A modulation method, system and medium for reducing transmitter noise floor and improving stability

Abstract

The present invention discloses a modulation method, system and medium for reducing transmitter background noise and improving stability, belonging to the field of transmitter technology. The method includes: when the transmitter receives a first modulation signal PTT and a high-speed detection circuit receives an excitation signal, the excitation signal is detected at high speed and the detection signal is output through a comparator; the first modulation signal PTT and the detection signal output by the comparator are input into an AND gate circuit to obtain a second modulation signal *PTT; the second modulation signal *PTT is used to modulate the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit, and the program-controlled attenuator is triggered to adjust from a full attenuation state to a normal attenuation state. The present invention increases the isolation of the circuit, so that the noise is increased from ‑36dBm to below ‑95dBm when the transmitter modulation signal is turned on, effectively improving the problem that the transmitter background noise (without excitation signal) is too large when the modulation signal is turned on, which seriously affects the receiving sensitivity.

Description

Technical Field

[0001] The present invention relates to the field of transmitter technology, and in particular to a modulation method, system and medium for reducing transmitter background noise and improving stability. Background Art

[0002] With the development of ATC secondary radar technology, the existing ATC secondary radar system needs to have the S-mode capability. Before the emergence of the S-mode, the traditional ATC secondary radar system (A / C mode) has been used in all countries in the world, so the S-mode needs to replace the A / C mode step by step. Therefore, the ATC secondary radar system with S-mode must be compatible with the traditional secondary radar system. In order to conduct an A / C mode interrogation while conducting an S-mode full call interrogation, an A / C / S mode full call interrogation format must be adopted. The difference between it and the standard A / C mode interrogation signal is that a P4 pulse is added after the pulse P3. In order to receive the complete P4 pulse, it is usually necessary to turn on the transmitter modulation signal (the ATC secondary radar uses pulse modulation technology) after receiving the P3 pulse. At this time, the system is in the receiving state, so it must be ensured that when the modulation signal is turned on, the transmitter noise floor cannot affect the reception of the P4 pulse, which puts high demands on the transmitter noise floor level.

[0003] In order to ensure the transmitter noise floor after the modulation signal is turned on, the current common practice is to adjust the static operating point of the amplification link in the transmitter to make the amplifier in a deep saturation state. However, this method has two main disadvantages: First, it is necessary to repeatedly debug the appropriate static operating point, which increases the difficulty of debugging. Second, the amplifier is in a deep saturation state, which will sacrifice the amplifier gain and linearity. Some existing modulation methods can control the noise floor to around -85dBm, but at this time it is close to the system receiving sensitivity and is easily interfered, causing system instability. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a modulation method, system and medium for reducing transmitter background noise and improving stability.

[0005] The object of the present invention is achieved through the following technical solutions: The first aspect of the present invention provides: a modulation method for reducing transmitter noise floor and improving stability, comprising the following steps:

[0006] The field programmable gate array FPGA detects whether the transmitter receives the first modulation signal PTT. If not, the transmitter does not work. When the transmitter receives the first modulation signal PTT, it determines whether the high-speed detection circuit receives the excitation signal. If not, the transmitter does not work.

[0007] When the transmitter receives the first modulation signal PTT and the high-speed detection circuit receives the excitation signal, the excitation signal is subjected to high-speed detection and the detection signal is output through the comparator;

[0008] Input the first modulation signal PTT and the detection signal output by the comparator into the AND gate circuit to obtain the second modulation signal *PTT;

[0009] The second modulation signal *PTT is used to modulate the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit, and at the same time trigger the programmable attenuator to adjust from the full attenuation state to the normal attenuation state.

[0010] Preferably, the second modulation signal *PTT modulates the drain voltage or gate voltage of the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit.

[0011] Preferably, the second modulation signal *PTT is the combined effect of the first modulation signal PTT and the detection signal. Only when the excitation signal is valid, the second modulation signal *PTT turns on the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit.

[0012] Preferably, the transmitter includes a pre-stage amplifier circuit, the input end of the pre-stage amplifier circuit is connected to the output end of the AND gate circuit, and the output end of the pre-stage amplifier circuit is connected to the input end of the programmable attenuation circuit; the input end of the AND gate circuit is connected to the output end of the high-speed detection circuit and is used to receive the first modulation signal PTT; the input end of the high-speed detection circuit is used to receive the excitation signal; the output end of the programmable attenuation circuit is connected to the input end of the intermediate-stage amplifier circuit; the input end of the intermediate-stage amplifier circuit is connected to the AND gate circuit, and the output end of the intermediate-stage amplifier circuit is connected to the input end of the final-stage amplifier circuit; the input end of the final-stage amplifier circuit is connected to the AND gate circuit, and the output end of the final-stage amplifier circuit is connected to the input end of the circulator; the output end of the circulator is connected to the receiving circuit and the filter; the filter is connected to the antenna port.

[0013] Preferably, the high-speed detection circuit comprises a detector, the input end of the detector is used to receive an excitation signal, the output end of the detector is connected to the input end of a comparator; and the output end of the comparator is connected to an AND gate circuit.

[0014] The second aspect of the present invention provides: a modulation system for reducing transmitter noise floor and improving stability, which is used to implement any of the above-mentioned modulation methods for reducing transmitter noise floor and improving stability, comprising:

[0015] The detection module is used to use the field programmable gate array FPGA to detect whether the transmitter receives the first modulation signal PTT. If not, the transmitter does not work. When the transmitter receives the first modulation signal PTT, it determines whether the high-speed detection circuit receives the excitation signal. If not, the transmitter does not work.

[0016] A detection module, used for performing high-speed detection on the excitation signal and outputting a detection signal through a comparator when the transmitter receives the first modulation signal PTT and the high-speed detection circuit receives the excitation signal;

[0017] A modulation signal generating module, used for inputting the first modulation signal PTT and the detection signal output by the comparator into an AND gate circuit to obtain a second modulation signal *PTT;

[0018] The modulation module is used to modulate the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit using the second modulation signal *PTT, and at the same time trigger the programmable attenuator to adjust from the full attenuation state to the normal attenuation state.

[0019] The third aspect of the present invention provides: a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and when the computer-executable instructions are loaded and executed by a processor, any of the above-mentioned modulation methods for reducing transmitter background noise and improving stability is implemented.

[0020] The beneficial effects of the present invention are:

[0021] 1) By using the first modulation signal PTT and the amplifier detection signal to jointly control the opening of each amplifier, and triggering the programmable attenuator circuit at the same time, the isolation of the circuit is increased, so that the noise of the transmitter is increased from -36dBm to below -95dBm when the modulation signal is turned on, effectively improving the problem that the transmitter noise floor (no excitation signal) is too large when the modulation signal is turned on, which seriously affects the receiving sensitivity.

[0022] 2) Effectively reduces the difficulty of debugging and has high consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Flowchart of modulation method to reduce transmitter noise floor and improve stability;

[0024] Figure 2 This is the transmitter principle block diagram;

[0025] Figure 3 It is the principle block diagram of high-speed detection circuit and AND gate circuit;

[0026] Figure 4 This is a schematic diagram of the noise floor before transmitter modulation;

[0027] Figure 5Schematic diagram of the noise floor after transmitter modulation. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. 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.

[0029] See also Figure 1-Figure 5 The first aspect of the present invention provides: a modulation method for reducing transmitter noise floor and improving stability, comprising the following steps:

[0030] The field programmable gate array FPGA detects whether the transmitter receives the first modulation signal PTT. If not, the transmitter does not work. When the transmitter receives the first modulation signal PTT, it determines whether the high-speed detection circuit receives the excitation signal. If not, the transmitter does not work.

[0031] When the transmitter receives the first modulation signal PTT and the high-speed detection circuit receives the excitation signal, the excitation signal is subjected to high-speed detection and the detection signal is output through the comparator;

[0032] Input the first modulation signal PTT and the detection signal output by the comparator into the AND gate circuit to obtain the second modulation signal *PTT;

[0033] The second modulation signal *PTT is used to modulate the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit, and at the same time trigger the programmable attenuator to adjust from the full attenuation state to the normal attenuation state.

[0034] In this embodiment, the transmitter amplification link is composed of a pre-stage amplifier circuit, an intermediate stage amplifier circuit, and a final stage amplifier circuit. The present invention takes a kilowatt-level solid-state pulse transmitter as an example, wherein PTT is a pulse modulation signal used to control the power amplifier to turn on. *PTT is the combined effect of PTT and the detection signal. Only when the excitation signal is valid, *PTT turns on the amplifier to suppress the background noise of the amplification link. The workflow is as follows: the FPGA in the transmitter detects whether the power amplifier gate opening signal PTT is received. When the FPGA detects the power amplifier gate opening signal PTT, it performs excitation signal detection. If there is no excitation signal, the transmitter does not work; after the excitation signal is detected, the comparator outputs TTL and the power amplifier gate opening signal PPT to obtain the modulation signal *PTT, and the *PTT signal modulates the amplifiers at all levels. In this way, during the period when the transmitter receives the power amplifier gate opening signal without the excitation signal, the amplifier circuits at all levels of the entire transmitter will not be turned on, the entire gain of the reflector is controlled, the background noise of the transmitter link is better reduced, and the receiving sensitivity is improved.

[0035] In some embodiments, the second modulation signal *PTT modulates the drain voltage or gate voltage of the pre-stage amplifier circuit, the intermediate stage amplifier circuit, and the final stage amplifier circuit.

[0036] In this embodiment, the amplifier is modulated, and gate modulation can be performed on various amplifiers (LDMOS and GaN), and drain modulation can also be performed on the GaN amplifier.

[0037] In some embodiments, the second modulation signal *PTT is the combined effect of the first modulation signal PTT and the detection signal. Only when the excitation signal is valid, the second modulation signal *PTT turns on the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit.

[0038] In some embodiments, the transmitter includes a pre-stage amplifier circuit, the input end of the pre-stage amplifier circuit is connected to the output end of the AND gate circuit, and the output end of the pre-stage amplifier circuit is connected to the input end of the programmable attenuation circuit; the input end of the AND gate circuit is connected to the output end of the high-speed detection circuit and is used to receive the first modulation signal PTT; the input end of the high-speed detection circuit is used to receive the excitation signal; the output end of the programmable attenuation circuit is connected to the input end of the intermediate stage amplifier circuit; the input end of the intermediate stage amplifier circuit is connected to the AND gate circuit, and the output end of the intermediate stage amplifier circuit is connected to the input end of the final stage amplifier circuit; the input end of the final stage amplifier circuit is connected to the AND gate circuit, and the output end of the final stage amplifier circuit is connected to the input end of the circulator; the output end of the circulator is connected to the receiving circuit and the filter; the filter is connected to the antenna port.

[0039] In this embodiment, the transmitter mainly completes the function of amplifying the excitation signal. The amplifier circuit performs pulse modulation and amplification on the input excitation signal to achieve the waveform and power required for transmission, and sends the amplified signal to the antenna port through a filter. The output end collects the detection and standing wave signals through coupling and sends them to the digital circuit for processing, and sends the signal received by the antenna to the receiving circuit through a circulator.

[0040] In some embodiments, the high-speed detection circuit includes a detector, the input end of the detector is used to receive an excitation signal, the output end of the detector is connected to the input end of a comparator; and the output end of the comparator is connected to an AND gate circuit.

[0041] In this embodiment, the high-speed detection circuit can detect the input excitation signal, and output the JB signal with the input excitation signal, and perform ANDing with the transmission start signal PTT to obtain the *PTT signal, which is used to turn on each level of amplifiers and trigger the programmable attenuator from the full attenuation state to the normal attenuation state.

[0042] The second aspect of the present invention provides: a modulation system for reducing transmitter noise floor and improving stability, which is used to implement any of the above-mentioned modulation methods for reducing transmitter noise floor and improving stability, comprising:

[0043] The detection module is used to use the field programmable gate array FPGA to detect whether the transmitter receives the first modulation signal PTT. If not, the transmitter does not work. When the transmitter receives the first modulation signal PTT, it determines whether the high-speed detection circuit receives the excitation signal. If not, the transmitter does not work.

[0044] A detection module, used for performing high-speed detection on the excitation signal and outputting a detection signal through a comparator when the transmitter receives the first modulation signal PTT and the high-speed detection circuit receives the excitation signal;

[0045] A modulation signal generating module, used for inputting the first modulation signal PTT and the detection signal output by the comparator into an AND gate circuit to obtain a second modulation signal *PTT;

[0046] The modulation module is used to modulate the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit using the second modulation signal *PTT, and at the same time trigger the programmable attenuator to adjust from the full attenuation state to the normal attenuation state.

[0047] The third aspect of the present invention provides: a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and when the computer-executable instructions are loaded and executed by a processor, any of the above-mentioned modulation methods for reducing transmitter background noise and improving stability is implemented.

[0048] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A modulation method for reducing transmitter noise floor and improving stability, characterized in that: The following steps are involved: The field programmable gate array FPGA detects whether the transmitter receives the first modulation signal PTT. If not, the transmitter does not work. When the transmitter receives the first modulation signal PTT, it determines whether the high-speed detection circuit receives the excitation signal. If not, the transmitter does not work. When the transmitter receives the first modulation signal PTT and the high-speed detection circuit receives the excitation signal, the excitation signal is subjected to high-speed detection and the detection signal is output through the comparator; Input the first modulation signal PTT and the detection signal output by the comparator into the AND gate circuit to obtain the second modulation signal *PTT; The second modulation signal *PTT is used to modulate the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit, and at the same time trigger the programmable attenuator to adjust from the full attenuation state to the normal attenuation state; The second modulation signal *PTT is the combined effect of the first modulation signal PTT and the detection signal. Only when the excitation signal is valid, the second modulation signal *PTT turns on the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit.

2. A modulation method for reducing transmitter noise floor and improving stability according to claim 1, characterized in that: The second modulation signal *PTT modulates the drain voltage or gate voltage of the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit.

3. The modulation method for reducing transmitter noise floor and improving stability according to claim 1, characterized in that: The transmitter comprises a pre-stage amplifier circuit, the input end of the pre-stage amplifier circuit is connected to the output end of the AND gate circuit, and the output end of the pre-stage amplifier circuit is connected to the input end of the programmable attenuation circuit; the input end of the AND gate circuit is connected to the output end of the high-speed detection circuit and is used to receive the first modulation signal PTT; the input end of the high-speed detection circuit is used to receive the excitation signal; the output end of the programmable attenuation circuit is connected to the input end of the intermediate stage amplifier circuit; the input end of the intermediate stage amplifier circuit is connected to the AND gate circuit, and the output end of the intermediate stage amplifier circuit is connected to the input end of the final stage amplifier circuit; the input end of the final stage amplifier circuit is connected to the AND gate circuit, and the output end of the final stage amplifier circuit is connected to the input end of the circulator; the output end of the circulator is connected to the receiving circuit and the filter; the filter is connected to the antenna port.

4. The modulation method for reducing transmitter noise floor and improving stability according to claim 1, characterized in that: The high-speed detection circuit comprises a detector, the input end of the detector is used to receive an excitation signal, the output end of the detector is connected to the input end of a comparator; and the output end of the comparator is connected to an AND gate circuit.

5. A modulation system for reducing transmitter noise floor and improving stability, characterized in that: A modulation method for reducing transmitter noise floor and improving stability as claimed in any one of claims 1 to 4, comprising: The detection module is used to use the field programmable gate array FPGA to detect whether the transmitter receives the first modulation signal PTT. If not, the transmitter does not work. When the transmitter receives the first modulation signal PTT, it determines whether the high-speed detection circuit receives the excitation signal. If not, the transmitter does not work. A detection module, used for performing high-speed detection on the excitation signal and outputting the detection signal through a comparator when the transmitter receives the first modulation signal PTT and the high-speed detection circuit receives the excitation signal; A modulation signal generating module, used for inputting the first modulation signal PTT and the detection signal output by the comparator into an AND gate circuit to obtain a second modulation signal *PTT; The modulation module is used to modulate the pre-stage amplifier circuit, the intermediate stage amplifier circuit and the final stage amplifier circuit using the second modulation signal *PTT, and at the same time trigger the programmable attenuator to adjust from the full attenuation state to the normal attenuation state.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions. When the computer-executable instructions are loaded and executed by the processor, the modulation method for reducing transmitter background noise and improving stability as described in any one of claims 1 to 4 is implemented.

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