CN105429656A - Signal processing device based on shortwave broadband reception demodulation front end - Google Patents
Signal processing device based on shortwave broadband reception demodulation front end Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
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- H04B1/1638—Special circuits to enhance selectivity of receivers not otherwise provided for
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Abstract
The invention relates to a signal processing device based on a shortwave broadband reception demodulation front end. The signal processing device comprises an attenuation regulator, a high-pass filter, a shortwave frequency-selection band-pass filter, a pre-amplifier, an automatic gain controller, a secondary amplifier, an AD sampling circuit, and a signal processor. According to the strength of signals acquired by the AD sampling circuit, the secondary amplifier is selectively accessed, high-gain amplification of weak reception signals is performed via a two-stage amplifier, and the secondary amplifier can be bypassed when the signals are strong so that the loss of electric energy and introduction of noises are reduced. The attenuation regulator and the automatic gain controller are cooperatively employed in the manner of two-stage attenuation so that phenomena of loss of useful signals due to over-large attenuation amount of a pre-stage attenuation regulator and saturation due to over-large input of signals of the secondary amplifier are effectively avoided. According to the signal processing device, in the severe electromagnetic environment, high-quality and undeformed pure signals can be demodulated from the weak useful signals.
Description
Technical field
The present invention relates to signal processing apparatus field, particularly relate to a kind of signal processing apparatus based on short wave bandwidth receiving demodulation front end.
Background technology
Along with the progress of the communication technology and the continuous increase of business demand, short wave bandwidth receives the important directions progressively becoming short wave communication.The demodulating process of short-wave reception equipment is mainly divided into: the process of receiving front-end radiofrequency signal forms with the signal receiving two parts receiving rear class.Process due to receiving front-end radiofrequency signal is positioned at receiver foremost, and the quality of signal processing technology directly decides the quality of whole performance of receiving system.
But, we are not difficult to find to make a general survey of short wave bandwidth receiving equipment outside Present Domestic: the useful signal intensity exported by receiving demodulation equipment still has very large definition demodulation space to promote, on Vehicles Collected from Market, the signal processing technology of short wave broadband receiver radio-frequency front-end is comparatively general, when receiving equipment is in comparatively severe electromagnetic environment, be difficult to demodulate comparatively faint useful signal, thus cause transmission data imperfect or Loss Rate is higher.
Summary of the invention
Based on this, when being necessary to be in comparatively severe electromagnetic environment for receiving equipment, be difficult to demodulate the problem of comparatively faint useful signal, a kind of signal processing apparatus based on short wave bandwidth receiving demodulation front end is provided.
Based on a signal processing apparatus for short wave bandwidth receiving demodulation front end, comprise Attenuation adjustable device, high pass filter, shortwave frequency-selecting band pass filter, preamplifier, automatic gain controller, second level amplifier, AD sample circuit and signal processor;
Described Attenuation adjustable device is through described high pass filter, described shortwave frequency-selecting band pass filter is connected with described preamplifier, described preamplifier is connected with described AD sample circuit through described automatic gain controller, input signal is successively via described Attenuation adjustable device, described high pass filter, described shortwave frequency-selecting band pass filter, described preamplifier, export after described automatic gain controller and described AD sample circuit, described signal processor respectively with described Attenuation adjustable device, described high pass filter, described shortwave frequency-selecting band pass filter, described automatic gain controller and described AD sample circuit connect,
Wherein, described signal processor controls the attenuation size of described Attenuation adjustable device and described automatic gain controller according to the signal strength signal intensity that described AD sample circuit collects, the signal strength signal intensity that described AD sample circuit collects is less, then to control the attenuation of described Attenuation adjustable device and described automatic gain controller less for described signal processor;
Described second level amplifier is selectivity place in circuit, when the signal strength signal intensity detecting that described AD sample circuit collects is less than predetermined threshold value, controlling described second level amplifier accesses between described automatic gain controller and described AD sample circuit, otherwise, described by described second level amplifier bypass.
Selectivity access second level amplifier is carried out according to the signal strength signal intensity size that AD sample circuit collects, so both by dual-stage amplifier, faint Received signal strength can be carried out the amplification of high-gain, to obtain the signal of some strength for late-class circuit demodulation, again can when signal is stronger by second level amplifier bypass, with the introducing of the loss and noise that subtract electric energy.Simultaneously by signal processor control that Attenuation adjustable device and automatic gain controller two-stage decay with the use of, can the excessive damage late-class circuit of anti-stop signal, and it is excessive and cause useful signal Loss and second level amplifier to occur saturated phenomenon because input signal is excessive to effectively prevent attenuation because of prime Attenuation adjustable device.In severe electromagnetic environment, comparatively faint useful signal can be demodulated high-quality and the purified signal that can not distort by said signal processing device, and is sent to the process of rear class demodulating equipment by the mode of digital differential.
Accompanying drawing explanation
Fig. 1 is the signal processing apparatus structural representation based on short wave bandwidth receiving demodulation front end in one embodiment of the invention;
Fig. 2 is the electrical block diagram of Attenuation adjustable device and high pass filter in the embodiment of the present invention;
Fig. 3 is the electrical block diagram of embodiment of the present invention intermediate waves frequency-selecting band pass filter;
Fig. 4 is the electrical block diagram of preamplifier in the embodiment of the present invention;
Fig. 5 is the electrical block diagram of AD sample circuit in the embodiment of the present invention;
Fig. 6 is the signal processing apparatus structural representation based on short wave bandwidth receiving demodulation front end in another embodiment of the present invention;
Fig. 7 is the electrical block diagram of protective circuit in the embodiment of the present invention, Attenuation adjustable device and high pass filter;
Fig. 8 is the power-switching circuit structural representation that in the embodiment of the present invention, 12V turns 5V;
Fig. 9 is the power-switching circuit structural representation that in the embodiment of the present invention, 5V turns 3.3V;
Figure 10 is that in the embodiment of the present invention, 12V turns the power-switching circuit structural representation that 11V turns 1.9V again.
Embodiment
In order to further set forth the technological means that the present invention takes and the effect obtained, below in conjunction with accompanying drawing and preferred embodiment, to technical scheme of the present invention, carry out clear and complete description.
Refer to Fig. 1, it is the signal processing apparatus structural representation based on short wave bandwidth receiving demodulation front end in one embodiment of the invention.
A kind of signal processing apparatus based on short wave bandwidth receiving demodulation front end, it is characterized in that, comprise Attenuation adjustable device 100, high pass filter 110, shortwave frequency-selecting band pass filter 120, preamplifier 130, automatic gain controller 140, second level amplifier 150, AD sample circuit 160 and signal processor 170;
Described Attenuation adjustable device 100 is through described high pass filter 110, described shortwave frequency-selecting band pass filter 120 is connected with described preamplifier 130, described preamplifier 130 is connected with described AD sample circuit 160 through described automatic gain controller 140, input signal is successively via described Attenuation adjustable device 100, described high pass filter 110, described shortwave frequency-selecting band pass filter 120, described preamplifier 130, export after described automatic gain controller 140 and described AD sample circuit 160, described signal processor 170 respectively with described Attenuation adjustable device 100, described high pass filter 110, described shortwave frequency-selecting band pass filter 120, described automatic gain controller 140 and described AD sample circuit 150 connect,
Wherein, described signal processor 170 controls the attenuation size of described Attenuation adjustable device 100 and described automatic gain controller 140 according to the signal strength signal intensity that described AD sample circuit 160 collects, the signal strength signal intensity that described AD sample circuit 160 collects is less, then to control the attenuation of described Attenuation adjustable device 100 and described automatic gain controller 140 less for described signal processor 170;
Described second level amplifier 150 is selectivity place in circuit, when the signal strength signal intensity detecting that described AD sample circuit 160 collects is less than predetermined threshold value, controlling described second level amplifier 150 accesses between described automatic gain controller 140 and described AD sample circuit 160, otherwise, described by amplifier 150 bypass of the described second level.
Selectivity access second level amplifier is carried out according to the signal strength signal intensity size that AD sample circuit collects, so both by dual-stage amplifier, faint Received signal strength can be carried out the amplification of high-gain, to obtain the signal of some strength for late-class circuit demodulation, again can when signal is stronger by second level amplifier bypass, with the introducing of the loss and noise that subtract electric energy.Simultaneously by signal processor control that Attenuation adjustable device and automatic gain controller two-stage decay with the use of, can the excessive damage late-class circuit of anti-stop signal, and it is excessive and cause useful signal Loss and second level amplifier to occur saturated phenomenon because input signal is excessive to effectively prevent attenuation because of prime Attenuation adjustable device.In severe electromagnetic environment, comparatively faint useful signal can be demodulated high-quality and the purified signal that can not distort by said signal processing device, and is sent to the process of rear class demodulating equipment by the mode of digital differential.
Refer to Fig. 2, it is the electrical block diagram of Attenuation adjustable device and high pass filter in the embodiment of the present invention.
In one embodiment, described Attenuation adjustable device 100 comprises the 3dB attenuation module 102,6dB attenuation module 104 and the 12dB attenuation module 106 that are cascaded;
Described 3dB attenuation module comprises 3dB attenuator and two first controlled single-pole double-throw switch (SPDT) K1B, K1C, the two ends of described 3dB attenuator are connected to described two first controlled single-pole double-throw switch (SPDT) K1B, K1C one not moved end respectively, and another of described two first controlled single-pole double-throw switch (SPDT) K1B, K1C is not connected by wire moved end;
Described 6dB attenuation module comprises 6dB attenuator and two second controlled single-pole double-throw switch (SPDT) K2B, K2C, the two ends of described 6dB attenuator are connected to described two second controlled single-pole double-throw switch (SPDT) K2B, K2C one not moved end respectively, and another of described two second controlled single-pole double-throw switch (SPDT) K2B, K2C is not connected by wire moved end;
Described 12dB attenuation module comprises 12dB attenuator and two the 3rd controlled single-pole double-throw switch (SPDT) K3B, K3C, the two ends of described 12dB attenuator are connected to described two the 3rd controlled single-pole double-throw switch (SPDT) K3B, K3C one not moved end respectively, and another of described two the 3rd controlled single-pole double-throw switch (SPDT) K3B, K3C is not connected by wire moved end.
In one embodiment, described 3dB attenuator comprises resistance R1, resistance R4 and resistance R5, and one end of described resistance R4 is connected to ground, and the other end is via ground connection after resistance R1 and resistance R5.
Annexation between the resistance number that described 6dB attenuator and described 12dB attenuator and described 3dB attenuator have respectively and resistance is identical, by regulating the resistance size of three resistance, can form the attenuator that attenuation is different.
3dB, 6dB, 12dB attenuation module in described Attenuation adjustable device, be the variable attenuation adjuster of stepping with 3dB in collocation composition 0 ~-21dB scope, the large I of the attenuation of Attenuation adjustable device is according to the signal strength signal intensity detecting rear class AD sample circuit and collect, regulating and controlling is carried out by signal processor, if detect, the signal strength signal intensity that described AD sample circuit collects is less, then the attenuation controlling described Attenuation adjustable device is less.
By Attenuation adjustable device, the decay of large-signal is suppressed, prevent from crossing ambassador's circuit phenomenon that is saturated or that damage because of signal to occur, must control to make preamplifier continuous firing in amplification region by attenuation simultaneously, avoid the phenomenon occurring that because input signal is excessive preamplifier is saturated.
In one embodiment, the cut-off frequency of described high pass filter 110 is 1.5MHz,
In a preferred embodiment, the cut-off frequency of described high pass filter 110 is the five rank elliptical high pass filter of 1.5MHz.
High pass filter is positioned at the rear end of Attenuation adjustable device, be mainly used in the signal of below filtering 1.5MHz, avoid low frequency signal to the interference of short-wave signal, be convenient to rear class and demodulate purer short-wave band signal, cut-off frequency is that the five rank elliptical high pass filter of 1.5MHz have better antijamming capability.
As shown in Figure 3, it is the electrical block diagram of embodiment of the present invention intermediate waves frequency-selecting band pass filter.
In one embodiment, described shortwave frequency-selecting band pass filter 120 comprises the band pass filter that six are selected a conducting, the frequency range of described band pass filter is respectively 1.5MHz ~ 5MHz, 5MHz ~ 10MHz, 10MHz ~ 15MHz, 15MHz ~ 20MHz, 20MHz ~ 25MHz and 25MHz ~ 30MHz, and described signal processor selects the conducting frequency range of described shortwave frequency-selecting band pass filter according to the signal frequency that described AD sample circuit collects.
As shown in Figure 3, the band pass filter 126 that the band pass filter 124 that the band pass filter 123 that shortwave frequency-selecting band pass filter 120 comprises band pass filter 122 that frequency range is 1.5MHz ~ 5MHz, frequency range is 5MHz ~ 10MHz, frequency range are 10MHz ~ 15MHz, frequency range are the band pass filter 125 of 15MHz ~ 20MHz, frequency range is 20MHz ~ 25MHz and frequency range are the band pass filter 127 of 25MHz ~ 30MHz.At synchronization, described signal processor selects one of them frequency range of described shortwave frequency-selecting band pass filter to carry out signal filtering according to the signal frequency that described AD sample circuit collects.Six frequency ranges of described shortwave frequency-selecting band pass filter cover the whole signals received in whole short-wave band (1.5MHz ~ 30MHz) scope.
Bandwidth-limited circuit is formed in parallel primarily of the band pass filter of six different frequency ranges, by selecting the filtering to useful signal to the switching of frequency range, thus the outer interference signal of inhibition zone, reduce total power signal to prevent circuit saturated.The each length of tape of band pass filter is wide fixing, any one frequency range in 1.5MHz ~ 5MHz, 5MHz ~ 10MHz, 10MHz ~ 15MHz, 15MHz ~ 20MHz, 20MHz ~ 25MHz and 25MHz ~ 30MHz can be selected to enter radio frequency path according to the frequency of useful signal.
In short wave communication, frequency is lower, then the interference be subject in transmitting procedure is larger, then filter bandwidht should be less.Therefore, the design of band pass filter take into account the situation of actual use, and in 1.5 ~ 5MHz shortwave low-frequency range, band pass filter bandwidth is 3.5MHz; In 5 ~ 30MHz shortwave frequency range, band pass filter bandwidth is 5MHz.
In a preferred embodiment, described band pass filter all selects the oval band pass filter in seven rank to carry out frequency-selective filtering to received signal.
By contrasting the simulation waveform graph discovery of oval band ripple device and Chebyshev filter: the Insertion Loss in the bandwidth of elliptic filter is less, the outer waveform of bandwidth is comparatively precipitous, and far-end Out-of-band rejection is poor; In Chebyshev filter band, Insertion Loss is comparatively large, band is outer comparatively gently, far-end Out-of-band rejection is better.Select the oval band pass filter in seven rank, under guarantee far-end Out-of-band rejection reaches the prerequisite of pre-provisioning request, the band internal loss of Received signal strength can be reduced, increase Out-of-band rejection steepness.
As shown in Figure 3, shortwave frequency-selecting band pass filter 120 also comprises direct current channel 121.
Use direct current channel in parallel with the band pass filter of six different frequency ranges, band pass filter can be cut off timely when breaking down, also can, when not needing to use band pass filter by its short circuit, the use of shortwave frequency-selecting band pass filter be made to have more flexibility.
As shown in Figure 4, it is the electrical block diagram of preamplifier in the embodiment of the present invention.
In one embodiment, preamplifier 130 is made up of the transistor circuit that input transformer Tin, output transformer Tout and two parts are identical.
Input transformer Tin is made up of enamelled wire and diplopore magnet ring, and the non-equilibrium signal of input can be converted into two input windings that two-way balanced signal delivers to output transformer Tout respectively by it.
In one embodiment, the transistor circuit that two parts are identical forms by several identical element circuit parallel join.Element circuit is made up of a NPN transistor (Q1, Q2 as Fig. 4) and peripheral components (comprising resistance, electric capacity).
Such as; transistor Q1 is according to grounded base basic configuration connecting circuit; the direct voltage of+1.9V by resistance Rb1, Re1 for transistor Q1 base stage and emitter-base bandgap grading provide direct current biasing; signal is inputted by the emitter of transistor Q1; exported by the collector electrode of transistor Q1; crystal diode V1 between base stage and emitter shields, and avoids transistor base emitter-base bandgap grading when large-signal inputs to be reversed and punctures.
The output signal of element circuit that transistor Q1 forms and the output signal of other element circuit (as the element circuit that transistor Q3 forms) merge the output winding exporting transformer Tout to.The signal output port Pout of circuit is a tap of output transformer Tout, and other two of it and transformer Tout export winding and form self coupling coil.
The preamplifier of said structure, circuit is simple, and the linearity is high, adopts transformer coupled cobasis category-A structure for amplifying, changes forward power gain by adjustment input and output transformer turn ratio, and lower with the I/O impedance degree of association, is easy to adjustment.The pre-amplification circuit with said structure has ultra-low noise coefficient, preferably second order and three rank indexs, intermodulation is high and dynamic range is large feature, thus ensure that Received signal strength can be able to high-quality and amplifies and do not produce signal distortion and distortion, filtered signal can be received and carry out amplifying to guarantee the reception to small-signal.
In a preferred embodiment, the number of described element circuit is eight.
In a preferred embodiment, the I/O turn ratio of input transformer Tin is 6:4, and the I/O turn ratio of output transformer Tout is 1:1:12:12:2.
The turn ratio of above-mentioned input and output transformer better can realize the input/output signal conversion of low noise amplifier circuit, and it exports forward power gain and reaches 11.46dB.
Emulated by the scattering parameter of the preamplifier to gain being 11dB, known at frequency 11.5MHz place, gain is 10.76dB, and input reflection coefficient is-24dB, and output reflection coefficient is-42dB, and reverse isolation degree is-11dB.
From the simulation result of circuit intermodulation component, the first-harmonic of input is respectively 7.0MHz, 11.9MHz, when power is 10dBm, the fundametal compoment of output port is 15.31dBm, the difference that third-order intermodulation product and first-harmonic export is 94.59dB, and third order intermodulation section power output is 15.31dBm+94.59/2dB=62.6dBm.And changed with input signal power from the gain of circuit forward power, be greater than 33dBm in the input power at 1dB compression point place.
Visible, have applicable element circuit number and the turn ratio of input and output transformer, then preamplifier then has lower noise, compared with high intermodulation and dynamic range is large.
The gain of preamplifier determines primarily of input and output transformer turn ratio, and forward power gain increases then number of turn index and increases, and just needs larger magnetic core aperture.But magnet ring not easily excessive, coiling needs the shortest, avoids the impact of distributed constant, thus improve self-resonant frequency with this.If the number of turn becomes large, distributed constant increases, and the loss of transformer also can become large.
In one embodiment, the adjustable attenuation scope of described automatic gain controller 140 is 0 ~ 31dB.
Gain amplification quantity due to preamplifier is fixed value, the signal after preamplifier amplifies is controlled by the gain reduction of automatic gain controller 0 ~ 31dB, the phenomenon of amplifier saturation occurs can effectively to prevent the second level amplifying circuit from occurring because input signal is excessive, thus make second level amplifier energy continuous firing in amplification region, also can the excessive damage late-class circuit of anti-stop signal; If only rely on front end 0 ~-21dB Attenuation adjustable device to be decayed to signal, there will be and cause useful signal to be lost because attenuation is excessive, adopt automatic gain controller can prevent the loss of useful signal, ensure that late-class circuit can sample the digital signal of certain amplitude.
In one embodiment, whether the signal strength signal intensity that signal processor can sample according to rear class AD sample circuit 160 controls second level amplifying circuit and accesses, when the signal strength signal intensity detecting that AD sample circuit 160 samples is less than predetermined threshold value, control described second level amplifier place in circuit, otherwise described second level amplifier does not connect place in circuit.
Utilize signal processor according to the feedback of AD sampling circuit samples to signal strength signal intensity, control second level amplifying circuit whether place in circuit, the signal processing of the whole signal processing apparatus based on short wave bandwidth receiving demodulation front end can be made more intelligent.When Received signal strength is comparatively faint, this circuit is linked among path, by two-stage amplifying circuit, faint Received signal strength is carried out the amplification of high-gain, to obtain the signal of some strength for late-class circuit demodulation.If the signal strength signal intensity received is enough to, for late-class circuit demodulation, be switched second level amplifying circuit bypass channel by relay, make signal keep the most original, introduce the minimum purified signal of noise for downstream component demodulation, and decrease the loss of electric energy and the introducing of noise.
Preferably, its power gain of described second level amplifying circuit is 10dB, noise factor 7dB, and output OIP3 is 41dBm, and second level amplifying circuit has the advantages that amplification performance is stablized, reliability is high, amplifying power is stronger.
As shown in Figure 5, it is the electrical block diagram of AD sample circuit in the embodiment of the present invention.
AD sample circuit can realize converting analog signal to digital signal, and the digital signal after conversion is supplied rear class demodulating equipment by the mode of difference output carries out steadily demodulation clearly, and can not be interfered because of the severe electromagnetic environment in the external world.
In one embodiment, described AD sample circuit 160 comprises prime filtering Circuit tuning and A/D chip, described prime filtering Circuit tuning have employed the radiofrequency signal nonequilibrium radiofrequency signal being transformed into empty balance, is more conducive to AD signals collecting, improves the antijamming capability that AD gathers.
The performance of A/D chip is the key factor affecting receiving sensitivity, dynamic range.If AD does not have enough bandwidth sum linear dynamic ranges, the frequency band of useful signal will be caused impaired, and large-signal floods small-signal, even occur blocking channel phenomenon, thus the reliability of receiving system and validity are declined.
In a preferred embodiment, the bit wide of described A/D chip is 16, and sample rate is 92.16MHz.A/D chip radio frequency signal gathers, and the data gathered is exported with the form of complement code, delivers to signal processor 170.The noise that the A/D chip that bit wide is 16, sample rate is 92.16MHz is lower, larger dynamic range and less power consumption.
In one embodiment, in order to optimize the low noise wide dynamic range characteristic of A/D chip, for reducing electromagnetic interference, the method for employing comprises:
By analog signal and digital signal arranged apart, the interference of digital noise to analog signal can be reduced;
AD sample circuit 160 is responsive easily disturbed circuit, adopts can shielding, reduces its interference of outer bound pair;
Preamplifier 130, second level amplifier 150 can adopt can to shield, and reduce the interference of strong signal to weak radiofrequency signal;
Adopt good power filter, decoupling circuit, the interference of the noise radio frequency signal of insulating power supply;
Use low pressure difference linear voltage regulator power supply to power separately to AD sample circuit 160, reduce power supply ripple and the interference of shake to AD sample circuit 160;
Preamplifier 130, second level amplifier 150, crystal oscillator, clock signal can form strong jamming by radio frequency signal, as far as possible away from radiofrequency signal.
As shown in Figure 6, it is the signal processing apparatus structural representation based on short wave bandwidth receiving demodulation front end in another embodiment of the present invention.
In one embodiment; also comprise the protective circuit 180 being connected to described Attenuation adjustable device 100 front end; described protective circuit 180 comprises thunder and lightning signal protection circuit and voltage clamping circuit, and described voltage clamping circuit is connected between described thunder and lightning signal protection circuit and described Attenuation adjustable device 100.
As shown in Figure 7; for the electrical block diagram of protective circuit in the embodiment of the present invention; described protective circuit 180 selects gas discharge tube directly by under the thunder and lightning signal that receives or the timely short circuit of high-power RF signal, guarantees that late-class circuit is not damaged by pouring into of large-signal.
Thunder and lightning signal protection circuit design has lightning protected device, when have larger thunder and lightning signal by time, lightning protected device by under thunder and lightning signal shorts, thus can ensure that late-class circuit can not be subject to the damage of large-signal; And for signal strength signal intensity more greatly but do not reach the signal of lightning protected thresholding, voltage clamping circuit can by clamped for this signal to predetermined threshold value after export to late-class circuit.First protective circuit carries out detection protection the signal received, and so both ensure that and can normally receive larger useful signal, turn avoid the signal of large intensity or interference signal to the destruction of rear class amplifying circuit.
As shown in Figure 6, in one embodiment, the low pass filter 190 being connected to described AD sample circuit 160 front end is also comprised.
In a preferred embodiment, the cut-off frequency of described low pass filter is 30MHz.
Described low pass filter has low-loss, the high advantage suppressed.
The signal of coming through second level amplifier 150 or bypass continues through the low pass filtered circuit that cut-off frequency is 30MHz, more than filtering 30MHz is humorous involve interference signal while, the useful signal loss amount of falling is arrived minimum.Described low pass filter and cut-off frequency are the high pass filter of 1.5MHz and to cover frequency range be that the shortwave frequency-selecting band pass filter of 1.5MHz ~ 30MHz forms three grades of filtering, the collocation of three grades of filter circuits uses the bank of filters that composition insertion loss is minimum, Out-of-band rejection is the highest, the insertion loss of useful signal can control within 0.2dB by this filter bank, Out-of-band rejection accomplishes below-70dB, the degree of purity that improve useful signal of maximum possible while ensureing that useful signal is the most original, not occurring to distort.
In one embodiment, also comprise power-switching circuit, the external input voltage of described power-switching circuit is 12V, and described power-switching circuit is connected respectively with described preamplifier, described automatic gain controller, described second level amplifier and described AD sample circuit.
In one embodiment, in circuit as shown in Figure 8, after 12V DC power supply can be converted to 5V by the power supply chip N2 of described power-switching circuit, be connected with described automatic gain controller 140 and described second level amplifier 150.
In one embodiment, in circuit as shown in Figure 9,5V DC power supply can be converted to 3.3V by the power supply chip N3 of described power-switching circuit, powers to described AD sample circuit 160.
In one embodiment, in circuit as shown in Figure 10,12V DC power supply can be converted to 11V by the power supply chip N4 of described power-switching circuit, and power supply chip N5 converts 11V DC power supply to 1.9V again, powers to described preamplifier 130.
Power-switching circuit can convert the fixing direct voltage of input the magnitude of voltage of different size to for different circuit blocks, decreases electric energy loss.
Each technical characteristic of the above embodiment can combine arbitrarily, for making description succinct, the all possible combination of each technical characteristic in above-described embodiment is not all described, but, as long as the combination of these technical characteristics does not exist contradiction, be all considered to be the scope that this specification is recorded.
The above embodiment only have expressed several execution mode of the present invention, and it describes comparatively concrete and detailed, but can not therefore be construed as limiting the scope of the patent.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection range of patent of the present invention should be as the criterion with claims.
Claims (10)
1. the signal processing apparatus based on short wave bandwidth receiving demodulation front end, it is characterized in that, comprise Attenuation adjustable device, high pass filter, shortwave frequency-selecting band pass filter, preamplifier, automatic gain controller, second level amplifier, AD sample circuit and signal processor;
Described Attenuation adjustable device is through described high pass filter, described shortwave frequency-selecting band pass filter is connected with described preamplifier, described preamplifier is connected with described AD sample circuit through described automatic gain controller, input signal is successively via described Attenuation adjustable device, described high pass filter, described shortwave frequency-selecting band pass filter, described preamplifier, export after described automatic gain controller and described AD sample circuit, described signal processor respectively with described Attenuation adjustable device, described high pass filter, described shortwave frequency-selecting band pass filter, described automatic gain controller and described AD sample circuit connect,
Wherein, described signal processor controls the attenuation size of described Attenuation adjustable device and described automatic gain controller according to the signal strength signal intensity that described AD sample circuit collects, the signal strength signal intensity that described AD sample circuit collects is less, then to control the attenuation of described Attenuation adjustable device and described automatic gain controller less for described signal processor;
Described second level amplifier is selectivity place in circuit, when the signal strength signal intensity detecting that described AD sample circuit collects is less than predetermined threshold value, controlling described second level amplifier accesses between described automatic gain controller and described AD sample circuit, otherwise, described by described second level amplifier bypass.
2. the signal processing apparatus based on short wave bandwidth receiving demodulation front end according to claim 1, is characterized in that, also comprises the low pass filter being connected to described AD sample circuit front end.
3. the signal processing apparatus based on short wave bandwidth receiving demodulation front end according to claim 2, is characterized in that, the cut-off frequency of described low pass filter is 30MHz.
4. the signal processing apparatus based on short wave bandwidth receiving demodulation front end according to claim 1 and 2; it is characterized in that; also comprise the protective circuit being connected to described Attenuation adjustable device front end; described protective circuit comprises thunder and lightning signal protection circuit and voltage clamping circuit, and described voltage clamping circuit is connected between described thunder and lightning signal protection circuit and described Attenuation adjustable device.
5., according to the signal processing apparatus based on short wave bandwidth receiving demodulation front end of claim 1 or 2 described in any one, it is characterized in that, described Attenuation adjustable device comprises the 3dB attenuation module, 6dB attenuation module and the 12dB attenuation module that are cascaded;
Described 3dB attenuation module comprises 3dB attenuator and two the first controlled single-pole double-throw switch (SPDT)s, the two ends of described 3dB attenuator are connected to one of described two the first controlled single-pole double-throw switch (SPDT)s not moved end respectively, and another of described two the first controlled single-pole double-throw switch (SPDT)s is not connected by wire moved end;
Described 6dB attenuation module comprises 6dB attenuator and two the second controlled single-pole double-throw switch (SPDT)s, the two ends of described 6dB attenuator are connected to one of described two the second controlled single-pole double-throw switch (SPDT)s not moved end respectively, and another of described two the second controlled single-pole double-throw switch (SPDT)s is not connected by wire moved end;
Described 12dB attenuation module comprises 12dB attenuator and two the 3rd controlled single-pole double-throw switch (SPDT)s, the two ends of described 12dB attenuator are connected to one of described two the 3rd controlled single-pole double-throw switch (SPDT)s not moved end respectively, and another of described two the 3rd controlled single-pole double-throw switch (SPDT)s is not connected by wire moved end.
6. the signal processing apparatus based on short wave bandwidth receiving demodulation front end according to claim 1 and 2, it is characterized in that, described shortwave frequency-selecting band pass filter comprises the band pass filter that six are selected a conducting, the frequency range of described band pass filter is respectively 1.5MHz ~ 5MHz, 5MHz ~ 10MHz, 10MHz ~ 15MHz, 15MHz ~ 20MHz, 20MHz ~ 25MHz and 25MHz ~ 30MHz, and described signal processor selects the conducting frequency range of described shortwave frequency-selecting band pass filter according to the signal frequency that described AD sample circuit collects.
7. the signal processing apparatus based on short wave bandwidth receiving demodulation front end according to claim 6, is characterized in that, the oval band pass filter in seven rank all selected by described band pass filter.
8. the signal processing apparatus based on short wave bandwidth receiving demodulation front end according to claim 1, is characterized in that, the adjustable attenuation scope of described automatic gain controller is 0 ~ 31dB.
9. the signal processing apparatus based on short wave bandwidth receiving demodulation front end according to claim 1, it is characterized in that, also comprise power-switching circuit, described power-switching circuit is connected respectively with described preamplifier, described automatic gain controller, described second level amplifier and described AD sample circuit.
10. the signal processing apparatus based on short wave bandwidth receiving demodulation front end according to claim 1, is characterized in that, the five rank elliptical high pass filter of described high pass filter to be cut-off frequency be 1.5MHz.
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