CN114696850B - Method for improving receiving sensitivity, communication device and storage medium - Google Patents
Method for improving receiving sensitivity, communication device and storage medium Download PDFInfo
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- CN114696850B CN114696850B CN202011613154.XA CN202011613154A CN114696850B CN 114696850 B CN114696850 B CN 114696850B CN 202011613154 A CN202011613154 A CN 202011613154A CN 114696850 B CN114696850 B CN 114696850B
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- 238000004891 communication Methods 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 title claims abstract description 29
- 230000035945 sensitivity Effects 0.000 title claims abstract description 27
- 238000012545 processing Methods 0.000 claims abstract description 67
- 239000003990 capacitor Substances 0.000 claims description 27
- 238000012360 testing method Methods 0.000 claims description 13
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- 238000004590 computer program Methods 0.000 claims description 6
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- 238000004519 manufacturing process Methods 0.000 description 2
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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
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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
- H04B1/18—Input circuits, e.g. for coupling to an antenna or a transmission line
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The application discloses a method for improving receiving sensitivity, a communication device and a storage medium, wherein the communication device comprises: a radio frequency front-end circuit and a receiving circuit; the radio frequency front-end circuit is used for processing the received signals; the receiving circuit comprises a control circuit, an electric tuning matching circuit, a processing circuit and a radio frequency circuit, wherein the control circuit is connected with the electric tuning matching circuit and the radio frequency circuit and is used for generating control voltage based on signals output by the radio frequency circuit and outputting the control voltage to the electric tuning matching circuit; the electric tuning matching circuit is connected with the radio frequency front-end circuit and the processing circuit and is used for adjusting the impedance based on the control voltage so as to match the output impedance of the electric tuning matching circuit with the input impedance of the processing circuit; the processing circuit is used for receiving and processing the signal output by the electric tuning matching circuit; the radio frequency circuit is connected with the processing circuit and is used for demodulating the signal output by the processing circuit to obtain a communication data signal. By the mode, the application can improve the receiving sensitivity.
Description
Technical Field
The present application relates to the field of communications technologies, and in particular, to a method for improving receiving sensitivity, a communications device, and a storage medium.
Background
The receiving sensitivity is one of the core indexes of the communication system, the receiving sensitivity directly influences the distance and the quality of communication, the receiving sensitivity is related to the noise coefficient of a receiving link, the influence of the circuit design on the receiving sensitivity is realized by the noise coefficient, the noise coefficient is mainly determined by the loss before signal amplification, and the loss is composed of two parts: 1) Absorption loss, resistance dissipation present in the circuit; 2) Reflection loss, due to mismatch of source impedance and load impedance, part of the signal is reflected by the load to the source device.
For absorption loss, the method for reducing loss is to select a device with high quality factor to reduce resistance; for reflection loss, the method for reducing loss is to realize the matching of source impedance and load impedance and realize the minimum reflection of signals. Because the resistance of the used device cannot be guaranteed to be smaller and the quality factor is higher in the practical application scene, the realization of impedance matching between circuits is one of important measures for reducing loss and improving receiving sensitivity.
Disclosure of Invention
The application provides a method for improving receiving sensitivity, a communication device and a storage medium, which can improve the receiving sensitivity.
In order to solve the above technical problem, the present application provides a communication device, including: a radio frequency front-end circuit and a receiving circuit; the radio frequency front-end circuit is used for processing the received signals; the receiving circuit comprises a control circuit, an electric tuning matching circuit, a processing circuit and a radio frequency circuit, wherein the control circuit is connected with the electric tuning matching circuit and the radio frequency circuit and is used for generating control voltage based on signals output by the radio frequency circuit and outputting the control voltage to the electric tuning matching circuit; the electric tuning matching circuit is connected with the radio frequency front-end circuit and the processing circuit and is used for adjusting the impedance based on the control voltage so as to match the output impedance of the electric tuning matching circuit with the input impedance of the processing circuit; the processing circuit is used for receiving and processing the signal output by the electric tuning matching circuit; the radio frequency circuit is connected with the processing circuit and is used for demodulating the signal output by the processing circuit to obtain a communication data signal.
In order to solve the above-mentioned problems, the present application provides a method for improving receiving sensitivity, which is applied to a communication device, and the method includes: the radio frequency front-end circuit, the electric tuning matching circuit, the processing circuit and the radio frequency circuit process the received signals in sequence to obtain communication data signals; the control circuit generates control voltage based on the communication data signal output by the radio frequency circuit and outputs the control voltage to the electric tuning matching circuit; the electric tuning matching circuit adjusts the impedance based on the control voltage so as to match the output impedance of the electric tuning matching circuit with the input impedance of the processing circuit; the processing circuit receives and processes the signal output by the electric tuning matching circuit; the radio frequency circuit receives and demodulates the signal output by the processing circuit to obtain a communication data signal.
In order to solve the above technical problem, another technical solution adopted by the present application is to provide a computer readable storage medium, where the computer readable storage medium is used for storing a computer program, and the computer program is used for implementing the method for improving the receiving sensitivity when being executed by a processor.
Through the scheme, the application has the beneficial effects that: an electric tuning matching circuit with adjustable parameters is arranged in a receiving circuit of the communication device, the electric tuning matching circuit is connected with a control circuit, a radio frequency front-end circuit and a processing circuit, the control circuit is connected with the electric tuning matching circuit and the radio frequency circuit, the control circuit adjusts the amplitude of control voltage output by the control circuit based on signals output by the radio frequency circuit, different control voltages can be output to the electric tuning matching circuit through the control circuit, after the electric tuning matching circuit receives the control voltage, circuit parameters are changed, the impedance of the electric tuning matching circuit is changed, the effect of matching the output impedance of the electric tuning circuit with the input impedance of the processing circuit is achieved, impedance matching between circuits with different frequencies and different impedances can be achieved, reflection loss can be reduced, and the lower the loss is, the higher the receiving sensitivity is, and the receiving sensitivity of the communication device can be improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. Wherein:
fig. 1 is a schematic structural diagram of an embodiment of a communication device provided by the present application;
fig. 2 is a schematic structural diagram of another embodiment of a communication device provided by the present application;
FIG. 3 is a schematic diagram of the structure of the electrically tuned matching circuit in the embodiment shown in FIG. 2;
FIG. 4 is a schematic diagram of impedance matching in the embodiment shown in FIG. 2;
FIG. 5 is a flow chart of an embodiment of a method for improving receiving sensitivity according to the present application;
fig. 6 is a schematic structural diagram of an embodiment of a computer readable storage medium according to the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
To reduce reflection losses between circuits, currently receivers typically add matching circuits to the circuits in several ways:
1) A fixed matching parameter circuit is used to cover a wide frequency range.
2) A plurality of matching circuits are used, each matching circuit is used for matching different frequencies, and the corresponding matching circuit is selected through a radio frequency switch according to the frequency band during use.
For the first mode, a fixed matching parameter circuit is used, the circuit can only realize conjugate matching in a very narrow frequency band range, and mismatch phenomena exist in other frequency bands, so that reflection is caused, and signal loss is increased. For the second approach, there are disadvantages of complex circuitry, high device cost, and large area occupied by the printed circuit board (PCB, printed Circuit Board). In addition, no matter which matching circuit is used, the conventional receiving circuit is designed only with the impedance of the antenna port being 50Ω, and the impedance of the antenna is not considered, and in practical use, the impedance of the intercom antenna deviates from 50Ω, so that the input reflection coefficient (S11) is poor, and the mismatch between the antenna and the receiving circuit is serious.
Based on the problems existing in the prior art, the application provides a scheme for improving the receiving sensitivity, and the impedance of the scheme is adjusted by electrically tuning the matching circuit, so that the impedance of a front-end circuit connected with the matching circuit and the impedance of a rear-end circuit connected with the matching circuit can be matched, the reflection loss is reduced, and the receiving sensitivity is improved.
Impedance matching refers to a working state that load impedance and internal impedance of an excitation source are mutually matched to obtain maximum power output, and matching conditions are as follows: 1) The load impedance is equal to the in-source impedance, i.e. their modes and argument are respectively equal, at which time a distortion-free voltage transmission is obtained at the load impedance. 2) The load impedance is equal to the conjugate value of the impedance in the source, i.e. their modes are equal and the sum of the argument is zero, at which time the maximum power is available at the load impedance, a condition called conjugate matching. If the source internal impedance and the load impedance are both purely resistive, then the two matching conditions are equivalent.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a communication device according to an embodiment of the present application, where the communication device includes: the radio frequency front-end circuit 10 and the receiving circuit 20.
The rf front-end circuit 10 is configured to process a received signal, and specifically, the received signal may be a signal transmitted by a cable or transmitted by radio wave radiation, which is a radio frequency signal, and the rf front-end circuit 10 may perform filtering processing or amplifying processing, etc.
The receiving circuit 20 includes: control circuitry 21, electrically tuned matching circuitry 22, processing circuitry 23, and radio frequency circuitry 24.
The control circuit 21 is connected to the electric tuning matching circuit 22 and the radio frequency circuit 24, and is configured to generate a control voltage based on a signal output by the radio frequency circuit 24, and output the control voltage to the electric tuning matching circuit 22, so as to adjust a circuit parameter of the electric tuning matching circuit 22, where the circuit parameter includes a capacitance value, an inductance value, or a resistance value.
The electric tuning matching circuit 22 is connected to the rf front-end circuit 10, the control circuit 21 and the processing circuit 23, and is configured to adjust the impedance based on the control voltage, so that the input impedance of the receiving circuit 20 is matched with the output impedance of the rf front-end circuit 10, where the type of impedance matching may be conjugate matching.
Further, the circuit parameters of the electric tuning matching circuit 22 may be adaptively adjusted along with the control voltage, which may include an inductance value-adjustable device, a resistance value-adjustable device, or a capacitance value-adjustable device, so that when receiving different control voltages, the inductance value, the resistance value, or the capacitance value changes along with the change, so that the impedance of the electric tuning matching circuit 22 changes, and thus, the input impedance of the electric tuning matching circuit 22 and the output impedance of the radio frequency front end circuit 10 achieve conjugate matching.
The processing circuit 23 is used for receiving and processing the signal output by the electric tuning matching circuit 22; the radio frequency circuit 24 is connected with the processing circuit 23 and is used for demodulating the signal output by the processing circuit 23 to obtain a communication data signal; specifically, the rf circuit 24 may be a device for converting the rf signal output by the processing circuit 23 into a baseband signal, for example, a superheterodyne receiver, where the rf circuit 24 may include a local oscillator, a mixer, a filter, an amplifier, a demodulator (not shown), and the like, and the local oscillator is used to generate a local oscillator signal, the mixer is used to mix the local oscillator signal with the signal output by the processing circuit 23 to obtain an intermediate frequency signal, and the intermediate frequency signal is filtered by the filter and amplified by the amplifier, and then enters the demodulator, and is demodulated by the demodulator to generate a baseband signal, that is, a communication data signal.
It will be understood that the effect of matching the input impedance of the receiving circuit 20 with the output impedance of the rf front-end circuit 10 and the effect of matching the output impedance of the electric tuning circuit 22 with the input impedance of the processing circuit 23 are the same, i.e. the state of the circuit of the communication device reaches the conjugate match when the communication device receives and processes signals.
In order to achieve impedance matching between the rf front-end circuit 10 and the processing circuit 23, the scheme provided in this embodiment sets an electric tuning matching circuit 22 with adjustable circuit parameters, that is, the fixed parameter matching circuit is changed into the electric tuning matching circuit 22, the signal output by the rf circuit 24 can affect the amplitude of the control voltage output by the control circuit 21, so that the control circuit 21 outputs different control voltages to the electric tuning matching circuit 22, after receiving the control voltages, some circuit parameters change by the electric tuning matching circuit 22, so that the impedance of the electric tuning matching circuit 22 changes, and conjugate matching between ports with different frequencies and different impedances can be achieved, and reflection loss can be reduced, thereby improving the receiving sensitivity of the communication device.
Referring to fig. 2, fig. 2 is a schematic structural diagram of another embodiment of a communication device according to the present application, where the communication device includes a radio frequency front-end circuit 10, a receiving circuit 20, and an antenna 30.
The antenna 30 is used for receiving signals, and it is understood that the antenna is an optional device, and the communication device of the present embodiment may be adapted by installing antennas of different models to receive radiation signals, or may be directly connected to an external device through a cable to receive signals.
The radio frequency front-end circuit 10 is connected with the antenna 30, and is used for acquiring a received signal through the antenna 30 and processing the received signal; specifically, as shown in fig. 2, the radio frequency front-end circuit 10 includes: the first filter 11 is connected to the switch 12, the first filter 11 is connected to the antenna 30, and is used for filtering the received signal to obtain a first filtered signal, and the first filter 11 may be a low-pass filter; the switch 12 is connected to the first filter 11 and the electrically tuned matching circuit 22 for turning on/off a path between the filter and the electrically tuned matching circuit 22.
Further, the switch 12 may be used in common with other devices (such as a transmitting circuit), and when the switch 12 receives a signal communicated with the receiving circuit 20, the antenna 30 is turned on to the electrically tuned matching circuit 22, and is in a state of receiving the signal; when the switch 12 receives a signal communicated with a transmitting circuit (not shown in the figure), the antenna 30 is conducted with the transmitting circuit, and is in a state of transmitting the signal.
It will be appreciated that the rf front-end circuit 10 may not include the switch 12, i.e. the antenna 30 is not shared, and the switch 12 is not required to switch the transceiving state.
The receiving circuit 20 includes: control circuitry 21, electrically tuned matching circuitry 22, processing circuitry 23, and radio frequency circuitry 24.
The control circuit 21 includes a control chip 211 and a digital-to-analog converter 212, the control chip 211 is connected with the radio frequency circuit 24, and is used for detecting the signal intensity of the communication data signal output by the radio frequency circuit 24, generating a digital signal corresponding to the signal intensity of the communication data signal, and the control chip 211 may be a central processing unit; the digital-to-analog converter 212 is connected to the control chip 211 and the electric tuning matching circuit 22, and is configured to convert a digital signal into a control voltage and output the control voltage to the electric tuning matching circuit 22, so that the corresponding control voltage can be output to the electric tuning matching circuit 22 at different frequencies.
Further, the control chip 211 stores a frequency-voltage mapping table, where the voltage mapping table includes the frequency of the received signal and a control voltage corresponding to the frequency of the received signal; the control chip 211 is further configured to adjust an amplitude of the initial control voltage within a preset voltage range of the initial control voltage, so as to adjust a signal strength of the communication data signal, and use the initial control voltage corresponding to the communication data signal with the largest signal strength as a control voltage corresponding to the current frequency, and store the control voltage; specifically, the initial control voltage may be a preset default value, the preset voltage range may be a preset voltage range, and the initial control voltage and the preset voltage range may be adjusted along with a specific application scenario.
When the received signal frequency is not in the voltage mapping table, 2 frequencies closest to the received signal frequency and corresponding control voltage values in the frequency-voltage mapping table are read, and the control voltage corresponding to the received signal frequency is calculated in a linear relation.
It will be appreciated that, in order to increase the processing speed, a memory (not shown) may be further disposed in the communication device, where the memory is connected to the control chip 211, and the control chip 211 may store data such as a frequency-voltage mapping table in the memory or read data from the memory.
The electric tuning matching circuit 22 is connected with the radio frequency front end circuit 10, the control circuit 21 and the processing circuit 23, and is used for adjusting impedance based on the control voltage so as to match the output impedance of the radio frequency front end circuit 10 with the input impedance of the processing circuit 23; for the received signals with different frequencies, the electric tuning matching circuit 22 can perform matching parameter adjustment to realize conjugate matching between the radio frequency front-end circuit 10 and the processing circuit 23.
Further, the control voltages include a first control voltage and a second control voltage, and the electrically tuned matching circuit 22 includes: a parallel resonant circuit 221 and a series resonant circuit 222.
The parallel resonant circuit 221 has one end connected between the rf front-end circuit 10 and the series resonant circuit 222, the other end grounded, and is connected to the control circuit 21, for adjusting the impedance of the parallel resonant circuit 221 based on the first control voltage output from the digital-to-analog converter 212; the series resonant circuit 222 is connected in series between the radio frequency front-end circuit 10 and the processing circuit 23, and is connected to the control circuit 21 for adjusting the impedance of the series resonant circuit 222 based on the second control voltage output from the digital-to-analog converter 212.
IN a specific embodiment, taking the capacitance adjustment as an example, as shown IN fig. 3, the port IN is connected to the switch 12, the port OUT is connected to the second filter 231, the port CV1 is used for receiving the first control voltage, and the port CV2 is used for receiving the second control voltage.
The parallel resonant circuit 221 includes a first resistor R1, a first varactor diode D1, a first capacitor C1, and a first inductor L1, where the first capacitor C1 is connected in series with the first varactor diode D1, one end of the first capacitor C1 is connected to the radio frequency front-end circuit 10, and one end D1 of the first varactor diode is grounded; the first inductor L1 is connected in parallel with the series circuit of the first capacitor C1 and the first varactor D1; the first resistor R1 has one end connected between the first capacitor C1 and the first varactor D1, and the other end connected to the control circuit 21, and is configured to receive a first control voltage.
Further, one end of the first resistor R1 is connected to one end of the first varactor D1 and one end of the first capacitor C1, and the other end of the first resistor R1 is connected to the digital-to-analog converter 212; the other end of the first varactor diode D1 is grounded, and the capacitance value of the first varactor diode D1 is automatically adjusted along with the amplitude of the first control voltage; the other end of the first capacitor C1 is connected to the switch 12 and one end of the first inductor L1, and the other end of the first inductor L1 is grounded.
The series resonant circuit 222 includes a second inductor L2, a second varactor D2, a second resistor R2, and a second capacitor C2, where the second inductor L2 is connected in series with the second varactor D2 and the second capacitor C2, one end of the second inductor L2 is connected to the radio frequency front end circuit 10, one end of the second capacitor C2 is connected to the processing circuit 23, one end of the second resistor R2 is connected between the second varactor D2 and the second capacitor C2, and the other end is connected to the control circuit 21, for receiving a second control voltage.
Further, the capacitance value of the second varactor diode D2 is automatically adjusted according to the amplitude of the second control voltage, one end of the second varactor diode D2 is connected to one end of the second resistor R2 and one end of the second capacitor C2, the other end of the second resistor R2 is connected to the digital-to-analog converter 212, the other end of the second capacitor C2 is connected to the second filter 231, one end of the second inductor L2 is connected to one end of the first inductor L1, and the other end of the second inductor L2 is connected to the other end of the second varactor diode D2.
The circuit for realizing electric tuning by using the varactor can form equivalent capacitance or inductance to replace the capacitance or inductance of the original fixed parameters; the control chip 211 can be used to adjust the bias voltage of the varactor, i.e. control the digital-to-analog converter 212 to output different control voltages to change the capacitance of the varactor, and the varactor can be equivalently a capacitive device after being connected in series or parallel with the inductor or capacitorThe matching parameters required by the parts or the inductive devices can be set under different frequencies; the proper inductance and the varactor diode can be selected, so that the resonance frequency of the varactor diode and the corresponding inductance is equal to the center frequency of the working frequency band of the communication device; for example, taking the first inductor L1 and the first varactor diode D1 as an example, assume that the center value of the varactor range of the first varactor diode D1 is Co, the inductance value of the first inductor L1 is Lo, and the operating frequency band is f L To f H The resonant frequency isThe resonant frequency and frequency (f L +f H ) And/2 is the same.
The processing circuit 23 is configured to receive the signal output by the electrically tuned matching circuit 22; as shown in fig. 2, the processing circuit 23 includes a second filter 231 and an amplifier 232, where the second filter 231 is connected to the electric tuning matching circuit 22 and is used for filtering the signal output by the electric tuning matching circuit 22 to obtain a second filtered signal, and the second filter 231 may be a band-pass filter; the amplifier 232 is connected to the second filter 231, and is configured to amplify the second filtered signal to obtain an amplified signal, where the amplifier 232 may be a low noise amplifier (LNA, low Noise Amplifier).
The radio frequency circuit 24 is connected to the amplifier 232 for demodulating the amplified signal output by the amplifier 232 to obtain a communication data signal.
In a specific embodiment, the usage modes of the communication device include a test mode and an antenna mode, and the test mode and the antenna mode are used to calibrate the control voltage of the electrically tuned matching circuit 22 of the communication device during production; the conjugate matching is realized under different frequencies, and the required control voltage amplitude can be different, so that each frequency can be calibrated and stored respectively; specifically, calibration can be performed within an operating frequency range of the communication device, and several frequencies are selected at equal intervals within the operating frequency range; for example, assume an operating band range of 400MHz to 470MHz, which is divided into 8 frequencies: 400.075MHz to 469.975MHz, with a frequency spacing of 10MHz, and for each frequency, calibration of the control voltage is performed.
In the test mode, the radio frequency front end circuit 10 is connected with external equipment (such as an instrument for generating signals) through a cable, and receives an electric signal output by the external equipment; the control chip 211 may output a default initial control voltage through the dac 212, where the initial control voltage is a voltage of the electric tuning matching circuit 22 close to the optimal conjugate matching, then the dac 212 continuously adjusts the voltage input to the electric tuning matching circuit 22, and the automation software in the testing device may record the received signal strengths (RSSI, received Signal Strength Indication) of the communication data signals under different voltages, and after the voltage adjustment of the initial control voltage is completed, the adc 212 directly outputs the voltage value when the RSSI is strongest, and uses the voltage value as the calibration value (i.e. the control voltage) of the current frequency, and stores the value.
In the antenna mode, fine tuning is performed in real time within a certain range of initial control voltage, so that the strongest RSSI is realized; specifically, the communication device is provided with an antenna 30, the radio frequency front-end circuit 10 is connected with the antenna 30, and signals radiated by external equipment are received through the antenna 30; the control chip 211 outputs a default initial control voltage through the digital-to-analog converter 212, the initial control voltage is a voltage of the electric tuning matching circuit 22 close to the optimal conjugate matching, then the digital-to-analog converter 212 continuously adjusts the voltage input to the electric tuning matching circuit 22, the automatic software in the testing device can be used for recording the RSSIs of communication data signals under different voltages, after the voltage adjustment of the initial control voltage is completed, the analog-to-digital converter 212 directly outputs the voltage with the strongest RSSI as a calibration value of the current frequency, and the calibration value is stored.
It can be understood that when the control voltage of other frequencies is calibrated, the calibration value of the current frequency can be calculated by reading the calibration values of frequencies near the current frequency; for example, the control voltage corresponding to 400MHz is V1, the control voltage corresponding to 410MHz is V2, and for 401MHz, the control voltage V1 and the control voltage V2 can be directly used for linear estimation without performing calibration operation.
In a specific embodiment, taking the communication device as an interphone as an example, a selection menu of a test mode and an antenna mode can be added on a display screen of the interphone so as to call a calibration value of a corresponding mode, and the optimal conjugate matching under the current mode is realized; for example, calibration at different frequencies may result in control voltages as shown in the following table:
the control voltages corresponding to different frequencies and different modes are shown
In a specific embodiment, the test mode may be verified using the vehicle-mounted platform, and the verification scheme is as follows:
1) The port of the antenna 30 is connected to a 50Ω dummy load.
2) The impedance of the switch 12 and the second filter 231 at different frequencies is tested.
For example, assuming frequencies of 380.075MHz, 401.075MHz and 429.975MHz, respectively, simulation testing can be performed using advanced design systems (ADS, advanced Design System) to obtain the data shown in the following table:
impedance and forward transmission coefficient at two different frequencies
Wherein S21 is a forward transmission coefficient in the S parameter.
3) LC parameters at different frequencies are determined on a Smith chart (Smith chart) from the conjugate matched impedance transformation.
The LC parameters include an inductance value and a capacitance value in the electrically tuned matching circuit 22, as shown in fig. 4, taking the output impedance of the switch 12 in table two as (25.5+j21.6) Ω, the input impedance of the second filter 231 as (20.6+j13) Ω, that is, the impedance of the port Term1 as (25.5+j21.6) Ω, and the impedance of the port Term2 as (20.6+j13) Ω as examples, for matching, a capacitor Ct may be connected in series and a capacitor Cp may be connected in parallel, the capacitance value of the capacitor Ct may be 35.6pF, and the capacitance value of the capacitor Cp may be 14.5pF.
4) Depending on the determined LC parameters, the type of suitable varactors and inductances may be selected.
5) Simulation is performed by using ADS software to realize conjugate matching of the electrically tuned matching circuit 22.
The data of the second table is obtained after impedance matching, and the data shown in the following table is obtained:
table three forward transmission coefficients at different frequencies
| frequency/MHz | S21 |
| 380.075 | 0 |
| 401.075 | 0 |
| 429.975 | 0 |
6) The electrically tuned matching circuit 22 is built on the vehicle-mounted station.
7) Testing increases the performance contrast of the electrically tuned matching circuit 22 before and after, as shown in the following table:
receive sensitivity at four different frequencies
From the above table, it can be seen that: the addition of the electrically tuned matching circuit 22 increases the strength of the input signal of the amplifier 232 by more than 1dB, and correspondingly increases the receiving sensitivity.
In another specific embodiment, the verification of the antenna pattern is performed using an intercom, the verification scheme being as follows:
1) The console sends a signal to the handheld intercom.
2) The impedance of the switch 12 and the second filter 231 at different frequencies is tested.
3) Simulation is performed by using ADS software to realize conjugate matching of the electrically tuned matching circuit 22.
4. An electrically tuned matching circuit 22 is built on the receiving path of the intercom.
5. Using the signal source to transmit a signal, an intercom having an electrically tuned matching circuit 22 receives the signal, and tests the RSSI before and after increasing the electrically tuned matching circuit 22 to obtain the data shown in the following table:
table five RSSI at different frequencies
From the above table, it can be seen that: in the antenna mode of the interphone, the RSSI is improved by 3.5dB on average.
In addition, the direct pull test of the interphone can be carried out to obtain the data shown in the following table:
table six communication distances at different frequencies
From the above table, it can be seen that: after the electric tuning matching circuit 22 is added, the open area can be increased by 20% of the communication distance.
The embodiment uses the varactor diode, the inductor and the capacitor to build the electric tuning matching circuit 22, has simple structure, can simplify the matching circuit, and realizes low cost and small area; all frequencies in the working frequency range can achieve optimal conjugate matching, reflection loss is reduced, and receiving sensitivity is improved; calibration of the control voltage can be performed during the production phase in order to directly invoke the calibration value in actual use; the impedance of the antenna 30 may vary from application to application, and the present embodiment enables conjugate matching of the electrically tunable matching circuit 22 and the antenna 30 to be achieved in any application.
Referring to fig. 5, fig. 5 is a flowchart of an embodiment of a method for improving receiving sensitivity according to the present application, where the method is applied to a communication device, and the communication device is a communication device in the above embodiment, and the method includes:
step 51: the radio frequency front-end circuit, the electric tuning matching circuit, the processing circuit and the radio frequency circuit process the received signals in sequence to obtain communication data signals.
The received signal can be transmitted to a radio frequency front-end circuit, and the radio frequency front-end circuit outputs a signal to a receiving circuit after amplifying or filtering the received signal, wherein the receiving circuit comprises a control circuit, an electric tuning matching circuit, a processing circuit and a radio frequency circuit.
Step 52: the control circuit generates a control voltage based on the communication data signal output from the radio frequency circuit and outputs the control voltage to the electrically tuned matching circuit.
The control circuit is connected with the radio frequency circuit and can generate a control voltage based on the communication data signal so as to adjust the circuit parameters of the electrically tuned matching circuit.
Step 53: the electrically tuned matching circuit adjusts the impedance based on the control voltage to match an output impedance of the electrically tuned matching circuit to an input impedance of the processing circuit.
After receiving the control voltage, the electric tuning matching circuit can adjust its own circuit parameters to realize the matching of the output impedance of the electric tuning matching circuit and the input impedance of the processing circuit, thereby reducing the reflection loss.
Step 54: the processing circuit receives and processes the signal output by the electric tuning matching circuit; the radio frequency circuit receives and demodulates the signal output by the processing circuit to obtain a communication data signal.
The processing circuit can receive and process the signal output by the electric tuning matching circuit, and output a radio frequency signal to the radio frequency circuit, and the radio frequency circuit demodulates the radio frequency signal to obtain a baseband signal, namely a communication data signal, so as to realize the signal reception.
The scheme provided in this embodiment can be applied to very high frequency (VHF, very High Frequency) and ultra high frequency (UHF, ultra High Frequency) bands, for example, to bands below 1 GHz.
Referring to fig. 6, fig. 6 is a schematic structural diagram of an embodiment of a computer readable storage medium 60 according to the present application, where the computer readable storage medium 60 is used to store a computer program 61, and the computer program 61, when executed by a processor, is used to implement the method for improving the receiving sensitivity in the above embodiment.
The computer readable storage medium 60 may be a server, a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, etc. various media capable of storing program codes.
In the several embodiments provided in the present application, it should be understood that the disclosed method and apparatus may be implemented in other manners. For example, the above-described device embodiments are merely illustrative, e.g., the division of modules or units is merely a logical functional division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The foregoing description is only illustrative of the present application and is not intended to limit the scope of the application, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present application.
Claims (9)
1. A communication device, comprising:
the radio frequency front-end circuit is used for processing the received signals;
the receiving circuit comprises a control circuit, an electric tuning matching circuit, a processing circuit and a radio frequency circuit, wherein the control circuit is connected with the electric tuning matching circuit and the radio frequency circuit and is used for generating control voltage based on signals output by the radio frequency circuit and outputting the control voltage to the electric tuning matching circuit; the electric tuning matching circuit is connected with the radio frequency front-end circuit, the control circuit and the processing circuit and is used for adjusting impedance based on the control voltage so as to match the output impedance of the electric tuning matching circuit with the input impedance of the processing circuit; the processing circuit is used for receiving and processing the signal output by the electric tuning matching circuit; the radio frequency circuit is connected with the processing circuit and is used for demodulating the signal output by the processing circuit to obtain a communication data signal;
the control voltage comprises a first control voltage and a second control voltage, the electric tuning matching circuit comprises a parallel resonance circuit and a series resonance circuit, one end of the parallel resonance circuit is connected between the radio frequency front-end circuit and the series resonance circuit, the other end of the parallel resonance circuit is grounded and connected with the control circuit, and the electric tuning matching circuit is used for adjusting the impedance of the parallel resonance circuit based on the first control voltage; the series resonance circuit is connected in series between the radio frequency front-end circuit and the processing circuit and is connected with the control circuit, and is used for adjusting the impedance of the series resonance circuit based on the second control voltage;
the parallel resonant circuit comprises a first resistor, a first varactor, a first capacitor and a first inductor; the first capacitor is connected with the first varactor diode in series, one end of the first capacitor is connected with the radio frequency front-end circuit, and one end of the first varactor diode is grounded; the first inductor is connected in parallel with a series circuit of the first capacitor and the first varactor; one end of the first resistor is connected between the first capacitor and the first varactor, and the other end of the first resistor is connected with the control circuit and is used for receiving the first control voltage; wherein, the capacitance value of the first varactor automatically adjusts along with the amplitude of the first control voltage;
the series resonance circuit comprises a second inductor, a second varactor, a second resistor and a second capacitor, wherein the second inductor is connected with the second varactor and the second capacitor in series, one end of the second inductor is connected with the radio frequency front end circuit, one end of the second capacitor is connected with the processing circuit, one end of the second resistor is connected between the second varactor and the second capacitor, the other end of the second resistor is connected with the control circuit and is used for receiving the second control voltage, and the capacitance value of the second varactor is automatically adjusted along with the amplitude of the second control voltage.
2. The communication device of claim 1, wherein the control circuit comprises:
the control chip is connected with the radio frequency circuit and used for detecting the signal intensity of the communication data signal and generating a digital signal corresponding to the signal intensity of the communication data signal;
and the digital-to-analog converter is connected with the control chip and the electric tuning matching circuit, and is used for converting the digital signal into the control voltage and outputting the control voltage to the electric tuning matching circuit.
3. The communication device according to claim 2, wherein,
the control chip stores a frequency-voltage mapping table, wherein the voltage mapping table comprises the frequency of the received signal and control voltage corresponding to the frequency of the received signal; the control chip is further used for adjusting the amplitude of the initial control voltage within a preset voltage range of the initial control voltage so as to adjust the signal strength of the communication data signal, and the initial control voltage corresponding to the communication data signal with the largest signal strength is used as the control voltage corresponding to the current frequency.
4. The communication device of claim 3, further comprising,
and when the received signal frequency is not in the frequency-voltage mapping table, 2 frequencies closest to the signal frequency in the frequency-voltage mapping table and corresponding control voltage values are read, and the control voltage corresponding to the signal frequency is calculated in a linear relation.
5. The communication device of claim 1, wherein the radio frequency front end circuit comprises:
the first filter is used for filtering the received signal to obtain a first filtered signal;
and the switch is connected with the first filter and the electric tuning matching circuit and is used for switching on/off a passage between the filter and the electric tuning matching circuit.
6. The communication device of claim 1, wherein the processing circuit comprises:
the second filter is connected with the electric tuning matching circuit and is used for filtering the signal output by the electric tuning matching circuit to obtain a second filtering signal;
and the amplifier is connected with the second filter and is used for amplifying the second filtered signal to obtain an amplified signal.
7. The communication device of claim 1, wherein the communication device comprises a plurality of communication devices,
the use mode of the communication device comprises a test mode and an antenna mode, wherein in the test mode, the radio frequency front-end circuit is connected with external equipment through a cable and receives an electric signal output by the external equipment; in the antenna mode, the communication device is provided with an antenna, the radio frequency front-end circuit is connected with the antenna, and signals radiated by external equipment are received through the antenna.
8. A method of improving reception sensitivity, applied to a communication apparatus as claimed in any one of claims 1 to 7, the method comprising:
the radio frequency front-end circuit, the electric tuning matching circuit, the processing circuit and the radio frequency circuit process the received signals in sequence to obtain communication data signals;
the control circuit generates a first control voltage and a second control voltage based on a communication data signal output by the radio frequency circuit and outputs the first control voltage and the second control voltage to the electric tuning matching circuit;
the parallel resonant circuit of the electric tuning matching circuit adjusts the impedance of the parallel resonant circuit based on the first control voltage, and the series resonant circuit of the electric tuning matching circuit adjusts the impedance of the series resonant circuit based on the second control voltage;
the processing circuit receives and processes the signal output by the electric tuning matching circuit;
the radio frequency circuit receives and demodulates the signal output by the processing circuit to obtain a communication data signal.
9. A computer-readable storage medium storing a computer program, characterized in that the computer program, when being executed by a processor, is adapted to carry out the method of improving the reception sensitivity as claimed in claim 8.
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