Active antenna detection circuit and active antenna circuit

Abstract

The utility model relates to the field of circuit detection, and discloses an active antenna detection circuit and an active antenna circuit, and the detection circuit comprises an operational amplifier and a detection resistor. The detection resistor is connected between an active antenna and a power supply of the active antenna; the non-inverting input end and the inverting input end of the operational amplifier are connected with the two ends of the detection resistor respectively, and the operational amplifier is used for detecting current passing through the detection resistor; the output end of the operational amplifier is connected with the MCU, and the MCU is used for judging the working state of the active antenna according to the magnitude of an output signal of the output end. The working state of the antenna is judged by detecting the voltage at the two ends of the detection resistor and calculating the working current, and the stability is high.

Description

Technical Field

[0001] The utility model relates to the field of circuit detection, in particular to an active antenna detection circuit and an active antenna circuit. Background Art

[0002] GNSS positioning technology is widely used in surveying and mapping, deformation monitoring, drones, intelligent driving, and continuously operating CORS base stations. Active antennas are an important part of them, responsible for low-noise power amplification of front-end signals to compensate for line loss, filter and power divider insertion loss in the RF link. From small ceramic active antennas to large CORS base station antennas, the coaxial feeder length ranges from 20 cm to 30 meters. Most antennas have a rated operating current range of 4mA to 55mA and a rated voltage range of 3V to 5V.

[0003] The quality of antenna connectivity directly determines the interruption of GNSS signal reception or the degradation of signal quality. Effective and quick troubleshooting of antenna open circuit and short circuit and timely reporting of fault codes can greatly reduce maintenance difficulty and operating costs, and improve product intelligence and safety. Especially in automotive functional safety certification, the antenna connection status diagnosis function is a standard function requirement and has become an issue that needs to be urgently addressed. Utility Model Content

[0004] In a first aspect, the present application provides an active antenna detection circuit, comprising: an operational amplifier and a detection resistor;

[0005] The detection resistor is connected between the active antenna and the power supply of the active antenna;

[0006] The non-inverting input terminal and the inverting input terminal of the operational amplifier are respectively connected to the two ends of the detection resistor, so as to detect the current passing through the detection resistor;

[0007] Wherein, the in-phase input terminal is connected to the side where the power supply is located, and the inverting input terminal is connected to the side where the active antenna is located;

[0008] The output end of the operational amplifier is connected to the MCU, and the MCU is used to determine the working state of the active antenna according to the output of the output end.

[0009] Furthermore, the circuit also includes a negative feedback circuit and a compensation circuit;

[0010] The negative feedback circuit comprises a feedback resistor, one end of the feedback resistor is connected to the inverting input terminal, and the other end of the feedback resistor is connected to the output terminal;

[0011] The compensation circuit comprises a compensation resistor, the resistance of the compensation resistor is the same as that of the feedback resistor, one end of the compensation resistor is connected to the in-phase input end, and the other end is grounded.

[0012] Furthermore, the negative feedback circuit further includes an inverting resistor, and the inverting resistor is connected to the inverting input terminal;

[0013] The non-inverting input terminal is also connected to a non-inverting resistor, and the resistance value of the non-inverting resistor is the same as the resistance value of the anti-inverting resistor.

[0014] Furthermore, the resistance of the feedback resistor is 0.5M ohm to 1.5M ohm.

[0015] Furthermore, the resistance of the reverse resistor is 15k ohms to 25k ohms.

[0016] Furthermore, the resistance of the detection resistor is 0.5 ohms to 2.2 ohms.

[0017] In a second aspect, the present application further provides an active antenna circuit, comprising: an active antenna working circuit and the active antenna detection circuit;

[0018] The active antenna working circuit comprises an active antenna and a power supply, wherein the power supply is used to supply power to the active antenna;

[0019] The active antenna detection circuit is connected in parallel with the active antenna working circuit, and is used to detect the working current of the active antenna, and determine the working state of the active antenna working circuit according to the working current.

[0020] Furthermore, the active antenna working circuit further includes: a choke inductor;

[0021] The choke inductor is arranged between the detection resistor and the active antenna, and is used for blocking alternating current and passing direct current.

[0022] Furthermore, the active antenna working circuit further includes: a safety unit;

[0023] The insurance unit is arranged between the power supply and the detection resistor, and is used to protect the circuit safety when the active antenna is short-circuited.

[0024] The utility model discloses an active antenna detection circuit and an active antenna circuit, wherein the detection circuit comprises: an operational amplifier and a detection resistor; the detection resistor is connected between an active antenna and a power supply of the active antenna; the in-phase input terminal and the inverting input terminal of the operational amplifier are respectively connected to the two ends of the detection resistor, and are used to detect the current passing through the detection resistor; wherein the in-phase input terminal is connected to the side where the power supply is located, and the inverting input terminal is connected to the side where the active antenna is located; the output terminal of the operational amplifier is connected to an MCU, and the MCU is used to judge the working state of the active antenna according to the output of the output terminal. The working state of the antenna is judged by detecting the voltage at the two ends of the detection resistor and calculating the working current, with high stability and accurate judgment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solution of the utility model, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the utility model and should not be regarded as limiting the scope of protection of the utility model. In each of the drawings, similar components are numbered similarly.

[0026] Figure 1 A schematic structural diagram of an active antenna circuit according to an embodiment of the present application is shown;

[0027] Figure 2 A schematic diagram of the structure of an active antenna detection circuit according to an embodiment of the present application is shown;

[0028] Figure 3 A schematic diagram showing the structure of another active antenna detection circuit according to an embodiment of the present application is shown;

[0029] Figure 4 A structural schematic diagram of an active antenna working circuit according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0031] The components of the embodiments of the present invention generally described and shown in the drawings herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0032] Hereinafter, the terms "including", "having" and their cognates, which may be used in various embodiments of the present invention, are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or adding the possibility of one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0033] Furthermore, the terms “first”, “second”, “third”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0034] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as those generally understood by ordinary technicians in the field to which the various embodiments of the present invention belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meanings as the contextual meanings in the relevant technical field and will not be interpreted as having idealized meanings or overly formal meanings unless clearly defined in various embodiments of the present invention.

[0035] The technical solution of the present application is mainly used for detecting the working state of an active antenna, especially for detecting an open circuit and a short circuit state, wherein the active antenna detection circuit comprises: an operational amplifier and a detection resistor; the detection resistor is connected between the active antenna and the power supply of the active antenna; the in-phase input terminal and the inverting input terminal of the operational amplifier are respectively connected to the two ends of the detection resistor, for detecting the current passing through the detection resistor; wherein the in-phase input terminal is connected to the side where the power supply is located, and the inverting input terminal is connected to the side where the active antenna is located; the output terminal of the operational amplifier is connected to an MCU (Microcontroller Unit), and the MCU is used to judge the working state of the active antenna according to the output of the output terminal, so as to judge the working state of the active antenna simply and quickly and find abnormalities in time.

[0036] Among them, the active antenna circuit can be applied to a base station or a router, and the above-mentioned MCU can be the MCU built into such a device. Through the active antenna detection circuit of the present application, the safety of these devices using active antennas during operation can be ensured, and the service life of such devices can be extended.

[0037] Next, the technical solution of the present application is described with specific embodiments.

[0038] Example 1

[0039] like Figure 1As shown, the active antenna circuit of this embodiment includes an active antenna detection circuit 200 and an active antenna working circuit 100.

[0040] The active antenna working circuit includes an active antenna 110 and a power supply 120, and the power supply 120 ensures the normal operation of the active antenna by supplying power to the active antenna 110. The active antenna detection circuit 200 is used to detect the current of the active antenna working circuit 100 to determine the working state of the active antenna.

[0041] The working state referred to in this embodiment refers to the three states of the entire active antenna working circuit 100 being in an open circuit, a short circuit, or a normal working state.

[0042] Specifically, the circuit diagram of the detection circuit of the embodiment is as follows Figure 2 As shown, the detection circuit includes an operational amplifier 210 and a detection resistor R1.

[0043] The detection resistor R1 is connected in series in the above-mentioned active antenna working circuit 100, one end of which is connected to the power supply 120, and the other end is connected to the active antenna 110. The in-phase input terminal IN+ and the inverting input terminal IN- of the operational amplifier are respectively connected to the two ends of the detection resistor R1, for detecting the current passing through the detection resistor.

[0044] The in-phase input terminal is connected to the side where the power supply is located, and the inverting input terminal is connected to the side where the active antenna is located. The voltage difference between the two sides of the detection resistor R1 is different, and the small voltage signal at both ends of the detection resistor is linearly amplified by the operational amplifier 210 and output from the output terminal V OUT The data is sent to the MCU processor for analysis to determine whether it is open circuit, short circuit or working according to the antenna current.

[0045] Specifically, the operational amplifier 210 has two input voltages, the non-inverting input voltage is denoted as V IN , the voltage at the inverting input is denoted as V LOAD , then the current flowing through the detection resistor R1 is recorded as I1, and there is an output voltage V OUT =V IN -V LOAD =I1·R1.

[0046] The output terminal V of the operational amplifier 210 OUT It is used to output the amplified voltage for the MCU to calculate according to the above formula to obtain the required I1. Because the value of R1 is known, V IN and V LOAD It is directly measured, so in the detection circuit of this embodiment, the MCU can directly calculate I1 through the above formula.

[0047] According to the size of I1, it can be determined whether the antenna is in an open circuit, short circuit or working state. Specifically, taking a vehicle-mounted GNSS antenna with a rated working current of 9±3mA as an example, the resistance of the detection resistor R1 is set to 1 ohm, and the normal working current range is generally set to 4mA~20mA. When it is less than 4mA, the antenna is considered to be open circuit, and when it is greater than 20mA, the antenna is considered to be short circuit.

[0048] Specifically, the antenna current I1 and the detected voltage V OUT The relationship with the working status can be shown in the following table:

[0049] state Vout voltage value Antenna current Antenna open circuit <0.2V <4mA The antenna is working properly 0.2V~1.0V 4mA~20mA Antenna short circuit >1V >20mA

[0050] The data in the table are shown using a vehicle-mounted GNSS antenna with a rated working current of 9±3mA as an example. When the working parameters of the antenna are different, the above data will also be different. This embodiment is only shown as an example. It can be seen from the above table that when the antenna current is no longer in the above normal working current range, it can be determined that the antenna is in an open circuit or short circuit.

[0051] It can be understood that if the normal working current range is 8mA to 30mA, then it is an open circuit when it is less than 8mA, and it is a short circuit when it is greater than 30mA. In order to realize the above judgment, it is only necessary to write the corresponding judgment program in the MCU.

[0052] Example 2

[0053] Among them, on the basis of embodiment 1, a negative feedback circuit can be added, and a compensation circuit can be added according to the negative feedback circuit, as shown in the following example: Figure 3 shown.

[0054] The negative feedback circuit includes a feedback resistor R5, one end of the feedback resistor R5 is connected to the inverting input end, and the other end of the feedback resistor R5 is connected to the output end.

[0055] The compensation circuit includes a compensation resistor R4, the resistance of the compensation resistor is the same as that of the feedback resistor, one end of the compensation resistor is connected to the in-phase input terminal, and the other end is grounded.

[0056] The negative feedback circuit further includes an inverting resistor R3, which is connected to the inverting input terminal IN-, and the compensation circuit further includes a non-inverting resistor R2, which is connected to the non-inverting input terminal IN+.

[0057] In addition to forming a negative feedback network, the inverting resistor R3 serves as the input resistor of the inverting terminal, and is symmetrical with the resistor R2, that is, R3 = R2. Similarly, the resistance of the compensation resistor R4 is the same as that of the feedback resistor R5, so that the resistance of the compensation circuit and the negative feedback circuit is the same, and their symmetry plays a role in mutual compensation, while suppressing temperature offset and improving the accuracy of the operational amplifier in a wide temperature working environment.

[0058] According to the virtual short characteristic of the operational amplifier 210, the voltage V P Equal to the inverting node voltage V N That is

[0059] According to the virtual-off characteristic of the operational amplifier 210, I N =0, the current flows from V LOAD Flows through R3 and R5 directly to Vout. The inverting input terminal is virtually disconnected and no current flows in. The current flowing through the feedback resistor is I R5 The calculation expression is as follows:

[0060]

[0061] Voltage across the feedback resistor

[0062] At this time there are:

[0063]

[0064] According to the previous V P =V N , that is,

[0065] The conclusion is:

[0066] It can be seen from the formula that the output voltage is proportional to the voltage at the detection resistor end, and the proportionality coefficient is In practical applications, by setting a certain detection resistance value and proportional coefficient, the output voltage V of the antenna under different load conditions can be measured. OUT , that is, there is a one-to-one correspondence between the output voltage of the operational amplifier 210 and the antenna load current.

[0067] Therefore, after the negative feedback circuit and the compensation circuit are added in this embodiment, the magnitude of the current I1 can also be calculated according to the above formula, so as to judge the working state of the antenna.

[0068] Among them, half of the amplification factor of the operational amplifier 210 is a fixed known value. When the above-mentioned inverting resistor R3 takes a value between 15k ohms and 25k ohms, the feedback resistor R5 can take a value between 0.5M ohms and 1.5M ohms. At this time, the input resistance is about 20K. Too small input resistance is easy to require a larger power supply current loss, so the input resistance is as large as possible. However, if the input resistance is too large, such as requiring the same 50-fold amplification factor, the feedback resistance is required to increase. In a possible case, when the feedback resistance exceeds 1MΩ too much, the resistance temperature stability, accuracy deteriorates and the ground line noise introduced becomes larger, so the feedback resistance is more suitable between 0.5M ohms and 1.5M ohms.

[0069] The detection resistor R1 can be set between 0.5 ohms and 2.2 ohms, for example, 1 ohm, as long as the appropriate package is selected to meet the maximum power consumption in overcurrent. The power calculation expression is: P = I1 2 ·R1.

[0070] When the MCU detects the voltage at the output end, it can perform the above calculations to determine the current working state. In case of short circuit, it can perform power-off protection. When an open circuit is detected, it can determine the current working state and whether there is a problem with the circuit, and can perform operations such as alarms. It can also be used to determine whether the open circuit state has indeed been entered after the circuit-breaking operation, and whether its own control has achieved the expected effect.

[0071] The detection circuit of this embodiment meets the requirements for detecting the open-circuit and short-circuit states of active antennas with different currents. Compared with the mirror proportional current source circuit, the lower and upper thresholds of the normal working current state are more accurate. The antenna current and the voltage of the detection resistor have an excellent linear relationship, and there will be no misjudgment. The judgment can be achieved by simply changing the judgment threshold of the MCU processor by software. At the same time, the temperature drift control of the operational amplifier is realized through the grounded compensation circuit, which has the characteristics of low offset and low temperature drift, and is suitable for amplifying and measuring the tiny signals of the GNSS active antenna.

[0072] Example 3

[0073] like Figure 4 As shown, this embodiment further provides a circuit diagram of a working circuit, which further includes a choke inductor L1 and a fuse unit F1.

[0074] The detection resistor R1 in the above-mentioned embodiment 1 and embodiment 2 may be installed between L1 and F1 (not shown in the figure).

[0075] F1 can be a PTC self-recovering fuse, and its rated specification can be 100mA / 15V. When the antenna load is short-circuited, the resistance at both ends of the fuse increases rapidly, and the voltage at both ends increases accordingly, causing the voltage shared on the detection resistor to decrease accordingly, thereby temporarily protecting the detection resistor and the antenna power supply line from being burned out until the MCU processor diagnoses that the antenna is short-circuited and turns off the power supply.

[0076] L1 is a choke inductor that blocks AC and allows DC to pass.

[0077] By adding the insurance unit F1, the antenna can be protected immediately when a short circuit occurs, giving the MCU enough time to control the antenna circuit to disconnect, reduce losses, and filter the AC through the choke inductor L1, so that the antenna is in a high impedance state within the GNSS frequency band, ensuring the stability of the antenna when working.

[0078] In the several embodiments provided in this application, it should be understood that the disclosed device can also be implemented in other ways. The device embodiments described above are only illustrative, for example, the flowcharts and structure diagrams in the accompanying drawings show devices according to multiple embodiments of the utility model.

[0079] In addition, the functional modules or units in the various embodiments of the present invention may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0080] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0081] The above description is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention.

Claims

1. An active antenna detection circuit, characterized in that: include: Operational amplifier and sense resistor; The detection resistor is connected between the active antenna and the power supply of the active antenna; The non-inverting input terminal and the inverting input terminal of the operational amplifier are respectively connected to the two ends of the detection resistor, so as to detect the current passing through the detection resistor; The output end of the operational amplifier is connected to the MCU, and the MCU is used to determine the working state of the active antenna according to the output signal size of the output end.

2. An active antenna detection circuit according to claim 1, characterized in that: It also includes negative feedback circuit and compensation circuit; The negative feedback circuit comprises a feedback resistor, one end of the feedback resistor is connected to the inverting input terminal, and the other end of the feedback resistor is connected to the output terminal; The compensation circuit comprises a compensation resistor, the resistance value of the compensation resistor is the same as the resistance value of the feedback resistor, one end of the compensation resistor is connected to the in-phase input end, and the other end is grounded.

3. An active antenna detection circuit according to claim 2, characterized in that: The negative feedback circuit further includes an inverting resistor, and the inverting resistor is connected to the inverting input terminal; The non-inverting input terminal is also connected to a non-inverting resistor, and the resistance value of the non-inverting resistor is the same as the resistance value of the anti-inverting resistor.

4. An active antenna detection circuit according to claim 2, characterized in that: The resistance of the feedback resistor is 0.5M ohm to 1.5M ohm.

5. An active antenna detection circuit according to claim 3, characterized in that: The resistance of the reverse resistor is 15k ohms to 25k ohms.

6. An active antenna detection circuit according to claim 1, characterized in that: The resistance of the detection resistor is 0.5 ohms to 2.2 ohms.

7. An active antenna detection circuit according to claim 1, characterized in that: The in-phase input terminal is connected to the side where the power supply is located, and the inverting input terminal is connected to the side where the active antenna is located.

8. An active antenna circuit, characterized in that: include: An active antenna working circuit and an active antenna detection circuit as claimed in any one of claims 1 to 7; The active antenna working circuit comprises an active antenna and a power supply, wherein the power supply is used to supply power to the active antenna; The active antenna detection circuit is connected in parallel with the active antenna working circuit, and is used to detect the working current of the active antenna, and determine the working state of the active antenna working circuit according to the working current.

9. An active antenna circuit according to claim 8, characterized in that: The active antenna working circuit further includes: a choke inductor; The choke inductor is arranged between the detection resistor and the active antenna.

10. An active antenna circuit according to claim 8, characterized in that: The active antenna working circuit further includes: a safety unit; The insurance unit is arranged between the power supply and the detection resistor, and is used for protecting the circuit by fusing when the active antenna is short-circuited.

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