CN115955256A - S-frequency-band measurement, control, transmission and isolation system for aerospace application - Google Patents
S-frequency-band measurement, control, transmission and isolation system for aerospace application Download PDFInfo
- Publication number
- CN115955256A CN115955256A CN202211107593.2A CN202211107593A CN115955256A CN 115955256 A CN115955256 A CN 115955256A CN 202211107593 A CN202211107593 A CN 202211107593A CN 115955256 A CN115955256 A CN 115955256A
- Authority
- CN
- China
- Prior art keywords
- receiving
- duplexer
- power
- antenna feed
- band
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000005259 measurement Methods 0.000 title claims abstract description 50
- 238000002955 isolation Methods 0.000 title claims abstract description 29
- 230000005540 biological transmission Effects 0.000 title description 13
- 238000000034 method Methods 0.000 claims abstract description 14
- 230000000903 blocking effect Effects 0.000 claims abstract description 13
- 230000003321 amplification Effects 0.000 claims abstract description 12
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 12
- 238000001914 filtration Methods 0.000 claims abstract description 5
- 239000004020 conductor Substances 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 4
- 238000003466 welding Methods 0.000 claims description 4
- 239000000523 sample Substances 0.000 claims description 3
- 238000001228 spectrum Methods 0.000 abstract description 19
- 238000013461 design Methods 0.000 abstract description 13
- 230000008569 process Effects 0.000 abstract description 7
- 230000001629 suppression Effects 0.000 description 16
- 238000005192 partition Methods 0.000 description 10
- 230000007480 spreading Effects 0.000 description 10
- 238000003892 spreading Methods 0.000 description 10
- 238000004458 analytical method Methods 0.000 description 6
- 230000003595 spectral effect Effects 0.000 description 6
- 238000004891 communication Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- 229920006395 saturated elastomer Polymers 0.000 description 4
- 230000008054 signal transmission Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241001125929 Trisopterus luscus Species 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- -1 are selected Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000002457 bidirectional effect Effects 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000006855 networking Effects 0.000 description 1
- 229910052755 nonmetal Inorganic materials 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000005316 response function Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
Images
Classifications
-
- 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
Landscapes
- Radio Relay Systems (AREA)
Abstract
The invention belongs to the technical field of space measurement and control, and provides an S frequency band measurement and control transmitting and receiving isolation system for space application, which comprises a baseband module, a power amplifier, a receiving and blocking filter, a waveguide switch, a duplexer, an antenna feed source and a low-noise amplifier; after the baseband module generates baseband signals, the baseband signals are subjected to power amplification and filtering by a receiving and blocking filter in sequence through a power amplifier, enter an antenna feed source through a waveguide switch and a duplexer and are sent to a satellite through the antenna feed source; after receiving satellite downlink signals, the antenna feed source enters a receiving link after being subjected to duplexer and low-noise amplification. The invention systematically designs and improves the processes of generating baseband signals, amplifying power, transmitting and receiving a resistance filter, a duplexer, transmitting a high-power signal to a receiving link signal, receiving and receiving isolation, and the like aiming at various transmitting systems such as standard TT & C, spread spectrum TT & C, spread frequency hopping TT & C (including long codes, short codes and long-short code combinations), and the like, thereby ensuring that the S frequency band transmitting-receiving isolation in the space flight measurement and control system meets the use requirement.
Description
Technical Field
The invention belongs to the technical field of aerospace measurement and control, and relates to an S-band measurement and control transmitting and receiving isolation system for aerospace application.
Background
According to the IEEE specification, the 2 to 4GHz band is called the S band, and is mainly used for weather radar, ship radar, and satellite communication. According to the full demonstration of Chinese measurement and control experts and the development of aerospace measurement and control fields for many years, the S frequency band measurement and control network has the following 5 major advantages:
first, the function is complete. The S frequency band measurement and control network constructed in China has the functions of precise tracking, distance measurement, speed measurement, aircraft remote control, remote measurement, bidirectional voice and downlink image transmission, and compared with the similar networks in China, the S frequency band measurement and control network has more elements, high precision and strong practicability, thereby having wider application.
Second, the regime is complete. The S frequency band function is single abroad, the aerospace measurement and control and the world communication are integrated in China, the aerospace measurement and control and the world communication can be integrated into a whole for two purposes, the complexity is reduced into the simplicity, the equipment is saved, and the contradiction between the measurement and control and the communication is eliminated.
Thirdly, one network has multiple purposes. The S frequency band measurement and control in China can meet the requirements of manned spaceflight, can complete measurement and control of a near-earth satellite and a geostationary satellite, and simultaneously adopts a new design standard to create a prerequisite for international networking.
Fourth, large scale. The national S-band measurement and control is a huge aerospace measurement and control network which is formed by a land-based measurement and control station, an offshore measuring ship, a vehicle-mounted measurement and control station and three centers of Beijing, xian and Jiuquan and is distributed all over the country and can navigate in three oceans.
Fifthly, the economic benefit is high. Multiple functions, multiple uses, such as sharing antennas, sharing communication channels, etc., are employed in the design of the device. Only this item can save billions of dollars of investment.
Therefore, S-band measurement and control is an important component of aerospace application, can support measurement and control tasks of targets such as geosynchronous orbit, medium-low earth orbit and the like, and meets the requirements of most aerospace tasks at present or in a long time in the future. Most of currently-built measurement and control data transmission systems have the transmitting frequency of 2025 MHz-2120.00 MHz, the receiving frequency of 2200 MHz-2300 MHz and the frequency interval of only 80M, and the existing S-band transmitting system comprises a plurality of combined modes such as standard TT & C, incoherent spread spectrum TT & C, spread frequency hopping TT & C and the like, and the transmitting frequency and the combined frequency components are complex, so that the transmitting-receiving isolation degree is a very important index in the field of aerospace measurement and control in the same day. Especially, when long and short codes in a spread spectrum frequency hopping mode work simultaneously, the condition that the transmitting dual-tone combined frequency falls into a receiving band can occur, so that receiving and transmitting intermodulation interference is caused, and the receiving performance is influenced. If the receiving and transmitting isolation is not well solved, the receiving link is saturated and cannot work normally when the transmitting link works.
Therefore, in order to ensure that the transmitting and receiving equipment of the ground measurement and control system can work normally, the transmitting and receiving isolation under different transmitting systems of S frequency bands needs to be effectively realized.
Disclosure of Invention
The invention aims to provide an S frequency band measurement, control, transceiving and isolating system for aerospace application, which can ensure that the normal work of a receiving link is not influenced when a transmitting link of the system works. The method specifically comprises the following steps:
1) When the power amplifier is started up with full power, the temperature increase of the thermal noise in the receiving band is less than 1K.
2) When the system works in an uplink mode, no interference signal is generated in a receiving frequency band.
In order to realize the purpose, the technical scheme adopted by the invention is as follows:
an S-band measurement and control transceiving isolation system for aerospace application comprises a baseband module, a power amplifier, a receive-stop filter, a waveguide switch, a duplexer, an antenna feed source and a low-noise amplifier;
the base band module in the transmitting link is sequentially connected with a power amplifier, a receiving and blocking filter and a waveguide switch and is connected with an antenna feed source through a duplexer; after the baseband module generates baseband signals, the baseband signals are sequentially subjected to power amplification through a power amplifier and filtering through a receiving and blocking filter, then enter an antenna feed source through a waveguide switch and a duplexer, and are sent to a satellite through the antenna feed source;
the antenna feed source is connected with a receiving link through a duplexer and a low-noise amplifier; after receiving satellite downlink signals, the antenna feed source enters a receiving link after being subjected to duplexer and low-noise amplification.
And when the power amplifier works at the full power of 400W by adopting a power backspacing method, the third-order intermodulation is-15 dBc.
The isolation degree adopted by the stop-receive filter is 110dB, and the isolation degree adopted by the duplexer is 110dB.
The antenna feed source comprises a loudspeaker, a connecting plate, a partition plate polarizer and a combined network, wherein the loudspeaker is connected with the partition plate polarizer through the connecting plate, and the combined network is positioned behind the partition plate polarizer; the partition plate polarizer comprises a main body cavity and a matching block, the matching block is located below the main body cavity and is tightly attached to the side wall of the main body cavity, and a probe is arranged at the tail end of the matching block and used for being connected with a combined network.
Wherein, the horn is formed by one-time tailor welding of a fully antirust aluminum plate; the matching block and the main body cavity are provided with a pin hole and a screw hole, and the two devices are positioned by pins and screws; the baffle polarizer is connected with the combined network connection surface by adding screws around the cavity; the combined network consists of three outer conductors and is connected between the outer conductors at the outermost edge and at the inner edge by a dense screw arrangement.
The invention has the following beneficial effects:
1. the invention carries out systematic design from the processes of baseband signal generation, power amplification, receiving and blocking filter and duplexer, high-power signal transmission to the receiving link signal reception, and the like, and is suitable for most space measurement and control systems.
2. The invention can be applied to the receiving and transmitting isolation effect evaluation and the system index decomposition of the space measurement and control system.
3. The method has the advantages of simple treatment process, strong universality and easy engineering realization.
Drawings
Fig. 1 is a model schematic diagram of an S-band measurement, control, transceiving and isolation system for aerospace application according to the present invention.
Fig. 2 is a frequency spectrum of a transmission center frequency of 2120MHz in the incoherent spread spectrum TT & C system of the present invention.
Fig. 3 is a frequency combination distribution diagram in the spreading frequency hopping TT & C long and short code operation mode of the present invention.
Fig. 4 is a schematic diagram of a modified front antenna feed network structure.
Fig. 5 is a schematic diagram of an improved antenna feed network structure.
Detailed Description
The technical personnel in the field can understand that, in order to meet the requirement that the normal operation of a receiving link is not affected when a transmitting link in an aerospace measurement and control system works, the signal needs to be considered from the generation of a baseband signal, and the signal passes through a power amplification process, a receiving and blocking filter, a duplexer, high-power signal transmission, space radiation, low-noise combination and the like to meet the receiving and transmitting isolation requirement that when a power amplifier is started at full power, the temperature increase of thermal noise in a receiving frequency band is less than 1K, and when the system works in an uplink mode, no interference signal is generated in the receiving frequency band.
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments (the power of the power amplifier at full power start-up is 400W in all cases).
An S-band measurement and control transmit-receive isolation system for aerospace application is shown in figure 1 and comprises a baseband module, a power amplifier, a receive-stop filter, a waveguide switch, a duplexer, an antenna feed source and a low-noise amplifier;
the base band module in the transmitting link is sequentially connected with a power amplifier, a receiving and blocking filter and a waveguide switch and is connected with an antenna feed source through a duplexer; after the baseband module generates baseband signals, the baseband signals are sequentially subjected to power amplification through a power amplifier and filtering through a receiving and blocking filter, then enter an antenna feed source through a waveguide switch and a duplexer, and are sent to a satellite through the antenna feed source;
the antenna feed source is connected with a receiving link through a duplexer and a low-noise amplifier; after receiving satellite downlink signals, the antenna feed source enters a receiving link after being subjected to duplexer and low-noise amplification.
With the development of the aerospace measurement and control system, the existing S system comprises multiple combined modes such as standard TT & C, incoherent spread spectrum TT & C, spread frequency hopping TT & C and the like.
The standard TT & C working bandwidth is very narrow, and the influence of the system on the receiving band in the standard TT & C mode mainly depends on the noise temperature generated by the power amplifier in the receiving band, the suppression degree of a receiving filter at the output end of the power amplifier and the suppression degree of an antenna duplexer on the receiving band.
While the incoherent spread spectrum TT & C has a working bandwidth of 20MHz, a BPSK modulation mode is adopted, the phase of a modulation signal is output mainly according to different modulation of input data, and the phases 0 and pi of the output modulation signal respectively represent 0 or 1 of a digital signal.
The time domain expression for BPSK is:
S BPSK (t)＝(∑ n a n g(t-nT S ))cos(ω c t) (1)
in the formula, a n Is a bipolar binary digit sequence with the value of positive 1 or negative 1,T S Is binary code element period, g (t) is impulse response function of the sending shaping filter of the base band, and generally has raised cosine characteristic; omega c Is the frequency of the modulated carrier.
That is, within a certain symbol duration Ts:
for spreading, let c (t) be the spreading code, in practical applications, the spreading code usually adopts dual polarity, i.e. c t = 1, +1, and thus the spread spectrum BPSK modulated signal can be expressed as being
Wherein,
is the initial phase of the modulated carrier, and if the considered information code is d (t), the BPSK modulation output of the direct sequence spread spectrum system is
According to the above analysis, an incoherent spread spectrum TT & C spectrum can be obtained, and those skilled in the art can understand that, since the transmission frequency of the current mainstream measurement and control system is 2025MHz to 2120.00MHz, and the reception frequency is 2200MHz to 2300MHz, the case where the transmit-receive isolation is the most serious, that is, the case where the transmission center frequency is 2120MHz, is considered here, as shown in fig. 2: the BPSK modulation spectrum theoretically occupies a wide signal bandwidth, while signal and side lobes may cause intermodulation signals to be generated (the carrier to noise signal amplitude ratio is 24.7dB at 7.5MHz offset from the carrier). Meanwhile, the actual signal generated by the baseband is tested. The ratio of the carrier to the noise signal amplitude is only 13.82dB when the measured result deviates from the carrier by 7.5 MHz. Therefore, in order to prevent the transmitting link from influencing the receiving link, the baseband generated signal is subjected to forming filtering, the high-order side lobe in the modulation power is eliminated, a high-quality baseband signal is generated, and the amplitude ratio of the carrier to the noise signal is 49.85dB when the processed baseband signal deviates from the carrier by 7.5 MHz.
And finally, spreading and hopping TT & C, which specifically comprises three working modes of a long code, a short code and a long and short code, wherein the long code and the short code are similar to the situation of incoherent spreading TT & C when working respectively. Under the long and short code working mode, two signals of long codes and short codes exist in an uplink working bandwidth at the same time, the condition that the transmitting double-tone combined frequency falls into a receiving band can occur, the receiving and transmitting intermodulation interference is caused, the receiving noise bottom is seriously interfered during the transmitting work, and the downlink normal work is influenced. Therefore, the following analysis is only performed for the long and short code operation mode.
Through frequency combination analysis and calculation, when two frequencies work simultaneously in the range of 2025MHz to 2120MHz, odd-order combined signals can be generated to fall into the receiving frequency range under a certain frequency relation. When considering two uplink signals, the frequency ranges of the third, fifth, and seventh order intermodulation signals of the two signals are shown in fig. 3: the third order intermodulation frequency range of the two transmitted signals covers a portion of the receive bandwidth (the receive low side), and the fifth and seventh order intermodulation covers the entire receive bandwidth. In order to prevent the influence of the transceiving intermodulation interference on the downlink normal work, the linearity design of the power amplifier is needed, and a high-order impedance filter is added at the transmitting end of the power amplifier.
The effect of power amplification on the receive chain is mainly reflected in two aspects: firstly, considering that the noise bottom is also raised in the signal amplification process, the noise temperature caused by the fact that the transmitting power falls in the receiver band is required to be not more than 1K when the transmitter outputs full power, namely the equivalent noise power spectral density of the signal is less than-228.6 dBW/Hz; secondly, it needs to be considered that after the combined interference signal generated on the transmitting link falls into the receiving frequency band, the spurious signal does not exceed the thermal noise level of the receiving link, and the efficiency is the highest when the solid-state power amplifier works in a saturated state, and the output power reaches the maximum.
Although the baseband can generate a high quality signal that meets mission requirements, when the power amplifier outputs a high power signal, the transmit power falling within the receiver band causes noise temperature variations; meanwhile, for the incoherent spread spectrum/spread frequency hopping TT & C mode, the signal bandwidth is wide, and the generation of an intermodulation signal is still caused.
According to the system requirement, when the transmitter outputs full power, the noise temperature caused by the transmission power falling in the receiver band is not more than 1K, and the noise temperature of the transmitter falling in the receiver band is less than-228.6 dBW/Hz, thus meeting the index requirement.
The solid-state power amplifier has the highest efficiency when working in a saturated state, and the output power reaches the maximum. For a GaN power tube, when the gain is compressed by 3dB in the S frequency band, the efficiency can reach more than 60%, and the linearity performance of a solid-state power amplifier can be seriously deteriorated due to the fact that the third-order intermodulation coefficient is not ideal. How to enable the solid-state power amplifier to work at high efficiency and have high linearity, the power amplifier linearity is generally improved by methods such as power back-off, predistortion technology, negative feedback, feedforward method and the like in engineering implementation. For S frequency band, the output power of single power tube can reach 200W, the invention adopts simple and reliable power back-off method to realize that the third-order intermodulation is-15 dBc when the power amplifier works with full power of 400W.
For the receiving-blocking filter, the main function is to suppress the receiving frequency band noise or intermodulation signal generated on the transmitting component, and ensure that the normal operation of the receiving link is not affected. By comprehensive consideration, the receiving and blocking filter in the transmitting component selects a cavity filter with low insertion loss, high suppression and high power capacity. And designed according to the following criteria.
In the signal transmission process, besides the interference generated by active intermodulation, passive intermodulation (hereinafter referred to as PIM) is also a non-negligible part. As will be appreciated by those skilled in the art, the passive intermodulation product level is related to the input power and order, with lower input power, higher intermodulation product order, and lower PIM level; conversely, the higher the PIM level. Compared with active intermodulation, the passive intermodulation product mainly has the following characteristics:
a) The passive intermodulation products cannot be filtered out by a filter.
b) The passive intermodulation products vary with time.
c) The passive intermodulation products have a threshold effect.
d) Passive intermodulation products exhibit unpredictability with respect to power level.
e) The passive intermodulation products may exhibit broadband noise characteristics.
In the microwave radio frequency link of the traditional aerospace measurement and control system, passive devices such as coaxial cables, waveguides, connectors, filters, duplexers, couplers and the like are reasonably designed. The influence generated by the passive intermodulation product is far smaller than the influence of the active intermodulation generated by the power amplifier. Therefore, the passive intermodulation generated from the power amplifier to the duplexer is negligible.
Therefore, the invention mainly solves the problem of passive interference of high-power signals in the transmission process of the S-band feed source network, and improves and designs the S-band feed source network.
The antenna feed network is composed of four parts, namely a loudspeaker, a connecting plate, a partition plate polarizer and a combined network, and the following description is provided for each improved part by combining fig. 4 and fig. 5:
the loudspeaker is connected with the partition plate polarizer through a connecting plate, and the combined network is positioned behind the partition plate polarizer; the diaphragm polarizer comprises a main body cavity and a matching block, the matching block is located below the main body cavity and clings to the side wall of the main body cavity, and a probe is arranged at the tail end of the matching block and used for being connected with a combined network.
The horn is formed by pasting carbon fiber materials on an aluminum flange in the traditional aerospace measurement and control system, and simultaneously comprises two materials, namely metal and nonmetal.
The connecting plate is used in the traditional aerospace measurement and control system, namely the connecting plate is used as a structural part and is used for connecting an electric part with a supporting sleeve; the rectangular cavity is used as an electric component, and the four rectangular cavities in the middle are also part of the electric component. When the connecting plate supports the feed source, the stress deformation possibly affects the electrical performance, so that the optimal design is carried out. The invention is modified in that the loudspeaker is directly connected with the baffle polarizer, and the connecting plate is independent from the electric device and only used as a structural member.
After the splicing welding of the main body cavity of the diaphragm polarizer in the conventional aerospace measurement and control system is completed, the matching block and the main body are tightly connected through two bolts, the contact area of the matching block and the main body cavity is large, the connection surface of the matching block can not be completely attached to the side wall of the main body, and the position of the matching block after the bolt connection can have large deviation with the theoretical position, so that the electrical performance is influenced. After the improvement, pin holes are firstly processed on the matching block and the main body cavity, and the two devices are firstly positioned by adopting pins, so that the matching block is ensured to be arranged on a correct theoretical position. Then the screw holes connected between the encryption matching block and the main body cavity are changed into six holes before improvement, so that the two contact surfaces are completely attached.
The initial thickness of the clapboard in the traditional aerospace measurement and control system is only 1mm, the material is rustproof soft aluminum, and the clapboard is too thin, so that the clapboard can be obviously deformed after welding is finished, thereby influencing the electrical performance. Therefore, the invention optimizes the sizes of the partition boards, thereby realizing that the thickness of the partition boards is changed into 5mm, and ensuring that the welded partition boards meet the index requirements.
The connection surface of the clapboard polarizer and the combined network adopts four bolts for connection in the traditional aerospace measurement and control system, so that the contact area is large, and whether two circular cavities in the center of the clapboard polarizer are tightly attached to the corresponding area of the combined network or not has great influence on electrical indexes, and only the connection of the four bolts cannot meet the requirement. After the improvement, 16 screws are added around the cavity for connection, so that the two circular cavities in the center of the separator polarizer are completely attached to the corresponding areas of the combined network, and the electrical performance is ensured.
The combined network consists of three outer conductors, and in the conventional space measurement and control system, the outer conductors are connected by two circles of screw holes, namely 20 bolts, only at the outermost edge and the inner edge. No screws are arranged near the inner cavity for pressing, so that no gap can be ensured between the upper layer cavity and the lower layer cavity after connection. After the improved structure is improved, M4 screws are arranged at the periphery of the inner cavity at intervals of 15mm and are connected in an arrangement mode through dense screws, so that no gap is formed between two contact surfaces.
For the duplexer, firstly, power resistance and low loss need to be ensured, and the duplexer adopted by the invention can meet the requirements of 1200W on power capacity and low loss. In terms of avoiding passive intermodulation: 1. from the electroplating point of view, in order to reduce passive intermodulation and reduce contact resistance, the thickness should be more than 6 μm, the plating layer should be free of impurities and passivated by chromate; 2. in the aspect of product structure design, impedance discontinuity is avoided as much as possible, consistent characteristic impedance is kept as much as possible, and nonlinear factors are reduced; 3. materials with high conductivity, such as copper and alloys, are selected, and stainless steel or other materials containing magnetism are avoided.
Through the design and the combination of the past engineering experience, the passive intermodulation can be ensured to have no influence on a receiving link in the process of high-power signal transmission.
The signal enters the receiving link after being transmitted, the S frequency band receiving link works in 2200.00 MHz-2300 MHz, the rejection of the transmitting-blocking filter of the antenna S frequency band duplexer to the transmitting frequency band signal is better than 90dB, the polarization isolation is 0dB, the transmitting maximum power is 400W (+ 56 dBm), so the level of the high-power transmitting signal falling to the entrance of the S frequency band receiving system (field discharge) is as follows:
+56dBm-90dB＝-34dBm；
in order to avoid the saturation of the field amplifier caused by a high-power transmitting signal, a transmit-stop filter is added in the S-band field amplifier (interstage), the transmit frequency is suppressed to 30dB, the P-1dB of the S-band field amplifier used by a receiving system is larger than +5dBm, and the gain is 60dB. The frequency-emitting signal level output by the field amplifier is as follows:
-34dBm-30dB +60dB = 4dBm, and the field discharge is not saturated when being lower than P-1 dB.
Index decomposition:
the antenna feeding subsystem provides (S frequency band) transmitting and receiving isolation: LTR-T is more than or equal to 90dB.
The S frequency band field is placed at 2025MHz-2120MHz to provide frequency transmission suppression: is more than or equal to 30dB.
According to the above analysis, it is summarized that the influence of the system working in uplink on the receiving band mainly includes four aspects
1) The power amplifier generates noise temperature in a receiving band;
2) The rejection degree of a stop-and-go filter at the output end of the power amplifier;
3) The degree of suppression of the antenna duplexer in a receiving band;
4) The intermodulation signal generated by the power amplifier uplink working signal falls into the clutter in the receiving band.
The following accounting and analysis are performed according to the working mode of the system in three cases:
firstly, the standard TT & C working bandwidth is very narrow, and the influence of the system on the receiving band in the standard TT & C mode mainly depends on the noise temperature generated by the power amplifier in the receiving band, the suppression degree of the receiving-blocking filter at the output end of the power amplifier, and the suppression degree of the antenna duplexer on the receiving band.
The system requires that when the transmitter outputs full power, the noise temperature caused by the transmission power falling in the receiver band is not more than 1K, and if the original receiving in-band noise temperature is T, the spectral density of the received in-band noise after 1K deterioration is as follows:
Φ(dBW/Hz)＝k(T+ΔT)＝kT+kΔT＝kT+228.6dBW/Hz；(ΔT＝1K)
where k is the boltzmann constant, so that the noise temperature of the transmitter falling within the receive band is less than
Namely, the noise temperature caused by falling in the receiver band when the transmitting power is not more than 1K.
The output noise power spectrum of the transmitting power amplifier is set to be phi out (dBW/Hz), and the isolation I of the duplexer TR (dB), the isolation of the stop-and-forward filter is I R (dB), then I TR And I R The following formula must be satisfied:
then it is possible to obtain:
when the power amplifier works at 400W, the noise power spectral density in a 2200 MHz-2300 MHz receiving frequency band is-120 dBW/Hz. And calculating according to the required-228.6 dBW/Hz, the suppression degree required when the noise of the receiving frequency band output by the power amplifier reaches the input end of the field amplifier is as follows:
then it can be obtained according to equation (7):
taking a certain margin into consideration during system design, and taking (I) TR +I R )≥120dB。
By reasonably distributing indexes to the receiving and blocking filter and the antenna duplexer, the noise power falling in a 2200 MHz-2300 MHz receiving frequency band does not influence the noise temperature of an S-band receiving link when the S-band power amplifier outputs 400W.
Secondly, the working bandwidth of the incoherent spread spectrum TT & C is 20MHz, and the influence of the system on a receiving band in the incoherent spread spectrum TT & C mode mainly depends on the noise temperature generated by the power amplifier in the receiving band, the suppression degree of a receiving filter at the output end of the power amplifier and the suppression degree of an antenna duplexer on the receiving band.
The system requires that when the transmitter outputs full power, the noise temperature caused by the transmission power falling in the receiver band is not more than 1K, and assuming that the original receiving in-band noise temperature is T, the spectral density of the receiving in-band noise after 1K deterioration is:
Φ(dBW/Hz)＝k(T+ΔT)＝kT+kΔT＝kT+228.6dBW/Hz；(ΔT＝1K)
therefore, the noise temperature caused by the fact that the noise temperature falling into the receiving band when the transmitter falls into the receiving band is less than-228.6 dBW/Hz, namely the noise temperature falling into the receiving band when the transmitting power is not more than 1K.
When the power amplifier works at the full power of 400W, because the incoherent spread spectrum bandwidth is wide, the power amplifier can generate a certain intermodulation extension interference signal out of the working frequency band due to the inherent nonlinear characteristic, when the system works at the high end 2120MHz, the influence of the extension interference signal in the receiving band is the largest, at the moment, the noise power spectral density in the receiving frequency band of 2200 MHz-2300 MHz is-100 dBW/Hz, the calculation is carried out according to the required-228.6 dBW/Hz, and the required suppression degree is that when the noise of the receiving frequency band output by the power amplifier reaches the field amplifier input end according to the formula (7):
taking a certain margin into consideration during system design, and taking (I) TR +I R )≥140dB。
By reasonably distributing indexes to the receiving and blocking filter and the antenna duplexer, the noise power falling in a 2200 MHz-2300 MHz receiving frequency band does not influence the noise temperature of an S-band receiving link when the S-band power amplifier outputs 400W.
Thirdly, the spread frequency hopping TT & C is divided into three working modes of long codes, short codes and long and short codes. In the long and short code working mode, two signals, namely, a long code and a short code, exist in an uplink working bandwidth at the same time, the interference generated in a receiving band is the largest, and only the long and short code working mode is analyzed. The influence of the system on the receiving band in the frequency spreading and hopping TT & C mode mainly depends on clutter of an intermodulation signal generated by an uplink working signal of the power amplifier falling into the receiving band, the suppression degree of a rejection filter at the output end of the power amplifier and the suppression degree of an antenna duplexer on the receiving band.
When the power amplifier works at the full power of 400W, because long code signals and short code signals exist in the power amplifier band at the same time, the two signals can generate intermodulation signals out of the working frequency band due to the nonlinear characteristic, when the two signals work at the upper high end 2120MHz and the upper low end 2030MHz respectively, the intermodulation signals 2210MHz of the power amplifier fall into the receiving band, and the influence on the receiving band is the largest at the moment. Setting the output power of transmitting power amplifier as Pout (dBm), three-order intermodulation suppression L3rd (dBc) of power amplifier and the isolation I between transmitting and receiving antennas TR (dB), the isolation of the stop-and-forward filter is I R (dB), then I TR And I R The following formula must be satisfied:
Pout-L 3rd -(I TR +I R )≤J 0 (8)
it is thus possible to obtain:
(I TR +I R )≥Pout-L 3rd -J 0 (9)
according to the above introduction, when the power amplifier is working at full power, the third order intermodulation is-15 dBc, and the noise power falling into the receiving band is:
Pout-L 3rd ＝53dBm-15dB＝38dBm＝8dBW
the spread spectrum rate of the direct sequence of the spread and frequency hopping is 10M, the modulation mode is BPSK modulation, and the average power spectral density falling into a receiving band after conversion is as follows:
Φ(dBW/Hz)＝Pout-10log(20MHz)＝8dBW-73dB＝-65dBW/Hz；
calculated according to the required-228.6 dBW/Hz, the suppression degree required when the noise of the receiving frequency band output by the power amplifier reaches the input end of the field amplifier according to the formula (9) is as follows
(I TR +I R )≥Pout-L 3rd -J 0 ＝-65--228.6＝163.6dB
I.e. requires work in the S frequency bandAfter the amplifying-receiving resistance filter and the antenna-fed S-band duplexer are cascaded, the minimum degree of signal suppression in a receiving band is 163.6dB, and according to the distribution of frequency spreading and hopping power spectrum density and actual engineering experience, a certain margin is required to be considered during system design, and (I) is obtained TR +I R )≥220dB。
Through reasonably distributing indexes to the receiving and blocking filter and the antenna duplexer, the noise power falling in a 2200 MHz-2300 MHz receiving frequency band does not influence the noise temperature of an S-band receiving link when the S-band power amplifier outputs 400W.
By integrating the analysis of the three working modes, the influence of uplink transmission on receiving is the largest under the working modes of the frequency spreading and hopping TT & C, so that the S-band receiving and transmitting isolation requirements for aerospace application can be realized by designing according to the frequency spreading and hopping mode during system design.
The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present invention, and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. An S-band measurement and control transceiving isolation system for aerospace application is characterized by comprising a baseband module, a power amplifier, a resistance receiving filter, a waveguide switch, a duplexer, an antenna feed source and a low-noise amplifier;
a baseband module in a transmitting link is sequentially connected with a power amplifier, a stop filter and a waveguide switch and is connected with an antenna feed source through a duplexer; after the baseband module generates baseband signals, the baseband signals are subjected to power amplification and filtering by a receiving and blocking filter in sequence through a power amplifier, enter an antenna feed source through a waveguide switch and a duplexer and are sent to a satellite through the antenna feed source;
the antenna feed source is connected with a receiving link through a duplexer and a low-noise amplifier; after receiving satellite downlink signals, the antenna feed source enters a receiving link after being subjected to duplexer and low-noise amplification.
2. The space application-oriented S-band measurement, control, transceiving and isolation system according to claim 1, wherein the power amplifier adopts a power backoff method to achieve-15 dBc of third-order intermodulation when the power amplifier works at full power of 400W.
3. The space application-oriented S-band measurement, control, transceiving and isolating system according to claim 1, wherein the isolation degree adopted by the transceiving filter is 110dB, and the isolation degree adopted by the duplexer is 110dB.
4. The space application-oriented S-band measurement, control, transceiving and isolation system according to claim 1, wherein the antenna feed comprises a horn, a connecting plate, a diaphragm polarizer and a combined network, the horn is connected with the diaphragm polarizer through the connecting plate, and the combined network is located behind the diaphragm polarizer; the diaphragm polarizer comprises a main body cavity and a matching block, the matching block is located below the main body cavity and clings to the side wall of the main body cavity, and a probe is arranged at the tail end of the matching block and used for being connected with a combined network.
5. The S-band measurement, control, transceiving and isolating system for aerospace application according to claim 4, wherein the horn is formed by one-time tailor welding of a full-rust-proof aluminum plate; the matching block and the main body cavity are provided with a pin hole and a screw hole, and the two devices are positioned by pins and screws; the baffle polarizer is connected with the combined network connecting surface by adding screws around the cavity; the combined network consists of three outer conductors and is connected between the outer conductors at the outermost edge and at the inner edge by a dense screw arrangement.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211107593.2A CN115955256A (en) | 2022-09-13 | 2022-09-13 | S-frequency-band measurement, control, transmission and isolation system for aerospace application |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211107593.2A CN115955256A (en) | 2022-09-13 | 2022-09-13 | S-frequency-band measurement, control, transmission and isolation system for aerospace application |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115955256A true CN115955256A (en) | 2023-04-11 |
Family
ID=87281618
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211107593.2A Pending CN115955256A (en) | 2022-09-13 | 2022-09-13 | S-frequency-band measurement, control, transmission and isolation system for aerospace application |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115955256A (en) |
-
2022
- 2022-09-13 CN CN202211107593.2A patent/CN115955256A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110429952B (en) | Ku wave band comprehensive radio frequency receiving and transmitting system | |
| US6745003B1 (en) | Adaptive cancellation for wireless repeaters | |
| CN107888273A (en) | A kind of link terminal radio-frequency channel | |
| CN110661536A (en) | Satellite half-duplex VDES system multi-channel radio frequency transceiver | |
| Li et al. | Design and implementation of an active array antenna with remote controllable radiation patterns for mobile communications | |
| CN109274617A (en) | Simultaneous same-frequency full-duplex measurement and control transponder | |
| CN103281114A (en) | Device and method for processing signals of pico-satellite transmitters | |
| Miao et al. | Digital cancellation scheme and hardware implementation for high-order passive intermodulation interference based on Hammerstein model | |
| CN115955256A (en) | S-frequency-band measurement, control, transmission and isolation system for aerospace application | |
| CN102624438B (en) | Satellite data collecting and receiving machine | |
| EP1782544B1 (en) | High power parallel block-up converter | |
| CN217985067U (en) | S-frequency-band measurement, control, transmission and isolation system for aerospace application | |
| US20200177216A1 (en) | Fully integrated radio frequency terminal system | |
| Zhang et al. | Study on waveform characteristic for simultaneous transmit and receive used in multifunction phased array | |
| CN112187182B (en) | Space-borne X-frequency-band miniaturized high-order frequency doubling device | |
| EP3472939B1 (en) | A wireless communication network node arranged for reduction of passive intermodulation | |
| Zhu et al. | A Ka-band transceiver front-end module for wide band wireless communication | |
| CN210129863U (en) | Multifunctional X-band transceiving component | |
| CN112332873B (en) | Broadband power division filtering component | |
| CN214069926U (en) | L-band communication simulator receiving link | |
| US20240213684A1 (en) | Ultra-wideband, low-distortion, omni-directional, and placement-insensitive antennas | |
| Nachouane et al. | Over-the-air investigation of transmitter and receiver nonlinear distortion using a mm-wave MIMO testbed | |
| JP3558260B2 (en) | High-sensitivity base station radio equipment | |
| Liu et al. | Application of X-band High Isolation Phased Array Payload in Satellite Data Transmission Communication | |
| Li et al. | Design of Low-Cost Vector Modulator for Ku-band Phased Array Transceiver Module |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |