CN210007695U - Ku waveband integrated radio frequency transceiving system - Google Patents
Ku waveband integrated radio frequency transceiving system Download PDFInfo
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- CN210007695U CN210007695U CN201920829767.3U CN201920829767U CN210007695U CN 210007695 U CN210007695 U CN 210007695U CN 201920829767 U CN201920829767 U CN 201920829767U CN 210007695 U CN210007695 U CN 210007695U
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Abstract
The utility model provides an kind of Ku wave band synthesis radio frequency transceiver system, including antenna, radio frequency receiver, radio frequency transmitter, frequency source, the antenna carry out the duplexer of keeping apart through the radio frequency signal to transmission and receipt and link to each other with radio frequency receiver and radio frequency transmitter respectively, radio frequency transmitter include the up-converter, the up-converter including with intermediate frequency signal for central frequency 280HMz bandwidth 40 MHz's modulating signal up-conversion improve the frequency to the level up-conversion mixer of L wave band and with the modulating signal up-conversion of L wave band improve the frequency to Ku wave band second level up-conversion mixer, radio frequency receiver include the down converter, the down converter include with the radio frequency signal of received Ku wave band down-convert to the modulating signal's of L wave band level down-conversion mixer and with the modulating signal down-convert to the second level down-conversion mixer of 200MHz intermediate frequency output of L wave band the Ku synthesis radio frequency transceiver system have the advantage of Ku frequency channel communication transmission.
Description
Technical Field
The utility model relates to a radio frequency receiving and dispatching system field, especially kinds of Ku wave band integrated radio frequency receiving and dispatching system.
Background
The radar system and communication system have developed independently in their own fields, and with the advance of technology and the upgrading of military electronic system, the radar and communication system have new requirements of hardware and software compatibility, and the radar and communication system have basically the same hardware structure and realize their functions via the transmission and receiving process of electromagnetic wave.
With the development of microelectronic integration technologies such as modern radio frequency chips and digital processing chips and the improvement of software engineering technologies, a multifunctional radio frequency system hardware platform based on a comprehensive radio frequency front end, a shared antenna, a transmitting system and a receiving system are partially or completely, and different functions such as radar and communication are realized through software programming dynamic configuration, so that the engineering implementation feasibility is achieved. The modern comprehensive radio frequency system has the characteristics of frequency hopping and frequency spreading functions, interference resistance, high data rate, high information safety, compact size and weight of terminal equipment and the like. The united states and the united nations of the north america and israel have developed a plurality of frequency band integrated radio frequency systems successively, work in C, X, Ku and other frequency bands, and have the functions of point-to-point line-of-sight data transmission, relay transmission, satellite communication, radar detection and the like.
The system has an advanced digital design scheme, combines low-cost civil devices and high-precision structural design, adopts an anti-interference communication system, adopts high-compression ratio image compression, has dynamic color image transmission capability, adopts a low-power consumption design, adopts a high-density printed board distribution technology to reduce the overall volume weight, adopts a light omnidirectional antenna design to meet the technical requirements of an unmanned aerial vehicle comprehensive radio frequency system, can completely replace similar products outside China, documents [ 2 ] including Wang Menu Kong Queen, Mitsugaku, Mitsu, et, Mitsu, et, Mitsu, et, Mitsukusan, et, Mitsu, Mitsukusan, et, Mitsukusan, et, Mitsu, et, Mitsukusan, et, Mitsu, et, Mitsukuan, et, Mitsui, et, Mitsu, et, Mitsui, et, Mitsui, et, Mitsui, et, Mitsui, et, Mitsui, et, Mitsui, et, Mitsui, et, Mitsui, et al, et al, et al, all of the technical systems, all of the same products, all of the technical systems, all include the technical systems, all of the same products, all of which have the technical systems, all the technical systems, all include the technical systems, all include the technical.
The basic communication system provides services for two places to communicate, and the two places are both provided with radio frequency transceiving components with the same or similar functions, for example, an aircraft data chain system comprises two parts of a pod data transmission system and a ground data transmission system, a downlink (pod- > ground) mainly transmits high-definition video signals and other related data, and an uplink (ground- > pod) mainly transmits data such as remote control commands of the ground, as shown in fig. 1.
The complete communication system (i.e. the airborne or ground equipment in fig. 1) comprises four parts, namely an antenna, a servo mechanism, a radio frequency transceiver and a signal processing module, wherein the ground antenna is a high-gain directional antenna and is used for data transmission, a tracking antenna is used for rough airplane positioning, the airborne antenna is a medium-gain directional antenna, the radio frequency transceiver is used for transmitting and receiving high-frequency microwave signals, the servo mechanism, the antenna and the signal processing module form closed-loop control and aim at the antenna in real time, the signal processing module is used for receiving and transmitting instructions, receiving and transmitting video data, controlling servo work and the like, the comprehensive radio frequency transceiver component is a core component of a communication and radar system, and the advanced comprehensive radio frequency system integrates high and new technologies such as a radio frequency front end comprehensive design technology, a modular design, a channelized design, a high-power broadband device technology, a micro system technology, a micro-electromechanical system technology and the like.
The radio frequency transceiving components used in in the prior art are mainly used for radio frequency hardware systems developed by single functions, and are difficult to realize transverse function expansion, while the radio frequency comprehensive degree of the existing comprehensive radio frequency system is not high, the hardware reuse degree is low, and in addition, the flexible configuration degree of a frequency source is low, so that the radio frequency transceiving components are difficult to adapt to the use of multi-waveform, multi-modulation and broadband radio frequency systems.
This is due to:
in the early radio frequency development, because the microwave device function is single , a radio frequency hardware system with single function is easy to realize, if a multifunctional integrated system is to be realized, a plurality of sets of subsystems are bound to be stacked, the development complexity and cost are improved, and the reliability of a product is reduced.
The radio frequency comprehensive degree of the existing comprehensive radio frequency system is not high, only slight expansion is carried out on the basis of a main functional module, an additional certain auxiliary function is realized, and actually the hardware reuse degree is still low.
The traditional microwave frequency source is only designed for a single -function radio frequency module, is low in flexible configuration degree, and has the problems of single waveform , no modulation function, insufficient frequency hopping bandwidth and the like.
SUMMERY OF THE UTILITY MODEL
The utility model discloses to the above-mentioned not enough of present radio frequency receiving and dispatching subassembly, provide kinds of Ku wave band integrated radio frequency receiving and dispatching systems realize following technical purpose:
1. the broadband radio frequency transceiving system with the Ku wave band covering the 2.5GHz bandwidth has the advantages of high receiving sensitivity, high dynamic range, high power output and the like.
2. The radio frequency link adopts a two-stage frequency conversion mode, local oscillators and two local oscillators both adopt broadband agile frequency hopping frequency sources, and the radio frequency channel adopts a multi-channel mode, so that a proper working bandwidth can be conveniently selected according to specific functions.
3. The frequency source adopts a DDS (direct digital synthesizer) matched multi-phase-locked loop mode, the frequency can be flexibly configured, the multi-waveform and multi-modulation functions can be realized, and a multi-phase-locked loop architecture is used for realizing a broadband radio frequency source
The utility model discloses a technical scheme that realizes that its technical purpose adopts is kind Ku wave band synthesis radio frequency transceiver system, including antenna, radio frequency receiver, radio frequency transmitter, frequency source, the antenna carry out the duplexer of keeping apart with the radio frequency signal of receiving through the transmission and link to each other with radio frequency receiver and radio frequency transmitter respectively, the radio frequency transmitter include the up-converter, the up-converter include with intermediate frequency signal for central frequency 280HMz bandwidth 40 MHz's modulated signal up-conversion improve the frequency to the level up-conversion mixer of L wave band and with the modulated signal up-conversion of L wave band improve the frequency to Ku wave band second level up-conversion mixer, the radio frequency receiver include the down converter, the down converter include with the radio frequency signal of received Ku wave band down convert to the second level down conversion mixer of the modulated signal of L wave band level down-conversion mixer of the modulated signal of L wave band to the 200MHz intermediate frequency output.
The utility model discloses a radio frequency receiving and dispatching system is synthesized to Ku wave band has Ku frequency channel communication transmission's advantage.
, in the Ku band integrated radio frequency transceiving system, the intermediate frequency signal processing device of the radio frequency transmitter comprises a transmitting VGA amplifier, a surface acoustic wave filter and a intermediate frequency LC filter, and an intermediate frequency signal with the central frequency of 280HMz and the bandwidth of 40MHz is amplified by the transmitting VGA amplifier, filtered by the surface acoustic wave filter and the intermediate frequency LC filter in sequence and then connected to the intermediate frequency signal input end of the th level up-conversion mixer of the up-converter.
, in the Ku band integrated RF transceiver system, the RF signal processing device of the RF transmitter includes a driving amplifier, an RF cavity filter, a power amplifier and a waveguide isolator, and the RF signal of Ku band output by the up-converter passes through the driving amplifier, the RF cavity filter, the power amplifier and the waveguide isolator in turn and is transmitted by the antenna.
, in the Ku band integrated RF transceiver system, the power amplifier of the RF transmitter is realized by cascade connection of three stages of amplifiers, TGA2514-FL, TGI1314-25L and TGI1414-50, and the power amplifier further comprises a heat sink which adopts a fin heat dissipation structure and adopts fan forced air cooling.
, in the Ku band integrated RF transceiver system, the IF signal processing unit of the RF receiver includes a LC filter, a second SAW filter, a receive AGC amplifier, and a second LC filter, wherein the output of the second down-conversion mixer of the down-converter is filtered by the LC filter and the second SAW filter, amplified by the receive AGC amplifier, and filtered by the second LC filter to output an IF signal of 200 MHz.
, in the Ku band integrated RF transceiver system, the frequency synthesizer generating local oscillation signals for the up-converter and the down-converter includes four independent phase-locked loops with 100MHz crystal oscillation frequencies of 4.25GHz, 4.55GHz, 4.85GHz and 5.15GHz respectively, and digital frequency synthesizers with 0.5-0.85GHz, wherein the frequency ranges generated by the digital frequency synthesizers and the independent phase-locked loops respectively are frequency sources with 4.75-5.1 GHz, 5.05-5.4 GHz, 5.35-5.7 GHz and 5.65-6 GHz.
The present invention will be described with reference to the accompanying drawings and the following detailed description in which the invention proceeds to step .
Drawings
FIG. 1 is an aircraft data link system.
Fig. 2 is the schematic block diagram of the Ku-band integrated radio frequency transceiving system of the present invention.
Fig. 3 is a schematic diagram of the generation of the DDS reference clock used in the present invention.
Figure 4 is the utility model discloses use two local oscillator design sketch maps.
Detailed Description
Embodiment 1, this embodiment is a Ku-band integrated radio frequency transceiving system, and is suitable for an unmanned aerial vehicle and ground to perform bidirectional communication, as shown in fig. 2, including an antenna 1, a radio frequency receiver, a radio frequency transmitter, and a frequency source; the antenna 1 is connected to a radio frequency receiver and a radio frequency transmitter, respectively, through a duplexer 2 for isolating the transmitted and received radio frequency signals.
Actually, there are two kinds of antennas 1, kinds of antennas are airborne antennas on the unmanned aerial vehicle, and another kinds of antennas are ground antennas of ground equipment, and the specific indexes are as follows:
an airborne antenna: frequency: 12-14.5 GHz, gain: 20dBi, axial ratio: less than or equal to 3dB, port standing wave: less than or equal to 1.5.
A ground antenna: frequency: 12-14.5 GHz, gain: 39dBi, axial ratio: less than or equal to 3dB, feeder loss: less than 2dB, standing wave: less than 1.5
The indexes of the radio frequency receiver, the radio frequency transmitter and the frequency source are respectively as follows:
a transmitter: radio frequency: 12 GHz-14.5 GHz; input frequency: 280 MHz; output power: not less than 43 dBm; input power: -10 ± 1 dBm; gain adjustment range: 30dB (0.5dB step adjustable); third-order intermodulation: -18dBc @43dBm (when the sum of the two-tone powers is 43 dBm); signal 3dB bandwidth: not less than 50 MHz; harmonic suppression: not less than 30 dBc; noise coefficient: less than or equal to 12 dB.
A receiver: input frequency: 12 GHz-14.5 GHz; input power: -110dBm to-10 dBm; output frequency: 200 MHz; noise: less than or equal to 4 dB; output power: -10dBm ± 0.5 dBm; third order intermodulation: no more than-40 dBc @10 dBm; signal 3dB bandwidth: the frequency of 50MHz/10MHz/1MHz/100kHz is adjustable; harmonic suppression: more than or equal to 65 dBc.
Frequency source requirements: in-band spurious suppression: not less than 60dBc, port standing wave: less than or equal to 1.5, frequency stability: better than ± 1 × 10-7, phase noise: less than or equal to 1KHz and less than or equal to-90 dBc/Hz, less than or equal to 10KHz and less than or equal to-100 dBc/Hz, and less than or equal to 100KHz and less than or equal to-100 dBc/Hz.
At present, most of civil wireless video transmission systems carry out data transmission based on technologies such as Bluetooth and WiFi, so the frequency is selected in two frequency bands of 2.4GHz and 5.8GHz, but as the frequency spectrum of the frequency band tends to be saturated, information transmission is difficult to obtain larger bandwidth, and the frequency band is easy to interfere and intercept, and the problems of poor multipath resistance and the like, the civil wireless video transmission systems are not suitable for military application. Therefore, the development trend of military video transmission is to gradually eliminate the S and C bands and develop the military video transmission to the high frequency band above X, for example, the video transmission band of military unmanned aerial vehicles in the united states is shifted from the C band to the Ku and Ka bands. Therefore, the video transmission system of the embodiment adopts the Ku waveband based on the technical research and development of high starting points and the requirements of future domestic unmanned planes.
Ku band communication transmission has the following advantages:
the information transmission bandwidth is large, the working bandwidth of 500 MHz-1 GHz is easy to obtain, and the video information is easy to transmit by using a spread spectrum working mode. This is difficult to achieve in the S-band and C-band.
Radio frequency systems, particularly antennas, are reduced by a factor of 6 in size and a corresponding hundred times in weight (relative to the S-band), and small and lightweight communication devices are important for drone systems with critical payload requirements.
In order to ensure S, C and Ku band common-view transmission, the radius of the Fresnel zone is 45m, 29m and 18m respectively at the transmission distance of 200km, so that the shielding with the same height has small influence on Ku band signals.
The anti-interference performance is good. The broadband transmission has strong capacity of resisting human broadband interference, narrow-band aiming interference and relay forwarding interference, is favorable for electronic anti-reactance, and is suitable for application in military communication systems. Compared with the conventional communication system, the direct sequence spread spectrum system, the frequency hopping spread spectrum system, the direct sequence-frequency hopping mixed spread spectrum system, the direct sequence-time hopping mixed spread spectrum system and the like are insensitive to the multipath interference, and if the technologies or measures such as adaptive cancellation, adaptive antenna, adaptive filtering and the like are adopted, the multipath interference can be eliminated. The broadband system also has very high processing gain, can inhibit input interference signals while enhancing signals, and has strong anti-interference capability.
The selective addressing capability is strong, and can be used for forming multi-address communication network by means of code division multiple access, all the receivers and transmitters in the multi-address communication network can be simultaneously used for working with identical frequency, and any transmitter in the network can be associated with the receiver using correspondent spread spectrum code by selecting different spread spectrum codes.
The security performance is good, and the information is concealed to prevent interception. Because the spread spectrum communication system uses a pseudo-random code with a long code period, the modulated digital information is similar to random noise, and an enemy cannot easily find and identify the signal. The power of the spread spectrum signal is distributed in a wide frequency range uniformly, so the power spectrum density of the transmitted signal is low, and the reconnaissance receiver is difficult to detect, so that the system has low interception probability, and the confidentiality of the system is improved.
The spectrum density is low, and the interference to other communication systems is small. In the case of the same output signal power, since the spread spectrum signal expands the frequency band, the power (energy) of the output signal in the unit frequency band is reduced, thereby reducing the flux density of the electric wave of the system in the unit frequency band. The spectrum density is low, and interference to other communication systems can not be caused.
The Ku band is compatible with satellite communications, and can transmit signals directly to a satellite when line-of-sight transmission is not possible, without the need for an additional satellite communication system.
The Ku frequency band is selected in the embodiment, the technology of devices at home and abroad in the frequency band is mature and reliable, the sizes of the antenna and the radio frequency module can be smaller, airborne application is facilitated, available bandwidth resources are wider, and the method is more suitable for transmission of broadband signals such as video, high-definition images and other information. The ground antenna and the airborne antenna both adopt circular polarized antennas with higher gain, so that the anti-interference and high-data-rate reliable transmission can be realized. According to the fries transmission equation, the channel attenuation is:
wherein R is the transmission distance and mu is the atmospheric attenuation coefficient. In the Ku band (14GHz, atmospheric attenuation 0.05dB/km), the link loss at 200km was calculated by equation (1) to be 172 dB. Assuming that the noise figure of the radio frequency receiver is 4dB, and the bandwidths are respectively 40MHz, 10MHz, 1MHz and 100kHz, the sensitivity of the receiver is-94 dBm, -100dBm, -110dBm and-120 dBm. Considering the 2dB and 1dB polarization loss of feeder line loss, and ensuring the error rate of a receiver and necessary system margin, the signal-to-noise ratio of 18dB needs to be reserved, and the sum of the transmitting power of a transmitter and the gain of a transmitting-receiving antenna is required to be more than 99 dB.
Therefore, the transmitter power and the gains of the transmitting and receiving antennas are reasonably distributed, the transmitter power is about 40dBm, the gain of the transmitting antenna (airborne) is about 21dB, and the gain of the receiving antenna (ground station) is about 38 dB. If the airborne antenna adopts an omnidirectional antenna (the gain is about 0dB), the transmitting power needs to be increased by 100 times or the caliber of the ground antenna needs to be increased by 100 times, and the power consumption and the size increase caused by the two solutions are intolerable. The 38dB ground dish antenna diameter is about 1.2m and the 21dB airborne antenna diameter is about 150 mm. When the omnidirectional antenna is matched with the airborne antenna, the data can be provided for independent data receiving units within the range of 20km (1/10 of the maximum working distance).
The integrated radio frequency system in the embodiment comprises 5 parts, namely a high-gain directional monopulse servo tracking antenna, an airborne antenna, a radio frequency receiver, a radio frequency transmitter and a frequency source. In the Ku frequency band, the output power of a tail end power amplifier of the airborne transmitter is not easy to be too large in consideration of power supply, size, heat dissipation and performance, and the selection is more suitable about 20W. The airborne antenna is not suitable for selecting a high-gain strong-directivity antenna, because the high-performance stable tracking servo system required by the strong-directivity antenna can obviously increase the volume and weight of the system, and therefore the airborne antenna can be selected to be an omnidirectional antenna or a small-size medium-gain wide-beam directional antenna. The system design margin is based on the omnidirectional antenna, and the gain of the omnidirectional antenna covered by the hemisphere is not less than 0 dBi. The system performance can be better (better interference resistance or higher communication data rate) by reloading the directional antenna, the ground system selects a high-gain antenna with a tracking servo system, and the transmitting power is also selected to be 20W.
Accordingly, the performance parameters of the front end of the system are determined as follows:
(1) working frequency band: ku band, 12-14.5 GHz;
(2) an airborne transceiver: the transmission power is 20W;
(3) a ground transceiver: the transmission power is 20W;
(4) an airborne antenna: a ring beam hemisphere covering antenna (antenna gain >0dBi, and selectable polarization mode);
(5) a ground antenna: directional tracking antenna (gain >39idBi, selectable polarization mode) with half power beam coverage of 2 degree x 2 degree.
The radio frequency transceiving component part consists of a receiver module, a transmitter module, a frequency synthesizer module, an interface module and a BIT fault detection module. The radio frequency part completes the functions of transmitting and receiving radio frequency signals. The main functions include: receiver front-end and band-limiting filters, radio frequency signal generation, mixing, frequency synthesis, automatic gain control, frequency tuning, transmit-receive conversion, etc. The interface with the antenna portion includes: radio frequency input signal, radio frequency output signal, external device interface. The interface to the digital part includes: outputting an intermediate frequency receiving signal, an intermediate frequency transmitting signal, a timing signal and a radio frequency reference signal; in addition, there are state controls, clock and reference frequency inputs, etc. By dividing the components, the internal components of each component comprise:
the radio frequency receiving channel mainly comprises a power detection circuit, a filter, an amplitude limiting circuit, a low noise amplifier, a down converter, a driving amplifier, an AGC and the like.
The radio frequency receiving channel is mainly composed of a power detection circuit, a standing wave protection circuit, a filter, an up-converter, a numerical control attenuator, a driving amplifier and a power amplifier.
The frequency synthesizer unit mainly comprises a constant temperature crystal oscillator circuit, a phase-locked loop circuit, a DDS functional chip and a control circuit, outputs -level and two-level local oscillator signals and supplies an external reference clock.
And the interface circuit is used for instruction receiving control and data reporting.
And the BIT detection unit has the functions of protecting power detection, temperature detection and the like.
The gain requirement of the transmitter is adjustable between 50dB and 70dB, as shown in FIG. 2, so 3-level driving is required. In order to prevent the instability of the system caused by high gain, the shielding of the structure and the front-back isolation of the signal channel are fully considered in the overall design. The airborne transmitter requires that the power output reaches 43dBm after the isolator and requires that the third order intermodulation is better than-18 dBc. In order to ensure the final output power and the third-order intermodulation index, the final-stage power amplifier is realized by adopting a 50W power amplifier tube working in a linear region. When the transmitter works at full power, 150W of heat power is expected to be output, and the transmitter needs to be effectively radiated to ensure the safety of a system. In addition, the power tube can generate 3dB gain change at ambient temperature, so that the grid voltage of the power tube must be compensated to overcome the temperature influence, meanwhile, a temperature monitoring and protecting circuit is added to avoid the chip from being burnt due to overhigh temperature, a temperature compensation attenuator can be inserted between circuit amplification stages, and the temperature stability of the transmitter is improved.
After the intermediate frequency of the up-conversion component is mixed, most local oscillator signals and image frequencies fall in the pass band, so that the problems of local oscillator leakage and image frequency interference need to be solved, the IQ up-converter adopting high local oscillator isolation can well inhibit the image frequency and the local oscillator, and the local oscillator leakage and the image frequency interference are further inhibited by steps by utilizing an adjustable band-pass filter.
The transmission link is shown in a schematic block diagram in fig. 2 (including a receiving link), an intermediate frequency signal is a modulation signal with a central frequency of 280HMz and a bandwidth of 40MHz, the frequency is increased to a Ku waveband through two-stage up-conversion, a multistage amplifier is adopted in the link to ensure system gain, meanwhile, -stage vga is added for expanding the dynamic range of the intermediate frequency signal, an IQ frequency converter with high local oscillation isolation is adopted for inhibiting local oscillation and image frequency interference, a multistage filter is inserted for ensuring spectrum purity, a power amplification module is a core part of the transmitter, the core part is realized by cascading three stages of TGA2514-FL, TGI1314-25L and TGI1414-50 amplifiers, according to device data, when Pout is 43dBm, IM3 is-19 dBc, PAE is 22%, when Pout is 37dBm, TGI1314-25L is 20%, IM3 is-25 c, PAE is 20%, power and cross modulation can meet the requirements of the system, and the total power consumption of the transmitter is about 140W.
The heat power consumption of the transmitter is about 120W, and a fin heat dissipation structure and fan forced air cooling are adopted. The thermal resistance of the power amplifier tube TGI1414-50 is 1.3 ℃/W, the junction temperature is raised by 78 ℃ when the thermal power is 60W, and the highest junction temperature limit is 175 ℃ for ensuring the service life of the power amplifier, so the temperature of the tube shell is lower than 97 ℃. Transmitter adopting flow of 24m3The/h fan is used for air cooling, when the highest ambient temperature is 50 ℃, the temperature of the tube shell of the power amplification tube is about 98 ℃, and is slightly higher, and if the radiation heat dissipation is considered, the heat dissipation design can meet the heat design requirement.
Specifically, as shown in fig. 2, the intermediate frequency signal is a modulated signal with a central frequency of 280HMz and a bandwidth of 40MHz, and is amplified by an th VGA amplifier 201, then is filtered by two stages of a th surface acoustic wave filter 202 and an intermediate frequency LC filter 203, and then enters an up-converter, and in the up-converter, the modulated signal firstly passes through an th up-conversion mixer 204 to be mixed with a th frequency source 205, and then passes through three stages of narrow band filters of an intermediate frequency LC filter 206, an intermediate frequency tunable filter 207, and an intermediate frequency filter 209 for filtering, wherein an amplifier 208 is further disposed between the intermediate frequency tunable filter 207 and the intermediate frequency filter 209, and the filtered narrow band L band modulated signal passes through a second up-conversion mixer 210 to be mixed with a second frequency source 211, and is output to be filtered by a radio frequency cavity filter 213 to form a radio frequency signal in a Ku band, and is amplified by a power amplifier 214, and then output from an antenna by a waveguide isolator 215 and a duplexer 2, and the up-converter.
The receiving part inputs intermediate frequency signals of-110 dBm to-10 dBm, the output requires stable output of-10 dBm, the maximum gain requires 70dB, therefore, multi-stage amplification is needed, and multi-stage AGC control is adopted to ensure the dynamic range. The third-order intermodulation of the receiving link needs to meet-40 dBc, so that the device selection of the link needs to be low in noise and high in linearity. The isolation between each stage is considered in the design of the link, and the crosstalk of signals is prevented. The design of the arrangement and structure of the circuit board also considers the stray and high gain of small signals and the mutual interference among signals brought by multi-frequency spectrums, thereby improving the quality of received signals.
The method comprises the steps of receiving signals with high frequency, low signal level and high requirement on frequency source spurious, outputting an intermediate frequency with 200MHz, needing two-stage down-conversion, changing the signals to an L wave band in -stage frequency conversion, mixing the L wave band to 200MHz in the second-stage frequency conversion, mainly considering the optimal local oscillator leakage and image frequency suppression of a mixer, enriching spectral components in the whole receiving link and having high requirement on spurious in the whole system, designing the principle, arranging circuits, and carefully designing a cavity shield to ensure that each link can meet the design requirement, adopting high-efficiency modulation technology (8PSK) adopted by a high-speed data radio station requires that a receiving channel has good linearity, adopting the receiving channel to ensure that the receiving channel linearly works, adopting the technology to ensure that the receiving channel has good linearity, keeping the performance of the receiving channel to be kept for 5 minutes, and keeping the performance of the receiver to be considered permanently, and causing the possibility of unqualified performance of the receiver due to the fact that the radio station has bad performance and AGC technology.
The system noise coefficient should be less than 4dB, the requirement of the system noise coefficient can be met by adopting the preposed low-noise amplifier, the HMC903 chip is adopted in the design, the single chip gain is 18dB, the noise coefficient is 1.8dB, the dynamic range of the receiving system is 100dB, the amplitude range of the intermediate frequency signal is 0dB, therefore, the dynamic range of AGC is more than 100dB, if the AGC chip with the dynamic range of 50dB is selected, two pieces of cascade connection are adopted, the two pieces of AGC are respectively arranged at the intermediate frequency and the intermediate frequency, the total dynamic range can reach 100dB, the AGC response time is less than 2us, and the requirement of the system index is met.
In order to meet the requirement of image frequency suppression of a system, a band-pass filter is required to be added at a proper position in a link, a 5-order radio frequency filter is adopted to generate 70dBc suppression at the nearest image frequency, an th intermediate frequency filter adopts a surface acoustic wave filter, a directional coupler is adopted at the input end and the output end of a receiving link to carry out power detection by using a logarithmic detector, the logarithmic detector adopts an AD8310 chip, the chip has a high dynamic range (60dB), the detectable power range is-87-13 dBm, the output voltage is 0.5-2.75V, sampling is carried out according to 8-bit AD conversion, and the power resolution can reach 100/256-0.4 dB.
The receiving adopts a multi-channel mode, the bandwidths are respectively set to be 40MHz, 10MHz, 1MHz and 100kHz, and the requirements of transmitting video data, image data, service data, voice data and the like are met.
From the above link analysis of the receiving link, it can be derived: the noise coefficient is 3.65dB, and the requirement that the index is not more than 4dB is met; the maximum gain is 100dB (the actual debugging can adjust the matching attenuation in the link); under the condition that the input signal is-10 dBm at the maximum, the link is not compressed, and the requirement of a dynamic range is met; the minimum detectable signal is-110 dBm, and the dynamic range meets 100 dB.
Because the system is full duplex operation, the receiving channel is required to be inhibited better at a higher transmission frequency band, the airborne equipment is a low-frequency band filter, the airborne equipment is required to be inhibited at a high frequency band, the ground equipment is required to be inhibited at a high frequency band, and the duplexer is required to be mutually isolated and kept at the level of a system if the system ground and the airborne duplexer, so that the same-order filter is adopted.
As shown in FIG. 2, the RF signal received by the antenna 1 passes through the duplexer 2, then is amplified by the low noise amplifier 101, and then enters the downconverter, where the RF signal is first mixed with the th downconversion local oscillator frequency source 103 by the downconverter 102, then is filtered by the second IF LC filter 104, the second IF tunable filter 105, and the second IF filter 107 to form an L-band modulated signal, and then enters the second downconverter 108 to be mixed with the second downconversion local oscillator frequency source 109, and then is amplified by the amplifier 106 before being filtered by the second IF filter 107. the output signal of the downconverter is filtered by the LC filter 110 and the second SAW filter 111, then is amplified by the reception AGC amplifier 112, and then is filtered by the second LC filter 113 to output a 200MHz IF signal.
The frequency synthesizer adopts a phase-locked loop (PLL) and a digital frequency synthesizer (DDS) to mix and synthesize. The DDS reference clock is realized by direct 20-frequency multiplication of a 100MHz reference crystal oscillator (as shown in figure 3), the phase noise of the generated 2GHz reference clock is deteriorated by 26dB relative to the crystal oscillator, and can reach-134 dBc @1kHz, -139dBc @10kHz, -139dBc @100kHz, and stray can be optimized to be more than 80dBc when being properly filtered. The DDS is equivalent to a frequency divider, and the phase noise after frequency division depends on the poor value of both the theoretical phase noise of the frequency division and the noise floor of the DDS. The DDS model adopted in the embodiment is AD9915, the frequency division noise bottom of the DDS model is-120 dBc @1kHz, -130dBc @10kHz, -130dBc @100kHz, and is worse than the reference clock, so the frequency phase noise generated by the DDS depends on the frequency division noise bottom.
local oscillator is realized by phase-locked loop, the transmitting local oscillator frequency is 2.22GHz, the receiving local oscillator frequency is 2.3GHz, and the phase noise can reach-112 dBc @1kHz, -112dBc @10kHz, -115dBc @100 kHz.
The two local oscillators are generated by mixing PLL and DDS, the bandwidth of a radio frequency system reaches 2.5GHz, therefore, a segmented frequency synthesis scheme is adopted, four independent PLLs and DDS are mixed to cover sections of relatively narrow frequency bands respectively, and then four sections are synthesized to form a broadband local oscillator frequency source, as shown in figure 4, the output frequency range of the DDS is 0.5-0.85GHz, the frequencies of the four independent PLLs are 4.25GHz, 4.55GHz, 4.85GHz and 5.15GHz respectively, the frequency range generated after the DDS is mixed with the frequencies of the phase-locked loops is 4.75-5.1 GHz, 5.05-5.4 GHz, 5.35-5.7 and 5.65-6 GHz, the sections are slightly overlapped, and are combined by a single-pole four-throw switch after being filtered by a filter, and then a double-frequency DDS signal is generated to be mixed with the PLL signal, the phase noise depends on the PLL, the phase noise and the stray noise and the frequency multiplication indexes after the two phases are 6dB and 6 kHz, the phase noise and the-95 kHz, the phase noise @ 105-10 dBc are better than the @ 70dBc and the dBc @100 dBc.
TABLE 1 stitch definition
| Interface line name | Use of |
| 24V：4A | Power amplifier |
| 8.5V：6A | Power amplifier |
| 6.5V：2A | Small signal part |
| 4.5V：2A | Small signal part |
| -6.5V：0.5A | Power amplifier grid voltage |
| TXD、RXD | Communication line (communication with internal ARM) |
| DIO1～DIO8 | Independent IO control line |
| DAC_V1～DAC_V6 | Analog control line |
| ADC_V1～ADC_V4 | BIT detection |
The external interfaces comprise (MCX) reference source interfaces of upper intermediate frequency, lower intermediate frequency and 100MHz respectively, radio frequency output ports (SMA or waveguide ports), the low-frequency connector is a J18-54 contact pin and comprises a power supply, a communication line, 8 groups of differential lines, four ADCs and 6 DAC signals, and the definition and distribution of the contact pin are shown in Table 1.
Claims (6)
- The Ku waveband comprehensive radio frequency transceiving system comprises an antenna (1), a radio frequency receiver, a radio frequency transmitter and a frequency source, wherein the antenna (1) is respectively connected with the radio frequency receiver and the radio frequency transmitter through a duplexer (2) for isolating transmitted and received radio frequency signals, and the Ku waveband comprehensive radio frequency transceiving system is characterized in that:the radio frequency transmitter comprises an up-converter, the up-converter comprises an th-level up-conversion mixer (204) for up-converting a modulation signal with an intermediate frequency of 280HMz and a bandwidth of 40MHz to increase the frequency to an L waveband, and a second-level up-conversion mixer (210) for up-converting a modulation signal with an L waveband to increase the frequency to a Ku waveband;the radio frequency receiver includes a downconverter including an th stage down-conversion mixer (102) for down-converting received Ku band radio frequency signals to L band modulated signals and a second stage down-conversion mixer (109) for down-converting L band modulated signals to a 200MHz intermediate frequency output.
- 2. The Ku-band integrated radio frequency transceiving system according to claim 1, wherein the intermediate frequency signal processing device of the radio frequency transmitter comprises a transmitting VGA amplifier (201), an th surface acoustic wave filter (202) and a th intermediate frequency LC filter (203), and an intermediate frequency signal with the central frequency of 280HMz and the bandwidth of 40MHz is amplified by the transmitting VGA amplifier (201), then sequentially filtered by the th surface acoustic wave filter (202) and the th intermediate frequency LC filter (203), and then connected to the intermediate frequency signal input end of a th up-conversion mixer (204) of the up-converter.
- 3. The Ku band integrated radio frequency transceiver system according to claim 2, wherein: the radio frequency signal processing device of the radio frequency transmitter comprises a driving amplifier (212), a radio frequency cavity filter (213), a power amplifier (214) and a waveguide isolator (215); the radio frequency signal of Ku wave band output by the up-converter is transmitted by the antenna (1) after passing through the driving amplifier (212), the radio frequency cavity filter (213), the power amplifier (214) and the waveguide isolator (215) in sequence.
- 4. The Ku band integrated radio frequency transceiver system according to claim 3, wherein: the power amplifier of the radio frequency transmitter is realized by three-stage amplifier cascade of TGA2514-FL, TGI1314-25L and TGI 1414-50; the power amplifier also comprises a heat dissipation device which adopts a fin heat dissipation structure and adopts a fan to perform forced air cooling.
- 5. The Ku band integrated radio frequency transceiving system of claim 1, wherein said intermediate frequency signal processing means of said radio frequency receiver comprises a th LC filter (110), a second surface acoustic wave filter (111), a receiving AGC amplifier (112) and a second LC filter (113), wherein an output of said second down-conversion mixer of said down-converter is filtered by a th LC filter (110) and a second surface acoustic wave filter (111) at two stages, amplified by said receiving AGC amplifier (112), and filtered by said second LC filter (113) to output an intermediate frequency signal of 200 MHz.
- 6. The Ku band integrated radio frequency transceiving system according to any of claims , wherein the frequency synthesizer generating the local oscillation signals for the up converter and the down converter comprises four independent phase-locked loops having 100MHz crystal oscillation frequencies of 4.25GHz, 4.55GHz, 4.85GHz and 5.15GHz respectively, and digital frequency synthesizers having 0.5 GHz to 0.85GHz, wherein the frequency ranges generated by the digital frequency synthesizers and the independent phase-locked loops through frequency mixing are frequency sources having 4.75 GHz to 5.1GHz, 5.05 GHz to 5.4GHz, 5.35 GHz to 5.7GHz and 5.65 GHz to 6GHz respectively.
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| CN201920829767.3U CN210007695U (en) | 2019-06-04 | 2019-06-04 | Ku waveband integrated radio frequency transceiving system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110429952A (en) * | 2019-06-04 | 2019-11-08 | 广东圣大电子有限公司 | A kind of comprehensive radio-frequency system of Ku wave band |
| CN111385017A (en) * | 2020-03-10 | 2020-07-07 | 四川灵通电讯有限公司 | KA frequency band high-power amplifier and implementation method thereof |
| CN114944865A (en) * | 2022-05-16 | 2022-08-26 | 河北东森电子科技有限公司 | Design and application method of ultra-wideband Ka-band satellite radio frequency unit |
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2019
- 2019-06-04 CN CN201920829767.3U patent/CN210007695U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110429952A (en) * | 2019-06-04 | 2019-11-08 | 广东圣大电子有限公司 | A kind of comprehensive radio-frequency system of Ku wave band |
| CN110429952B (en) * | 2019-06-04 | 2024-04-19 | 广东圣大电子有限公司 | Ku wave band comprehensive radio frequency receiving and transmitting system |
| CN111385017A (en) * | 2020-03-10 | 2020-07-07 | 四川灵通电讯有限公司 | KA frequency band high-power amplifier and implementation method thereof |
| CN114944865A (en) * | 2022-05-16 | 2022-08-26 | 河北东森电子科技有限公司 | Design and application method of ultra-wideband Ka-band satellite radio frequency unit |
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