CN104184471A - Aviation wireless communication frequency detector and frequency detection method thereof - Google Patents
Aviation wireless communication frequency detector and frequency detection method thereof Download PDFInfo
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- CN104184471A CN104184471A CN201410406550.3A CN201410406550A CN104184471A CN 104184471 A CN104184471 A CN 104184471A CN 201410406550 A CN201410406550 A CN 201410406550A CN 104184471 A CN104184471 A CN 104184471A
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Abstract
The invention discloses an aviation wireless communication frequency detector which comprises a frequency scanning and detecting module, an FFT frequency detecting module and a frequency detection control module. The frequency scanning and detecting module is used for conducting frequency scanning and detecting processing on quasi complex base band signals to obtain a frequency scanning and detecting state and frequency scanning and detecting frequency information. The FFT frequency detecting module is used for conducting FFT frequency detection processing on the quasi complex base band signals to obtain an FFT frequency detection state and FFT frequency detection frequency information. The frequency detection control module is used for analyzing content output by the frequency scanning and detecting module and the FFT frequency detecting module, outputting rough frequency offset information, used for quasi complex base band signal extraction, to a digital down converter, outputting fine frequency offset information, used for residual frequency offset compensation of the quasi complex base band signals, to a secondary frequency converter, and completing system frequency offset identification and compensation. The aviation wireless communication frequency detector can meet the harsh requirements for the frequency detection function in the channel environment with bad wireless communication equipment.
Description
Technical field
The present invention relates to aerospace wireless communication field, relate in particular to the radio communication frequency discriminator device in aerospace flight vehicle, is the implementation method of the frequency discriminator of a kind of comprehensive frequency sweep frequency discrimination technology proposing towards noisy channels transmission environment and FFT frequency discrimination technology.
Technical background
The high speed relative motion of aerospace flight vehicle will produce Doppler effect, and there is inherent frequency error in the transceiver local oscillator of Wireless Telecom Equipment, cause having larger deviation between signal(-) carrier frequency that receiver receives and the transmission carrier frequency of sender, have a strong impact on information capture and the demodulation of receiver.Therefore, frequency discriminator is the requisite functional module of Wireless Telecom Equipment on various aerospace flight vehicles.There is the contradiction between acquisition speed and tracking accuracy in the technology that traditional employing PHASE-LOCKED LOOP PLL TECHNIQUE is extracted carrier wave, the more difficult requirement that simultaneously meets dynamic and steady-state behaviour under high dynamic environment; And under the restriction of high dynamic environment and efficiency of transmission, there is the signal to noise ratio problem that is difficult to adopt matched filter to obtain in real time spread processing and gains to improve frequency discrimination analyzing and processing signal in the receiver of Wireless Telecom Equipment, cause adopting FFT frequency discrimination technology to have frequency discrimination noise bottleneck, do not meet the frequency discrimination demand under the noisy channels such as low signal-to-noise ratio, multipath fading environment.
Summary of the invention
How to face the severe channel circumstance of Wireless Telecom Equipment for solving, meet its harsh requirement to frequency discrimination function, goal of the invention of the present invention is to provide a kind of aviation radio communication frequency discriminator, and the thought that adopts frequency sweep and preliminary treatment fft analysis algorithm to carry out the complementary backup of two-shipper is carried out frequency discriminator design.Utilize the good frequency discrimination performance of Method of Sweeping Algorithm under low signal-to-noise ratio, noisy channels environment to solve the frequency discrimination bottleneck that under this application scenarios, fft algorithm exists; Utilize frequency sweep frequency discriminator block under FFT frequency discrimination good this application scenarios of frequency discrimination performance reasonably avoiding under better quality channel circumstance that the deficiency of remaining larger frequency deviation under condition is set at low threshold; Utilize frequency discrimination control module to analyze the output information of frequency sweep frequency discriminator block and FFT frequency discriminator block, adopt thick, smart frequency deviation output mode, respectively the fixing frequency deviation of system and transceiver Doppler frequency deviation are rationally calibrated, make frequency discriminator under same time index condition, obtain the rationally compromise of frequency discrimination scope and frequency discrimination precision.
Goal of the invention of the present invention is achieved through the following technical solutions:
A kind of aviation radio communication frequency discriminator, comprises frequency sweep frequency discriminator block, FFT frequency discriminator block and frequency discrimination control module, and described frequency sweep frequency discriminator block is used for aiming at complex baseband signal and carries out the processing of frequency sweep frequency discrimination, obtains frequency sweep frequency discrimination state information and frequency sweep frequency discrimination frequency information; Described frequency sweep frequency discrimination state information comprises scanning, catches, follows the tracks of, locks four kinds of states;
Described FFT frequency discriminator block is used for aiming at complex baseband signal and carries out the processing of FFT frequency discrimination, obtains FFT frequency discrimination state information and FFT frequency discrimination frequency information; Described FFT frequency discrimination state information comprises to be intercepted and locks two states;
Described frequency discrimination control module is used for analyzing described frequency sweep frequency discrimination state information, FFT frequency discrimination state information, lead to the thick frequency deviation information of the sampling theorem theory of computation or current thick frequency deviation information is carried out to the correction based on frequency sweep frequency discrimination frequency information according to midband, exporting thick frequency deviation information and extract to the valid complex baseband signal of digital down converter; If the FFT frequency discrimination state information of FFT frequency discriminator block output is selected FFT frequency discrimination frequency information for locking; If the FFT frequency discrimination state information of FFT frequency discriminator block output selects frequency sweep frequency discrimination frequency information to export smart frequency deviation information for intercepting, give the residual frequency deviation compensation of the valid complex baseband signal of double conversion device, final completion system entirety frequency deviation is differentiated and compensation.
According to above-mentioned feature, described FFT frequency discriminator block comprises frequency spectrum and resolves output calibration unit, described frequency spectrum is resolved output calibration unit certain count range is set, whether the FFT frequency discrimination frequency information by the output of latch comparison FFT frequency discriminator block conforms to count range, if conform to, FFT frequency discrimination state is in the lock state, and represents that now FFT frequency discrimination frequency information is stable.
According to above-mentioned feature, described frequency sweep frequency discriminator block comprises center frequency conversion sequences match correlator, multichannel frequency conversion sequences match integrator, frequency sweep state machine, mark time schedule controller, described frequency sweep frequency discriminator block will be divided into the identical shunt multiplexed signals in 6 tunnels through the accurate complex baseband signal of Digital Down Convert processing, wherein 1 tunnel along separate routes multiplexed signals send into described center frequency conversion sequences match correlator and carry out compensate of frequency deviation and frequency expansion sequence related operation, other 5 tunnels along separate routes multiplexed signalss are caught and are offset f according to the spreading code length computation frequency sweep of wireless communication baseband data rate and employing
dcaptureand f
dtrackwith frequency sweep centre frequency f
centreform distributed extension frequency set [f
centre-f
dtrack, f
centre-f
dcapture, f
centre, f
centre+ f
dcapture, f
centre+ f
dtrack] 5 branch roads sending into respectively described multichannel frequency conversion sequences match integrator carry out compensate of frequency deviation and frequency expansion sequence related operation;
Described mark time schedule controller produces and controls sequential according to the peak pulse of center frequency conversion sequences match correlator, make described frequency sweep state machine read the peak pulse information of multichannel frequency conversion sequences match integrator output on time, control the state circulation of frequency sweep state machine, output center frequency and frequency sweep frequency discrimination state information;
Described frequency sweep state machine carries out state circulation according to the peak pulse information of multichannel frequency conversion sequences match integrator output, output center frequency and frequency sweep frequency discrimination state, and select frequency corresponding to signal to supply with described center frequency conversion sequences match correlator and select suitable processing frequency.
According to above-mentioned feature, the frequency sweep state of described frequency sweep state machine is divided into scanning, catches, follows the tracks of, locks one of four states, correlation information and the drop-out mark of the multichannel frequency conversion sequences match integrator output of extracting according to commutator pulse carry out state transition, to guide compensation and the mode of Contrary compensation to adjust in time the centre frequency of described frequency sweep state machine output.
According to above-mentioned feature, described frequency sweep frequency discriminator block also comprises output interface unit, produce centre frequency according to the frequency sweep state transition of frequency sweep state machine and upgrade pulse, under the triggering of centre frequency renewal pulse, analyze the difference relation of current centre frequency and latch frequency, if this difference is less, abandons this secondary frequencies and upgrade; If this difference is larger, implements this secondary frequencies and upgrade, latch the frequency sweep frequency discrimination frequency information of output to external interface.
Another object of the present invention provides a kind of aviation radio communication frequency discrimination method, comprises following steps:
Step 1, the AD data of input intermediate frequency bandpass sampling are carried out to the Digital Down Convert based on thick frequency deviation value, obtain accurate complex baseband signal;
Step 2, aligning complex baseband signal carry out respectively frequency sweep frequency discrimination to be processed and the processing of FFT frequency discrimination, obtains frequency sweep frequency discrimination state, frequency sweep frequency discrimination frequency information, FFT frequency discrimination state, FFT frequency discrimination frequency information; Described FFT frequency discrimination state information comprises to be intercepted and locks two states; Described frequency sweep frequency discrimination state information comprises scanning, catches, follows the tracks of, locks four kinds of states;
Step 3, frequency discrimination control module are analyzed frequency sweep frequency discrimination state information, FFT frequency discrimination state information, lead to the thick frequency deviation information of the sampling theorem theory of computation or current thick frequency deviation information is carried out to the correction based on frequency sweep frequency discrimination frequency information according to midband, exporting thick frequency deviation information and extract to the valid complex baseband signal of digital down converter; If the FFT frequency discrimination state information of FFT frequency discriminator block output is selected FFT frequency discrimination frequency information for locking; If the FFT frequency discrimination state information of FFT frequency discriminator block output selects frequency sweep frequency discrimination frequency information to export smart frequency deviation information for intercepting, give the residual frequency deviation compensation of the valid complex baseband signal of double conversion device, final completion system entirety frequency deviation is differentiated and compensation.
According to above-mentioned feature, described FFT frequency discrimination pack processing contains following steps:
1.1) aiming at complex baseband signal goes modulated information data preliminary treatment, filtering extraction, buffer memory, employing fft analysis to obtain the frequency deviation information of every section of observation data;
1.2) output calibration unit is set and certain count range is set, adopt the strategy of latch comparison, whether the frequency deviation information that obtains every section of observation data by latch comparison fft analysis conforms to count range, if conform to, FFT frequency discrimination state is in the lock state, and represents that now FFT frequency discrimination frequency information is stable.
According to above-mentioned feature, described frequency sweep frequency discrimination pack processing contains following steps:
2.1) accurate complex baseband signal is divided into the identical shunt multiplexed signals in 6 tunnels, center frequency conversion sequences match correlator is sent on the 1st tunnel along separate routes multiplexed signals, and skew f is caught according to the spreading code length computation frequency sweep of wireless communication baseband data rate and employing in other 5 tunnels along separate routes multiplexed signals
dcaptureand f
dtrackwith frequency sweep centre frequency f
centreform distributed extension frequency set [f
centre-f
dtrack, f
centre-f
dcapture, f
centre, f
centre+ f
dcapture, f
centre+ f
dtrack] send into respectively multichannel frequency conversion sequences match integrator, aim at respectively complex baseband signal and carry out compensate of frequency deviation and frequency expansion sequence related operation;
2.2) produce and control sequential by the peak pulse of center frequency conversion sequences match correlator, make frequency sweep state machine read the correlation information of multichannel frequency conversion sequences match integrator output on time, control the state circulation of frequency sweep state machine, output center frequency and frequency sweep frequency discrimination state information;
2.3) select frequency values backbone frequency conversion sequences match correlator corresponding to signal to select suitable processing frequency by frequency sweep state machine output center frequency, control mark time schedule controller and catch in time frequency expansion sequence information, accelerate the convergence of frequency sweep state;
2.4) by output interface module monitoring frequency sweep state and frequency sweep centre frequency thereof, produce centre frequency according to the frequency sweep state transition of frequency sweep state machine and upgrade pulse, under the triggering of centre frequency renewal pulse, analyze the difference relation of current center frequency value and latch frequency, if this difference is less, abandons this secondary frequencies and upgrade; If this difference is larger, implements this secondary frequencies and upgrade, latch the frequency sweep frequency discrimination information of output to external interface.
According to above-mentioned feature, described frequency sweep state machine divides one of four states running, and concrete steps are as follows:
3.1) frequency sweep state machine in the system reset moment in scanning mode, adopt maximum frequency sweep step-length and single frequency sweep direction: if multichannel frequency conversion sequences match integrator can occur peak pulse under scanning mode, frequency sweep state machine will switch to trapped state; Otherwise it is all the time in scanning mode, and carry out frequency scanning according to controlling sequential;
3.2) frequency sweep state machine adopts less frequency sweep step-length in the time of trapped state, distribute and adjust in real time frequency sweep direction according to the peak pulse of multichannel frequency conversion sequences match integrator: if frequency sweep state machine does not detect yet peak pulse information in the time that control sequential is overtime, oppositely adjust frequency sweep centre frequency and switch to scanning mode; If multiple peak pulse information detected, frequency sweep state machine switches to tracking mode; If a small amount of peak pulse information detected, frequency sweep state machine carries out frequency scanning by analyzing peak pulse information distribution adjustment frequency sweep direction in trapped state;
3.3) frequency sweep state machine adopts minimum frequency sweep step-length in the time of tracking mode, distribute and adjust in real time frequency sweep direction according to the peak pulse of multichannel frequency conversion sequences match integrator: if frequency sweep state machine peak pulse information do not detected yet or a small amount of peak pulse information only detected when overtime controlling sequential, frequency sweep state machine switches to trapped state; Be multiple peak pulse information that symmetrical expression distributes if detect, frequency sweep state machine switches to lock-out state; Be multiple peak pulse information of asymmetric distribution if detect, frequency sweep state machine carries out frequency scanning by analyzing peak pulse information distribution adjustment frequency sweep direction in tracking mode;
3.4) frequency sweep state machine is in the lock state and does not carry out frequency sweep, if frequency sweep state machine peak pulse information do not detected yet or a small amount of peak pulse information only detected when overtime controlling sequential, frequency sweep state machine switches to trapped state; The multiple peak pulse information that are asymmetric distribution if detect, frequency sweep state machine switches to tracking mode; Otherwise frequency sweep state machine keeps lock-out state.
According to above-mentioned feature, described step 3 comprises following steps:
4.1) frequency discrimination control module in the time of system reset in the state of intercepting, calculate theoretical frequency deviation value and export thick frequency deviation information interface to according to the logical sampling theorem of midband, select the frequency discrimination frequency information of FFT frequency discrimination submodule or the output of frequency sweep frequency discrimination submodule to export smart frequency deviation information interface to according to the FFT frequency discrimination state information of FFT frequency discriminator block output all the time; If frequency sweep frequency discrimination state jumps to trapped state by scanning mode, frequency discrimination control module is carried out the correction of frequency sweep frequency discrimination frequency information to theoretical frequency deviation value, exports thick frequency deviation information interface to, and switches to completion status;
4.2) frequency discrimination control module, in the time of completion status, contrasts frequency sweep frequency discrimination frequency information and FFT frequency discrimination frequency information, if thick, smart frequency deviation information sum exceeds system priori index, and frequency discrimination control module output frequency discrimination repositioning information, and switch to the state of intercepting; If the stable state frequency difference of frequency sweep frequency discrimination frequency information and FFT frequency discrimination frequency information exceeds system priori index, frequency discrimination control module is carried out the correction of frequency sweep frequency discrimination frequency information to current thick frequency deviation information, and switches to the state of intercepting.
Beneficial effect of the present invention is mainly the following aspects:
1, be subject to the defect of channel circumstance and default threshold constraint for the FFT frequency discriminator block deficiency that frequency discrimination lost efficacy under noisy channels and frequency sweep frequency discriminator block frequency discrimination precision, this radio communication frequency discriminator adopts the complementary thought that backs up, preferentially exports of two-shipper, reasonably avoiding the shortcoming of two class frequency discriminators, can realize the frequency discrimination function under the noisy channels such as low signal-to-noise ratio, multipath fading environment, there is very high dynamic range.Under awgn channel environment, test result shows: this radio communication frequency discriminator is preferred FFT frequency discrimination branch road in the time that signal to noise ratio is higher, remaining frequency difference is not more than 0.003% times of character rate, preferred frequency sweep frequency discrimination branch road in the time that signal to noise ratio is lower, residual frequency deviation is not more than 0.008% times of character rate, and in the scope that meets frequency discrimination function, residual frequency deviation reduces with the reduction of signal to noise ratio, at E
b/ N
0during for-11dB, be no more than 0.0001% times of character rate; Under multidiameter fading channel environment, test shows: this radio communication frequency discriminator preferred FFT frequency discrimination branch road when less or Rice factor is larger in path loss, remaining frequency difference is not more than 0.003% times of character rate, the large or hour preferred frequency sweep frequency discrimination branch road of Rice factor in path loss, its residual frequency deviation is not more than 0.004% times of character rate, and residual frequency deviation residual frequency deviation in the scope that meets frequency discrimination function reduces with the reduction of signal to noise ratio.
2, be subject to device batch, system works environmental impact, in the time there is relatively large deviation in transceiver local oscillator, frequency discrimination control module can be identified by analyzing the output state of FFT frequency discriminator block and frequency sweep frequency discriminator block the abnormality of the thick frequency deviation value of digital receiver down-conversion employing, and then by the intrinsic frequency offset correction of the effective completion system of thick frequency deviation update algorithm, can make the frequency deviation dynamic range design of frequency discriminator minimize, make to obtain higher frequency discrimination precision under same time index demand.
Brief description of the drawings
Fig. 1 is the structural representation of a kind of aviation radio communication of the present invention frequency discriminator;
Fig. 2 is the structural representation of FFT frequency discriminator block in the present invention;
Fig. 3 is the structural representation of frequency sweep frequency discriminator block in the present invention;
Fig. 4 is the state transition figure of frequency sweep state machine in the present invention.
Embodiment
Below in conjunction with accompanying drawing, the invention will be further described; This example is implemented on the basis taking technical solution of the present invention as prerequisite, and provides detailed execution mode and concrete operating process, but protection scope of the present invention is not limited to following embodiment.
The present invention mainly comprises: frequency sweep frequency discriminator block, FFT frequency discriminator block and frequency discrimination control module.Basic procedure block diagram as shown in Figure 1, carries out the Digital Down Convert based on thick frequency deviation value to the AD data of input intermediate frequency bandpass sampling, obtains accurate complex baseband signal; FFT frequency discriminator block and frequency sweep frequency discriminator block are aimed at complex baseband signal and are carried out respectively the processing of frequency sweep frequency discrimination and the processing of FFT frequency discrimination, obtain frequency sweep frequency discrimination state, frequency sweep frequency discrimination frequency information, FFT frequency discrimination state, FFT frequency discrimination frequency information; Frequency discrimination control module is used for analyzing frequency sweep frequency discrimination state information, FFT frequency discrimination state information, lead to the thick frequency deviation information of the sampling theorem theory of computation or current thick frequency deviation information is carried out to the correction based on frequency sweep frequency discrimination frequency information according to midband, exporting thick frequency deviation information and extract to the valid complex baseband signal of digital down converter; If the FFT frequency discrimination state information of FFT frequency discriminator block output is selected FFT frequency discrimination frequency information for locking; If the FFT frequency discrimination state information of FFT frequency discriminator block output selects frequency sweep frequency discrimination frequency information to export smart frequency deviation information for intercepting, give the residual frequency deviation compensation of the valid complex baseband signal of double conversion device, final completion system entirety frequency deviation is differentiated and compensation.
Below the modules in the present invention is elaborated.
(1) FFT frequency discriminator block
FFT frequency discriminator block is to going modulated information data preliminary treatment through the accurate complex baseband signal of Digital Down Convert processing, filtering extraction, buffer memory, fft analysis obtains the frequency deviation information of every section of observation data, be provided with frequency spectrum at output port place and resolve output calibration unit, by certain count range is set, adopt the strategy of latch comparison, accurately latch numerical value and the confidence level of output FFT frequency discrimination output frequency deviation, whether the FFT frequency discrimination frequency information by the output of latch comparison FFT frequency discriminator block conforms to count range, if conform to, confidence level is 1, FFT frequency discrimination state is in the lock state, represent that now FFT frequency discrimination frequency information is stable.Fig. 2 is shown in by its structure chart.
(2) frequency sweep frequency discriminator block
Fig. 3 is shown in by its structure chart, described frequency sweep frequency discriminator block comprises center frequency conversion sequences match correlator, multichannel frequency conversion sequences match integrator, frequency sweep state machine, mark time schedule controller, described frequency sweep frequency discriminator block will be divided into the identical shunt multiplexed signals in 6 tunnels through the accurate complex baseband signal of Digital Down Convert processing, wherein 1 tunnel along separate routes multiplexed signals send into described center frequency conversion sequences match correlator and carry out compensate of frequency deviation and frequency expansion sequence related operation, other 5 tunnels along separate routes multiplexed signalss are caught and are offset f according to the spreading code length computation frequency sweep of wireless communication baseband data rate and employing
dcaptureand f
dtrackwith frequency sweep centre frequency f
centreform distributed extension frequency set [f
centre-f
dtrack, f
centre-f
dcapture, f
centre, f
centre+ f
dcapture, f
centre+ f
dtrack] 5 branch roads sending into respectively described multichannel frequency conversion sequences match integrator carry out compensate of frequency deviation and frequency expansion sequence related operation.
The input control signal of center frequency conversion sequences match correlator is the center frequency deviation value of frequency sweep frequency discriminator block identification, adopt this frequency deviation value to carry out to received signal compensate of frequency deviation and can obtain higher correlation, generate trigger condition using the control signal as scanning system.Multichannel frequency conversion sequences match integrator adopts integrator form to complete the relevant treatment of multichannel frequency variation signal, and principle of operation is consistent with sequences match correlator, but it greatly reduces resource consumption.
Described mark time schedule controller produces and controls sequential according to the peak pulse of center frequency conversion sequences match correlator, make described frequency sweep state machine read the peak pulse information of multichannel frequency conversion sequences match integrator output on time, control the state circulation of frequency sweep state machine, output center frequency and frequency sweep frequency discrimination state information;
Described frequency sweep state machine carries out state circulation according to the peak pulse information of multichannel frequency conversion sequences match integrator output, output center frequency and frequency sweep frequency discrimination state, and select frequency corresponding to signal to supply with described center frequency conversion sequences match correlator and select suitable processing frequency, catch in time frequency expansion sequence information, the convergence of acceleration frequency sweep state to ensure mark time schedule controller.
For obtaining lower frequency sweep capture time and higher frequency sweep frequency discrimination precision, frequency sweep state machine is divided into scanning, catches, follows the tracks of, locks one of four states, and this one of four states has different frequency scanning steppings.Correlation information and the drop-out mark of the 5 branch road sequences match integrator outputs of extracting according to commutator pulse carry out state transition, to guide compensation and the mode of Contrary compensation to adjust in time the centre frequency f of frequency sweep state machine output
centre.The state transition diagram of frequency sweep state machine as shown in Figure 4.
Frequency sweep state machine in scanning mode, adopts maximum frequency sweep step-length and single frequency sweep direction in the system reset moment: if multichannel frequency conversion sequences match integrator can occur peak pulse under scanning mode, frequency sweep state machine will switch to trapped state; Otherwise it is all the time in scanning mode, and carry out frequency scanning according to controlling sequential;
Frequency sweep state machine adopts less frequency sweep step-length in the time of trapped state, distribute and adjust in real time frequency sweep direction according to the peak pulse of multichannel frequency conversion sequences match integrator: if frequency sweep state machine does not detect yet peak pulse information in the time that control sequential is overtime, oppositely adjust frequency sweep centre frequency and switch to scanning mode; If multiple peak pulse information detected, frequency sweep state machine switches to tracking mode; If a small amount of peak pulse information detected, frequency sweep state machine carries out frequency scanning by analyzing peak pulse information distribution adjustment frequency sweep direction in trapped state;
Frequency sweep state machine adopts minimum frequency sweep step-length in the time of tracking mode, distribute and adjust in real time frequency sweep direction according to the peak pulse of multichannel frequency conversion sequences match integrator: if frequency sweep state machine peak pulse information do not detected yet or a small amount of peak pulse information only detected when overtime controlling sequential, frequency sweep state machine switches to trapped state; Be multiple peak pulse information that symmetrical expression distributes if detect, frequency sweep state machine switches to lock-out state; Be multiple peak pulse information of asymmetric distribution if detect, frequency sweep state machine carries out frequency scanning by analyzing peak pulse information distribution adjustment frequency sweep direction in tracking mode;
Frequency sweep state machine is in the lock state and does not carry out frequency sweep, if frequency sweep state machine peak pulse information do not detected yet or a small amount of peak pulse information only detected when overtime controlling sequential, frequency sweep state machine switches to trapped state; The multiple peak pulse information that are asymmetric distribution if detect, frequency sweep state machine switches to tracking mode; Otherwise frequency sweep state machine keeps lock-out state.
Need specify, the frequency sweep step-length of described minimum, less frequency sweep step-length and maximum frequency sweep step-length refer to frequency sweep state machine selected frequency sweep step-length under different states, minimum, less, maximum is the sequence that the length of these three frequency sweep step-lengths is relatively done, and those skilled in the art can arrange the frequency sweep step-length of random length as required.
For solving the frequent centre frequency f causing that switches of the long-term resident scanning mode of frequency sweep state machine or state
centreunsettled phenomenon, output interface is logical produces centre frequency renewal pulse according to the frequency sweep state transition of frequency sweep state machine, under the triggering of centre frequency renewal pulse, analyze the difference relation of current center frequency value and latch frequency, if this difference is less, abandons this secondary frequencies and upgrade; If this difference is larger, implements this secondary frequencies and upgrade, latch frequency sweep frequency discrimination information and the frequency sweep state information of output to external interface.
(3) frequency discrimination control module
Frequency discrimination control module is by operational module/state information interface control frequency sweep state machine sequential, and read FFT frequency discriminator block and frequency sweep frequency discriminator block job information carries out frequency analysis, exporting the system frequency deviation that thick frequency deviation information brings transceiver local oscillator difference calibrates, the frequency discrimination scope that completes the frequency discriminator of local oscillator frequency offset correction only needs covering system Doppler broadening, has greatly improved frequency discriminator in the frequency discrimination precision meeting under time index condition.
Frequency discrimination control module in the time of system reset in the state of intercepting, calculate theoretical frequency deviation value and export thick frequency deviation information interface to according to the logical sampling theorem of midband, select the frequency discrimination frequency information of FFT frequency discrimination submodule or the output of frequency sweep frequency discrimination submodule to export smart frequency deviation information interface to according to the FFT frequency discrimination state information of FFT frequency discriminator block output all the time; If frequency sweep frequency discrimination state jumps to trapped state by scanning mode, frequency discrimination control module is carried out the correction of frequency sweep frequency discrimination frequency information to theoretical frequency deviation value, exports thick frequency deviation information interface to, and switches to completion status;
Frequency discrimination control module, in the time of completion status, contrasts frequency sweep frequency discrimination frequency information and FFT frequency discrimination frequency information, if thick, smart frequency deviation information sum exceeds system priori index, and frequency discrimination control module output frequency discrimination repositioning information, and switch to the state of intercepting; If the stable state frequency difference of frequency sweep frequency discrimination frequency information and FFT frequency discrimination frequency information exceeds system priori index, frequency discrimination control module is carried out the correction of frequency sweep frequency discrimination frequency information to current thick frequency deviation information, and switches to the state of intercepting.
Frequency discrimination control module effectively utilizes FFT frequency discrimination under high s/n ratio environment to have accurate, stable frequency discrimination performance to make up low threshold frequency sweep frequency discriminator block and have under high s/n ratio environment the defect of larger locking residual frequency deviation, make frequency sweep frequency discriminator block not need the problem of considering that thresholding is adjusted, greatly improved the stability of frequency discrimination system.
Claims (10)
1. an aviation radio communication frequency discriminator, comprises frequency sweep frequency discriminator block, FFT frequency discriminator block and frequency discrimination control module, it is characterized in that:
Described frequency sweep frequency discriminator block is used for aiming at complex baseband signal and carries out the processing of frequency sweep frequency discrimination, obtains frequency sweep frequency discrimination state information and frequency sweep frequency discrimination frequency information; Described frequency sweep frequency discrimination state information comprises scanning, catches, follows the tracks of, locks four kinds of states;
Described FFT frequency discriminator block is used for aiming at complex baseband signal and carries out the processing of FFT frequency discrimination, obtains FFT frequency discrimination state information and FFT frequency discrimination frequency information; Described FFT frequency discrimination state information comprises to be intercepted and locks two states;
Described frequency discrimination control module is used for analyzing described frequency sweep frequency discrimination state information, FFT frequency discrimination state information, lead to the thick frequency deviation information of the sampling theorem theory of computation or current thick frequency deviation information is carried out to the correction based on frequency sweep frequency discrimination frequency information according to midband, exporting thick frequency deviation information and extract to the valid complex baseband signal of digital down converter; If the FFT frequency discrimination state information of FFT frequency discriminator block output is selected FFT frequency discrimination frequency information for locking; If the FFT frequency discrimination state information of FFT frequency discriminator block output selects frequency sweep frequency discrimination frequency information to export smart frequency deviation information for intercepting, give the residual frequency deviation compensation of the valid complex baseband signal of double conversion device, final completion system entirety frequency deviation is differentiated and compensation.
2. a kind of aviation radio communication frequency discriminator according to claim 1, it is characterized in that described FFT frequency discriminator block comprises frequency spectrum and resolves output calibration unit, described frequency spectrum is resolved output calibration unit certain count range is set, whether the FFT frequency discrimination frequency information by the output of latch comparison FFT frequency discriminator block conforms to count range, if conform to, FFT frequency discrimination state is in the lock state, and represents that now FFT frequency discrimination frequency information is stable.
3. a kind of aviation radio communication frequency discriminator according to claim 1, it is characterized in that described frequency sweep frequency discriminator block comprises center frequency conversion sequences match correlator, multichannel frequency conversion sequences match integrator, frequency sweep state machine, mark time schedule controller, described frequency sweep frequency discriminator block will be divided into the identical shunt multiplexed signals in 6 tunnels through the accurate complex baseband signal of Digital Down Convert processing, wherein 1 tunnel along separate routes multiplexed signals send into described center frequency conversion sequences match correlator and carry out compensate of frequency deviation and frequency expansion sequence related operation, skew f is caught according to the spreading code length computation frequency sweep of wireless communication baseband data rate and employing in other 5 tunnels along separate routes multiplexed signals
dcaptureand f
dtrackwith frequency sweep centre frequency f
centreform distributed extension frequency set [f
centre-f
dtrack, f
centre-f
dcapture, f
centre, f
centre+ f
dcapture, f
centre+ f
dtrack] 5 branch roads sending into respectively described multichannel frequency conversion sequences match integrator carry out compensate of frequency deviation and frequency expansion sequence related operation,
Described mark time schedule controller produces and controls sequential according to the peak pulse of center frequency conversion sequences match correlator, make described frequency sweep state machine read the peak pulse information of multichannel frequency conversion sequences match integrator output on time, control the state circulation of frequency sweep state machine, output center frequency and frequency sweep frequency discrimination state;
Described frequency sweep state machine carries out state circulation according to the peak pulse information of multichannel frequency conversion sequences match integrator output, output center frequency and frequency sweep frequency discrimination state, and select frequency corresponding to signal to supply with described center frequency conversion sequences match correlator and select suitable processing frequency.
4. a kind of aviation radio communication frequency discriminator according to claim 3, the frequency sweep state that it is characterized in that described frequency sweep state machine is divided into scanning, catches, follows the tracks of, locks one of four states, correlation information and the drop-out mark of the multichannel frequency conversion sequences match integrator output of extracting according to commutator pulse carry out state transition, to guide compensation and the mode of Contrary compensation to adjust in time the centre frequency of described frequency sweep state machine output.
5. according to a kind of aviation radio communication frequency discriminator described in claim 3 or 4, it is characterized in that described frequency sweep frequency discriminator block also comprises output interface unit, produce centre frequency according to the frequency sweep state transition of frequency sweep state machine and upgrade pulse, under the triggering of centre frequency renewal pulse, analyze the difference relation of current centre frequency and latch frequency, if this difference is less, abandons this secondary frequencies and upgrade; If this difference is larger, implements this secondary frequencies and upgrade, latch the frequency sweep frequency discrimination frequency information of output to external interface.
6. an aviation radio communication frequency discrimination method, comprises following steps:
Step 1, the AD data of input intermediate frequency bandpass sampling are carried out to the Digital Down Convert based on thick frequency deviation value, obtain accurate complex baseband signal;
Step 2, aligning complex baseband signal carry out respectively frequency sweep frequency discrimination to be processed and the processing of FFT frequency discrimination, obtains frequency sweep frequency discrimination state, frequency sweep frequency discrimination frequency information, FFT frequency discrimination state, FFT frequency discrimination frequency information; Described FFT frequency discrimination state information comprises to be intercepted and locks two states; Described frequency sweep frequency discrimination state information comprises scanning, catches, follows the tracks of, locks four kinds of states;
Step 3, frequency discrimination control module are analyzed frequency sweep frequency discrimination state information, FFT frequency discrimination state information, lead to the thick frequency deviation information of the sampling theorem theory of computation or current thick frequency deviation information is carried out to the correction based on frequency sweep frequency discrimination frequency information according to midband, exporting thick frequency deviation information and extract to the valid complex baseband signal of digital down converter; If the FFT frequency discrimination state information of FFT frequency discriminator block output is selected FFT frequency discrimination frequency information for locking; If the FFT frequency discrimination state information of FFT frequency discriminator block output selects frequency sweep frequency discrimination frequency information to export smart frequency deviation information for intercepting, give the residual frequency deviation compensation of the valid complex baseband signal of double conversion device, final completion system entirety frequency deviation is differentiated and compensation.
7. a kind of aviation radio communication frequency discrimination method according to claim 6, is characterized in that described FFT frequency discrimination pack processing contains following steps:
1.1) aiming at complex baseband signal goes modulated information data preliminary treatment, filtering extraction, buffer memory, employing fft analysis to obtain the frequency deviation information of every section of observation data;
1.2) output calibration unit is set and certain count range is set, adopt the strategy of latch comparison, whether the frequency deviation information that obtains every section of observation data by latch comparison fft analysis conforms to count range, if conform to, FFT frequency discrimination state is in the lock state, and represents that now FFT frequency discrimination frequency information is stable.
8. a kind of aviation radio communication frequency discrimination method according to claim 6, is characterized in that described frequency sweep frequency discrimination pack processing contains following steps:
2.1) accurate complex baseband signal is divided into the identical shunt multiplexed signals in 6 tunnels, center frequency conversion sequences match correlator is sent on the 1st tunnel along separate routes multiplexed signals, and skew f is caught according to the spreading code length computation frequency sweep of wireless communication baseband data rate and employing in other 5 tunnels along separate routes multiplexed signals
dcaptureand f
dtrackwith frequency sweep centre frequency f
centreform distributed extension frequency set [f
centre-f
dtrack, f
centre-f
dcapture, f
centre, f
centre+ f
dcapture, f
centre+ f
dtrack] send into respectively multichannel frequency conversion sequences match integrator, aim at respectively complex baseband signal and carry out compensate of frequency deviation and frequency expansion sequence related operation;
2.2) produce and control sequential by the peak pulse of center frequency conversion sequences match correlator, make frequency sweep state machine read the correlation information of multichannel frequency conversion sequences match integrator output on time, control the state circulation of frequency sweep state machine, output center frequency and frequency sweep frequency discrimination state information;
2.3) select frequency values backbone frequency conversion sequences match correlator corresponding to signal to select suitable processing frequency by frequency sweep state machine output center frequency, control mark time schedule controller and catch in time frequency expansion sequence information, accelerate the convergence of frequency sweep state;
2.4) by output interface module monitoring frequency sweep state and frequency sweep centre frequency thereof, produce centre frequency according to the frequency sweep state transition of frequency sweep state machine and upgrade pulse, under the triggering of centre frequency renewal pulse, analyze the difference relation of current center frequency value and latch frequency, if this difference is less, abandons this secondary frequencies and upgrade; If this difference is larger, implements this secondary frequencies and upgrade, latch the frequency sweep frequency discrimination information of output to external interface.
9. a kind of aviation radio communication frequency discrimination method according to claim 8, is characterized in that described frequency sweep state machine divides one of four states running, and concrete steps are as follows:
3.1) frequency sweep state machine in the system reset moment in scanning mode, adopt maximum frequency sweep step-length and single frequency sweep direction: if multichannel frequency conversion sequences match integrator can occur peak pulse under scanning mode, frequency sweep state machine will switch to trapped state; Otherwise it is all the time in scanning mode, and carry out frequency scanning according to controlling sequential;
3.2) frequency sweep state machine adopts less frequency sweep step-length in the time of trapped state, distribute and adjust in real time frequency sweep direction according to the peak pulse of multichannel frequency conversion sequences match integrator: if frequency sweep state machine does not detect yet peak pulse information in the time that control sequential is overtime, oppositely adjust frequency sweep centre frequency and switch to scanning mode; If multiple peak pulse information detected, frequency sweep state machine switches to tracking mode; If a small amount of peak pulse information detected, frequency sweep state machine carries out frequency scanning by analyzing peak pulse information distribution adjustment frequency sweep direction in trapped state;
3.3) frequency sweep state machine adopts minimum frequency sweep step-length in the time of tracking mode, distribute and adjust in real time frequency sweep direction according to the peak pulse of multichannel frequency conversion sequences match integrator: if frequency sweep state machine peak pulse information do not detected yet or a small amount of peak pulse information only detected when overtime controlling sequential, frequency sweep state machine switches to trapped state; Be multiple peak pulse information that symmetrical expression distributes if detect, frequency sweep state machine switches to lock-out state; Be multiple peak pulse information of asymmetric distribution if detect, frequency sweep state machine carries out frequency scanning by analyzing peak pulse information distribution adjustment frequency sweep direction in tracking mode;
3.4) frequency sweep state machine is in the lock state and does not carry out frequency sweep, if frequency sweep state machine peak pulse information do not detected yet or a small amount of peak pulse information only detected when overtime controlling sequential, frequency sweep state machine switches to trapped state; The multiple peak pulse information that are asymmetric distribution if detect, frequency sweep state machine switches to tracking mode; Otherwise frequency sweep state machine keeps lock-out state.
10. a kind of aviation radio communication frequency discrimination method according to claim 6, is characterized in that described step 3 comprises following steps:
4.1) frequency discrimination control module in the time of system reset in the state of intercepting, calculate theoretical frequency deviation value and export thick frequency deviation information interface to according to the logical sampling theorem of midband, select the frequency discrimination frequency information of FFT frequency discrimination submodule or the output of frequency sweep frequency discrimination submodule to export smart frequency deviation information interface to according to the FFT frequency discrimination state information of FFT frequency discriminator block output all the time; If frequency sweep frequency discrimination state jumps to trapped state by scanning mode, frequency discrimination control module is carried out the correction of frequency sweep frequency discrimination frequency information to theoretical frequency deviation value, exports thick frequency deviation information interface to, and switches to completion status;
4.2) frequency discrimination control module, in the time of completion status, contrasts frequency sweep frequency discrimination frequency information and FFT frequency discrimination frequency information, if thick, smart frequency deviation information sum exceeds system priori index, and frequency discrimination control module output frequency discrimination repositioning information, and switch to the state of intercepting; If the stable state frequency difference of frequency sweep frequency discrimination frequency information and FFT frequency discrimination frequency information exceeds system priori index, frequency discrimination control module is carried out the correction of frequency sweep frequency discrimination frequency information to current thick frequency deviation information, and switches to the state of intercepting.
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