Summary of the invention
The present invention has designed a kind of tunable bilateral band microwave photon filter based on stimulated Brillouin scattering, on the one handBy biasing feedback control module, electrooptic modulator is carried out to closed-loop control, make the electrooptic modulator in carrier wave holddownOutput dual wavelength Brillouin pumping; Be carried on the other hand the frequency of radiofrequency signal on electrooptic modulator by change, Ke YigaiBecome modulation sideband, residing frequency location, thereby realize tuning to dual wavelength pump frequency interval, by two pairs of Brillouins' spectrumsActing in conjunction finally on filter response, form two passbands that amplitude is consistent that two centre frequencies can be tuning. Er-doped lightFiber amplifier carries out power amplification to dual wavelength pumping, thereby realizes the stopband rejection ratio of superelevation. Experimental result shows,1.8GHz is tuning to realizing within the scope of 20GHz, and stopband rejection ratio all exceedes 35dB simultaneously.
The present invention is a kind of tunable bilateral band microwave photon filter based on stimulated Brillouin scattering, this wave filter bagDrawn together signal source unit (1), filtering signal generation unit (2), multi wavelength pumping unit (3), biasing feedback control module (4) andThe first photodetector (5);
Described signal source unit (1) carries light wave and pumping light wave for generation of light; Signal source unit includes light source in (1)(1A), the first isolator (1B) and the first coupler (1C), and light source (1A), the first isolator (1B) and the first coupler (1C)Input be in turn connect, an output of the first coupler (1C) is connected with the second Polarization Controller (2A), first be coupledAnother output of device (1C) is connected with the first Polarization Controller (3A);
Described filtering signal generation unit (2) is for required frequency range is optionally amplified, and output selectivity is putLight wave after large; In filtering signal generation unit (2), include the second Polarization Controller (2A), phase-modulator (2B), secondIsolator (2C), single-mode fiber (2D), circulator (2E) and dispersion compensator (2F), and the second Polarization Controller (2A), phase placeModulator (2B), the second isolator (2C), single-mode fiber (2D), circulator (2E) and dispersion compensator (2F) be for being connected in turn,The output of dispersion compensator (2F) is connected with the first photodetector (5); 1 port of circulator (2E) and Er-doped fiber amplifyThe output of device (3E) connects, and 2 ports of circulator (2E) are connected with one end of single-mode fiber (2D), 3 ends of circulator (2E)Mouth is connected with the input of dispersion compensator (2F);
The double sideband modulation signal that described multi wavelength pumping unit (3) suppresses for the narrow ripple of stable output; Multiple wavelength pumpUnit, Pu (3) includes the first Polarization Controller (3A), electrooptic modulator (3C), the second coupler (3D), Er-doped fiber amplificationDevice (3E) and signal generator (3B); Signal generator (3B) is connected with 1 port of electrooptic modulator (3C), the first Polarization ControlDevice (3A) is connected with 2 ports of electrooptic modulator (3C), and 3 ports of electrooptic modulator (3C) are connected with the second coupler (3D),One output of the second coupler (3D) is connected with the input of erbium-doped fiber amplifier (3E), another of the second coupler (3D)Output is connected with the second photodetector (4A), 1 port of the output of erbium-doped fiber amplifier (3E) and circulator (2E)Be connected, 4 ports of electrooptic modulator (3C) are connected with biasing feedback control module (4B);
Described biasing feedback control module (4) is the biasing voltage signal at minimum bias point for stable output; Setover backFeedback control module (4) include the second photodetector (4A) and setover control module (4B), the second photodetector (4A) andPolarization Modulation module (4B) is for connecting in turn; 4 ports of described electrooptic modulator (3C) and bias control circuit module (4B) connectConnect;
Described the first photodetector (5) is for output filtering microwave signal RF after treatmentout。
The advantage that the present invention is based on the tunable bilateral band microwave photon filter of stimulated Brillouin scattering is:
1. on electrooptic modulator 3C, use biasing control module 4C, make the described electrooptic modulator 3C moment in carrier waveHolddown, thus realize high stopband rejection ratio, improve the stability of filter response.
2. the tunable bilateral band microwave photon filter of the present invention's design has been considered stimulated Brillouin scattering (SBS) simultaneouslyThe impact of gain spectral and decay spectra, adopts the frequency of biasing control module 4C and the tuning dual wavelength pumping of coordinating of electrooptic modulator 3CRate position, realizes two passband filtering based on stimulated Brillouin scattering filter tunable that band-pass behavior is basically identical.
3. before injecting single-mode fiber 2D, dual wavelength pump light uses high performance erbium-doped fiber amplifier 3E, compensating lightLoss in road, makes filter response realize narrower bandwidth and higher stopband rejection ratio.
4. the second road light wave L that the present invention exports multi wavelength pumping unit 33D_2Through photodetector, 4A is converted to radio frequencySignal, by the frequency analysis of biasing control module 4C, thus high performance the moving of bias voltage of having realized electrooptic modulator 3CState regulates, and is conducive to improve the stability of filter response.
Detailed description of the invention
Below in conjunction with drawings and Examples, the present invention is described in further detail.
Shown in Figure 2, a kind of tunable bilateral band microwave photon based on stimulated Brillouin scattering of the present invention's designWave filter, it includes signal source unit 1, filtering signal generation unit 2, multi wavelength pumping unit 3, biasing feedback control module4 and first photodetector 5.
Described signal source unit 1 carries light wave and pumping light wave for generation of light.
Described filtering signal generation unit 2 is for required frequency range is optionally amplified, and output selectivity amplifiesAfter light wave.
The double sideband modulation signal that described multi wavelength pumping unit 3 suppresses for the narrow ripple of stable output.
Described biasing feedback control module 4 is the biasing voltage signal at minimum bias point for stable output.
Described the first photodetector 5 is for output filtering microwave signal RF after treatmentout. The first photodetector 5 selectsWith the photodetector of 50GHz investigative range.
Shown in Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, the tunable bilateral band that the present invention is based on stimulated Brillouin scattering is micro-The device connection description of glistening light of waves subfilter:
Shown in Fig. 5 in the present invention, in signal source unit 1, include light source 1A, the first isolator 1B and the first couplingDevice 1C, and the input of light source 1A, the first isolator 1B and the first coupler 1C is for being connected in turn, the first coupler 1C's is one defeatedGo out end and be connected with the second Polarization Controller 2A, another output of the first coupler 1C is connected with the first Polarization Controller 3A. LightThe ORION semiconductor laser module that source 1A selects RIO company to produce, centre wavelength is 1550.023nm, Output optical power is22mW。
Shown in Fig. 6 in the present invention, in filtering signal generation unit 2, include the second Polarization Controller 2A, phase place tuneDevice 2B processed, the second isolator 2C, single-mode fiber 2D, circulator 2E and dispersion compensator 2F, and the second Polarization Controller 2A, phase placeModulator 2B, the second isolator 2C, single-mode fiber 2D, circulator 2E with dispersion compensator 2F for being connected in turn, dispersion compensatorThe output of 2F is connected with the first photodetector 5. 1 port of circulator 2E and the output of erbium-doped fiber amplifier 3E connectConnect, 2 ports of circulator 2E are connected with one end of single-mode fiber 2D, 3 ports of circulator 2E and the input of dispersion compensator 2FEnd connects. The MPZ-LN-20 model that phase-modulator 2B selects Photline company to produce, bandwidth is 20GHz.
Shown in Fig. 3 in the present invention, multi wavelength pumping unit 3 includes the first Polarization Controller 3A, electrooptic modulator3C, the second coupler 3D, erbium-doped fiber amplifier 3E and signal generator 3B; 1 of signal generator 3B and electrooptic modulator 3CPort connects, and the first Polarization Controller 3A is connected with 2 ports of electrooptic modulator 3C, 3 ports and second of electrooptic modulator 3CCoupler 3D is connected, and an output of the second coupler 3D is connected with the input of erbium-doped fiber amplifier 3E, the second couplerAnother output of 3D is connected with the second photodetector 4A, 1 end of the output of erbium-doped fiber amplifier 3E and circulator 2EMouth is connected, and 4 ports of electrooptic modulator 3C are connected with biasing feedback control module 4B. Electrooptic modulator 3C selects Optilab public affairsThe IM-1550-20-PM model that department produces, effective bandwidth is 20GHz.
Shown in Fig. 4 in the present invention, biasing feedback control module 4 includes the second photodetector 4A and biasing is controlledModule 4B, the second photodetector 4A with Polarization Modulation module 4B for being connected in turn; 4 ports of described electrooptic modulator 3C are with inclined to one sidePutting control circuit module 4B connects. The second photodetector 4A selects the photodetector of 50MHz investigative range.
The light channel structure of signal source unit 1 is:
Shown in Figure 5, the light source 1A in signal source unit 1 is used for exporting the continuous light wave of narrow linewidth, and its operation wavelength is C+ L-band (1530nm~1625nm); The first isolator 1B is for stoping the reverse passback of light source continuous light; The first coupler 1C(50/50) be the carrier wave (L of two bundle constant powers by the narrow linewidth continuous light wavelength-division of light source 1A output1C_1、L1C_2) output, L1C_1DefeatedGo out to the second Polarization Controller 2A, L1C_2Export to the first Polarization Controller 3A.
In the present invention, light source 1A is semiconductor laser, and the centre frequency of the laser light wave of its output is fc, this laserLight wave is divided into two-beam ripple after the first isolator 1B, and the first bundle light wave is designated as L1C_1, the second bundle light wave is designated as L1C_2。
The light channel structure of filtering signal generation unit 2 is:
Shown in Figure 6, the second Polarization Controller 2A is to the first bundle light wave L1C_1Carry out polarization state control, for reducing partiallyThe relevant loss of shaking, thereby output polarization control light wave L2AGive phase-modulator 2B.
Phase-modulator 2B is by pending radiofrequency signal RFinBe modulated at Polarization Control light wave L2AUpper, form two phase placesContrary sideband modulation ripple, i.e. S1For lower sideband modulating wave, S2For upper side band modulating wave (as shown in Figure 6A), thus output phaseLight wave L after modulation2BGive the second isolator 2C.
The second isolator 2C is on the one hand by light wave L after phase-modulation2BTransfer to single-mode fiber 2D; On the other hand that pumping is saturatingPenetrate light wave L2D_1Isolate.
In single-mode fiber 2D, the dual wavelength pumping light wave L of inverse injection3CProduce the stokes wave that oppositely passes ripple with anti-Stokes wave, and form gain1 between corresponding Stokes gain region, gain2 and anti-Stokes wave loss intervalLoss1, loss2; And to light wave L after phase-modulation2BModulation sideband, selectively amplify or decay, finally by after treatmentLight wave L2D_2Export to a circulator 2E.
Circulator 2E first aspect is used for the dual wavelength pumping light wave L after amplifying3CIn inverse injection single-mode fiber 2D; TheTwo aspects are by light wave L after treatment2D_2Be transferred to dispersion compensator 2F.
Dispersion compensator 2F is to light wave L after treatment2D_2Carry out dispersion compensation, be compensated rear light wave L2F, after this compensationLight wave L2FReceived by the first photodetector 5.
In the present invention, be carried in the pending radiofrequency signal RF on phase-modulator 2BinCentre frequency be designated as f.By the optical signal L after phase-modulator 2B modulation2BInject single-mode fiber (SMF) 2D. For fear of anti-phase transmission light waveDisturb, by the second isolator 2C be placed on phase-modulator 2B after.
Shown in Fig. 6 A, phase-modulator 2B produces two centre frequencies and is positioned at fc+ f and fcThe modulation sideband, of-f, underSideband modulation ripple S1, upper side band modulating wave S2, described S1And S2Single spin-echo, amplitude equate.
In Stimulated Brillouin Scattering Process, the stokes wave of forward and reverse stokes wave are to exist simultaneously, therefore the pass of the Brillouin of single wavelength pumping spectrum is:
The relation of Brillouin's spectrum of above-mentioned single wavelength pumping comes from the 21st volume " OPTICSEXPRESS " on January 28th, 2013In " Anultrawidetunablerangesinglepassbandmicrowavephotonicfi lter is disclosedBasedonstimulatedBrillouinscattering ", translation is: a kind of single-pass band of super large tuning range is excitedBrillouin scattering microwave photon filter. Formula (1) in the document and formula (2). Wherein, g0For brillouin gain coefficientPeak value, IpFor Brillouin's pumping intensity of wave, Δ f is the side-play amount that departs from Brillouin shift spectrum centre frequency, ΓBFor the line of SBSWide, j is imaginary part.
In the present invention, will produce dual wavelength pumping in the electrooptic modulator 3C of carrier wave holddown, so as Fig. 6 AInstitute is shown with two brillouin gain spectrums and two Brillouin's decay spectras. Therefore the upper side band of the modulation signal of phase-modulator 2BModulating wave S1Can be at fc-f-(fp2-fB) and fc-f-(fp1-fB) gain of two frequency location experience amplifies, same lower sideband modulationRipple S2Can be at fp1+fB-(fc+ f) and fp2+fB-(fc+ f) two frequency location experience attenuation effect, wherein fp1It is the first pump lightThe centre frequency of ripple, fp2Be the centre frequency of the second pumping light wave, fBFor the centre frequency of Brillouin shift, in single-mode fiberIts value is 10.9GHz left and right (variation of environment temperature, humidity etc. can cause it to change). Therefore entering the first photodetectorBefore 5, the frequency location between the gain region of electric-field intensity and stimulated Brillouin scattering (SBS) and between decay area is relevant.
Consider the situation of the small signal modulation of phase-modulator 2B, and dual wavelength Brillouin pumping there is equal intensity.The microwave radio signal RF of output after the first photodetector 5outThe high-order of dc noise composition and beat signal will be ignored, electric field emphasizes that I (t) is:
I (t) represents the rear light wave L of compensation2FThe electric-field intensity of beat signal;
J0Represent zeroth order Bessel function;
J1Represent single order Bessel function;
m2BRepresent the modulation depth of phase-modulator 2B;
G(fm+fB-f) represent first pumping light wave pump1 produce stimulated Brillouin scattering (SBS) gain region between to modulationThe impact of signal;
G(fB-fm-f) represent second pumping light wave pump2 produce stimulated Brillouin scattering (SBS) gain region between to modulationThe impact of signal;
Α(fm+fB-f) represent first pumping light wave pump1 produce stimulated Brillouin scattering (SBS) decay area between exchangeThe impact of signal processed;
Α(fB-fm-f) represent second pumping light wave pump2 produce stimulated Brillouin scattering (SBS) decay area between exchangeThe impact of signal processed;
T represents time domain;
Φ(fm+fB-f) represent that gain1 is combined the rear impact on modulating signal phase with loss2;
Φ(fB-fm-f) represent that gain2 is combined the rear impact on modulating signal phase with loss1.
The response amplitude of the tunable bilateral band microwave photon filter designing in the present invention is:
The response amplitude of the wave filter characterizing according to formula (4), the filter response of its each passband is identical, and by BrillouinThe coefficient of gain and loss determines jointly. The corresponding peak value of biobelt lays respectively at f=fm+fBAnd f=fB-fm. Due to Electro-optical ModulationThe driving frequency f of device 3CmCan control by signal generator 3B, therefore there is the filter characteristic of tunable bilateral band.
The light channel structure of dual wavelength pumping source unit 3 is:
Shown in Figure 3, the first Polarization Controller 3A in dual wavelength pumping source unit 3 is to the second bundle light wave L1C_2Carry outPolarization state control, for reducing the loss that polarization is relevant, the light carrier L after output polarization state control3AGive electrooptic modulator 3C.
Under the radiofrequency signal of the frequency-tunable providing at signal generator 3B, electrooptic modulator 3C is to after polarization state systemLight carrier L3ASpectrum modulate, output frequency position tunable dual wavelength Brillouin pumping light wave L3CTo the second couplingDevice 3D, carrier wave is suppressed modulated light wave L by the second coupler 3D3CBe divided into two-way, i.e. first via light wave L3D_1With the second road light waveL3D_2;L3D_1Inject erbium-doped fiber amplifier 3E, the dual wavelength Brillouin pumping light wave L after output is amplified3EBy circulator 2E1 port inverse injection single-mode fiber 2D, L3D_2Export to the second photodetector 4A.
Described dual wavelength pumping source unit 3 is in light path, at driving frequency fmLower electrooptic modulator 3C can produce carrier waveThe double sideband modulation signal suppressing, this double sideband modulation signal is designated as respectively pump1, pump2. Dual wavelength Brillouin pumping light waveL3CIn the pump1 centre frequency of ordering be fc+fm, the centre frequency f that pump2 is orderedc-fm. So, can be at upper and lower sidebandSpectral regions form the two pairs of gain regions and decay area, thereby in frequency response, be mapped to the logical of two stopband rejection ratio superelevationBand response.
In the present invention, the luminous power that the second coupler 3D selects is than being 9:1. Therefore first via light wave L3D_1With the second tunnelLight wave L3D_2Luminous power than for 9:1. By first via light wave L3D_1As SBS dual wavelength pumping wave, by the second road light wave L3D_2DoFor the input signal of feedback control module, can realize effective utilization of energy.
In the present invention, by the frequency of control signal generator 3B output radiofrequency signal, control Brillouin's pumpingFrequency location, realizes the tuning object of filter pass band centre frequency thereby reach. Signal generator 3B selects Agilent company rawThe E8267D-520 model of producing, frequency 250KHz~20GHz.
Biasing feedback control module 4:
In the present invention, it is upper that design biasing feedback control module 4 is carried in electrooptic modulator 3C, makes its transmission curve stableOn minimum bias point, thus the double sideband modulation signal that the narrow ripple of electrooptic modulator stable output is suppressed. Stable filteringResponse output as shown in figure 10.
Shown in Fig. 2, Fig. 4, biasing feedback control module 4 includes the second photodetector 4A and biasing control module4B. The second photodetector 4A is used for receiving the second road light wave L3D_2, and to the second road light wave L3D_2Process rear output radio frequencySignal RF4A. Biasing control module 4B is used for radiofrequency signal RF4ACarry out filtering high frequency-harmonic wave detection-biased electrical swagingAfter formula-bias-adjusted is processed, output offset voltage signal V4BGive electrooptic modulator 3C.
Wherein, biasing control module 4B is believed by modulation signal filter circuit 4B1, center processor circuit 4B2, low frequency radio frequencyNumber produce circuit 4B3 and bias voltage treatment circuit 4B4 composition. The signal of telecommunication of center processor circuit 4B2 is believed with modulation respectivelyThe signal of telecommunication of number filter circuit 4B1, low frequency radio frequency signal generating circuit 4B3 and bias voltage treatment circuit 4B4 connects. DescribedBiasing control module 4B is integrated on a circuit board.
Biasing control module 4C:
Shown in Fig. 4 A~4E, biasing control module 4C is the circuit structure that electronic component forms. Except selectingNeed outside the connection between chip, the pin connected mode of chip is conventional connection.
Shown in Fig. 4 D, Fig. 4 E, what the center processor chip in center processor circuit 4B2 was selected isTMS320F2812 chip (being designated as U0). Each pin in center processor circuit 4B2 is connected to:
45 pin of chip U0,46 pin, 47 pin, 28 pin, 29 pin, 40 pin, 41 pin respectively with 10 of active filter chip U3Pin, 7 pin, 6 pin, 19 pin, 15 pin, 14 pin, 13 pin connect, 48 pin of chip U0,49 pin, 50 pin, 53 pin, 55 pin, 59 pin, 60Pin, 87 pin are connected with 16 pin, 15 pin, 14 pin, 13 pin, 12 pin, 11 pin, 10 pin, 9 pin of waveform generator chip U6 respectively. Core109 pin of sheet U0 are connected with 6 pin of FV convertor chip U5.
2 pin, 3 pin of chip U0 are connected with 1 pin, 7 pin of bilateral operational amplifier chip U1 respectively. 4 pin of chip U0 with7 pin of bilateral operational amplifier chip U2 connect.
5 pin, 6 pin, 7 pin, 8 pin, 9 pin, 12 pin, 15 pin, 176 pin, 175 pin and 165 pin connect in analog; 17 pin, 19 pin, 32Pin, 38 pin, 129 pin, 120 pin, 113 pin, 105 pin, 99 pin, 52 pin, 58 pin, 70 pin, 78 pin, 86 pin, 167-174 pin, 163Pin, 152 pin and 142 pin connect digitally. 1 pin connects simulation 3.3V voltage, and through capacitor C 66, capacitor C 67 and the capacitor C 68 of series connectionAfter connect in analog; 2 pin are connected with 1 pin of bilateral operational amplifier U1 (selecting LM358 chip) after resistance CD1; 2 pin are through two utmost pointsAfter pipe D2, meet digital 3.3V; 2 pin connect digitally after diode D3; After 2 foot meridian capacitor C14, connect digitally.
3 pin are connected with 7 pin of bilateral operational amplifier U1 (selecting LM358 chip) after resistance CD2; 2 pin are through diodeAfter D4, meet digital 3.3V; 2 pin connect digitally after diode D5; After 2 foot meridian capacitor C15, connect digitally;
4 pin are connected with 7 pin of bilateral operational amplifier U2 (selecting LM358 chip) after resistance CB2; 2 pin are through diodeAfter D6, meet digital 3.3V; 2 pin connect digitally after diode D7; After 2 foot meridian capacitor C16, connect digitally.
Low frequency radio frequency signal generating circuit 4B3 selects AD9834 chip U6. Shown in Fig. 4 C, low frequency radio frequency signal producesThe circuit of raw circuit 4B3 is connected to: 1 pin is ground connection after capacitor C in parallel 25, resistance R 69; Ground connection after 2 foot meridian capacitor C26; 3 pinAfter capacitor C 23, be connected with 4 pin, 5 pin, after connect 3.3V voltage, and after capacitor C in parallel 60, polar capacitor CT9 ground connection; 6 pinGround connection after capacitor C in parallel 22, capacitor C 21; 7 pin connect digitally; 8 pin are through being connected with 3 pin of active crystal oscillator U8; 9 pin meet U0,For frequency is selected input; 9 pin are ground connection after resistance R 12; 10 pin meet U0, are Selecting phasing input; 10 pin are after resistance R 13Ground connection; 11 pin meet U0, for activating high-order digit input; 12 pin meet U0, for activating high-order digit input; 13 pin meet U0, forDigital serial port input; 14 pin meet U0, are serial clock input; 15 pin meet U0, for activating control input end, status; 16 pin connectU0 is logic output; Ground connection after 17 foot meridian capacitor C17; 17 pin connect 19 pin after resistance R 16; 18 pin connect in analog; 19 pin are through stringAfter capacitor C 27, resistance CA and the resistance R 18 of connection, be connected with 2 pin of bilateral operational amplifier U7 (selecting LM358 chip); 19 pinResistance R 17 through series connection is connected with ground; 20 pin are ground connection after capacitor C in parallel 19, variable resistor R14, by Sub-miniature B P5 withGround connects; P5 is as the test interface of chip.
1 pin in low frequency radio frequency signal generating circuit chip U7 (selecting LM358 chip) after resistance R 19 with 2 pin phasesConnect; 1 pin is connected to the ground after resistance R 15; 1 pin is connected with 6 pin through capacitor C 28, the resistance R 62 of series connection; 2 pin are through the resistance of series connectionAfter R18, resistance CA, capacitor C 27, be connected to the ground through resistance R 17; 2 pin after the resistance R 18, resistance CA, capacitor C 27 of series connection with19 pin of Direct Digital synthesis chip U6 (selecting AD9834 chip) are connected; 3 pin are ground connection after capacitor C in parallel 24, resistance R 9;3 pin connect 5V voltage after the resistance R 11 of series connection; 4 pin ground connection; 5 pin are ground connection after capacitor C in parallel 18, resistance R 64; 5 pin are through stringAfter the variable resistor R65 of connection, be connected with the bias voltage Vbias2 of bilateral operational amplifier U4 (selecting LM358 chip) output; 6Pin is connected with 7 pin through the variable resistor R63 of series connection; 6 pin are through the resistance R 62 of series connection, capacitor C 28, the rear ground connection of resistance R 15; 6 pin warpsThe resistance R 62 of series connection, is connected with 1 pin after capacitor C 28; 7 pin are connected with electrooptic modulator 3C; 8 pin are through polar capacitor in parallelCT16, the rear ground connection of capacitor C 29; 8 pin connect 5V voltage.
Bias voltage treatment circuit is selected LM331 chip (U5). Shown in Fig. 4 B, the connection of bias voltage treatment circuitFor: 1 pin is ground connection after capacitor C T8 in parallel, resistance R 1; 1 pin through series connection resistance CG1, R32 after with bilateral operational amplifier core5 pin of sheet U4 (selecting LM358 chip) join; 2 pin are connected to the ground through resistance R s2, the variable resistor Rs1 of series connection; 3 pin and 4 pinGround connection after being connected; 5 pin are ground connection after polar capacitor Ct; 5 pin connect 5V voltage after resistance R t; 6 pin connect 5V electricity after resistance R 52Press; 6 pin meet U0 after the resistance CF, capacitor C 48 of series connection, are impulse modulation interface; 7 pin are connected with 8 pin after resistance R 46; 7 pinAfter resistance R 46, connect 5V voltage; 7 pin are ground connection after the resistance R 46, R51 of series connection; 8 pin connect 5V voltage; After 8 foot meridian capacitor C47, connectGround.
1 pin process in the bilateral operational amplifier chip U4 (selecting LM358 chip) of bias voltage transformation applications canPower transformation resistance R58 is connected with 6 pin; 1 pin joins through variable resistor R66 and 2 pin; 1 pin is through variable resistor R66, the resistance R 53 of series connectionRear ground connection; 2 pin are through resistance R 53 ground connection; 3 pin connect 5V voltage after resistance R 29; 4 pin ground connection; 5 pin are through the resistance of series connection1 pin of R32, resistance CG1 and FV convertor U5 (selecting LM331 chip) joins; 6 pin are through the variable resistor R67 of series connectionJoin with 7 pin; 6 pin are output offset voltage Vbias2 after variable resistor R67, the resistance CG2 of series connection; 8 pin are through polarity in parallelCapacitor C T15, the rear ground connection of capacitor C 50; 8 connect 5V voltage.
Modulation signal filter circuit 4B1 selects LM358 chip (U2). Shown in Fig. 4 A, modulation signal filter circuit 4B1Each pin be connected to: 1 pin is connected with 6 pin through resistance R 21; 1 pin joins through resistance R 21, variable resistor R30 and 7 pin of series connection;1 pin is connected with 2 pin through variable resistor R24; 1 pin is ground connection after the variable resistor R24, resistance R 23, capacitor C 30 of series connection; 3 pin warpsThe rear ground connection of resistance R 20; 3 pin join with 5V power supply after resistance R 22; 4 pin ground connection; 5 pin are ground connection after resistance R 26; 5 pin are through resistanceAfter R25, join with 5V power supply; 6 pin join through variable resistor R30 and 7 pin; 7 pin are through capacitor C 32, the resistance CB1 of series connection, reversal connectionDiode D9 joins with-5V power supply; Diode D8 and 5V power supply that 7 pin through the capacitor C 32, resistance CB1 of series connection, are just connecing join; 7Pin joins through 5 pin of capacitor C 32, resistance CB1 and the universal active filter (selecting MAX261 chip) of series connection; 7 pin are through series connection23 pin of capacitor C 32, resistance CB1 and active filter (selecting MAX261 chip) join; 7 pin are ground connection after resistance R 31; 7Pin is output signal Signal2 after resistance CB2; 8 pin are ground connection after capacitor C in parallel 34, polar capacitor CT11; 5 pin connect 5V electricitySource.
1 pin in active filter chip U3 (selecting MAX261 chip) meets U0; The logical output of band; 6 pin meet U0; DataInput; 7 pin meet U0; Address input end; 8 pin and 12 pin join; 9 pin connect after capacitor C in parallel 37, polar capacitor CT12Ground; 9 pin connect 5V power supply; 10 pin meet U0; Address input end; 11 pin join with 18 pin after crystal oscillator X2; 13 pin meet U0; Address inputEnd; 14 pin meet U0; Address input end; 15 pin meet U0; Write energy input; 16 pin are after capacitor C in parallel 39, polar capacitor CT13Ground connection; Connect-5V of 16 pin power supply; 17 pin ground connection; 19 pin meet U0; Data input pin; 21 pin meet U0; The logical output of band.
U1(LM358)
1 pin in the bilateral operational amplifier chip U1 (selecting LM358 chip) processing in filtering signal amplification is through resistanceAfter R36, join with 2 pin; 1 pin after the resistance R 36, resistance R 34, resistance CC1, capacitor C 40 of series connection with universal active filter U3(MAX261) 1 pin joins; 1 pin after the resistance R 36, resistance R 34, resistance CC1, capacitor C 40, electric capacity R27 of series connection with ground phaseConnect; Filtering signal 1KOuttoDSP after 1 pin output is amplified; 3 pin are ground connection after capacitor C in parallel 41, resistance R 39; 3 pin warpsAfter variable resistor R36, connect 5V power supply; 4 pin ground connection; 5 pin are ground connection after capacitor C in parallel 45, resistance R 45; 5 pin are through variable resistorAfter R44, connect 5V power supply; 6 pin are connected with 7 pin through variable resistor R42; 6 pin are through resistance R 43, resistance CC2, capacitor C 42, the electricity of series connectionGround connection after resistance R28; 6 pin after the resistance R 43, resistance CC2, capacitor C 42 of series connection with universal active filter U3's (MAX261)21 pin join; Filtering signal 2KOuttoDSP after 7 pin outputs are amplified; 8 pin are through capacitor C in parallel 61, polar capacitor CT14Rear ground connection; 8 pin connect 5V power supply.