Circuit for improving stability and signal resolving rate of microwave landing receiving channel

Abstract

The utility model discloses a circuit for improving the stability and the signal resolving rate of a microwave landing receiving channel, which comprises a first-stage 40dB electrically controlled attenuator, the working frequency of the first-stage 40dB electrically controlled attenuator is 227.1 MHz, the first-stage 40dB electrically controlled attenuator has two working modes: attenuation in a low-level mode and insertion loss in a high-level mode, and the attenuation amount is determined by control voltage; the first-stage 63dB numerical control attenuator is a 6-bit attenuator and is controlled through combination of six pins, attenuation control of 1-63dB is achieved, and the stepping is 1dB; by fitting control curves of an electrically controlled attenuator and a numerical control attenuator, control logic is optimized, pure linear channel gain control is realized, and meanwhile, a large dynamic range of a microwave receiving channel is ensured; the beneficial effects of the utility model are that through fitting design, linear control of a microwave receiving channel in the whole level input range (-17 dB to 110 dB) can be realized, stepping can be accurate to 1dB, and a finally output intermediate frequency signal can be controlled to a median of a judgment threshold no matter in a strong signal area or a weak signal area, thereby improving signal stability and data solution rate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microwave receiving technology in the radio communication navigation technology, and particularly relates to a circuit for improving the stability of a microwave landing receiving channel and the signal solution rate. BACKGROUND

[0002] The microwave landing system is one of the current international mainstream landing systems, and multiple military airports are equipped with microwave ground stations and microwave shipboard stations. In recent years, the models loaded with microwave landing receiving modules are becoming larger and larger, and the distance from the microwave landing antenna to the microwave landing receiving module is becoming longer and longer, so the sensitivity index of the module needs to be higher and higher. In order to ensure the high sensitivity of the microwave receiving channel, when the signal-to-noise ratio cannot be obviously improved, the channel gain needs to be moderately increased, which will bring a problem, that is, the higher the channel gain, the greater the signal amplitude that needs to be attenuated when the receiving channel is in a strong signal input state, and therefore the microwave channel needs to have excellent linearity in the entire strong and weak signal interval.

[0003] The current microwave receiving channel design idea mainly includes two kinds:

[0004] a) Dynamic control is realized by cascading AGC amplifiers: two-stage AGC amplifiers are cascaded, in a strong signal state, the amplifier is in a negative gain attenuation state, and in a weak signal state, the amplifier is in a positive gain state. Since the gain characteristic of the AGC amplifier is relatively steep in a strong signal state at a low control voltage, the amplitude-frequency characteristic of the receiver is also relatively steep in a strong signal interval and is gentle and approximately linear in a weak signal interval. Advantage: a large dynamic range can be realized. Disadvantage: the channel is a logarithmic channel, the gain curve is relatively steep in a strong signal state, and in a strong signal input state, it is easy to appear uncontrollable, that is, the signal amplitudes controlled by two adjacent AGC values are outside the upper and lower thresholds of the solution, and it is easy to jump large data, the data amplitude control is not within the threshold range, and the data solution is out of tolerance.

[0005] b) Dynamic control is realized by multi-stage numerical control attenuators: first, a receiving channel meeting the gain requirement is designed, which is usually realized by 5 to 6 stages of amplifiers, including a high-gain amplifier; the control logic is that the numerical control attenuator is not controlled in a weak signal state, that is, in a loss state, and the numerical control attenuator is controlled in a strong signal state, that is, in an attenuation state; advantage: large dynamic range, the channel is a linear channel, and it will not jump large data; disadvantage: in order to realize a large dynamic range, two to three numerical control attenuators are often needed, 5 or 6 control lines are needed for a single-stage attenuator, a large amount of control resources are needed, it is difficult to realize, and it is expensive.

[0006] Therefore, it is of great significance to design a receiving channel with excellent linearity for improving the sensitivity, dynamic range and precision of the microwave receiving channel. Meanwhile, under the background of current lean production, a stable and easy-to-debug microwave receiving channel can greatly shorten the worker debugging time, reduce the production cost and field maintenance cost, and has practical significance for factory cost reduction and efficiency improvement. SUMMARY

[0007] The present application aims to provide a circuit for improving the stability of a microwave landing receiving channel and the signal resolving rate, the dynamic passing of the channel is realized by fitting a first electrically-controlled attenuator and a first digital-controlled attenuator, so that the microwave receiving channel can work stably and reliably in the case of strong signal and weak signal, and the data validity in the whole signal coverage area can be ensured.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a circuit for improving the stability of a microwave landing receiving channel and the signal resolving rate, comprising

[0009] a first 40dB electrically-controlled attenuator, which has a working frequency of 227.1MHz and has two working modes: attenuation in the low-level mode and insertion loss in the high-level mode, and the attenuation amount is determined by the control voltage;

[0010] a first 63dB digital-controlled attenuator, which is a 6-bit attenuator and realizes 1-63dB attenuation control through 6-pin combination control with a step of 1dB;

[0011] The control curves of the electrically-controlled attenuator and the digital-controlled attenuator are fitted, and the control logic is optimized to realize pure linear channel gain control and ensure the large dynamic range of the microwave receiving channel.

[0012] As a preferred technical scheme of the present application, the control voltage of the electrically-controlled attenuator is realized by an NPN tube P1 and peripheral circuits, P1 works in the saturated state, when the control logic is given a TTL high level, P1 is turned on, the voltage on the electrically-controlled attenuator is the voltage on R6, and the attenuator is in the attenuation state; when the control logic is given a TTL low level, P1 is turned off, the voltage on the electrically-controlled attenuator is 12V, and the attenuator is in the insertion loss state.

[0013] As a preferred technical scheme of the present application, the working frequency of the electrically-controlled attenuator is 227.1MHz, when R6 is adjusted to 51 ohms, the control voltage is 1V, and the attenuation amount of the electrically-controlled attenuator is 40dB, which is combined with the 63dB attenuation amount of the digital-controlled attenuator, and the dynamic range realized by the two stages exceeds 100dB.

[0014] As a preferred technical scheme of the present application, the fitting logic of the two-stage attenuators is that the digital-controlled attenuator is started preferentially, and the electrically-controlled attenuator is released preferentially; the digital-controlled attenuator is controlled according to 1-6 bits, and the electrically-controlled attenuator is used as the 7th bit; when the signal changes from weak to strong, the digital-controlled attenuator is started first; when the signal changes from strong to weak, the electrically-controlled attenuator is released first, and then the digital-controlled attenuator is released.

[0015] As a preferred technical scheme of the present application, the digital-controlled attenuator is controlled according to 1-6 bits, i.e. 1-63dB.

[0016] As a preferred technical scheme of the present application, the electrically adjustable attenuator is regarded as 64dB as the 7th.

[0017] As a preferred technical scheme of the present application, when the signal is from weak to strong, the digital control attenuator is started first, and when the required attenuation is greater than 63dB, the electrically adjustable attenuator is started, and the 24dB phase difference is compensated by the digital control attenuator.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] Through the fitting design, the linear control of the microwave receiving channel in the whole level input range (-17dB-110dB) can be realized, and the step can be accurately to 1dB. Whether in the strong signal area or the weak signal area, the final output intermediate frequency signal can be controlled on the median value of the judgment threshold, so that the signal stability and the data solving rate are improved.

[0020] Under this design, the microwave channel sensitivity is -110, the dynamic range is 93dB, and the precision meets the national military standard requirements. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a partial link diagram of the microwave receiving channel of the present application;

[0022] Figure 2 is a control curve diagram of the electrically adjustable attenuator of the present application;

[0023] Figure 3 is a true value logic diagram of the control end of the electrically adjustable attenuator of the present application;

[0024] Figure 4 is a true value logic diagram of the control end of the digital control attenuator of the present application;

[0025] Figure 5 is a fitting control true value logic diagram of the present application;

[0026] Figure 6 is a fitting logic implementation flowchart of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0028] Please refer to Figures 1-6The application provides a circuit for improving stability of a microwave landing receiving channel and signal solution rate, which comprises a first 40dB electrically-adjusted attenuator and a first 63dB digitally-controlled attenuator, and realizes pure linear channel gain control by fitting control curves of the two and optimizing control logic, while ensuring large dynamic of the microwave receiving channel.

[0029] Figure 1 Figure for the microwave receiving channel part of the application; A8 is an electrically-adjusted attenuator, and A13 is a digitally-controlled attenuator; the electrically-adjusted attenuator and the digitally-controlled attenuator cooperate to control input strong and weak signals (-17dBm to -110dBm) within a threshold range (-5dBm to +8dBm).

[0030] a) Electrically-adjusted attenuator

[0031] The electrically-adjusted attenuator HE411A works at a frequency of 227.1MHz in the application, and has two working modes by designing a switch circuit: low level, attenuation; high level, insertion loss (attenuation amount is determined by control voltage); the attenuation amount of the electrically-adjusted attenuator and the control voltage relationship curve is as shown in Figure 2 .

[0032] The control voltage of the electrically-adjusted attenuator is realized by an NPN tube P1 and peripheral circuits; when the control logic is TTL high level, the tube is turned on, and the voltage added to the electrically-adjusted attenuator is the voltage on R6, and the attenuator is in the attenuation state; when the control logic is TTL low level, the tube is cut off, and the voltage added to the electrically-adjusted attenuator is about 12V, and the attenuator is in the insertion loss state; the true value logic of the control end X7 of the electrically-adjusted attenuator is as shown in Figure 3 .

[0033] b) Digitally-controlled attenuator

[0034] The digitally-controlled attenuator HEM751 is a 6-bit attenuator, and can realize control amount of 1-63dB by 6-pin combination control, with 1dB step; the pin and corresponding attenuation relationship is as shown in the following table:

[0035] Table 1 Pin definition of the digitally-controlled attenuator

[0036]

[0037]

[0038] The true value logic of the control end X1-X6 of the digitally-controlled attenuator is as shown in Figure 4 .

[0039] Fitting logic of the two-stage attenuator

[0040] The frequency at which the electrically adjustable attenuator works in the application is 227.1 MHz, the control voltage is about 1V when R6 is adjusted to 51 ohms, the attenuation of the electrically adjustable attenuator is 40dB, the attenuation of the digital control attenuator is 63dB, the dynamic range of two stages can exceed 100dB, the fitting control logic is that the digital control attenuator is started preferentially, and the electrically adjustable attenuator is released preferentially; the digital control attenuator is controlled according to 1 to 6 bits (1-63dB), and the electrically adjustable attenuator is regarded as the 7th bit (64dB); when the signal becomes stronger, the digital control attenuator is started first, when the attenuation required is greater than 63dB, the electrically adjustable attenuator is started, the electrically adjustable attenuator is regarded as 64dB when it is started, and the actual attenuation of the electrically adjustable attenuator is 40dB, so the difference of 24dB needs to be compensated by releasing the attenuation of the digital control attenuator when the electrically adjustable attenuator is started; when the signal becomes weaker, the electrically adjustable attenuator is released first, and then the digital control attenuator is released; the specific fitting points are shown in Table 2, and the fitting control true value logic is shown in Figure 5 .

[0041] Table 2 fitting logic of two-stage attenuators

[0042]

[0043]

[0044] Implementation flow chart

[0045] The implementation flow chart of the fitting control of the electrically adjustable attenuator and the digital control attenuator is shown in Figure 6

[0046]

[0047] The application has been used in the microwave landing receiving module of the anti-XX platform comprehensive radio frequency system, and the specific implementation is divided into two parts: channel hardware circuit construction and control logic; the control logic is realized by the microwave landing function FPGA software residing in the module; at present, the microwave landing receiving module based on the design has passed the functional performance test, various environmental tests and flight verification, and the project has passed the identification; the application performs well in improving the channel stability and data solving rate, and achieves the expected purpose.

[0048] Although the embodiments of the application have been shown and described in detail, as described above, it can be understood by those skilled in the art that various changes, modifications, replacements and modifications can be made to the embodiments without departing from the principles and spirits of the application, the scope of the application is defined by the appended claims and their equivalents.​

Claims

1. A circuit for improving the stability of a microwave landing receiver channel and the rate of signal resolution, characterized by: Comprising A first 40dB electrically adjustable attenuator, whose working frequency is 227.1MHz, has two working modes: low level mode attenuates, high level mode inserts loss, and the attenuation is determined by the control voltage; A first 63dB digitally controlled attenuator, which is a 6-bit attenuator, is controlled by 6 pins, and realizes 1-63dB attenuation control with 1dB step. By fitting the control curves of the electrically adjustable attenuator and the digitally controlled attenuator, the control logic is optimized to realize pure linear channel gain control, while ensuring a large dynamic range of the microwave receiving channel.

2. The circuit for improving the stability of the microwave landing receiving channel and the signal solution rate according to claim 1, characterized in that: The control voltage of the electrically adjustable attenuator is realized by an NPN tube P1 and peripheral circuit. P1 works in saturation state. When the control logic is given TTL high level, P1 is turned on, the voltage on the electrically adjustable attenuator is the voltage on R6, and the attenuator is in attenuation state; when the control logic is given TTL low level, P1 is turned off, the voltage on the electrically adjustable attenuator is 12V, and the attenuator is in loss state.

3. The circuit for improving the stability of the microwave landing receiving channel and the signal solution rate according to claim 1, characterized in that: The working frequency of the electrically adjustable attenuator is 227.1MHz. When R6 is adjusted to 51 ohms, the control voltage is 1V, and the attenuation of the electrically adjustable attenuator is 40dB. Combined with the 63dB attenuation of the digitally controlled attenuator, the dynamic range of the two stages can exceed 100dB.

4. The circuit for improving the stability of the microwave landing receiving channel and the signal solution rate according to claim 3, characterized in that: The fitting logic of the two-stage attenuator is: the digitally controlled attenuator is started first, and the electrically adjustable attenuator is released first; the digitally controlled attenuator is controlled by 1-6 bits, and the electrically adjustable attenuator is controlled as the 7th bit; when the signal becomes stronger, the digitally controlled attenuator is started first; when the signal becomes weaker, the electrically adjustable attenuator is released first, and then the digitally controlled attenuator is released.

5. The circuit for improving the stability of the microwave landing receiving channel and the signal solution rate according to claim 4, characterized in that: The digitally controlled attenuator is controlled by 1-6 bits, i.e. 1-63dB.

6. The circuit for improving the stability of the microwave landing receiving channel and the signal solution rate according to claim 4, characterized in that: The electrically adjustable attenuator is controlled as the 7th bit, which is regarded as 64dB.

7. The circuit for improving the stability of the microwave landing receiving channel and the signal solution rate according to claim 4, characterized in that: When the signal becomes stronger, the digitally controlled attenuator is started first. When the required attenuation is greater than 63dB, the electrically adjustable attenuator is started, and the difference of 24dB is compensated by releasing the attenuation of the digitally controlled attenuator.

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