(3) summary of the invention
Technical problem to be solved by this invention provides a kind of signal interference cancellation device and signal interference cancellation method, can effectively eliminate user's unwanted signal that receiving terminal receives in the multi-carrier transmission process, and has the precision of delay height, the characteristics that anti-electromagnetic interference is strong.
Basic design of the present invention is: be modulated light signal disturbing electrical signal conversion at first, transfer to fibre delay line then, change light signal the corresponding light path of process realize the delay of light signal, at last light signal is converted to the signal of telecommunication, thereby realizes rf signal phase shift (2n+1) 180 ° of all after dates, wherein n=0,1,2,3 ..., influence the interference signal of useful signal by offseting filtering.
In order to address the above problem, a kind of signal interference cancellation device that the present invention is designed comprises main channel, delayed branch and offsets module.Described main channel is used for pending rf signal exported to and offsets module; Export to after described delayed branch is used for rf signal to be postponed handled and offset module; The described module that offsets is used for the rf signal of delay that pending rf signal that the main channel is sent and delayed branch send and offsets, and obtains required useful signal.Difference of the present invention is: described delayed branch comprises electrooptic conversion module, fibre delay line module and photoelectric conversion module.Described electrooptic conversion module is used for postponing rf signal after signal processing with waiting, is transformed into the light signal of this signal modulation.Described fibre delay line module is used for the frequency according to the interference signal of required elimination, the control light signal the distance of process come delayed optical signal.The light signal that described photoelectric conversion module is used for postponing phase shift through the fibre delay line module is reduced to former and waits to postpone the consistent rf signal of delay of rf signal amplitude after signal processing.
In the such scheme, described fibre delay line module comprises a coarse adjustment module and/or fine setting module.Described coarse adjustment module comprises 1 * N optical switch and N * 1 optical switch, between N input of N output of 1 * N optical switch and N * 1 optical switch, be connected with the optical fiber of different length, the input of 1 * N optical switch links to each other with electrooptic conversion module, and the output of N * 1 optical switch links to each other with photoelectric conversion module; Select the fiber lengths of access delay branch road by optical switch, the control light signal the path of process, realize the coarse adjustment that light signal postpones.Described fine setting module comprises input and the electrooptic conversion module that is connected on 1 * N optical switch, and/or the output of N * 1 optical switch and at least one pair of the delay collimater between the photoelectric conversion module, one of them postpones collimater by Electric Machine Control, can be parallel to two in the drive lower edge of motor and postpone to move on the direction of collimater axial connecting lines; By the distance between the control lag collimater, the control light signal the path of process, realize the fine setting that light signal postpones.
The signal interference cancellation method that above-mentioned signal interference cancellation device is adopted comprises:
Step 1, pending rf signal exported to offset module;
Step 2, export to after will rf signal be postponed handling and offset module;
The rf signal of delay that step 3, the pending rf signal that the main channel is sent and delayed branch send offsets and obtains useful signal;
Its difference is: described step 2 comprises
Step 2-1, will wait to postpone rf signal after signal processing, be transformed into the light signal of this signal modulation;
Step 2-2, according to the frequency of the interference signal of required elimination, the control light signal the distance of process come delayed optical signal;
Step 2-3, will postpone the light signal of 180 ° of all after dates of phase shift (2n+1), n=0 wherein, 1,2,3 through accurate automatic and adjustable fibre delay line module ..., be reduced to former and wait to postpone the consistent rf signal of delay of rf signal amplitude.
In the such scheme, described step 1 comprises:
Step 1-1, realization impedance transformation make the impedance matching of waiting to postpone rf signal and band pass filter of input;
Step 1-2, select needed useful signal;
Step 1-3, filtered useful signal is amplified in advance the attenuation losses that causes with the compensating band bandpass filter;
Step 1-4, the signal of telecommunication after will amplifying are sent to drive laser work;
Step 1-5, signal of telecommunication modulation is become light signal send.
In order further to export stable luminous power, before the signal of telecommunication after the amplification of described step 1-4 goes drive laser work, also comprise light-operated step and/or temperature control step.So-called light-operated step promptly utilizes the signal of laser inner detector output to carry out the rectification amplification, makes it to become the control voltage with the luminous power size variation, thereby the biasing circuit of control laser reaches the purpose of controlling Output optical power.So-called temperature control step is promptly utilized the thermistor of laser inside, add precision resistance and be connected into bridge circuit, variation of temperature is become the variation of voltage, amplifying through direct current goes control flows to cross the size of current of the refrigerator of laser organ pipe in-core again, reach thermostatic effect, thereby the variation that guarantees the luminous power of laser remains within certain scope.
In the such scheme, described step 3 comprises:
Step 3-1, the light signal that receives is converted to the signal of telecommunication;
Step 3-2, the above-mentioned signal of telecommunication of changing out is carried out preposition amplification;
Step 3-3, the signal of telecommunication after the preposition amplification is carried out high-pass filtering, filtering low-frequency noise and interference;
Step 3-4, select useful signal;
Step 3-5, useful signal is amplified in advance, the gain of the signal of telecommunication is modulated and the frequency of the signal of telecommunication is carried out corresponding compensation;
Step 3-6, pre-amplifying signal is amplified to once more the amplitude that needs.
For the amplitude that postpones rf signal that guarantees to export with postpone before the amplitude that postpones rf signal of waiting be consistent, the signal of described above-mentioned steps 3 also comprises the amplitude regulating step before output, promptly carry out continuously adjustable to the radiofrequency signal amplitude of exporting in the photoelectric conversion module.
Below we describe the principle of fibre delay line:
Rf signal input laser diode, the light signal that laser diode becomes this signal to modulate the input radio frequency converting electrical signal is by light joint coupled into optical fibres.Photoelectric detector is transformed to original rf signal again with the light signal of rf modulations.The frequency spectrum of the rf signal of output is fully identical with the frequency spectrum of the input radio frequency signal of telecommunication, just postponed a period of time as medium with optical fiber, that is to say, radiofrequency signal is instantaneous to be stored in the fibre delay line unit, the length of time of storage is directly proportional with the length of optical fiber, the principle of Here it is fibre delay line.
When light wave was propagated with speed v in optical fiber, the length of delay was proportional to the length L of optical fiber, and the time delay that produces of the optical fiber of length-specific L can be expressed as so:
Δt=L/v=Ln/c
In the following formula, n is that wavelength is the refractive index of light wave in optical fiber of λ, and c is the propagation velocity of light wave in free space.By the expression formula of Δ t, we as can be seen, the length of time of delay is directly proportional with fiber lengths L, as long as can change the length of optical fiber, perhaps selects the optical fiber of different length by optical switch, just can realize different time of delay.
The present invention compared with prior art has following advantage:
1, the fibre delay line module can accurately be regulated light path, and according to the frequency of signal, and the time of required delay is controlled the length that optical fiber postpones, thereby realize the delay of light signal, and then realize 180 ° of the accurate phase shifts (2n+1) of the signal of telecommunication, wherein n=0,1,2,3
2, can realize the tracking of amplitude by increasing the amplitude regulating circuit, realize that output amplitude is adjustable continuously, keep consistent, to eliminate owing to the certain influence of optical transceiver itself to the output amplitude generation of signal with the original signal amplitude;
Advantages such as 3, signal transmits with optical fiber, and it is little to have a loss, postpones the precision height, and anti-electromagnetic interference is strong can increase substantially the performance index and the reliability of system.
(5) embodiment
Fig. 1 comprises main channel, delayed branch and offsets module for the schematic diagram of a kind of preferred signals interference cancellation of the present invention device.The rf signal of two-way at least that comes from the emission of different radio station receives by antenna, and these rf signals are the receiving terminal of entering signal interference cancellation device simultaneously.The receiving terminal of canceller include one initiatively induction influence receiver module, this module can be picked out user's unwanted signal, different active induction influences the signal of telecommunication that receiver module can be responded to different frequency, and with it as waiting that postponing rf signal imports different delayed branch respectively into.The signal that is not induced then imports in the main channel as pending rf signal, and directly sends in the canceller by cable.
Delayed branch of the present invention when promptly the signal that receives when receiving terminal is one road useful signal and a tunnel " interference " signal, then is provided with one road delayed branch according to the frequency configuration of " interference " signal of required elimination; And the signal that receives when receiving terminal then is provided with the two-way delayed branch when being " interference " signal of one road useful signal and two-way different frequency, and the rest may be inferred ..., be used for rf signal to be postponed is converted to light signal; According to the frequency of the signal of required elimination, the control light signal the light path of process come delayed optical signal; Light signal through after postponing 180 ° of phase shifts, is reduced to former and waits to postpone the consistent rf signal of delay of rf signal amplitude, export at last and offset module.Delayed branch of the present invention mainly is made of Tiny Electro-Optic modular converter, fibre delay line module and photoelectric conversion module.
Electrooptic conversion module is used for postponing rf signal after signal processing with waiting, is transformed into the light signal of this signal modulation, and it comprises input matching circuit, band pass filter, pre-amplifying circuit, drive circuit for laser, laser and power supply.The electrooptic conversion module of present embodiment mainly is made up of drive circuit, indicating circuit, laser and the power supply of input matching circuit, band pass filter, pre-amplifying circuit, laser as shown in Figure 2.Pending rf signal is realized impedance transformation through match circuit, makes the impedance matching of input impedance and filter, reduces reflection; Select needed useful signal rf signal promptly to be postponed through band pass filter then; Then amplify in advance through pre-amplifying circuit again, signal is amplified about 10dB, the attenuation losses that causes with the compensating band bandpass filter; Signal after the amplification is divided into two-way through distributor, and one the tunnel sends to the drive circuit of drive laser, and the indicating circuit display working condition is given on another road.In order to guarantee the stable luminous power of laser output, present embodiment can also add accurate light-operated and temperature control circuit in electrooptic conversion module.Light-operated circuit is exactly to utilize the signal that is made in the output of laser inner detector to carry out rectification to amplify, and make it to become the control voltage with the luminous power size variation, thereby the biasing circuit of control laser reaches the purpose of controlling Output optical power.Temperature control circuit then is the thermistor that utilizes laser inside, add precision resistance and be connected into bridge circuit, variation of temperature is become the variation of voltage, amplifying through direct current goes control flows to cross the size of current of the refrigerator of laser organ pipe in-core again, reach thermostatic effect, thereby the variation that guarantees the luminous power of laser remains within certain scope.
The fibre delay line module links to each other with controller by data wire, according to the frequency of interference signal of the required elimination of input in controller, thereby the control light signal the distance of process, realize 180 ° of the delay phase shifts of light signal.Light signal after the modulation enters in the fibre delay line module and postpones, because the light signal of different frequency postpones 180 ° of required optical fiber of phase shift and postpones the length difference, the length of manual adjustments optical fiber can not guarantee 180 ° of accurate phase shifts, so present embodiment adopts accurate automatic and adjustable fibre delay line module to carry out 180 ° of the accurate delay phase shifts of light signal.As shown in Figure 3, accurate automatic and adjustable fibre delay line module mainly is made up of optical switch, optical fiber, collimater, motor, encoder and controller.Controller is used to coordinate to control the work of whole optical fiber delay line module.Described optical switch effect is that the whole length of the optical fiber that inserts is selected, realize the coarse adjustment that light signal postpones, comprise 1 * N optical switch and N * 1 optical switch, be connected with the optical fiber of different length between N input of N output of 1 * N optical switch and N * 1 optical switch, 1 * N optical switch links to each other with photoelectric conversion module with electrooptic conversion module respectively with N * 1 optical switch.The gear that the delay of above-mentioned N value and this signal interference cancellation device is regulated is relevant, by the switching of optical switch, selects the fiber lengths of access delay branch road, regulate light signal the light path of process, realize the coarse adjustment of light signal delay.For light path is further accurately regulated, present embodiment also comprises input and the electrooptic conversion module that at least one pair of is connected on 1 * N optical switch, and/or the output of N * 1 optical switch and the delay of the light signal between photoelectric conversion module collimater, its effect is to regulate light beam, the light path of control beam between two collimaters, realize the fine setting that light signal postpones, and make it can accurately enter optical fiber.Every collimation device all is horizontally fixed on the anchor clamps, and one of them postpones collimater by Electric Machine Control, can be parallel to two in the drive lower edge of motor and postpone to move on the direction of collimater axial connecting lines; By the distance between the control lag collimater, the control light signal the path of process, realize the fine setting that light signal postpones.Motor then drives collimater and moves, and guarantees the accurate delay of light signal, thereby reaches the fine setting purpose of delay.Encoder comes down to use as counting, and the angular transition that it turns over motor is that corresponding information feedback is given controller.Controller carries out control corresponding through data processing and to motor, makes motor to move.Accurate automatic and adjustable fibre delay line module routine is as follows: when certain signal frequency of input in controller, controller control optical switch selects to insert the whole length of corresponding optical fiber, the coarse adjustment that postpones; Thereby the while motor is driven the drive slide block and moves, move the distance (distance of adjusting is according to the frequency shift of signal) of regulating between the collimater by slide block, the fine setting that postpones, thus guarantee that different optical fiber postpones length and can be consistent with correspondent frequency.When motor forwards the angle of regulation to, the distance between the collimater reaches the delay necessary requirement, and encoder feedback information is given controller, and controller stops drive motors; Otherwise controller will continue drive motors and rotate, and encoder is monitored and in real time in time to the controller feedback information.
After photoelectric conversion module is used for the light signal that postpones phase shift through the fibre delay line module handled, is reduced to former and waits to postpone the consistent rf signal of delay of rf signal amplitude.The micro photo electric modular converter of present embodiment mainly is made up of pre-amplification circuit, high pass filter, band pass filter, pre-amplifying circuit, coupling output amplifier, distributor, indicating circuit, detector and power supply as shown in Figure 4.Light signal is converted into the signal of telecommunication by detector, the signal of telecommunication at first carries out small-signal through pre-amplification circuit and amplifies, the signal of pre-amplification circuit output is through high pass filter filtering low-frequency noise and interference, select useful signal through band pass filter again, amplify in advance by pre-amplifying circuit then, by output amplifier, signal is amplified to the amplitude that needs at last.The signal of telecommunication of output amplifier output is through distributor, and one the tunnel exports to as signal and to offset module, and test port and indicating circuit are given in another road.Because the delayed electric signal amplitude of output is subjected to the influence of optical transceiver module gain, for the amplitude of the pending radiofrequency signal transmitted in the amplitude that makes delayed radio frequence and the main channel is consistent, present embodiment is introduced the amplitude adjustment module to the signal of telecommunication of photoelectric conversion module output, as Fig. 5.Amplitude regulating circuit operation principle is as follows: the signal of input is through behind the amplifier, the voltage magnitude of output signal is different along with the difference of frequency input signal, by comparing the amplitude of inhibit signal and original signal, utilize external knob to regulate the resistance of R16 slide-changing resistor, thereby the amplitude of control output signal guarantees that the amplitude of the pending signal of transmission in inhibit signal and the main channel is consistent.
180 ° of the phasic differences mutually of the last pending rf signal that has postponed rf signal and normal transmission, but amplitude is identical, and both pass through and offset module is after superposeing in the mixer, the interference signal of the useful signal of finally eliminating the effects of the act.For the multi-carrier communication circuit that needs are eliminated multichannel " interference " signal, can adopt mode in parallel, promptly adopt a plurality of active inductions to influence receiver module and from the rf signal that receives, select " interference " signal of frequency match with it respectively, send into respectively and postpone 180 ° of phase shifts in the different delayed branch, send in the lump to offset in the module then and once eliminate.
The present invention can be 0.5 cycle with treating that delayed optical signal postpones 180 ° of phase shifts not only; also can delayed optical signal delay 1.5 cycles of phase shift, 2.5 cycles, 3.5 cycles will be treated ... be about to treat that delayed optical signal postpones 180 ° of cycles of phase shift (2n+1); n=0 wherein, 1,2; 3 ... send in the canceller again and offset, but as long as realize indirectly that by light signal the delay of the signal of telecommunication offsets in the signal interference cancellation device, promptly within protection scope of the present invention.