CN101136887A - DRM receiver radio frequency receiving front-end circuit - Google Patents
DRM receiver radio frequency receiving front-end circuit Download PDFInfo
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- CN101136887A CN101136887A CNA2007100612991A CN200710061299A CN101136887A CN 101136887 A CN101136887 A CN 101136887A CN A2007100612991 A CNA2007100612991 A CN A2007100612991A CN 200710061299 A CN200710061299 A CN 200710061299A CN 101136887 A CN101136887 A CN 101136887A
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Abstract
The front-end circuit includes power supply management circuit, radio-receiving circuit (RRC) of analogy radio set (ARS), and secondary frequency converting circuit. RRC of ARS is in use for receiving radio signal in digital radio modulation (DRM), and converting down frequency to 465kHz intermediate frequency signal (IFS). The secondary frequency converting circuit includes divider circuit, dc blocking filter circuit, mixer circuit, and local oscillation circuit. Through the divider circuit and the dc blocking filter circuit, 465kHz IFS input from RRC of ARS is connected to mixer circuit. Then, the mixer circuit converts 465kHz IFS down to 12kHz IFS. The local oscillation circuit is in use for providing sinusoidal local oscillation signal for the mixer circuit. Comparing with overseas product, the disclosed front-end circuit possesses features of low cost, and easy of implementation. The front-end circuit is accorded with current standard of AM receiver.
Description
Technical field
The invention belongs to communication technical field, relate to a kind of digital am broadcasting (DRM) ' radio frequency receiving front-end circuit.
Background technology
At present, digital sound broadcasting system has satellite digital sound radio DSB (Digital SatelliteBroadcasting), digital audio broadcasting DAB (Digital Audio Broadcasting) and digital am broadcasting DRM three kinds of modes such as (Digital Radio Mondiale).Wherein digital satellite broadcasting can not be applied in the ground broadcast transfer system; DAB is at 30MHz ~ digitized technology of 3000MHz frequency range sound radio, can not satisfy the digitized requirement of AM broadcasting; And be operated in below the 30MHz, technical day by day ripe DRM technology can solve the digitlization problem of simulation AM broadcasting well, and the DRM system is designed to simulate at present the final replacer of AM broadcasting.It has incomparable superiority than simulation AM broadcasting the various advanced technology decisions of DRM:
1, has international digital AM technical standard.The DRM system is the unified opening of using in worldwide, off-patent digital AM standard, still use original 30MHz following long wave, medium wave and shortwave frequency range, and still use existing transmitting station, existing frequency, do not need newly-increased frequency spectrum or planning, do not have very complicated frequency planning problem again;
2, under the situation of identical covering, it is 6～8dB that the DRM transmitter can reduce more than 3/4ths than the power of simulating the AM transmitter, cuts down the consumption of energy, and has improved transmitter frequency and economic benefit; If instead keep equal power grade, the coverage of signal will be expanded greatly;
3, significantly improve the sound quality of AM broadcasting, under the situation that keeps existing bandwidth 9KHz or 10KHz, utilize voice data rate compress technique and DSP technology, can reach the sound quality of FM broadcasting,, can reach the tonequality of CD if bandwidth doubles;
4, owing to be the transmission of digital signal, the interference of having avoided the transmission of ionospheric fading and multipath to cause has greatly strengthened antijamming capability, has guaranteed the reliability that the AM broadcast singal transmits and receives;
5, can utilize current broadcast facility to greatest extent again, can realize analog and digital signal with broadcasting, and can be progressively to totally digitilized transition;
6, when transmitting broadcast program, can carry additional data message business, expand service content;
7, existing intermediate waves broadcast transmitter is carried out the transformation of digital AM broadcast technology, expense is cheap.As long as the addition portion subset just can be formed DRM transmission emission system with original PDM, PSM, DX series transmitter;
8, the receiver volume is little, cheap, portable, can also move reception;
9, support single frequency network (SFN), improve the utilance of frequency spectrum.
By as can be seen above, DRM gives AM broadcasting new life, is the outlet and the future of traditional AM broadcasting.
It is simple that tradition AM broadcasting has modulation technique as a kind of important wireless medium, wide coverage, advantages such as propagation distance is far away and receiver is portable, cheapness.But develop rapidly along with digital technology and wireless technology, technology such as radio transmission system such as FM, DAB and satellite all are greatly improved and use widely, and AM broadcasting also still rests on traditional dummy level, shortcomings such as it significantly is subject to disturb, business is single, sound quality is low, force it to have to seek technical thorough change, to satisfy numerous AM broadcasting fan's demand.The digitlization of AM broadcasting is the optimal selection that addresses this problem.DRM (Digital Radio Mondiale) technology grows up under such background just as the unique worldwide standard of digital AM broadcasting.DRM has solved the digitlization problem of simulation AM broadcasting well, is designated as the final substitute of present traditional AM broadcasting.It has not only kept the traditional advantages of AM broadcasting, and has solved many shortcomings of traditional AM broadcasting, as has significantly improved the sound quality of AM broadcasting, and antijamming capability is strengthened greatly, improves transmission quality etc.Can realize that in addition current AM system to the seamlessly transitting of DRM system, brings the sufficient adjustment time for operator and equipment manufacturers.At present, external DRM broadcasting has begun to pilot, but its DRM special chip and module are externally not open.Therefore develop the DRM receiver that has China's independent intellectual property right and seem most important.The Digital Signal Processing part of the standard code of DRM for radio frequency leading portion part, does not have specified in more detail, and as long as principle is supporting with the DRM standard, can receive aerial medium wave and short-wave signal just.
China is the big country of AM broadcasting, and the western Innovation project that the new century comes into effect also will further enlarge the scale of AM broadcasting, improves the broadcasting coverage rate and changes the aerial order in outlying district.But be not easy to cover in the such big country of China, thereby digital am broadcasting has very big market by frequency modulation (FM) broadcasting.
The research and development of current DRM in the world are popular domains, are subjected to the extensive concern of broadcast world, scientific and technological circle and industrial quarters, though developed country's starting early, and obtained certain experience, network plan method and system parameters await to test to be determined.And mostly being greatly of using now test use receiver, volume and power consumption also not to reach to move and the requirement of portable receiver, cost is also than higher, these problems need be developed large scale integrated circuit and the solution of exploiting market.
Had the radio-frequency front-end receiver to sell abroad, but cost an arm and a leg, and the internal circuit technical data is secret, we can't obtain.The receiver external with regard to the technical merit effect can receive the DRM signal clearly.In addition, external amplitude modulation broadcasting receiver output intermediate frequency is 455kHz, and domestic is 465kHz, so when doing mixing, local oscillator is also different.External receiver will produce the local oscillation signal of 467kHz, and we will produce the local oscillation signal of 477kHz.
Summary of the invention
The objective of the invention is to overcome the above-mentioned defective of prior art, a kind of receiver radio frequency fore-end circuit that meets domestic current DRM standard is provided.
For this reason, the present invention adopts following technical scheme:
A kind of DRM receiver radio frequency receiving front-end circuit, comprise electric power management circuit, simulation broadcast receiver radio-frequency (RF) receiving circuit and double conversion circuit, described simulation broadcast receiver radio-frequency (RF) receiving circuit is in order to receive the DRM radiofrequency signal, and it is downconverted to the intermediate-freuqncy signal of 465kHz, it is characterized in that, described double conversion circuit comprises bleeder circuit, every straight filter circuit, mixting circuit and local oscillation circuit, from the intermediate-freuqncy signal of the 465kHz of simulation broadcast receiver radio-frequency (RF) receiving circuit input through the step-down of bleeder circuit with after the filtering of straight filter circuit, receive mixting circuit, by mixting circuit the intermediate-freuqncy signal of 465kHz is downconverted to the intermediate-freuqncy signal of 12kHz, described local oscillation circuit is with thinking that mixting circuit provides sinusoidal wave local oscillation signal.
As preferred version, in the above-mentioned DRM receiver radio frequency receiving front-end circuit, local oscillation circuit comprises active crystal oscillator, frequency divider and the sinusoidal wave generation circuit that links to each other by successively, frequency of oscillation is after 8 frequency divisions of frequency divider are passed through in the output of the active crystal oscillator of 3.816MHz, through the 477kHz sinusoidal signal after the sinusoidal wave generation circuit generation decay, this signal is the sinusoidal wave local oscillation signal that local oscillation circuit produces again.
Mixting circuit of the present invention can be made of SA612A mixing chip and RC low-pass filter circuit, and the mixed frequency signal that obtains from SA612A mixing chip is to export after the RC low-pass filter circuit filtering of 15.924kHz through cut-off frequency.
Utilization of the present invention obtains the 465kHz intermediate-freuqncy signal from simulating wireless RF end, pass through the secondary frequency reducing again, obtain the intermediate-freuqncy signal of 12kHz, the external product cost of comparing is low, is easy to realize, the more important thing is, the present invention is directed to the 465kHz intermediate-freuqncy signal of domestic amplitude modulation broadcasting receiver output, design produces the local oscillation circuit of 477kHz local oscillation signal, and the redesign mixting circuit, thereby a kind of DRM receiver radio frequency receiving front-end circuit that meets the AM receiver standard of domestic current is provided.
Description of drawings
Fig. 1 DRM receiver hardware system implementation;
The wireless circuit theory diagrams of Fig. 2 analog AM;
The circuit theory diagrams of Fig. 3 SA612A;
The design principle figure of Fig. 4 477kHz square wave;
Fig. 5 square wave is shaped as sinusoidal wave design circuit;
Fig. 6 5V reduces to the power supply design principle figure of 3V.
Embodiment
Below in conjunction with drawings and Examples the present invention is further described.
Fig. 1 is the hardware structure diagram of the complete DRM receiver system test platform of a cover.Be DRM receiver radio frequency (RF) receiving front-end circuit installation drawing partly in the dotted line among the figure.This platform has comprised modules such as DRM receiver RF front end receiving circuit, A/D conversion, metadata cache and local controller, leave analogue audio frequency output interface, USB interface and with DaVinciEVM board communications interface.Can realize that the simulated audio signal that the RF front end is received passes through sound card and delivers to PC, or the digital signal of simulated audio signal after special audio A/D conversion passed through USB interface deliver to PC, by the DRM receiving software verification algorithm of microcomputer loading and the correctness of circuit design; This platform is supported the function of data passback simultaneously, is about to voice data that DRM receiving software that microcomputer loads handles and delivers to D/A converter on this platform through the USB mouth, and the DRM audio-frequency information is restored.This platform has been realized the function of complete DRM receiver substantially, for DaVinci EVM plate or following DaVinci Target Board provide complete RF receiving front-end circuit, but and the correctness of verification algorithm and circuit design.
The invention provides a kind of DRM receiver RF receiving front-end circuit based on discrete analogue device and integrated chip, this circuit is used the DRM receiver RF front-end circuit that the wireless receiving circuit of traditional analog is realized.
Simulation broadcast receiver its major function is generally finished by six triodes, so often be called six pipe broadcast receivers, in order to receive the DRM radiofrequency signal, and signal is downconverted to the intermediate frequency of 465kHz, and the present invention is from the signal of simulation receiver circuit intercepting 465kHz.The wireless principle of six pipes that following brief analysis is traditional, and the optimum method of acquisition 465kHz.
Manually transfer six of platform to manage wireless schematic diagram as shown in Figure 2.The space electromagnetic wave signal enters receiving circuit by antenna, the AM receiver uses be the bar magnet coil as reception antenna, this is determined by AM broadcast singal frequency characteristic.According to
As can be known, by the manual adjustments variable capacitance, can change the resonance frequency of oscillation circuit, resonant tank plays the effect of filtering, and the signal that enters antenna has only the signal identical with resonance frequency just can enter receiving loop.Input signal is delivered to the base stage of frequency-converter tube BG1 through B1.BG1 itself also constitutes a transformer feedback formula self-excited oscillator except the effect of amplification is arranged.B2 is a feedback transformer, and by emitter injection, C2 is a shunt capacitance to oscillator signal, and is very little to high-frequency resistance through the C3 coupling, is common-base circuit to local oscillator therefore.The duplex structure is by changing variable capacitance C1a, C1b simultaneously, make the intermediate frequency of the 465kHz that output after the frequency conversion is fixing, therefore this intermediate-freuqncy signal can not produce interference away from input signal and local oscillation signal, R1, R2 are biasing resistor, are used for determining the quiescent point of BG1.The 465kHz intermediate-freuqncy signal that obtains after the frequency conversion be very weak, it must be delivered to intermediate-frequency strip amplifies, signal is coupled to the base stage of putting pipe BG2 in the common emitting stage by the first intermediate frequency transformer B3, after the BG2 amplification, deliver to the second intermediate frequency transformer B4 again, because two intermediate frequency transformers of B3, B4 all are transferred on the IF spot of 465kHz, so the intermediate-freuqncy signal of 465kHz can be smoothly by and obtain enough big amplification, also suppressed simultaneously the signal on other frequencies, the sensitivity that has improved receiver.This receiver uses the mode of triode emitter-base bandgap grading output to carry out envelope detection, as shown in Figure 2, C6 is a shunt capacitance, B63 is operated in the common collector state, be added in the base stage of detection tube through the intermediate-freuqncy signal of final stage intermediate frequency transformer coupling, utilize be to tie the distinctive non-linear detection of carrying out, on emitter resistance W, obtain audio signal, W is volume control potentiometer simultaneously, the size of scalable output audio signal.For the difference of the radio signals of different frequency that receiver is received, different capacity, different distance drops to minimumly, circuit has used automatic gain control (AGC) circuit, flows through the direct current I of BG3
0Be directly proportional with the power of input signal, therefore along with the increase of input signal, the direct current that flows through B63 will increase, and the pressure drop at R4 two ends increases, the collector voltage of B63 reduces, the bias current of BG2, BG3 reduces, and quiescent point reduces, and gain descends, that is to say that input signal is strong more, it is low more to gain, and uprises otherwise gain, and therefore plays the effect of automatic gain control.Audio signal through wave detector output is faint, must amplify this low frequency signal, and to promote power-amplifier stage, rectified signal amplifies the back and delivers to power-amplifier stage by B5 through the base stage that C8 is coupled to low frequency amplifier BG4.B5 realizes the impedance matching of prestage and push-pull power amplifier, power output is sent to greatest extent recommend power stage.BG5, BG6 and input, output transformer B5, B6 constitutes push-pull power amplifier circuit, when the input of transformer B5 is added with sinusoidal signal, it secondary, just obtain equal and opposite in direction with respect to centre cap, opposite polarity two sinusoidal signals, B5 plays the effect of paraphase, positive half cycle at input signal, between the base stage of B65 and emitter because of adding the positive signal conducting, add negative signal between the base stage of BG6 and emitter and end, like this, in the one-period of input signal, BG5, BG6 takes turns to operate, and pushes away one and draws as same, so claim by " push-pull circuit ", final output transformer B6 pieces together them, forms the complete signal waveform that amplifies and delivers to loud speaker, obtains melodized sound.
As can be seen from Figure 2, the collector electrode of BG1 has just produced the intermediate-freuqncy signal of 465kHz, but the intermediate-freuqncy signal of this moment is very faint, if draw the signal of 465kHz from here, needs to amplify in the DRM system again.And through after the intermediate frequency amplification, deliver to the intermediate-freuqncy signal of the 465kHz of wave detector BG3 base stage, amplitude is very big, and through repeatedly not having other frequency component after the filtering, antijamming capability is stronger, can directly draw 465kHz from here and use for the secondary down-conversion of DRM system.Therefore the inventor selects the intermediate-freuqncy signal of drawing 465kHz from the base stage of BG3.
According to DRM receiver system design, from simulating the 465kHz intermediate-freuqncy signal that wireless RF end obtains, need frequency reducing once more, the intermediate-freuqncy signal that obtains 12kHz is to satisfy the input requirement of PC sound card and audio A/D transducer.The present invention selects for use the SA612A of Philips as the mixing chip.Its circuit design as shown in Figure 3.
SA612A is the bistable state mixing chip of a low-power consumption, low noise high-gain, and working range is 0 ~ 500MHz, and two inputs are arranged, and local oscillator can provide supply voltage 4.5V ~ 8V by auto-excitation type LC vibration, passive crystal oscillator or three kinds of modes of active crystal oscillator.The several problems that should be noted that in this circuit design are:
1) the 465kHz intermediate-freuqncy signal is imported, and needs the electric capacity of a stopping direct current, also is in order not influence traditional wireless operate as normal simultaneously;
2) the present invention uses active crystal oscillator as local oscillator, therefore needs the electric capacity such as the C30 of stopping direct current;
3), preferably use sinusoidal wave input, and the amplitude range of SA612A regulation local oscillator is: 200mV in order to guarantee the accuracy of mixing
P-p~ 300mV
P-p, this is the design's key.In the process of repeatedly experiment,, be the result that can not obtain mixing if we find not meet this requirement;
4) the SA612A input signal amplitude should be close with local oscillation signal, and the intermediate-freuqncy signal of introducing from broadcast receiver is greatly about 700mV
P-p~ 880mV
P-pTherefore need decay, R2 and R19 have constituted the most basic electric resistance partial pressure type circuit among Fig. 3, and the signal amplitude after the decay is 240mV
P-p~ 300mV
P-p
5) input needs the pull down resistor R18 of 1.5k ohm, improves the driving force of signal;
6) another input must add filter capacitor ground connection, prevents to disturb, as C27 among Fig. 3;
7) adopt the 5V DC power supply;
8) output connects the 100n capacitor C 28 (SA612A recommendation) of stopping direct current;
9) to obtain the accurate of 12kHz signal in order guaranteeing, to allow output signal pass through the RC low-pass filter circuit, as R20 among Fig. 3, C32 constitutes low-pass first order filter, and cut-off frequency is:
The present invention adopts active crystal oscillator to provide local oscillation signal to SA612A, because the active crystal oscillator of k level is difficult to realize and the cost height, so we select the active crystal oscillator of M level for use, and the method by frequency division obtains the local oscillation signal that the design needs then.As Fig. 4, the supply voltage of the active crystal oscillator of 3.816MHz is 3V, by the partiting dc capacitor C8 of 10n, deliver to the counter 74LS93 of 16 systems, utilize the every counting of 74LS93 during 8 work periods, highest order Q3 will change the operation principle of its polarity, realizes 8 frequency divisions to input signal.Be output as 3.816MHz ÷ 8=477kHz this moment.Because the operating voltage of 74LS93 is 5V, so output also needs to add the capacitor C 9 of stopping direct current.
The signal of the 477kHz that obtain this moment is a square wave, and for the ease of the mixing of SA612A, local oscillation signal is sine wave signal preferably, therefore need change square wave into sine wave.Present embodiment provides this changing function realized of the RC low-pass filter circuit of simple three-stage cascade of a kind of use.Its circuit design as shown in Figure 5, the amplitude of the sine wave that obtains after three filtering descends to some extent.For the scope of the signal amplitude that satisfies SA612A local oscillator input, the sine wave signal that obtains needs decay, through as the bleeder circuit that constitutes of the R5 among Fig. 5 and R21, finally obtained the local oscillation signal of SA612A needs.
More than design needs 2 DC power supply 3V and 5V, considers that receiver is with single power supply, therefore needs electric power management circuit.If select power supply by 3V, just need the DC-DC of Step-Up type, if select then the single power supply of 5V, then need the DC-DC of Step-Down type.Step-Up compares maximum shortcoming with Step-Down be that power is restricted, very flexible, output current behind the DC-DC is limited, driving force dies down, if there are a plurality of IC to need the power supply of high power supply in the design, then electricity shortage will appear in system, causes the unstable or inoperable consequence of system works.Therefore the design we select the 5V single power supply for use, use the DC-DC of Step-Down type to obtain the direct voltage of 3V.LM1117 is an a simplicity of design, easy to use, the IC of fixing output 3V.Its circuit design as shown in Figure 6.
Present embodiment selects for use SA612A as frequency mixer, in the practical application, can also select other mixing chip for use, as the AD8343 chip of ADI company.
Utilize the RF receiving front-end circuit based on discrete analogue device design provided by the invention, analogue audio frequency output interface by DRM receiver test platform, the signal of 12kHz is introduced the sound card of PC, the DRM receiving software that uses microcomputer to load is handled to the received signal, the DRM audio signal restores the most at last, and through PC sound card output audio signal, put outward by sound, can hear than the better station information of traditional analog broadcast receiver tonequality.The radio station voice signal centre frequency of output is about 12kHz, and frequency spectrum mainly concentrates on 12 ± 4.5kHz, and this is because the bandwidth of amplitude modulation broadcasting is 9kHz.Also have frequency information among the figure on other frequency bands, this is the interference signal of PC inside and process RF module input sound card, and these interference signals can be used the digital filter filtering that realizes in the receiving software.
Claims (3)
1. DRM receiver radio frequency receiving front-end circuit, comprise electric power management circuit, simulation broadcast receiver radio-frequency (RF) receiving circuit and double conversion circuit, described simulation broadcast receiver radio-frequency (RF) receiving circuit is in order to receive the DRM radiofrequency signal, and it is downconverted to the intermediate-freuqncy signal of 465kHz, it is characterized in that, described double conversion circuit comprises bleeder circuit, every straight filter circuit, mixting circuit and local oscillation circuit, from the intermediate-freuqncy signal of the 465kHz of simulation broadcast receiver radio-frequency (RF) receiving circuit input through the step-down of bleeder circuit with after the filtering of straight filter circuit, receive mixting circuit, by mixting circuit the intermediate-freuqncy signal of 465kHz is downconverted to the intermediate-freuqncy signal of 12kHz, described local oscillation circuit is with thinking that mixting circuit provides sinusoidal wave local oscillation signal.
2. DRM receiver radio frequency receiving front-end circuit according to claim 1, it is characterized in that, described local oscillation circuit comprises active crystal oscillator, frequency divider and the sinusoidal wave generation circuit that links to each other by successively, frequency of oscillation is after 8 frequency divisions of frequency divider are passed through in the output of the active crystal oscillator of 3.816MHz, through the 477kHz sinusoidal signal after the sinusoidal wave generation circuit generation decay, this signal is the sinusoidal wave local oscillation signal that local oscillation circuit produces again.
3. DRM receiver radio frequency receiving front-end circuit according to claim 1, it is characterized in that, described mixting circuit comprises SA612A mixing chip and RC low-pass filter circuit, and the mixed frequency signal that obtains from SA612A mixing chip is to export after the RC low-pass filter circuit filtering of 15.924kHz through cut-off frequency.
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| CNA2007100612991A CN101136887A (en) | 2007-09-29 | 2007-09-29 | DRM receiver radio frequency receiving front-end circuit |
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| CNA2007100612991A CN101136887A (en) | 2007-09-29 | 2007-09-29 | DRM receiver radio frequency receiving front-end circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102253397A (en) * | 2011-04-22 | 2011-11-23 | 上海迦美信芯通讯技术有限公司 | Novel system architecture of navigation radio frequency (RF) receiver with low power consumption |
| CN101436869B (en) * | 2008-11-27 | 2012-07-04 | 华为技术有限公司 | Equivalent radio frequency belt defect wave filter circuit, radio frequency chip and receiver |
| CN105871490A (en) * | 2016-05-20 | 2016-08-17 | 镇江阿翁电子科技有限公司 | DRM (digital radio mondiale) digital amplitude modulation broadcast receiver |
| CN109817238A (en) * | 2019-03-14 | 2019-05-28 | 百度在线网络技术（北京）有限公司 | Audio signal sample device, acoustic signal processing method and device |
| CN110798361A (en) * | 2019-11-15 | 2020-02-14 | 天津光电通信技术有限公司 | Short-wave direct-sampling system configuration method |
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2007
- 2007-09-29 CN CNA2007100612991A patent/CN101136887A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101436869B (en) * | 2008-11-27 | 2012-07-04 | 华为技术有限公司 | Equivalent radio frequency belt defect wave filter circuit, radio frequency chip and receiver |
| US8385873B2 (en) | 2008-11-27 | 2013-02-26 | Huawei Technologies Co., Ltd. | Equivalent radio frequency notch filter, radio frequency chip, and receiver |
| CN102253397A (en) * | 2011-04-22 | 2011-11-23 | 上海迦美信芯通讯技术有限公司 | Novel system architecture of navigation radio frequency (RF) receiver with low power consumption |
| CN105871490A (en) * | 2016-05-20 | 2016-08-17 | 镇江阿翁电子科技有限公司 | DRM (digital radio mondiale) digital amplitude modulation broadcast receiver |
| CN105871490B (en) * | 2016-05-20 | 2018-07-27 | 镇江乾坤电子科技有限公司 | A kind of DRM digital dispatching systems receiver |
| CN109817238A (en) * | 2019-03-14 | 2019-05-28 | 百度在线网络技术（北京）有限公司 | Audio signal sample device, acoustic signal processing method and device |
| CN109817238B (en) * | 2019-03-14 | 2021-08-24 | 百度在线网络技术（北京）有限公司 | Audio signal acquisition device, audio signal processing method and device |
| CN110798361A (en) * | 2019-11-15 | 2020-02-14 | 天津光电通信技术有限公司 | Short-wave direct-sampling system configuration method |
| CN110798361B (en) * | 2019-11-15 | 2023-03-24 | 天津光电通信技术有限公司 | Short-wave direct-sampling system configuration method |
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Open date: 20080305 |