CN102195664B - Multi-path microwave digital receiver - Google Patents
Multi-path microwave digital receiver Download PDFInfo
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- CN102195664B CN102195664B CN201110093174.3A CN201110093174A CN102195664B CN 102195664 B CN102195664 B CN 102195664B CN 201110093174 A CN201110093174 A CN 201110093174A CN 102195664 B CN102195664 B CN 102195664B
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Abstract
The invention discloses a multi-path microwave digital receiver, which comprises an H.264 image decoding unit, a plurality of channel demodulation units, a plurality of microwave receiving channel units, a microwave radio frequency receiving unit, a splitter unit, a master control unit and a power supply, wherein the microwave radio frequency receiving unit selectively receives electromagnetic waves of available frequency bands, performs gain amplification, transmits the electromagnetic waves into the splitter unit, and uniformly distributes radio frequency signals to each microwave channel; a plurality of microwave receiving channels internally utilize a superheterodyne receiving technology and a broadband phase locking technology, outputs fixed intermediate frequency signals by twice frequency conversion, and transmits the fixed intermediate frequency signals into the demodulation unit, and outputs accurate baseband digital signals corresponding to an inverse process of a transmitter modulation way; and the digital signals are transmitted into the H.264 image decoding unit, decoded and recovered into the video information and output by an analogue interface if being judged to be real-time video information according to a certain communication protocol, and are transmitted into the master control unit, subjected to corresponding data format conversion and transmitted to an Ethernet interface for output if being judged to be data information.
Description
Technical field
The present invention relates to a kind of multi-path microwave digital receiver, belong to technical field of micro communication.
Background technology
It is strong that digital imagery transmission system has antijamming capability, adapts to multiple multiplexing system, many outstanding advantages such as strong security, product be widely used in public security, fire-fighting, traffic monitoring, seashore anti-, military etc. every field.
Because current domestic Digital Image Transmission product adopts MPEG-2/MPEG-4 image compression algorithm mostly, utilize external COFDM modulation module assembled, use frequency limited amount, substantially be all operated under point-to-point working method, do not possess the ability of transfer of data, in confidentiality, reliability, maintenanceability instructions for use occasion, can not meet user's demand.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of multi-path microwave digital receiver for the deficiencies in the prior art.Adopt following technical scheme:
A kind of multi-path microwave digital receiver, comprises H.264 image decoding unit, multiple channel demodulations unit, multiple microwave receiving channel unit, microwave radio receiving element, splitter unit, main control unit and power supply; Described microwave radio receiving element optionally receives the electromagnetic wave of available frequency band, by gain, is amplified and is sent into splitter unit, and radiofrequency signal mean allocation is arrived to each microwave channel; Multiple microwave receiving channel interior are utilized superheterodyne reception technology and broadband Phase Lock Technique, export fixed intermediate frequency signal send into demodulating unit by double conversion, and the inverse process of corresponding transmitter modulation system, exports correct baseband digital signal.These digital signals are according to certain communication protocol, if real-time video information is sent into H.264 image decoding unit, decoding reduction video information, exports by analog interface; If data message is sent into main control unit, its data format is carried out to corresponding conversion, be sent to Ethernet interface output.
Described multi-path microwave digital receiver, described microwave radio receiving element comprises that microwave band-pass preselection filter, low noise amplifier, high pass filter connect, amplifier, multi-path power divider; The electromagnetic wave signal arriving by antenna reception, by described microwave band-pass preselection filter, the signal extraction in useful frequency range is gone out, give described low noise amplifier, by stube cable, send into described high pass filter, through filtering low frequency signal again, send into described amplifier and carry out small-signal amplification, then send into described multi-path power divider.
Described multi-path microwave digital receiver, described microwave receiving channel unit comprises master control, frequency mixer, broadband phase-looked loop circuit, intermediate-frequency filter, amplifier, numerical-control attenuator, narrow band filter, wave detector and ADC sample circuit; The identical radiofrequency signal of being exported by described multi-path power divider, give respectively each receive path, according to agreement in advance, by broadband phase-looked loop circuit described in described master control control, produce corresponding local frequency and described radiofrequency signal mixing, output intermediate-freuqncy signal, this intermediate-freuqncy signal is carried out small-signal amplification through sending into described amplifier after described intermediate-frequency filter filtering, then enters numerical-control attenuator, by narrow band filter, only extract effective intermediate-freuqncy signal again, be sent to demodulating unit; Described effective intermediate-freuqncy signal is sent to master control by wave detector and ADC sample circuit, forms an AGC loop together with numerical-control attenuator, by master control control numerical-control attenuator attenuation.
This multi-path microwave digital receiver adopts following series of key techniques, has solved the shortcoming and defect of traditional microwave digital imagery transmission system:
1) multichannel reception technique, realizes receiver and receives simultaneously the function of different frequent points signal.
2) star-like networking technology, the point-to-points point type network configuration that realization is put take many transmitters as terminal, centered by a receiver, system is take frequency division in the time period as basis, and receiving terminal can receive at synchronization the electromagnetic wave signal that more than 4 frequency sends.Utilize frequency division multiple access reception technique to save receiving terminal antenna usage quantity, improved rapid deployment and the maintainability of system, reduced system cost simultaneously.
3) transmission range problem, utilize H.264 high efficiency of compression code decode algorithm and anti-many through modulation-demodulation technique, system signal bandwidth reduction, at very little (in 1MHz), is improved to communications reception sensitivity, the direct transmission range of raising system under same efficiency.
Accompanying drawing explanation
Fig. 1 is microwave digital image transmission system transmitting terminal A form of the present invention;
Fig. 2 is that microwave digital image transmission system transmitting terminal B of the present invention is containing trunking;
Fig. 3 is microwave digital image transmission system transmitter internal frame diagram of the present invention;
Fig. 4 is microwave digital image transmission system Digital Microwave repeater theory diagram of the present invention;
Fig. 5 is microwave digital image transmission system receiving terminal A theory diagram of the present invention;
Fig. 6 is microwave digital image transmission system receiving terminal B theory diagram of the present invention;
Fig. 7 is microwave digital image transmission system single channel receiver principle block diagram of the present invention;
Fig. 8 is microwave digital image transmission system multipath receiver theory diagram of the present invention;
Fig. 9 is microwave digital image transmission system multipath receiver rf receiver unit theory diagram of the present invention;
Figure 10 is microwave digital image transmission system multipath receiver receive path theory diagram of the present invention;
Figure 11 is microwave digital image transmission system network server end theory diagram of the present invention.
Embodiment
Below in conjunction with specific embodiment, the present invention is described in detail.
First the present invention provides a kind of microwave digital image transmission system, comprises transmitting terminal, receiving terminal, the webserver three parts:
Embodiment 1: transmitting terminal
Consider the characteristic that microwave system is propagated at wireless channel, and the propagation path between transmitter and receiver is likely the sight line between 2, also likely has the barriers such as mountain range, building.So transmitting terminal is divided into multiple situation when disposing, the basic transmitting terminal unit being first comprised of acquisition camera (head), microwave transmitter, transmitting antenna can be deployed in high-altitude and closely (transmitting terminal A) during environment for use; Secondly when having the obstacle environments such as mountain range, highland, building, between basic transmitter unit and receiving terminal, (as top, highland, mountain range, building top) increases trunking (transmitting terminal B), completes the forwarding of image information; Finally, if in the time of need to transmitting data, can on basic transmitter unit basis, increase data transmission terminal, both connect by netting twine, realize the transfer function of data message.
According to environment for use difference, system transmitting terminal has A, two kinds of composition forms of B.
Transmitting terminal A form
As shown in Figure 1, under system reaches sighting condition, use transmitting terminal A form, comprise video capture device, data transmission terminal, microwave transmitter and antenna.Video capture device is used for gathering real-time video, audio-frequency information, and real-time video, audio-frequency information are sent into microwave transmitter by analog interface and gone out by antenna transmission; Data transmission terminal is for sending into microwave transmitter the data message in data transmission terminal by Ethernet interface, and microwave transmitter sends by antenna data message with electromagnetic wave form.
Transmitting terminal B form
As shown in Figure 2, in system is used, exist the barrier cannot intervisibility, or while needing farther transmission range, use transmitting terminal B form, comprise video capture device, data transmission terminal, microwave transmitter, Digital Microwave trunking and antenna.Can respectively the real-time video being collected by video capture device, audio-frequency information be sent into microwave transmitter by analog interface; Or the fileinfo in data transmission terminal is sent into microwave transmitter by Ethernet interface, microwave transmitter sends by antenna these signals of telecommunication with electromagnetic wave form.Digital Microwave trunking is launched after such electromagnetic wave signal is arrived by antenna reception again.
As shown in Figure 3, microwave transmitter comprises H.264 Image Coding unit, Channel Modulation unit and microwave radio transmitter unit, main control unit and power supply.Video/audio information from analog interface is passed through H.264 Image Coding unit, and mass data is compressed in to 1Mbps with the interior Channel Modulation unit of sending into; Data message from Ethernet interface is sent into main control unit according to (UDP or TCP/IP) communication protocol of agreement, main control unit becomes these data transaction the TS stream of standard, according to the information format of every bag 188 bytes, by serial data interface make information rate remain on 1Mbps with interior by sending into Channel Modulation unit.Channel digital modulating unit by these data messages by corresponding digital modulation technique (digital modulation technique the 11st page have explanation), in conjunction with broadband phase-looked loop technology, signal spectrum is moved and required, in frequency microwave frequency range, with electromagnetic wave form, to launch.
As shown in Figure 4, Digital Microwave repeater comprises RF receive channel unit, channel demodulation unit, Channel Modulation unit, microwave radio transmitter unit, main control unit and power supply.RF receive channel unit is in superhet double conversion mode, the fixed intermediate frequency frequency (70MHz or 36.1MHz) electromagnetic wave signal frequency spectrum shift being needed to channel demodulation unit in conjunction with broadband phase-looked loop technology, by demodulation process, analog signal is converted into digital signal, such digital signal is carried out to transmitter processes process again one time, send into Channel Modulation unit and microwave radio transmitter unit, with electromagnetic wave form, launch, complete digital junction process.
Embodiment 2: receiving terminal
Receiving terminal, according to environment for use requirement, is selected single channel receiving equipment (receiving terminal A) under limited place, single transmission demand, directly utilizes monitor to complete the reproduction of transmitting terminal information; When needs multicast communication, multiple scene monitoring, select multipath reception equipment (receiving terminal B), utilize monitor to complete the reproduction to multiple transmitting terminal information.
Receiving terminal A form
As shown in Figure 5, when general operational requirement, be used in conjunction with single transmitter, use A form, comprise picture monitor, computer, single channel microwave receiver and antenna.Antenna reception is sent into single channel microwave receiver after electromagnetic wave signal, and single channel microwave receiver is reduced to by useful signal real time video image information or the data message that transmitting terminal is launched, respectively by picture monitor and computer reproduction.
As shown in Figure 7, single channel microwave receiver comprises H.264 image decoding unit, channel demodulation unit and microwave radio receiving element, main control unit and power supply.Microwave radio receiving element by frequency spectrum shift, optionally obtains the electromagnetic wave signal receiving effective intermediate-freuqncy signal and sends into demodulating unit, and the inverse process of corresponding transmitter modulation system, exports correct baseband digital signal.Communication protocol according to a preconcerted arrangement, if described baseband digital signal real-time video information is sent into H.264 image decoding unit, decoding reduction video information; If data message is sent into main control unit, its data format is carried out to corresponding conversion (for example, the TS flow data of every bag 188 bytes being transformed to the data message of UDP or ICP/IP protocol form), be sent to Ethernet interface output.
Receiving terminal B form
In actual use, receiving terminal is mostly command post, information processing centre, only can receive that single information is inadequate, and outside transmitter is more than one, if receiving terminal is corresponding one by one with transmitting terminal, receiving device quantity is increased, cost is high, and the shortcoming that space is large, so used B form at receiving terminal, as shown in Figure 6, comprise multichannel microwave receiver, picture monitor, computer and antenna.Antenna is sent into multichannel microwave receiver after electromagnetic wave signal is received, multichannel microwave receiver is processed useful signal respectively, according in advance with the agreement of each transmitting terminal, restore real time video image information or data message that each road transmitting terminal is launched, respectively by picture monitor and computer reproduction.
The present embodiment provides a kind of multi-path microwave digital receiver, as shown in Figure 8, multi-path microwave digital receiver comprises H.264 image decoding unit, multiple channel demodulations unit, multiple microwave receiving passage, microwave radio receiving element, splitter unit, main control unit and power supply.Microwave radio receiving element optionally receives the electromagnetic wave of available frequency band, by gain, is amplified and is sent into splitter unit, and radiofrequency signal mean allocation is arrived to each microwave channel.Multiple microwave receiving channel interior are utilized superheterodyne reception technology and broadband Phase Lock Technique, export fixed intermediate frequency signal send into demodulating unit by double conversion, and the inverse process of corresponding transmitter modulation system, exports correct baseband digital signal.These digital signals are according to certain communication protocol, if real-time video information is sent into H.264 image decoding unit, decoding reduction video information, exports by analog interface; If data message is sent into main control unit, its data format is carried out to corresponding conversion, be sent to Ethernet interface output.
As shown in Figure 9, the microwave radio receiving element of multipath receiver comprise that microwave band-pass preselection filter, low noise amplifier (LNA), high pass filter connect, amplifier, multi-path power divider.Realize little noise factor, well intermediate frequency, picture frequency suppress the function that He Si road (more than Huo Si road) merit is divided.The electromagnetic wave signal arriving by antenna reception, by preselection filter, the signal extraction in useful frequency range is gone out, give low noise amplifier, by stube cable, send into high pass filter, through filtering low frequency signal again, send into amplifier and carry out small-signal amplification, then send into multi-path power divider, the useful radiofrequency signal in passband is equally divided into multiple signals output and is sent to microwave receiving channel unit.
As shown in figure 10, microwave receiving channel unit comprises master control, frequency mixer, broadband phase-looked loop circuit (PLL), intermediate-frequency filter, numerical-control attenuator, amplifier, wave detector and ADC sample circuit (ADC).Mainly realizing frequency translation obtains intermediate-freuqncy signal and AGC function and comes tuningly to guarantee that intermediate-freuqncy signal meets receiving demodulation device semaphore request.
The identical radiofrequency signal of being exported by multi-path power divider, give respectively each receive path, according to agreement in advance, by master control control broadband phase-looked loop circuit, produce corresponding local frequency and radiofrequency signal mixing, output intermediate-freuqncy signal, this intermediate-freuqncy signal is sent into amplifier after device filtering after filtering and is carried out small-signal amplification, then enters numerical-control attenuator, by narrow band filter, only extract effective intermediate-freuqncy signal again, be sent to demodulating unit.Above-mentioned effective intermediate-freuqncy signal is sent to master control by wave detector and ADC sample circuit simultaneously, forms an AGC loop together with numerical-control attenuator, by master control control numerical-control attenuator attenuation, effectively improves the reception dynamic range of receiver.
Embodiment 3: network server end
Because microwave digital image transmission system is by carrying out space transmission by electromagnetic wave, in emergency communication, rapid deployment, mobile flexibility, there is some superiority, but on communication distance, be subject to certain restriction, for the function that meets remote access, use, commander increases network server end, utilize existing public information network as cable networks such as the Internet, 3G nets, improve the range of application of system.
As shown in figure 11, can also increase in microwave receiver rear end network server end, the such as equipment such as terminal/server, 3G network terminal.The Ethernet interface of microwave receiver is connected with the terminal or the server that are connected into the Internet, by IP, can makes the Internet remote computer access microwave receiver, the effective image of the transmitter terminal of acquisition, data message; These information exchanges can also be crossed to 3G network terminal and send to the user on 3G network simultaneously.
The modulation-demodulation technique that the present invention adopts:
Based on multi-carrier OFDM modulation system, adopt LDPC channel coding technology.
OFDM technology is the technology of processing based on data " piece ".Multicarrier system is famous with availability of frequency spectrum height, but due to OFDM technology in actual use, added protection interval and a large amount of pilot frequency informations, therefore make the availability of frequency spectrum decline; For intersymbol interference ISI, OFDM not only can be by inserting the method for Cyclic Prefix (CP), effectively restrain the ISI interference that multipath brings, can also pass through the reasonable estimation to channel time-varying characteristics, the symbol lengths of design system neatly, alleviates the impact of channel time-varying characteristics on systematic function.Multicarrier system is because data have been averaged in on each subcarrier, and therefore the ability of contrary frequency selectivity decline is stronger, but to intrinsic helpless to carrier deviation and timing error sensitivity of multicarrier system; Utilize digital pre-distortion DPD technology, reduce OFDM and modulate the higher peak of bringing all than the adverse effect of (peak-to-average power ratio, PAPR).
OFDM is as a kind of multi-carrier digital modulation technique, can in channel capacity, have great advantage but the not ability of improved system performance own, its all effort is all that keeping system performance does not decline under the prerequisite of spectrum efficient utilization, but OFDM technology can adopt relatively simple method to overcome the impact that systematic function is declined after all, in addition, on frequency domain, also provide a kind of desirable frequency spectrum programme, ability and the thinking of potential improved system performance have importantly been provided, therefore, OFDM technology set up one can effective use channel width resource platform.
Should be understood that, for those of ordinary skills, can be improved according to the above description or convert, and all these improvement and conversion all should belong to the protection range of claims of the present invention.
Claims (2)
1. a multi-path microwave digital receiver, is characterized in that, comprises H.264 image decoding unit, multiple channel demodulations unit, multiple microwave receiving channel unit, microwave radio receiving element, splitter unit, main control unit and power supply; Described microwave radio receiving element optionally receives the electromagnetic wave of available frequency band, by gain, is amplified and is sent into splitter unit, and radiofrequency signal mean allocation is arrived to each microwave channel; Multiple microwave receiving channel interior are utilized superheterodyne reception technology and broadband Phase Lock Technique, export fixed intermediate frequency signal send into demodulating unit by double conversion, and the inverse process of corresponding transmitter modulation system, exports correct baseband digital signal; These digital signals are according to certain communication protocol, if real-time video information is sent into H.264 image decoding unit, decoding reduction video information, exports by analog interface; If data message is sent into main control unit, its data format is carried out to corresponding conversion, be sent to Ethernet interface output; Described microwave receiving channel unit comprises master control, frequency mixer, broadband phase-looked loop circuit, intermediate-frequency filter, amplifier, numerical-control attenuator, narrow band filter, wave detector and ADC sample circuit; By the identical radiofrequency signal of described splitter unit output, give respectively each receive path unit, according to agreement in advance, by broadband phase-looked loop circuit described in described master control control, produce corresponding local frequency and described radiofrequency signal mixing, output intermediate-freuqncy signal, this intermediate-freuqncy signal is carried out small-signal amplification through sending into described amplifier after described intermediate-frequency filter filtering, then enters numerical-control attenuator, by narrow band filter, only extract effective intermediate-freuqncy signal again, be sent to demodulating unit; Described effective intermediate-freuqncy signal is sent to master control by wave detector and ADC sample circuit, forms an AGC loop together with numerical-control attenuator, by master control control numerical-control attenuator attenuation.
2. multi-path microwave digital receiver according to claim 1, is characterized in that, described microwave radio receiving element comprises microwave band-pass preselection filter, low noise amplifier, high pass filter, amplifier; The electromagnetic wave signal arriving by antenna reception, by described microwave band-pass preselection filter, the signal extraction in useful frequency range is gone out, give described low noise amplifier, by stube cable, send into described high pass filter, through filtering low frequency signal again, send into described amplifier and carry out small-signal amplification, then send into described splitter unit.
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| CN104202002B (en) * | 2014-09-18 | 2017-05-17 | 天津七一二通信广播股份有限公司 | FPGA (field programmable gate array) based digital AGC (automatic gain control) system and method of ultra-short wave radio set |
| US9407205B2 (en) * | 2014-12-23 | 2016-08-02 | Macom Technology Solutions Holdings, Inc. | Double down-conversion with multiple independent intermediate frequencies for E-band applications |
| CN109752694B (en) * | 2017-11-01 | 2021-10-29 | 北京振兴计量测试研究所 | Dual-band microwave signal detection device |
| CN110830406B (en) * | 2019-11-11 | 2022-02-22 | 华滋奔腾（苏州）安监仪器有限公司 | Demodulator and demodulation method of transmission type coaxial cable Fabry-Perot sensor |
| CN112332873B (en) * | 2020-09-21 | 2022-09-23 | 北京无线电测量研究所 | Broadband power division filtering component |
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| CN1595977A (en) * | 2003-09-10 | 2005-03-16 | 陈意辉 | Province level multiplex decimeter wave adjacent frequency digital wireless television transmission system |
| CN201409207Y (en) * | 2009-03-24 | 2010-02-17 | 桂林南方通信设备工程公司 | Digital mobile multimedia transmission device |
| CN201533412U (en) * | 2009-05-07 | 2010-07-21 | 谭小碧 | Dual-mode transmitter |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1595977A (en) * | 2003-09-10 | 2005-03-16 | 陈意辉 | Province level multiplex decimeter wave adjacent frequency digital wireless television transmission system |
| CN201409207Y (en) * | 2009-03-24 | 2010-02-17 | 桂林南方通信设备工程公司 | Digital mobile multimedia transmission device |
| CN201533412U (en) * | 2009-05-07 | 2010-07-21 | 谭小碧 | Dual-mode transmitter |
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