gain module, the sampling detection point is arranged between the second intermediate frequency filter and the third variable gain module, and the third detector converts the signal power intensity at the input end of the third variable gain module into a voltage value which is called a third voltage value;
the first variable gain module is used for amplifying or attenuating radio frequency signals, and gain is controlled by the controller;
the second variable gain module is used for amplifying or attenuating the first intermediate frequency signal, and the gain is controlled by the controller;
the third variable gain module is used for amplifying or attenuating the second intermediate frequency signal, and the gain is controlled by the controller;
the multichannel analog-to-digital converter is arranged among the first detector, the second detector, the third detector and the controller and is used for converting the first voltage value, the second voltage value and the third voltage value into digital signals and sending the digital signals to the controller;
the controller correspondingly adjusts the gains of the first variable gain module, the second variable gain module and the third variable gain module according to the first voltage value, the second voltage value and the third voltage value received by the multichannel analog-to-digital converter, so that a frequency hopping signal RF received by the antenna sequentially passes through the first variable gain module, the first intermediate frequency filter circuit, the second variable gain module, the second intermediate frequency filter circuit and the third variable gain module, and then a second intermediate frequency signal IF2 with relatively stable amplitude is obtained and input into the controller.
Preferably, the system also comprises a first mixer and a first local oscillation source; the first mixer is arranged between the first variable gain module and the first intermediate frequency filter, and the first local vibration source is electrically connected with the first mixer.
Preferably, the system further comprises a second mixer and a second local vibration source; the second mixer is arranged between the second variable gain module and the second intermediate frequency filter, and the second local vibration source is electrically connected with the second mixer.
Preferably, the system further comprises a high-speed analog-to-digital converter, wherein the high-speed analog-to-digital converter is arranged between the third variable gain module and the controller;
and the second intermediate frequency signal IF2 is input into the controller through the high-speed analog-to-digital converter.
When the receiver works, the signal output received by the antenna sequentially passes through the frequency conversion band-pass filter, the first variable gain module, the first intermediate frequency filter, the second variable gain module, the second intermediate frequency filter and the third variable gain module, the controller receives the first voltage value, the second voltage value and the third voltage value according to the multi-channel analog-to-digital converter, and according to the gain automatic control method, the gain adjustment is correspondingly carried out on the first variable gain module, the second variable gain module and the third variable gain module, so that the frequency hopping signal RF received by the antenna is processed by the first variable gain module, the second variable gain module and the third variable gain module to obtain a second intermediate frequency signal IF2 with relatively stable amplitude.
A method for automatic gain control in a frequency hopping receiver, the method comprising:
based on the frequency hopping receiver, a distributed control method is adopted to distribute the task of signal gain adjustment among a first variable gain module, a second variable gain module and a third variable gain module;
after the frequency hopping receiving signal enters a receiving circuit, the received signal is measured and adjusted step by step according to the signal processing flow and the time sequence of a first variable gain module, a second variable gain module and a third variable gain module;
after a gain adjustment process is triggered and started, the controller independently completes gain gear adjustment of the variable gain module according to a frequency hopping synchronous search state, a frequency hopping synchronous working state and an adjacent channel interference state and according to a signal power voltage and gain gear relation table preset at the current stage, and ensures that the gain gear of the circuit at the current stage is adaptive to the current signal power strength;
the condition for triggering the start of the gain adjustment process is that a frequency conversion pulse signal and a strong signal indicate.
Preferably, a control mode of thickness combination is adopted to reduce the iteration time of gain adjustment, specifically:
the gains of the first variable gain module and the second variable gain module are divided into 2-3 gears, and coarse adjustment is carried out in a large step mode;
the gain of the third variable gain module is divided into n fine stepping gears, and fine adjustment in a small stepping mode is achieved, wherein n is an integer larger than 10.
The step-by-step measurement and adjustment of the frequency hopping receiving signals according to the signal processing flow and the time sequence specifically comprises the following three steps:
the first step is as follows: reading a first voltage value, a second voltage value and a third voltage value of each detector at T0 time, and judging whether the current detector is in an adjacent channel interference state or not by means of state combination characteristics of the voltage values:
if so, setting the gain requirement according to the interference state of the adjacent channel, and stopping the following second step and third step;
if not, looking up a table according to a preset relationship table between the first voltage value and the gear value of the first variable gain module to set the gear value of the first variable gain module, and continuing to execute the second step and the third step;
the second step is that: reading a second voltage value of the second detector at the time T1, and setting a gear value of the second variable gain module by looking up a table according to a preset gear value relation table of the second voltage value and the second variable gain module;
the third step: and reading a third voltage value of the third detector at the time T2, and setting a gear value of the third variable gain module by looking up a table according to a preset gear value relation table of the third voltage value and the third variable gain module.
Furthermore, the frequency hopping synchronous search state refers to a working state that the real-time working frequency of the frequency hopping receiver is not consistent with that of the transmitting end and the frequency hopping receiver is waiting for receiving frequency hopping synchronous information according to synchronous hopping;
when the receiver is in the state, the controller presets the front end of the receiver to be maximum gain, continuously reads a third voltage value of the third detector according to a fixed time interval, judges that the current signal is a strong signal when the third voltage value is larger than a certain preset reference value, and triggers a gain adjustment process; otherwise, the signal is judged to be a small signal, and the frequency hopping receiver keeps the maximum gain; wherein said time interval is less than a frequency hopping period.
Furthermore, the frequency hopping synchronization working state is that after the frequency hopping receiver completes frequency hopping synchronization, the working frequency of the frequency hopping receiver is consistent with that of the transmitting end and synchronously hops along with time variation;
when the frequency hopping receiver is in the state, a frequency hopping pulse signal triggers and starts a gain adjustment process, each frequency hopping carrier signal received by the frequency hopping receiver is subjected to gain adjustment once, and the adjustment time is limited in a non-useful data period at the beginning end of each frequency hopping carrier period;
further, the adjacent channel interference state refers to that a strong interference signal exists on a frequency adjacent to the current operating frequency of the receiver, and the state is identified by the combined characteristics of the first voltage value, the second voltage value and the third voltage value, and the specific characteristics are as follows: the first voltage value and the second voltage value are larger than a certain voltage reference value, and the third voltage value is equal to or close to the voltage reference value in the absence of signals;
when the frequency hopping receiver is in the state, the gain gears of the first variable gain module, the second variable gain module and the third variable gain module of the frequency hopping receiver are all set to be the maximum gain gear.
The invention has the following beneficial effects:
the invention is different from the automatic gain control method of other frequency hopping receivers, carries out step-by-step measurement and adjustment according to the signal processing flow and the time sequence, and has simple and flexible control method, configurable precision, dynamic range and response time and strong applicability. Meanwhile, various working states of the frequency hopping receiver are fully considered, the gain control method is distinguished, the problem that the receiving performance is reduced due to frequency fading and near-far effect is effectively solved, and a practical, effective and reliable solution is provided for automatic gain control of the frequency hopping receiver.
Drawings
Fig. 1 is a circuit schematic of a frequency hopping receiver according to the present invention.
Fig. 2 shows the steps of the gain adjustment process according to the present invention.
Fig. 3 is a time domain diagram of the output signal of the second intermediate frequency IF2 of the example of the present invention.
Detailed Description
The invention is described in detail below with reference to the drawings and the detailed description.
Example 1
As shown in fig. 1, a frequency hopping receiver includes a first detector, a second detector, a third detector, a first variable gain module, a second variable gain module, a third variable gain module, a multi-channel analog-to-digital converter, a controller, a frequency conversion band-pass filter, a first intermediate frequency filter, and a second intermediate frequency filter.
The variable-frequency band-pass filter, the first variable-gain module, the first intermediate-frequency filter, the second variable-gain module, the second intermediate-frequency filter, the third variable-gain module and the controller are electrically connected in sequence.
The first detector is used for detecting the signal power intensity of the input end of the first variable gain module, the sampling detection point is arranged between the variable frequency band-pass filter and the first variable gain module, and the first detector converts the signal power intensity of the input end of the first variable gain module into a voltage value, namely a first voltage value.
The second detector is used for detecting the signal power intensity of the input end of the second variable gain module, the sampling detection point is arranged between the first intermediate frequency filter and the second variable gain module, and the second detector converts the signal power intensity of the input end of the second variable gain module into a voltage value, namely a second voltage value.
The third detector is used for detecting the signal power intensity of the input end of the third variable gain module, the sampling detection point is arranged between the second intermediate frequency filter and the third variable gain module, and the third detector converts the signal power intensity of the input end of the third variable gain module into a voltage value called a third voltage value.
The first variable gain module is used for amplifying or attenuating radio frequency signals, and gain is controlled by the controller.
The second variable gain module is used for amplifying or attenuating the first intermediate frequency signal, and the gain is controlled by the controller.
The third variable gain module is used for amplifying or attenuating the second intermediate frequency signal, and the gain is controlled by the controller.
The multichannel analog-to-digital converter is arranged among the first detector, the second detector, the third detector and the controller and is used for converting the first voltage value, the second voltage value and the third voltage value into digital signals and sending the digital signals to the controller;
the controller correspondingly performs gain adjustment on the first variable gain module, the second variable gain module and the third variable gain module according to the first voltage value, the second voltage value and the third voltage value received by the multichannel analog-to-digital converter, so that an intermediate frequency signal IF with relatively stable amplitude is obtained after a frequency hopping signal RF received by an antenna sequentially passes through the first variable gain module, the first intermediate frequency filter circuit, the second variable gain module, the second intermediate frequency filter circuit and the third variable gain module, and is input into the controller.
The variable frequency band-pass filter is connected between an antenna port and the first variable gain module and used for filtering interference clutter signals at the RF far end of a frequency hopping signal.
In this embodiment, the first variable gain module is designed by using a low noise amplifier, so that the receiver obtains a lower noise coefficient, and the gain is set to-10 dB and +20 dB.
The second variable gain module is used for amplifying or attenuating the first intermediate frequency signal, the gain is controlled by the controller, and the gain is set to be two gears of-10 dB and +20 dB.
The third variable gain module is used for amplifying or attenuating the second intermediate frequency signal, the gain is controlled by the controller, the gain of the embodiment is set to be-20 dB- +30dB, the gain is averagely divided into 25 gears (n = 25), each step is 2dB, and in principle, the larger n is, the higher the fine adjustment precision is.
In this embodiment, the signal input power range of the receiver is divided into three intervals, such as: the three detectors distributed on different positions of a receiver channel are detected in a division relay mode, wherein the three detectors are between +10dBm (upper limit) and-20 dBm, between-21 dBm and-60 dBm, between-61 dBm and-100 dBm (lower limit).
The sampling detection point of the first detector is arranged between the variable-frequency band-pass filter and the first variable gain module, and the signal range for detection is as follows: +20dBm (upper limit) to-20 dBm.
The sampling detection point of the second detector is arranged between the first intermediate frequency filter and the second variable gain module, and the signal range which is responsible for detection is as follows: -21dBm through-60 dBm.
The sampling detection point of the third detector is arranged between the second intermediate frequency filter and the third variable gain module, and the signal range for detection is as follows: -61dBm to-100 dBm (lower limit).
Example 2
As shown in fig. 1, a frequency hopping receiver circuit includes a frequency conversion band-pass filter, a first variable gain module, a second variable gain module, a third variable gain module, a first mixer, a second mixer, a first intermediate frequency filter, a second intermediate frequency filter, a first local oscillation source, a second local oscillation source, a first detector, a second detector, a third detector, a multi-channel analog-to-digital converter, a high-speed analog-to-digital converter, and a controller.
The variable-frequency band-pass filter, the first variable gain module, the first frequency mixer, the first intermediate frequency filter, the second variable gain module, the second frequency mixer, the second intermediate frequency filter, the third variable gain module, the high-speed analog-to-digital converter and the controller are electrically connected in sequence.
The first mixer is arranged between the first variable gain module and the first intermediate frequency filter, and the first local vibration source is electrically connected with the first mixer.
The second mixer is arranged between the second variable gain module and the second intermediate frequency filter, and the second local vibration source is electrically connected with the second mixer.
The high-speed analog-to-digital converter is arranged between the third variable gain module and the controller;
the intermediate frequency signal IF is input to a controller through a high-speed analog-to-digital converter.
The variable frequency band-pass filter is connected between an antenna port and the first variable gain module and used for filtering interference clutter signals at the RF far end of a frequency hopping signal.
In this embodiment, the first variable gain module is designed by using a low noise type amplifier, so that the receiver obtains a lower noise coefficient, and the gain is set to two stages, namely-10 dB and +20 dB.
The second variable gain module is arranged between the first intermediate frequency filter and the second mixer and used for amplifying or attenuating the first intermediate frequency signal, the gain is controlled by the controller, and the gain is set to be two stages of-10 dB and +20 dB.
The third variable gain module is arranged between the second intermediate frequency filter and the high-speed analog-to-digital converter and used for amplifying or attenuating the second intermediate frequency signal, the gain is controlled by the controller, the gain of the embodiment is set to be-20 dB to +30dB, the gain is averagely divided into 25 gears (n = 25), each step is 2dB, and in principle, the larger n is, the higher the fine adjustment precision is.
The first mixer is connected between the first variable gain module and the first intermediate frequency filter, and is configured to shift a frequency of the frequency hopping signal RF to a first intermediate frequency IF1, and the first local oscillator provides a fast hopping local oscillator frequency Lo1 to the first local oscillator, where IF1= RF ± Lo1.
The second mixer is connected between the second variable gain module and the second intermediate frequency filter, and is configured to shift the frequency of the first intermediate frequency IF1 to a second intermediate frequency IF2, and the second local oscillator provides a local oscillator signal Lo2 with a fixed frequency to the second local oscillator, so that IF2= IF1 ± Lo2.
The first local vibration source is a high-speed frequency conversion type frequency synthesizer, and the second local vibration source is a fixed frequency source.
The first intermediate frequency filter is connected between the first mixer and the second variable gain module and is used for filtering interference clutter signals outside the first intermediate frequency IF1 passband.
And the second intermediate frequency filter is connected between the second mixer and the third variable gain module and is used for filtering interference clutter signals outside the second intermediate frequency IF2 passband.
In this embodiment, the signal input power range of the receiver is divided into three intervals, such as: the three detectors distributed on different positions of a receiver channel are detected in a division relay mode, wherein the three detectors are between +10dBm (upper limit) and-20 dBm, between-21 dBm and-60 dBm, between-61 dBm and-100 dBm (lower limit).
The sampling detection point of the first detector is arranged between the variable-frequency band-pass filter and the first variable gain module, and the signal range for detection is as follows: +20dBm (upper limit) to-20 dBm.
The sampling detection point of the second detector is arranged between the first intermediate frequency filter and the second variable gain module, and the signal range which is responsible for detection is as follows: -21dBm to-60 dBm.
The sampling detection point of the third detector is arranged between the second intermediate frequency filter and the third variable gain module, and the signal range for detection is as follows: -61dBm to-100 dBm (lower limit).
The multichannel analog-to-digital converter is arranged between the first detector, the second detector and the third detector and the controller and is used for converting the first voltage value, the second voltage value and the third voltage value into digital signals to be input into the controller.
The high-speed analog-to-digital converter is arranged between the third variable gain module and the controller, and is used for converting the analog second intermediate frequency signal IF2 into a digital signal, and sending the digital signal to the baseband processing unit through the controller, wherein the conversion rate requirement is usually not lower than 100 MSPS.
The controller is a control center of a front-end circuit of the receiver, is responsible for working state control, parameter configuration and gain control of each module circuit, is connected with the baseband processing unit through a communication interface, and is connected with a control instruction, and the controller preferably selects an FPGA.
Example 3
A method for automatic gain control in a frequency hopping receiver, the method comprising:
based on the frequency hopping receiver as described in embodiment 1 or embodiment 2, a distributed control method is adopted to distribute the task of signal gain adjustment among the first variable gain module, the second variable gain module, and the third variable gain module;
the control mode of combining thickness and fineness is adopted to reduce the iteration time of gain adjustment and quickly approach a target value;
after the frequency hopping receiving signal enters a receiving circuit, the received signal is measured and adjusted step by step according to the signal processing flow and the time sequence of a first variable gain module, a second variable gain module and a third variable gain module;
after the gain adjustment process is triggered and started, the controller independently completes the gain gear adjustment of the variable gain module of the current stage according to a frequency hopping synchronous searching state, a frequency hopping synchronous working state and an adjacent channel interference state and a preset signal power voltage and gain gear relation table of the current stage, and ensures that the gain gear of the circuit of the current stage is adaptive to the current signal power intensity.
The condition for triggering the start of the gain adjustment process is that a frequency conversion pulse signal and a strong signal indicate.
Preferably, a control mode of thickness combination is adopted to reduce the iteration time of gain adjustment, specifically:
the gains of the first variable gain module and the second variable gain module are divided into 2-3 gears, and coarse adjustment is carried out in a large step mode;
the gain of the third variable gain module is divided into n fine stepping gears, and fine adjustment in a small stepping mode is achieved, wherein n is an integer larger than 10.
The step-by-step measurement and adjustment of the frequency hopping receiving signals according to the signal processing flow and the time sequence specifically comprises the following three steps:
the first step is as follows: reading a first voltage value, a second voltage value and a third voltage value of each detector at T0 time, and judging whether the current detector is in an adjacent channel interference state or not by means of state combination characteristics of the voltage values:
if so, setting the gain requirement according to the interference state of the adjacent channel, and stopping the following second step and third step;
if not, looking up a table according to the read first voltage value, a preset first voltage value and a gear relation table of the first variable gain module to set a gear value of the first variable gain module, and continuously executing the second step and the third step;
the second step is that: reading a second voltage value of the second detector at the time of T1, and setting a gear value of the second variable gain module by looking up a table according to a preset gear value relation table of the second voltage value and the second variable gain module;
the third step: and reading a third voltage value of the third detector at the time T2, and setting a gear value of the third variable gain module by looking up a table according to a preset relationship table between the third voltage value and the gear value of the third variable gain module.
In a specific embodiment, the power of the input signal of the receiver is inversely proportional to the gain values of the first, second, and third variable gain modules, and table 1 shows the gain control relationship of the embodiment:
table 1 reception gain control relation table
Note: 1. in the table, A1, A2 and A3 respectively represent a first variable gain module, a second variable gain module and a third variable gain module;
2. the IF2 output intermediate frequency amplitude is equal to the algebraic sum of RF, A1, A2, A3.
The conditions for triggering and starting the gain adjustment process are respectively indicated by a frequency conversion pulse signal and a strong signal, and state indication signals of frequency hopping synchronous searching and frequency hopping synchronous working come from a control instruction of a baseband processing unit.
Furthermore, the frequency hopping synchronous search state refers to a working state that the real-time working frequency of the frequency hopping receiver is not consistent with that of the transmitting end and the frequency hopping receiver is waiting for receiving frequency hopping synchronous information according to synchronous hopping;
when the receiver is in the state, the controller firstly presets the front end of the receiver to be maximum gain, then continuously reads a third voltage value of a third detector according to a fixed time interval, when the third voltage value is larger than a certain preset reference value, the current signal is judged to be a strong signal, the strong signal is indicated to be effective, and a gain adjustment process is triggered once; otherwise, the signal is judged to be a small signal, and the frequency hopping receiver keeps the maximum gain; wherein said time interval is less than a frequency hopping period; the method aims to solve the problem of gain control before synchronization of the frequency hopping receiver in a near-field large signal environment and avoid the problem that the frequency hopping synchronization information cannot be received due to large signal blockage;
furthermore, the frequency hopping synchronization working state is that after the frequency hopping receiver completes frequency hopping synchronization, the working frequency of the frequency hopping receiver is consistent with that of the transmitting end and synchronously hops along with time variation;
when the receiver is in the state, a frequency-changing pulse signal triggers and starts a gain adjustment process, each frequency-hopping signal received by the frequency-hopping receiver is subjected to gain adjustment once, and the adjustment time is limited in a period of non-useful data at the beginning of each frequency-hopping carrier cycle, namely, the gain adjustment operation needs to be completed before the useful data is transmitted in each frequency-hopping cycle, so that the data loss caused by the operation in the period of transmitting the useful data is avoided;
further, the adjacent channel interference state refers to a strong interference signal existing on a frequency adjacent to the current operating frequency of the receiver, and the state is identified by the combined characteristics of the first voltage value, the second voltage value and the third voltage value, and the specific characteristics are as follows: the first voltage value and the second voltage value are larger than a certain voltage reference value, and the third voltage value is equal to or close to the voltage reference value in the absence of signals;
when the frequency hopping receiver circuit is in the state, the gain gears of the first variable gain module, the second variable gain module and the third variable gain module of the frequency hopping receiver circuit are all set to be the maximum gain gear.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. A frequency hopping receiver, characterized by: the multi-channel digital-to-analog converter comprises a first detector, a second detector, a third detector, a first variable gain module, a second variable gain module, a third variable gain module, a multi-channel analog-to-digital converter, a controller, a frequency conversion band-pass filter, a first intermediate frequency filter and a second intermediate frequency filter;
the variable-frequency band-pass filter, the first variable gain module, the first intermediate frequency filter, the second variable gain module, the second intermediate frequency filter, the third variable gain module and the controller are electrically connected in sequence;
the first detector is used for detecting the signal power intensity of the input end of the first variable gain module, a sampling detection point is arranged between the variable frequency band-pass filter and the first variable gain module, and the first detector converts the signal power intensity of the input end of the first variable gain module into a voltage value, namely a first voltage value;
the second detector is used for detecting the signal power intensity of the input end of the second variable gain module, the sampling detection point is arranged between the first intermediate frequency filter and the second variable gain module, and the second detector converts the signal power intensity of the input end of the second variable gain module into a voltage value which is called a second voltage value;
the third detector is used for detecting the signal power intensity of the input end of the third variable gain module, the sampling detection point is arranged between the second intermediate frequency filter and the third variable gain module, and the third detector converts the signal power intensity of the input end of the third variable gain module into a voltage value which is called a third voltage value;
the first variable gain module is used for amplifying or attenuating radio frequency signals, and gain is controlled by the controller;
the second variable gain module is used for amplifying or attenuating the first intermediate frequency signal, and the gain is controlled by the controller;
the third variable gain module is used for amplifying or attenuating the second intermediate frequency signal, and the gain is controlled by the controller;
the multichannel analog-to-digital converter is arranged among the first detector, the second detector, the third detector and the controller and is used for converting the first voltage value, the second voltage value and the third voltage value into digital signals and sending the digital signals to the controller;
the controller correspondingly adjusts the gains of the first variable gain module, the second variable gain module and the third variable gain module according to the first voltage value, the second voltage value and the third voltage value received by the multichannel analog-to-digital converter, so that a frequency hopping signal RF received by the antenna sequentially passes through the first variable gain module, the first intermediate frequency filter circuit, the second variable gain module, the second intermediate frequency filter circuit and the third variable gain module, and then a second intermediate frequency signal IF2 with relatively stable amplitude is obtained and input into the controller.
2. The frequency hopping receiver of claim 1, wherein: the frequency converter also comprises a first frequency mixer and a first local vibration source; the first mixer is arranged between the first variable gain module and the first intermediate frequency filter, and the first local vibration source is electrically connected with the first mixer.
3. The frequency hopping receiver of claim 1, wherein: the frequency converter also comprises a second frequency mixer and a second local vibration source; the second mixer is arranged between the second variable gain module and the second intermediate frequency filter, and the second local oscillation source is electrically connected with the second mixer.
4. The frequency hopping receiver of claim 1, wherein: the high-speed analog-to-digital converter is arranged between the third variable gain module and the controller;
the second intermediate frequency signal IF2 is input to the controller through the high-speed analog-to-digital converter.
5. A gain automatic control method of a frequency hopping receiver is characterized in that: the method comprises the following steps:
the frequency hopping receiver according to any one of claims 1 to 4, wherein the task of signal gain adjustment is distributed among the first variable gain module, the second variable gain module and the third variable gain module by using a distributed control method;
after a received signal enters a front-end circuit of a receiver, the received signal is measured and adjusted step by step according to the signal processing flow and the time sequence of a first variable gain module, a second variable gain module and a third variable gain module;
after a gain adjustment process is triggered and started, the controller independently completes gain gear adjustment of the variable gain module according to a frequency hopping synchronous search state, a frequency hopping synchronous working state and an adjacent channel interference state and according to a signal power voltage and gain gear relation table preset at the current stage, and ensures that the gain gear of the circuit at the current stage is adaptive to the current signal power strength;
the condition for triggering the start of the gain adjustment process is the presence of the frequency conversion pulse signal and the strong signal indication.
6. The method of claim 5 for automatic gain control in a frequency hopping receiver, wherein: and reducing the iteration time of gain adjustment by adopting a control mode of combining thickness and fineness, specifically:
the gains of the first variable gain module and the second variable gain module are divided into 2-3 gears, and coarse adjustment is carried out in a large step mode;
and the gain of the third variable gain module is divided into n fine stepping gears, and fine adjustment is performed in a small stepping mode, wherein n is an integer larger than 10, and the larger the value of n is, the higher the control precision of the output amplitude of the second intermediate frequency signal IF2 is.
7. The method of claim 5 for automatic gain control in a frequency hopping receiver, wherein: the step-by-step measurement and adjustment of the frequency hopping receiving signals according to the signal processing flow and the time sequence specifically comprises the following three steps:
the first step is as follows: reading a first voltage value, a second voltage value and a third voltage value of each detector at T0 time, and judging whether the current detector is in an adjacent channel interference state or not by means of state combination characteristics of the voltage values:
if so, setting the gain requirement according to the interference state of the adjacent channel, and stopping the following second step and third step;
if not, looking up a table to set a gear value of the first variable gain module according to a preset relationship table between the first voltage value and the gear value of the first variable gain module, and continuously executing the second step and the third step;
the second step: reading a second voltage value of the second detector at the time of T1, and setting a gear value of the second variable gain module by looking up a table according to a preset gear value relation table of the second voltage value and the second variable gain module;
the third step: and reading a third voltage value of the third detector at the time T2, and setting a gear value of the third variable gain module by looking up a table according to a preset gear value relation table of the third voltage value and the third variable gain module.
8. The method of claim 5 for automatic gain control in a frequency hopping receiver, wherein: the frequency hopping synchronous searching state means that the real-time working frequency of the frequency hopping receiver is not consistent with that of the transmitting end, and the frequency hopping synchronous searching state is in a working state of waiting for receiving frequency hopping synchronous information according to synchronous hopping;
when the receiver is in the state, the controller presets the front end of the receiver to be the maximum gain, continuously reads a third voltage value of a third detector according to a fixed time interval, and when the third voltage value is larger than a certain preset reference value, the current signal is judged to be a strong signal which indicates that the action is to trigger a gain adjustment process; otherwise, the signal is judged to be a small signal, and the frequency hopping receiver keeps the maximum gain; wherein the time interval is less than the frequency hopping period.
9. The method of claim 5 for automatic gain control in a frequency hopping receiver, wherein: the frequency hopping synchronous working state refers to that after the frequency hopping receiver finishes frequency hopping synchronization, the working frequency of the frequency hopping receiver is consistent with that of a transmitting end and changes along with time to synchronously hop;
when the frequency hopping receiver is in the state, the frequency hopping pulse signal triggers and starts a gain adjustment process, each frequency hopping carrier signal received by the frequency hopping receiver is subjected to gain adjustment once, and the adjustment time is limited in the period of non-useful data at the beginning of each frequency hopping carrier period.
10. The method of claim 5 for automatic gain control in a frequency hopping receiver, wherein: the adjacent channel interference state refers to the existence of strong interference signals on the adjacent frequency of the current working frequency of the receiver, and the state is identified by the combined characteristics of the first voltage value, the second voltage value and the third voltage value, and the specific characteristics are as follows: the first voltage value and the second voltage value are larger than a certain reference value, and the third voltage value is equal to or close to the voltage reference value when no signal exists;
when the frequency hopping receiver is in the state, the gain gears of the first variable gain module, the second variable gain module and the third variable gain module of the frequency hopping receiver are all set as the maximum gain gear.
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