CN104092967B - Receiver system and receiving method with cognitive function - Google Patents
Receiver system and receiving method with cognitive function Download PDFInfo
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Abstract
The invention discloses a receiver system and receiving method with the cognitive function. A radio frequency front end module is connected with a digital circuit module through an analog-digital conversion module. A radio frequency preselecting filter with the tuned bandwidth and under digital control is introduced to the radio frequency front end so that mirror image and harmonic interference can be effectively avoided and control can be convenient. Meanwhile, spectrum sensing and cognitive user data receiving are combined into a whole, a feature detection algorithm based on cyclic prefix correlation is adopted, spectrum sensing and data receiving can be conducted at the same time, intervention of signals of a main user can be found in time, a silent period is avoided, and communication efficiency is improved. In addition, idle channels can be provided for cognitive users and the current idle channels are continuously monitored. Under the condition that a local oscillator is not changed, spectrum sensing is conducted on other channels in an XMHZ and spare channels are provided. When the main user occupies an authorized frequency band again, the idle channels can be dynamically and intelligently switched in real time.
Description
Technical field
The invention belongs to communication technical field is and in particular to a kind of receiver system with cognitive function and method.
Background technology
In modern communicationses, the restriction wireless communication technology that lowly becomes of the scarcity of frequency spectrum resource and spectrum management efficiency develops
Bottleneck.And cognitive radio technology is a kind of effective means solving current problem.Meanwhile, terrestrial DTV (DVB-T)
As a pith of people's amusement and recreation, in the time, frequency and spatially there are a lot of idle frequency spectrums.By cognition
Radiotechnics, cognitive user can enter row data communication in unauthorized DTV idle frequency spectrum.
The utilization of terrestrial DTV idle frequency spectrum it is necessary first to determine the free time of terrestrial DTV by frequency spectrum perception
Then the idle frequency spectrum perceiving is distributed to cognitive user and is used by frequency spectrum.Special perception is adopted in cognitive radio networks
The scheme of receiver data communication control processor, this not only adds system complexity, and is unfavorable for the system integration.Therefore,
Proposing a kind of receiver system simply with cognitive function becomes a new direction of research.On this basis, wide
The energy detection algorithm of general employing is although enable the frequency spectrum perception of received terrestrial digital broadcasting frequency range.But it is present to ensure that frequency spectrum sense
The reliability known, perception needs to use quiet period.In quiet period, cognitive user must interrupt self transmission, thus leading to
Discontinuous, the impact communication efficiency of data transfer.Furthermore, how to build spectrum pool, dynamically the offer idle spare letter of intelligence
Road uses for cognitive user, is also the problem that this reception system needs to solve.That is, when primary user resumes mandate frequency range
When, cognitive user should carry out the continuous switching between channel in real time.
Additionally, the wideband segment limit for terrestrial DTV.While realizing wide-band covering, reduce Image interference
Harmonious wave interference, is also the emphasis that method of reseptance and system need consideration.
Content of the invention
The technical problem to be solved is to provide a kind of receiver system with cognitive function and method, its energy
The idle frequency spectrum of effectively perceive terrestrial DTV frequency range, and cognitive user is carried out by cognitive corresponding free time frequency range of distributing
Data receiver, it possesses, and frequency spectrum perception is parallel with data receiver, and multiple available channels are standby, high performance feature.
For solving the above problems, the present invention is achieved by the following technical solutions：
A kind of receiver system with cognitive function, mainly by RF front-end module, analog-to-digital conversion module and numeral electricity
Road module composition.The outfan of RF front-end module is connected with the input of analog-to-digital conversion module, the output of analog-to-digital conversion module
End connects digital circuit blocks.Above-mentioned radio-frequency front-end includes RF preselection wave filter, low-noise amplifier, the first local oscillations
Device, the first frequency mixer, band filter, amplifier, the second local oscillator, the second frequency mixer, intermediate-frequency filter and automatic increasing
Beneficial controller.The DVB-T signal of outside input or the input of cognitive user signal feeding RF preselection wave filter.RF preselection
The outfan of wave filter is connected with an input of the first mixer module via low-noise amplifier, the output of the first frequency mixer
End is input to the input of amplifier through band filter, and the outfan of amplifier connects an input of the second frequency mixer, the
The outfan of two frequency mixers is connected with the input of automatic gain controller through intermediate-frequency filter.First local oscillator connects the
Another input of one frequency mixer；Second local oscillator connects another input of the second frequency mixer.Automatic gain controller
Outfan connect modulus conversion module input.Above-mentioned digital circuit blocks include the first digitally tunable filters, feature
Testing circuit, spectrum memory, on-off circuit, the second digitally tunable filters, digital down converter, demodulator, clock circuit
And control unit.The outfan of analog-to-digital conversion module is divided into two-way, road the first digitally tunable filters connection features detection
The input of circuit, the outfan of signature detection circuit connects spectrum memory, and the outfan of spectrum memory connects control list
The input of unit, is consequently formed the perception link of DVB-T signal；Another road connects the second digitally tunable filters through on-off circuit
Input, the outfan of the second digitally tunable filters connects the input of demodulator through digital down converter, demodulator to
Outside output cognitive user signal；It is consequently formed the demodulation link of cognitive user signal.Clock circuit is connected with control unit,
The outfan connecting valve circuit of control unit, the second digitally tunable filters, digital down converter, the first digital adjustable filtering
Device, signature detection circuit, the cognitive user of RF preselection wave filter, the first local oscillator and outside.Control unit is mainly
Under clock circuit control, coordinate the work of cognitive user, digital circuit blocks and RF front-end module.
In above-mentioned reception system, described RF preselection wave filter is mainly by the first decoupling capacitor circuit, the first notch filter
Circuit, the first impedance matching circuit, three rank resonator filter circuit, Coupled Inductor Circuit, the second impedance matching circuit, the second trap
Filter circuit and the second decoupling capacitor circuit composition.The input of the first decoupling capacitor circuit receives the radio frequency letter of outside input
Number, the first decoupling capacitor circuit outfan through first notch filter circuit input the first impedance matching circuit input；
The positive output end of the first impedance matching circuit is connected with the positive input terminal of the second impedance matching circuit through three rank resonator filter circuit,
The negative output terminal of the first impedance matching circuit is connected with the negative input end of the second impedance matching circuit with Coupled Inductor Circuit and connects
Ground；Second impedance matching circuit connects the input of the second decoupling capacitor circuit, the second decoupling electricity through the second notch filter circuit
The outfan of capacitive circuit is connected with low-noise amplifier.
In above-mentioned reception system, described first digitally tunable filters and the second digitally tunable filters all can using coefficient
The finite impulse response digital filter becoming.
In above-mentioned reception system, described signature detection circuit is mainly by down-sampling circuit, delay circuit, conjugate multiplication electricity
Road, sliding window summation circuit and decision circuit are constituted.The input of down-sampling circuit is connected with the first digitally tunable filters,
The delayed circuit of outfan of down-sampling circuit connects the input of conjugate multiplication circuit, and the outfan of conjugate multiplication circuit is through cunning
Dynamic window summation circuit connects the input of decision circuit, and the outfan of decision circuit is connected with spectrum memory.
A kind of method of reseptance with cognitive function realized based on above-mentioned reception system, is comprised the steps：
(1) with XMHZ for frequency sub-band bandwidth, DVB-T frequency range is divided into x frequency sub-band, wherein each frequency sub-band corresponding
The Frequency Band Selection control word of the frequency of individual local oscillator and RF preselection wave filter；Again with YMHZ as subchannel bandwidth, will be every
Individual frequency sub-band is divided into y sub-channels；
(2) control unit exports the frequency of Frequency Band Selection control word corresponding to first frequency sub-band and local oscillator every time
Rate, to the RF preselection wave filter and the first local oscillator of RF front-end module, controls needed for the reception of RF front-end module
Frequency sub-band in signal；
(3) sub-band signals that RF front-end module receives are sent in analog-to-digital conversion module, to the frequency sub-band receiving
Interior signal obtains the sampled signal in frequency sub-band after carrying out analog-to-digital conversion；
(4) sampled signal in frequency sub-band is sent in the perception link of digital circuit blocks, adjustable by the first numeral
Wave filter selects subchannel one by one, and carries out feature detection to every sub-channels respectively, determines whether DVB-T signal takies currently
Subchannel, thus obtaining channel condition information, and channel condition information is stored in spectrum memory is stored；
(5) control unit constantly inquires about the channel condition information of spectrum memory memory storage；When finding idle channel, that is,
When DVB-T signal is not take up present channel, then immediately cognitive user is sent a signal to by a feedback link, allow cognitive user
Idle channel using this frequency sub-band sends cognitive user signal；And open on-off circuit unlatching demodulation link immediately, selecting should
Idle channel, as the working channel of the demodulation link of digital circuit blocks, carries out data demodulation for cognitive subscriber signal and recovers；
(6) control unit adjusts the filter coefficient of the second digitally tunable filters so as to be operated in selected subchannel；And
Control digital down converter that the cognitive user signal in selected subchannel is down-converted to base band, be then fed into carrying out in demodulator
Demodulation process；
(7) while demodulation, control unit is looked into the currently used sub-channel in spectrum memory always
Ask；When finding that currently used channel is occupied, then continue down to execute；
(8) control unit carries out a wheel inquiry to spectrum memory；If finding other idle sub-channels, by this free time
Channel replaces with working channel, and return to step (6) continues operation；If all idle sub-channels are entirely occupied, export next
The frequency of the Frequency Band Selection control word corresponding to frequency sub-band and local oscillator, to RF front-end module, receives next frequency sub-band
Interior signal, and return to step (3) continues operation；If whole frequency sub-band all perceive, return to step (2), carry out complete again
The frequency spectrum perception operation of a new round.
In above-mentioned method of reseptance, described step (4) is specific as follows：
(4.1) control unit selects the first digitally tunable filters to be operated in first group of filter factor, to selected son first
The first sub-channels in frequency band signals carry out digital filtering；
(4.2) by the signal after digital filtering, send into feature detection module and carry out frequency spectrum perception, obtain the first sub-channels
Channel condition information, and status information be stored in spectrum memory stored；
(4.3) control unit makes the first digitally tunable filters be operated in next again and organizes filter coefficient, until by son frequently
In section, all sub-channel perception complete, and are stored in spectrum memory, each channel status in real-time update spectrum memory.
In above-mentioned method of reseptance, the feature detection in described step (4) is specific as follows：
The L data receiving before a, the L data to current Received Signal and N number of moment carries out cross-correlation, time delay phase
Close value be：
B, to the L data conjugate multiplication postponing after N number of moment, again square, the judgement expression formula obtaining is for cumulative summation：
C, set P (n) threshold value as λ；Then when adjudicating expression formula P (n) >=λ, then differentiate that this subchannel is occupied, exist
DVB-T signal；Conversely, there is not DVB-T signal in this subchannel free time；
In upper two formulas, r (n) is current Received Signal, and L is taken as the OFDM circulating prefix-length of known DVB-T signal, and N takes
OFDM significant character length for DVB-T signal.
In above-mentioned method of reseptance, in described step (1), with 40MHZ for frequency sub-band bandwidth, the DVB-T to 410～850MHZ
Frequency range is divided and is preselected filtering, and simultaneity factor is divided to each frequency sub-band with 8MHZ for subchannel bandwidth and samples,
Each frequency sub-band is divided into 5 sub-channels.
Want to compare with prior art, the invention has the characteristics that：
1st, radio-frequency front-end introduce numerically controlled can wide-band tuning RF preselection wave filter, can be prevented effectively from mirror image and
Harmonic wave disturbs, easy to control.
2nd, frequency spectrum perception is merged one with cognitive user data receiver, using the feature inspection based on Cyclic Prefix dependency
Method of determining and calculating, enables frequency spectrum perception and carries out with while data receiver, and can timely find the intervention of primary user's signal, it is to avoid
Quiet period, improves communication efficiency.
3rd, it is provided that idle channel to cognitive user, and constantly monitor current idle channel.Can also be in constant local oscillations
In the case of device, frequency spectrum perception is carried out to other subchannels in XMHZ, alternate channel is provided.When primary user resumes mandate
During frequency range, the real-time switching realizing idle channel of dynamic and intelligent.
Brief description
Fig. 1 novel cognitive radio receiver structure block diagram.
Fig. 2 divides schematic diagram for frequency range.
Fig. 3 is RF preselection filter circuit figure.
Fig. 4 is characterized detection and realizes block diagram.
Specific embodiment
A kind of receiver system with cognitive function as shown in Figure 1, mainly by RF front-end module, analog-to-digital conversion mould
Block and digital circuit blocks are constituted.The outfan of RF front-end module is connected with the input of analog-to-digital conversion module, analog-to-digital conversion
The outfan of module connects digital circuit blocks.It is pre- that the RF front-end module in front end for the present invention introduces digital adjustable radio frequency
Selecting filter.The effect of the RF preselection wave filter of RF front-end module is to carry out pre-selection filtering to reception radiofrequency signal, selected
Filtering bandwidth is frequency sub-band bandwidth XMHZ of segmentation, so can reduce the mirror image harmony wave interference of system broad reception, and right
Desired signal bandwidth carries out one and accurately preselects.This reception system adopts super-heterodyne architecture, with XMHZ for frequency sub-band band
Width, DVB-T frequency range is divided into x frequency sub-band.By RF preselection wave filter, signal is carried out with the pre-selection filtering of XMHZ, then leads to
Cross the first frequency mixer and moved fixing high intermediate frequency, through the filtering of XMHZ high if bandpas filter, then through the second frequency mixer
Down-convert the signals to Low Medium Frequency, after XMHZ Low Medium Frequency bandpass filtering, be sent directly into analog-to-digital conversion module (i.e. A/D).With
YMHZ is subchannel bandwidth, and each frequency sub-band is divided into y sub-channels.The control unit of the digital circuit blocks of rear end can have
Effect controls RF preselection wave filter and the first local oscillator to choose frequency sub-band, and by controlling the adjustable filter of numeral of perception link
Ripple device is perceived one by one to channels multiple in frequency sub-band, and is communicated using perceiving out certain idle sub-channels.At this
In invention preferred embodiment, the band limits selecting DVB-T is 410-850MHZ, is divided into multiple frequency sub-band with X=40MHZ,
For the DVB-T signal of Y=8MHZ channel width, each frequency sub-band includes 5 sub-channels again.Referring to Fig. 2.
Above-mentioned radio-frequency front-end includes RF preselection wave filter, low-noise amplifier, the first local oscillator, the first mixing
Device, band filter, amplifier, the second local oscillator, the second frequency mixer, intermediate-frequency filter and automatic gain controller.Outward
The DVB-T signal of portion's input or the input of cognitive user signal feeding RF preselection wave filter.RF preselection wave filter defeated
Go out end to be connected with an input of the first mixer module via low-noise amplifier, the outfan of the first frequency mixer is filtered through band logical
Ripple device is input to the input of amplifier, and the outfan of amplifier connects an input of the second frequency mixer, the second frequency mixer
Outfan is connected with the input of automatic gain controller through intermediate-frequency filter.First local oscillator connects the first frequency mixer
Another input.Second local oscillator connects another input of the second frequency mixer.The outfan of automatic gain controller is even
Connect the input of analog-to-digital conversion module.
In a preferred embodiment of the invention, RF preselection wave filter as shown in figure 3, main by the first decoupling capacitor circuit,
First notch filter circuit, the first impedance matching circuit, three rank resonator filter circuit, Coupled Inductor Circuit, the second impedance matching
Circuit, the second notch filter circuit and the second decoupling capacitor circuit composition.The input of the first decoupling capacitor circuit receives outside
Input radiofrequency signal, the first decoupling capacitor circuit outfan through first notch filter circuit input first impedance matching electricity
The input on road；The positive output end of the first impedance matching circuit is through three rank resonator filter circuit with the second impedance matching circuit just
Input is connected, the coupled inductive circuit of negative output terminal of the first impedance matching circuit and the negative input of the second impedance matching circuit
End is connected and is grounded；Second impedance matching circuit connects the input of the second decoupling capacitor circuit through the second notch filter circuit,
The outfan of the second decoupling capacitor circuit is connected with low-noise amplifier.Decoupling capacitor circuit mainly removes external disturbance.Fall into
Ripple filter circuit guarantees the good Out-of-band rejection characteristic of RF preselection wave filter.Impedance matching circuit realizes wave filter and front and back end
The impedance matching that 50 ohm of circuit, realizes power and maximizes transmission.Coupled Inductor Circuit is used for the coupling of three rank resonance circuits, real
Existing required filtering bandwidth.From three rank resonator, filters in the case of ensureing stopband suppression it is ensured that wide-band tuning scope and needs
Filtering bandwidth., in the band limits of 410～850MHZ, 3dB signal bandwidth 40MHZ, with frequency for this RF preselection wave filter
Rate increases and slightly increases, the insertion loss of 5.5dB, and band width interpolation damages fluctuation range 0.5dB, and Out-of-band rejection reaches 50dB.Pass through
This RF preselection wave filter can effectively suppress the Image interference harmony wave interference in frequency sub-band, improves the quality of receipt signal.
In the present invention, the analog-to-digital conversion module of collection signal using the ADS4129 maximum sample rate of TI company is
250MHZ.In a preferred embodiment of the invention, the sample rate of analog-to-digital conversion module is chosen as 200MHZ.
Above-mentioned digital circuit blocks include the first digitally tunable filters, signature detection circuit, spectrum memory, switch electricity
Road, the second digitally tunable filters, digital down converter, demodulator, clock circuit and control unit.Analog-to-digital conversion module defeated
Go out end and be divided into two-way, the input of road the first digitally tunable filters connection features testing circuit, signature detection circuit
Outfan connects spectrum memory, and the outfan of spectrum memory connects the input of control unit, is consequently formed DVB-T signal
Perception link.Another road connects the input of the second digitally tunable filters, the second digitally tunable filters through on-off circuit
Outfan connect the input of demodulator through digital down converter, demodulator is to outside output cognitive user signal.By this shape
Become the demodulation link of cognitive user signal.Clock circuit is connected with control unit, the outfan connecting valve electricity of control unit
Road, the second digitally tunable filters, digital down converter, the first digitally tunable filters, signature detection circuit, RF preselection filter
The cognitive user of ripple device, the first local oscillator and outside.Control unit is mainly under clock circuit control, coordinates cognitive using
The work of family, digital circuit blocks and RF front-end module.
In a preferred embodiment of the invention, the first and second digitally tunable filters adopt variable FIR (the limited arteries and veins of coefficient
Punching response) digital filter, by regulable center frequency is carried out to the control of filter coefficient, the certain digital filtering of bandwidth.
Finite Impulse Response filter, while ensureing that amplitude characteristic meets technical requirements, has strict linear phase, is suitably applied this
System.By the storage to filter coefficient in advance, the variable multigroup wave filter of the certain mid frequency of bandwidth can be produced.Pass through
The control of groups of filter coefficients selection signal, can select the filter coefficient needing to be refined frequency range filtering work accordingly
Make, the function that the digital slip Channel assignment realizing needing filters.
In a preferred embodiment of the invention, signature detection circuit implements shown in block diagram 4, mainly by down-sampling circuit,
Delay circuit, conjugate multiplication circuit, sliding window summation circuit and decision circuit are constituted.The input of down-sampling circuit and first
Digitally tunable filters are connected, and the delayed circuit of outfan of down-sampling circuit connects the input of conjugate multiplication circuit, conjugation
The outfan of multiplication circuit connects input, the outfan of decision circuit and the frequency spectrum of decision circuit through sliding window summation circuit
Memorizer is connected.Down-sampling circuit is transferred to base band by I/Q solution, reduces sampling rate.Signal significant character realized by delay circuit
The delay of length.Conjugate multiplication circuit realiration postpones signal and the conjugate multiplication of current input signal.Sliding window summation circuit
Realize the data accumulation summation under Cyclic Prefix length of window.Decision circuit sets threshold discrimination signal.Feature detection adopts base
In the characteristic detection method of Cyclic Prefix dependency, the method can effectively identify DVB-T signal, facilitate hardware to realize again.
In a preferred embodiment of the invention, by spectrum memory, the X/8 sub-channels in frequency sub-band are stored, and
Constantly update.Used for demodulation link with selecting idle channel by the inquiry of control unit, so effectively construct
Small-sized spectrum pool, facilitates the real-time switching of channel.
In the preferred embodiment of the present invention, the digital local oscillator of Digital Down Convert is the selected sky that controlled unit controls
The mid frequency of idle channel.
A kind of method of reseptance with cognitive function realized based on above-mentioned reception system, is comprised the steps：
(1) with XMHZ for frequency sub-band bandwidth, DVB-T frequency range is divided into x frequency sub-band, wherein each frequency sub-band corresponding
The Frequency Band Selection control word of the frequency of individual local oscillator and RF preselection wave filter.Again with YMHZ as subchannel bandwidth, will be every
Individual frequency sub-band is divided into y sub-channels.
In a preferred embodiment of the invention, with 40MHZ for frequency sub-band bandwidth, the DVB-T frequency range of 410～850MHZ is carried out
Divide and pre-selection filtering, simultaneity factor is divided to each frequency sub-band with 8MHZ for subchannel bandwidth and samples, every height frequency
Section is divided into 5 sub-channels.
(2) control unit exports the frequency of Frequency Band Selection control word corresponding to first frequency sub-band and local oscillator every time
Rate, to the RF preselection wave filter and the first local oscillator of RF front-end module, controls needed for the reception of RF front-end module
Frequency sub-band in signal.
In a preferred embodiment of the invention, RF preselection wave filter, frequency range according to needed for digital end are introduced in radio-frequency front-end
Bandwidth, digital control by control unit, with 40MHZ, pre-selection filtering is carried out to the frequency range of 400-850MHZ.Avoid mirror image
Harmonious wave interference, effectively improves systematic function.Simultaneity factor is divided with 40MHZ and is sampled, and the signal after sampling includes 5
DVB-T channel.Frequency control word is the value of six depositors of phase-locked loop chip ADF4350, defeated in order under sequencing contro
Go out the corresponding local frequency of DVB-T each 40MHZ frequency range.
(3) sub-band signals that RF front-end module receives are sent in analog-to-digital conversion module, to the frequency sub-band receiving
Interior signal obtains the sampled signal in frequency sub-band after carrying out analog-to-digital conversion.
(4) sampled signal in frequency sub-band is sent in the perception link of digital circuit blocks, adjustable by the first numeral
Wave filter selects subchannel one by one, and carries out feature detection to every sub-channels respectively, determines whether DVB-T signal takies currently
Subchannel, thus obtaining channel condition information, and channel condition information is stored in spectrum memory is stored；
(4.1) control unit selects the first digitally tunable filters to be operated in first group of filter factor, to selected son first
The first sub-channels in frequency band signals carry out digital filtering.
(4.2) by the signal after digital filtering, send into feature detection module and carry out frequency spectrum perception, obtain the first sub-channels
Channel condition information, and status information be stored in spectrum memory stored.
In invention preferred embodiment, feature detection, from the characteristic detection method based on Cyclic Prefix dependency, is compared
Energy measuring, the method can find the intervention of primary user's signal, when primary user's letter in time when cognitive user is using idle frequency range
When number occurring, make cognitive user switching channel immediately, it is to avoid primary user's signal is disturbed.The feature detection of the present invention is concrete such as
Under：
The L data receiving before a, the L data to current Received Signal and N number of moment carries out cross-correlation, time delay phase
Close value be：
B, to the L data conjugate multiplication postponing after N number of moment, again square, the judgement expression formula obtaining is for cumulative summation：
C, set P (n) threshold value as λ；Then when adjudicating expression formula P (n) >=λ, then differentiate that this subchannel is occupied, exist
DVB-T signal；Conversely, there is not DVB-T signal in this subchannel free time；
In upper two formulas, r (n) is current Received Signal, and when in the case of known to the frame structure of DVB-T signal, L is taken as
The OFDM circulating prefix-length of DVB-T signal, such as L=64；N is taken as the OFDM significant character length of DVB-T signal, such as N=
2048.
(4.3) control unit makes the first digitally tunable filters be operated in next again and organizes filter coefficient, until by son frequently
In section, all sub-channel perception complete, and are stored in spectrum memory, each channel status in real-time update spectrum memory.
(5) control unit constantly inquires about the channel condition information of spectrum memory memory storage；When finding idle channel, that is,
When DVB-T signal is not take up present channel, then immediately cognitive user is sent a signal to by a feedback link, allow cognitive user
Idle channel using this frequency sub-band sends cognitive user signal；And open on-off circuit unlatching demodulation link immediately, selecting should
Idle channel, as the working channel of the demodulation link of digital circuit blocks, carries out data demodulation for cognitive subscriber signal and recovers.
(6) control unit adjusts the filter coefficient of the second digitally tunable filters so as to be operated in selected subchannel；And
Control digital down converter that the cognitive user signal in selected subchannel is down-converted to base band, be then fed into carrying out in demodulator
Demodulation process.
(7) while demodulation, control unit is looked into the currently used sub-channel in spectrum memory always
Ask.When finding that currently used channel is occupied, then continue down to execute.
(8) control unit carries out a wheel inquiry to spectrum memory.If finding other idle sub-channels, by this free time
Channel replaces with working channel, and return to step (6) continues operation.If all idle sub-channels are entirely occupied, export next
The frequency of the Frequency Band Selection control word corresponding to frequency sub-band and local oscillator, to RF front-end module, receives next frequency sub-band
Interior signal, and return to step (3) continues operation.If whole frequency sub-band all perceive, return to step (2), carry out complete again
The frequency spectrum perception operation of a new round.
Claims (8)
1. a kind of receiver system with cognitive function, mainly by RF front-end module, analog-to-digital conversion module and digital circuit
Module composition；The outfan of RF front-end module is connected with the input of analog-to-digital conversion module, the outfan of analog-to-digital conversion module
Connect digital circuit blocks；It is characterized in that：
Above-mentioned RF front-end module includes RF preselection wave filter, low-noise amplifier, the first local oscillator, the first mixing
Device, band filter, amplifier, the second local oscillator, the second frequency mixer, intermediate-frequency filter and automatic gain controller；Outward
The DVB-T signal of portion's input or the input of cognitive user signal feeding RF preselection wave filter；RF preselection wave filter defeated
Go out end to be connected with an input of the first mixer module via low-noise amplifier, the outfan of the first frequency mixer is filtered through band logical
Ripple device is input to the input of amplifier, and the outfan of amplifier connects an input of the second frequency mixer, the second frequency mixer
Outfan is connected with the input of automatic gain controller through intermediate-frequency filter；First local oscillator connects the first frequency mixer
Another input；Second local oscillator connects another input of the second frequency mixer；The outfan of automatic gain controller is even
Connect the input of analog-to-digital conversion module；
Above-mentioned digital circuit blocks include the first digitally tunable filters, signature detection circuit, spectrum memory, on-off circuit,
Second digitally tunable filters, digital down converter, demodulator, clock circuit and control unit；The output of analog-to-digital conversion module
End is divided into two-way, the input of road the first digitally tunable filters connection features testing circuit, signature detection circuit defeated
Go out end and connect spectrum memory, the outfan of spectrum memory connects the input of control unit, is consequently formed DVB-T signal
Perception link；Another road connects the input of the second digitally tunable filters through on-off circuit, the second digitally tunable filters
Outfan connects the input of demodulator through digital down converter, and demodulator is to outside output cognitive user signal；It is consequently formed
The demodulation link of cognitive user signal；Clock circuit is connected with control unit, the outfan connecting valve circuit of control unit,
Second digitally tunable filters, digital down converter, the first digitally tunable filters, signature detection circuit, RF preselection filtering
The cognitive user of device, the first local oscillator and outside.
2. a kind of receiver system with cognitive function according to claim 1 it is characterised in that：
Described RF preselection wave filter is mainly by the first decoupling capacitor circuit, the first notch filter circuit, the first impedance matching electricity
Road, three rank resonator filter circuit, Coupled Inductor Circuit, the second impedance matching circuit, the second notch filter circuit and the second decoupling
Condenser network forms；
The input of the first decoupling capacitor circuit receives the radiofrequency signal of outside input, the first decoupling capacitor circuit outfan
Input the input of the first impedance matching circuit through the first notch filter circuit；The positive output end of the first impedance matching circuit is through three
Rank resonator filter circuit is connected with the positive input terminal of the second impedance matching circuit, and the negative output terminal of the first impedance matching circuit is through coupling
Close inductive circuit to be connected with the negative input end of the second impedance matching circuit and be grounded；Second impedance matching circuit is filtered through the second trap
Wave circuit connects input, the outfan of the second decoupling capacitor circuit and the low-noise amplifier phase of the second decoupling capacitor circuit
Even.
3. a kind of receiver system with cognitive function according to claim 1 it is characterised in that：
Described first digitally tunable filters and the second digitally tunable filters are all using the finite impulse response (FIR) number that coefficient is variable
Word wave filter.
4. a kind of receiver system with cognitive function according to claim 1 it is characterised in that：
Described signature detection circuit mainly by down-sampling circuit, delay circuit, conjugate multiplication circuit, sliding window summation circuit and
Decision circuit is constituted；The input of down-sampling circuit is connected with the first digitally tunable filters, the outfan warp of down-sampling circuit
Delay circuit connects the input of conjugate multiplication circuit, and the outfan of conjugate multiplication circuit connects through sliding window summation circuit to be sentenced
The certainly input of circuit, the outfan of decision circuit is connected with spectrum memory.
5. a kind of method of reseptance with cognitive function realized based on receiver system described in claim 1, be is characterized in that,
Comprise the steps：
(1) with XMHZ for frequency sub-band bandwidth, DVB-T frequency range is divided into x frequency sub-band, wherein each frequency sub-band corresponds to a basis
The ground frequency of agitator and the Frequency Band Selection control word of RF preselection wave filter；Again with YMHZ as subchannel bandwidth, by every height
Frequency range is divided into y sub-channels；
(2) control unit exports the frequency of Frequency Band Selection control word corresponding to first frequency sub-band and local oscillator extremely every time
In the RF preselection wave filter and the first local oscillator of RF front-end module, control RF front-end module receives required son
Signal in frequency range；
(3) sub-band signals that RF front-end module receives are sent in analog-to-digital conversion module, in the frequency sub-band receiving
Signal obtains the sampled signal in frequency sub-band after carrying out analog-to-digital conversion；
(4) sampled signal in frequency sub-band is sent in the perception link of digital circuit blocks, by the first digital adjustable filtering
Device selects subchannel one by one, and carries out feature detection to every sub-channels respectively, determines whether DVB-T signal takies currently son letter
Road, thus obtaining channel condition information, and channel condition information is stored in spectrum memory is stored；
(5) control unit constantly inquires about the channel condition information of spectrum memory memory storage；When finding idle channel, i.e. DVB-
When T signal is not take up present channel, then immediately cognitive user is sent a signal to by a feedback link, allow cognitive user to utilize
The idle channel of this frequency sub-band sends cognitive user signal；And open on-off circuit unlatching demodulation link immediately, select this free time
Channel, as the working channel of the demodulation link of digital circuit blocks, carries out data demodulation for cognitive subscriber signal and recovers；
(6) control unit adjusts the filter coefficient of the second digitally tunable filters so as to be operated in selected subchannel；And control
Cognitive user signal in selected subchannel is down-converted to base band by digital down converter, is then fed into being demodulated in demodulator
Process；
(7) while demodulation, control unit is inquired about to the currently used sub-channel in spectrum memory always；One
When denier finds that currently used channel is occupied, then continue down to execute；
(8) control unit carries out a wheel inquiry to spectrum memory；If finding other idle sub-channels, by this idle sub-channels
Replace with working channel, and return to step (6) continues operation；If all idle sub-channels are entirely occupied, export next son frequency
The frequency of the Frequency Band Selection control word corresponding to section and local oscillator, to RF front-end module, receives in next frequency sub-band
Signal, and return to step (3) continues operation；If whole frequency sub-band all perceive, return to step (2) carries out brand-new one again
The frequency spectrum perception operation of wheel.
6. a kind of method of reseptance with cognitive function according to claim 5, is characterized in that, described step (4) is concrete
As follows：
(4.1) control unit selects the first digitally tunable filters to be operated in first group of filter factor, to selected frequency sub-band first
The first sub-channels in signal carry out digital filtering；
(4.2) by the signal after digital filtering, send into feature detection module and carry out frequency spectrum perception, obtain the letter of the first sub-channels
Channel state information, and status information is stored in spectrum memory is stored；
(4.3) control unit makes the first digitally tunable filters be operated in next again and organizes filter coefficient, until by frequency sub-band
All sub-channel perception complete, and are stored in spectrum memory, each channel status in real-time update spectrum memory.
7. a kind of method of reseptance with cognitive function according to claim 5, is characterized in that, in described step (4)
Feature detection is specific as follows：
The L data receiving before a, the L data to current Received Signal and N number of moment carries out cross-correlation, time delay correlation
It is worth and be：
B, to the L data conjugate multiplication postponing after N number of moment, again square, the judgement expression formula obtaining is for cumulative summation：
C, set P (n) threshold value as λ；Then as judgement expression formula P (n) >=λ2When, then differentiate that this subchannel is occupied, there is DVB-
T signal；Conversely, there is not DVB-T signal in this subchannel free time；
In upper two formulas, r (n) is current Received Signal, and L is taken as the OFDM circulating prefix-length of DVB-T signal, and N is taken as DVB-T letter
Number OFDM significant character length.
8. a kind of method of reseptance with cognitive function according to claim 5, is characterized in that, in described step (1), with
40MHZ is frequency sub-band bandwidth, is divided and preselected filtering to the DVB-T frequency range of 410～850MHZ, simultaneity factor with 8MHZ is
Subchannel bandwidth is divided to each frequency sub-band and is sampled, and each frequency sub-band is divided into 5 sub-channels.
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| CN105187078B (en) * | 2015-08-05 | 2018-01-16 | 广州海格通信集团股份有限公司 | The digital display circuit and its implementation that a kind of low intermediate frequency receiver mirror image suppresses |
| CN105590416A (en) * | 2015-12-19 | 2016-05-18 | 成都尼奥尔电子科技有限公司 | Long-distance wireless natural gas detector based on self-gain amplification circuit |
| CN105488960A (en) * | 2015-12-19 | 2016-04-13 | 成都尼奥尔电子科技有限公司 | Wireless natural gas detector based on self-gain amplification circuit |
| CN105608846A (en) * | 2015-12-19 | 2016-05-25 | 成都尼奥尔电子科技有限公司 | High precision wireless natural gas detector based on notch filter circuit |
| CN105551198A (en) * | 2015-12-19 | 2016-05-04 | 成都尼奥尔电子科技有限公司 | Long-distance wireless natural gas detector based on trap wave filtering circuit |
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| CN108400860A (en) * | 2018-05-09 | 2018-08-14 | 浙江赛威通信技术有限公司 | Distributed channel system and method |
| WO2021087707A1 (en) * | 2019-11-04 | 2021-05-14 | 深圳市大疆创新科技有限公司 | Dual-frequency-band multi-frequency-point adaptive channel estimation method and apparatus, and storage medium |
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