CN1222008A - Method and apparatus for fast recovery from loss of lock in phase locked loop - Google Patents
Method and apparatus for fast recovery from loss of lock in phase locked loop Download PDFInfo
- Publication number
- CN1222008A CN1222008A CN 98123596 CN98123596A CN1222008A CN 1222008 A CN1222008 A CN 1222008A CN 98123596 CN98123596 CN 98123596 CN 98123596 A CN98123596 A CN 98123596A CN 1222008 A CN1222008 A CN 1222008A
- Authority
- CN
- China
- Prior art keywords
- loop
- loop filter
- carrier tracking
- tracking loop
- filter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 37
- 238000011084 recovery Methods 0.000 title abstract description 17
- 238000001514 detection method Methods 0.000 claims abstract 4
- 230000007704 transition Effects 0.000 claims description 40
- 230000004044 response Effects 0.000 claims description 13
- 238000012937 correction Methods 0.000 claims description 9
- 230000001419 dependent effect Effects 0.000 claims description 6
- 230000001360 synchronised effect Effects 0.000 claims description 5
- 230000003466 anti-cipated effect Effects 0.000 abstract 1
- 238000000746 purification Methods 0.000 description 13
- 230000001052 transient effect Effects 0.000 description 10
- 230000008569 process Effects 0.000 description 9
- 235000014676 Phragmites communis Nutrition 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 238000005352 clarification Methods 0.000 description 4
- 238000004891 communication Methods 0.000 description 4
- 230000033228 biological regulation Effects 0.000 description 3
- 230000014509 gene expression Effects 0.000 description 3
- 230000010363 phase shift Effects 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 230000003044 adaptive effect Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- APTZNLHMIGJTEW-UHFFFAOYSA-N pyraflufen-ethyl Chemical compound C1=C(Cl)C(OCC(=O)OCC)=CC(C=2C(=C(OC(F)F)N(C)N=2)Cl)=C1F APTZNLHMIGJTEW-UHFFFAOYSA-N 0.000 description 1
- WYROLENTHWJFLR-ACLDMZEESA-N queuine Chemical compound C1=2C(=O)NC(N)=NC=2NC=C1CN[C@H]1C=C[C@H](O)[C@@H]1O WYROLENTHWJFLR-ACLDMZEESA-N 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000007634 remodeling Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000005236 sound signal Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000013519 translation Methods 0.000 description 1
Images
Landscapes
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
Abstract
The invnetion provides a method for fast recovery from loss of carrier wave received by satellite or earth modulator demodulator. The modulator demodulator includes a carrier wave tracking loop and a loop filter for guiding loops, which for detecting appearance of ringing situtation of the carrier wave tracking loop, responding to the ringing detection, the loop filter is purified according to a slot determined by a anticipated length of the ringing situtation. During the purified step, the loop filter is guided to a predetermined value before ringing. After purified, the carrier wave tracking loop is try to reobtain the carrier wave quickly.
Description
The present invention relates to a kind ofly be used to make that phase-locked loop (PLL) can recover to lock loses and be used to recapture the method and apparatus of getting the signal of being followed the tracks of by this PLL.The present invention comprises that at the communication control processor of any type (but not limiting) is used to receiving digital data,, be useful in the satellite modem of digital video and/or digitized audio message.
Satellite modem is one to be used for the carrier wave that the quilt that includes numerical data, digital video and/or digitized audio message is digitally modulated is changed and the receiver of demodulation.This carrier signal is carried out QPSK (Quadrature Phase Shift Keying) or OQPSK (offset quadrature phase-shift-keying) modulation usually.Yet this carrier wave selectively is carried out M-ary psk (phase shift keying) modulation.Other modulation format also can be used.Although satellite modem can be provided as independently product, more generally be used as the element in the integrated receiver decoder (IRD).
This satellite modem by obtain, follow the tracks of, synchronously and demodulation one (signal is transmitted thereon) carrier wave receive this signal.Then digital video, digital audio and data are sent to a digital back-end treatment region downwards and be used for the vision signal that to watch with a usual manner reconstruct and the audio signal that can hear.
When ending, it is invalid that video and voice data become when instantaneous (for example, number Millisecond) that the carrier wave reception occurs.This can make video and audio frequency not be provided for the beholder constantly, causes unacceptable interruption or gap in the just viewed service (for example TV programme).For example, when voice data when being invalid, audio frequency output can be become effectively until audio frequency by noise elimination.If satellite modem is not recaptured carrier wave very apace and got and demodulation, the artefact (artifact) of tangible noise elimination and/or video will appear.
The instantaneous termination that carrier wave receives can be caused by a variety of causes.Some more common reasons are that the radio frequency (RF) from radar and surface state, thunder and lightning and power line transient phenomena (not Wu as voltage step-down or power failure) disturbs.Because the IRD product worldwide is used, they are worked comprising under the multiple ambient conditions of some or all the problems referred to above.Use one type of prior art syringe, will reach three seconds the recovery time of termination sometimes, can occur video and tone squelch (blanking) in this duration.
It is favourable that a kind of instantaneous method and apparatus of losing that is used for recovering apace a carrier wave that receives is provided.It is particularly advantageous that a kind of instantaneous the losing that can successfully recover the carrier wave that receives through satellite is provided.The invention provides a kind of above-mentioned and method and apparatus other advantage of having.
Minimum recovery time of ending for the moment that makes a receiver (for example satellite IRD, satellite modem etc.), the present invention remains on the demodulator control signal in this receiver in the window of one regulation, in case the actual cause of ending is decorporated, one resets fast recaptures this receiver of permission as quickly as possible and to get and this signal of demodulation (suppose this receiver work in the nominal predetermined parameter).
A method according to the present present invention has guaranteed that the instantaneous of carrier wave that fast quick-recovery one receives lose.Carrier tracking loop with a loop filter is provided.One guiding loop also is provided, has been used for instantaneous the losing that this carrier tracking loop maintenance is locked with fast quick-recovery in position.When appearance one influenced the transition situation of this carrier tracking loop, this transition situation was detected.For example, by one forward the unusual high bit error rate (BER) that detects of error correction processor can indicate such transition situation.
In response to detecting a transition situation, this loop filter is cleaned the time that (flushed) decides on the length of this transition situation of expection.For example, determined that the transient influence of thunder and lightning in signal of communication continues about 5 milliseconds usually.20 milliseconds clarification time section therefore will be more than enough to the compensation of the transition of a lightning induction.
In this purifying step, when this loop filter is cleaned, this loop filter output voltage is forced to towards a predetermined reference value (for example, in the scope definite by " window " with a upper and lower threshold value) so that any variation minimum in the frequency of this carrier tracking loop.As an example, the scope that this window can comprise from pact ± 0.1 of about 1 volt nominal loop filter voltage volt.After this purifying step finished, this carrier tracking loop attempted to introduce the frequency and the phase place of this carrier wave.
Before the purifying step during the normal carrier operation, this carrier tracking loop is worked with a loop bandwidth BW.One guiding loop is directed to suitable position with this carrier tracking loop and is used for fast quick-recovery and can influences normal tracking operation sharply.In one embodiment, when carrier track when being effective, one processor is measured this loop filter output voltage, adds to this loop filter output voltage by the voltage source with plurality of separate, at leisure this loop filter output voltage is directed to this predetermined reference voltage.The voltage source of these separation can be provided by D/A (DAC).In normal demodulator carrier track, slowly DAC (slowDAC) variation causes the equal and opposite in direction and the opposite change of direction of the correspondence of loop filter output voltage, causes this predetermined reference voltage that is directed to of expecting.Transient event may force carrier loop to go out of lock, and order about the loop filter output voltage and leave this reference voltage (normal trace point) also outside the window of upper and lower threshold value.This purification turns back to the loop filter output voltage in the value before this transient event (maybe near this value).
After finishing purifying step, use this loop bandwidth BW to start this carrier tracking loop.This for example can be by immediately storing this loop bandwidth before purifying, and use this storing value to reopen the carrier track and being implemented of beginning in this purifications back with same BW then.Selectively, a fiducial value can be used to set a nominal loop BW value.
This forward error correction processor can be used to be begun the synchronous again of this carrier tracking loop and described carrier wave after losing at carrier track and bit timing.
A kind of instantaneous device of losing that is used to recover a reception carrier is disclosed.This device comprises the carrier tracking loop with a loop filter and is used for a guiding loop of this carrier tracking loop.Provide the checkout gear that is used to detect the appearance that influences the transition of this carrier tracking loop situation.This loop filter response is in this checkout gear, is cleaned according to the expection length of this transition situation and a fixed time period.Provide and be used for following the tracks of and during this loop filter frame is cleaned simultaneously, with the voltage guiding of this loop filter device to a predetermined value normal.This guiding operation makes the achievement maximum that the variation of frequency of this carrier tracking loop during the purification run is minimum and carrier track is recovered.Then, this carrier tracking loop attempts to introduce the frequency and the phase place of this carrier wave.
In the embodiment of an explanation, the instantaneous device of losing that is used to recover a carrier wave that receives comprises the carrier tracking loop with a loop filter and an oscillator.One forward error-corrector the influence when a transition situation of carrier tracking loop occurs, an error signal is provided.One processor is coupled with in response to this error signal, and this loop filter is purified the fixed time period according to the length of this transition situation of expecting.The voltage of this this loop filter of processor monitors, and control this oscillator with when this loop filter just is being cleaned, this loop filter voltage is remained in the preset range, thereby make the variation minimum of the frequency of this carrier tracking loop when this loop filter is cleaned.This processor among one embodiment continues this oscillator of control in the operating period of described carrier tracking loop, so that this loop filter voltage is remained in this preset range.
This loop filter can be implemented as make it in response to this processor to set up a bandwidth of this carrier tracking loop.And in such embodiment, this processor can be controlled this loop filter so that this bandwidth is turned back to a predetermined value after this filter is cleaned.
Fig. 1 is for embodying the block diagram that transition synchronization loss of the present invention recovers the acceptor device of feature;
Fig. 2 is the explanation figure of operating in carrier tracking loop (CTL) guiding of normal (non-transient state) operating period of the present invention;
Fig. 3 is for being used to guide this CTL with the flow chart with the program of this loop filter substitution limit according to of the present invention;
Fig. 4 is according to the flow chart that is used to recapture the program of getting a carrier wave of the present invention;
Fig. 5 recaptures the flow chart of getting algorithm for another kind of carrier wave according to the present invention.
The present invention has realized the instantaneous fast quick-recovery of losing of a carrier wave that receives.Particularly, lose when occurring when carrier lock instantaneous, the carrier tracking loop of a receiver (CTL) is cleaned (for example by zero setting).This CTL is cleaned the length that is dependent on this transition situation and a fixed time period.The purification of this CTL can for example use one can be implemented by the switch of microprocessor actuating.After transition by the time in the past, this CTL uses its previous loop bandwidth (bandwidth when promptly this loop is worked before this transition) or is activated and is allowed to pull-in frequency and phase place in the bandwidth of operation of a nominal.After carrier track and bit timing were resumed, error correction forward (FEC) circuit of a routine continued this heavy synchronizing process.
Keep this CTL loop filter voltage or carry out near the background process of " loop purification " value and to continue to follow the tracks of so that in this " loop purification " frequency Δ (frequency change) minimum when occurring.To be supposition do not change and remain under the situation in this introducing scope of this carrier tracking loop in input received signal frequency one key element of this quick recovery method significantly.Although between transient period, bit timing may be lost, and supposes after this transient influence is decorporated, and this bit timing loop self obtains.
Introduce phase place and frequency in order to make this CTL purify the back at a loop, purifying the frequency shift (FS) of being introduced by this loop must be in this loop noise bandwidth.For guaranteeing this condition, must carry out CTL tracking loop filter voltage purifies the identical value of voltage towards this loop real-time guiding.Fig. 1 provides a system block diagram and Fig. 2 to illustrate during normal demodulator is followed the tracks of, i.e. the guiding of CTL filter when not having transition situation operation.
Referring to Fig. 1, an input signal, for example the RF signal that receives from a satellite, cable or other communication channels is coupled to a tuner 12.This tuner selects one of several signals that are transmitted to do to handle further, for example serves video frequency program to a user to provide.This tuner frequencies is controlled (AFC) loop by an automatic frequency and is held, and this AFC loop comprises pre-scale output 13 and one a control signal input 15.This pre-scale output 13 is provided for a microprocessor 34, this microprocessor responds its, this control signal input 15 is provided.
As shown in Figure 1, demodulator 14 is in response to the local oscillator frequency from a voltage controlled oscillator (VCO) 16.One prescaler 18 also receives this VCO output to provide a loop control signal to microprocessor 34.CTL VCO control voltage control VCO output frequency on this microprocessor via line 31.
(promptly by demodulation) homophase (I) of demodulator 14 output base band and quadrature be (Q) signal component mutually.These base band component are transfused to mould/number (ADC) transducer, and this ADC transducer provides corresponding I data and Q data to carrier tracking loop phase detectors and and D/A (DAC) 26.This I and Q data also are provided for conventional error correction forward (FEC) circuit 22.Shown in Figure 1 only be among the embodiment of one of various schemes in the cards, I data and I-mid data that a bit timing loop 24 receives from ADC20.This is well known in the prior art the middle data of the data represented I channel of I-mid eye pattern.
The CTL phase detectors are determined the phase place of this I and the input of Q data and are become an analog signal to input to a CTL loop filter 28 this information translation with DAC26.This loop filter can comprise, for example, an operational amplifier (op amp) integrator circuit, this operational amplifier (op amp) integrator circuit comprises that a RC circuit is to provide integration.According to the present invention, describe more all sidedly as following, in case a transient signal occurs, this CTL loop filter 28 is cleaned to realize fast quick-recovery.In case detect an instantaneous loss situation, provide a loop clean signal from microprocessor 34.This loop clean signal can be for example only one with the capacity earth of the RC integrator circuit that is provided with in the loop filter 28 by the ground of switch.In such scheme, this loop purifies and makes this capacitance charge zero setting and the loop filter output voltage is setovered this loop of locus guiding to by prior lock constant reference voltage regularly from power supply.After purification, the resistance value of RC circuit will be determined the bandwidth (BW) of this loop.Therefore, may control this loop bandwidth after the purification to this RC circuit by a control voltage is provided.Such control voltage can be set through a BW control signal 29 by microprocessor 34.
The output of CTL loop filter 28 comprises a loop filter floating voltage, this voltage in an adder 30 by with a frequency scanning and the addition of CTL loop filter steering signal from filter 38.Filter 38 can comprise that for example, a resistor/capacitor (RC) circuit is used for the frequency control signal that inputs to it is carried out integration.Particularly, filter 38 receives the frequency signal of falling a frequency scanning DAC36 of instruction from DAC liter and DAC in response to microprocessor 34.Instruction falls in this DAC liter and DAC can be provided the CTL VCO by filter 38 restrictions is controlled the thin of voltage or slightly control as required in response to the computing of being carried out by microprocessor.
Loop filter floating voltage from CTL loop filter 28 also is provided for an ADC32, and the aanalogvoltage that ADC32 will be somebody's turn to do from loop filter 28 converts the digital data signal of a correspondence to input to microprocessor 34.Microprocessor determines that from this numerical data the amplitude of this loop filter floating voltage is whether in the scope (" loop purification value window ") 42 of being determined by a coboundary 40 and a lower boundary 44 shown in Fig. 2.If should value outside this normal loop filter following range 42, microprocessor with the thick and/or fine control of control filters 38 with order about lentamente this loop filter floating voltage get back in this scope 42 a bit.
Loop filter guiding is to remove outside this CTL, uses a voltage-tracing loop to be implemented, and this voltage-tracing loop is gone up operation and utilization " small-signal " with respect to this CTL in a lower bandwidth (with respect to this CTL).This has guaranteed that acceleration (loop stress) effect would not cause cycle slip or the faults in the demodulator.Voltage guiding source is frequency scanning DAC36, and this frequency scanning DAC36 also is used and is used for this CTL of frequency scanning during obtaining.
Loop filter voltage is measured by microprocessor 34, and microprocessor 34 is compared it with the loop purification value window of demarcating.If this voltage in this window, is not changed to the input of frequency scanning DAC36.If this voltage outside this limit, then this frequency scanning DAC be adjusted (with a step-length and do not exceed this CTL follow the tracks of a dynamic speed) until this CTL tracking filter voltage in this appointed limit.This transition restoration methods only is only after CTL tracking filter voltage reaches this loop purification value (in this appointed window) effectively.
The hardware of prior art (for example DigiCipher II system (" DC II ") that is provided by the general instrument Corp. of California, USA) can not open this process of beginning behind at least 15 seconds of initial carrier lock.This is owing to due to the charge constant that is used to " loop stress " correction " slowly DAC " function.This slow DAC is required to import minimum so that arrive the acceleration of CTL, so that do not cause cycle slip or faults.
In a single day in the present invention, a similarly slow DAC function is provided, and has been engaged, can carry out correction towards the desired value of being demarcated.Particularly, be provided to during the CTL loop tracks, provide thick control from " the slowly DAC " of microprocessor 34 outputs via line 37.The electric capacity that this signal is used with switched filter 38 changes with slow DAC output during following the tracks of.Purpose is to guide this CTL loop filter floating voltage 33 as soon as possible to realize this desired value, so that demodulator can be prepared to recapture program fetch fast.Correction to these DAC can be very fast, for example quickens to enter on the order of magnitude of CTL at about 1.0MHz per second.This has supposed and has used 8 resolution, is offered about 1.28MHz refrequency control range of the thin DAC control of frequency scanning DAC36 by microprocessor 34.Such execution will provide and 20 seconds the transient activities and the recovery of reinforcement once in per then 5 seconds occur to initially obtaining the back.
The flow chart of CTL loop guided procedure is provided in Fig. 3.This process starts from frame 50, when FEC circuit 22 (Fig. 1) detects whole FEC locking.Then, suppose a for example incident of channel variation just to occur that beginning waits for that to one of signal (for example 15 seconds) are to settle out (settle out) shown in frame 52.Begin the coarse regulation of filter 38 by microprocessor 34 (falling control signal) then, and determine at frame 54 whether CTL loop filter output 28 is being represented in the window 42 of normal loop filter tracking through slow DAC function and/or through DAC liter and DAC.If rely on to comprise that the AFC circuit of pre-scale 13 of tuner and control signal 15 is to keep correct tuner frequencies.
If this CTL loop filter is not in this suitable limit, microprocessor 34 is the thin or coarse regulation of initial frequency scanning DAC36 as required, so that the CTL loop filter is brought back in this normal window of operation.This step is by frame 56 expressions.Carry out of short duration waiting (for example 5 milliseconds) at frame 58, and frame 54 is tested with definite this suitable limit whether it is operating again to the CTL loop filter in.This process will continue until this CTL loop filter (numeral 42 indications have the operation of normal tracking in promptly as Fig. 2) in this predetermined window.
In case realize this CTL loop filter desired value, recapture fast get recovery program by initial.This program is illustrated in the flow chart of Fig. 4, when receiving a Reed one Saloman (RS) interruption, begins this program from frame 60.This Reed one Saloman interruption is to be generated by the encoder that uses well-known Reed one Saloman non-binary linear block code to revise a routine of symbol error.
In case generating Reed one Saloman interrupts, the signal that expression receives must be recaptured and be got, one trial and error process is begun, in this process, the wetby decoder of the routine that comprises in the digit receiver is adjusted to rotate by all possible combination of polyphase signa conformation and to overturn this Wei Te than handling.This process is by frame 62 expressions.At frame 64, determine whether to realize synchronously heavy.If do not need to recapture and get this signal and control and be drawn towards the heavy synchronization program of RS, the heavy remainder of this FEC synchronously of this program.On the other hand, if in that not obtain Wei Te proportion after the making great efforts several times of frame 62 and 64 synchronous, CTL loop filter 28 is continued to purify the short times, for example 20 milliseconds (if or provide an adaptive control according to dissimilar transition situations, continue the variable time).This purification duration is set the time period with the whole expection of Bao Nayi transition.For example, therefore 20 milliseconds clarification time section is enough for such transition usually less than 20 milliseconds the duration of having found most of transitions of being caused by thunderbolt.Like this, continuous loop purifies or is selected as resetting time one " the wait for storm go over " time before CTL being recaptured get.This loop clarification time should lack as much as possible, but will be long enough to allow transition decorporate.The loop clarification time is long more, passes to the digital video transmission approach and to generate more visible artifactitious incorrect bit many more.This transient recovery time can be the instantaneous type of losing for the carrier wave that stands usually at a specified place, no matter be transition (causing losing of locking and this IRD that do not reset) or other phenomenons that thunder and lightning, moment RF miss, moment RF disturbs (for example radar), power line to bring out, the feature of a user-programmable that can be optimised.
After loop purifies, as frame 66 indications, microprocessor 34 (through BW control signal 29 shown in Figure 1) with loop bandwidth (BW) establish to one with startup recapture get value.For example, this loop bandwidth can be set to previous CTL tracking bandwidth (being the last bandwidth of CTL when correctly following the tracks of the signal of reception).In case this bandwidth is set, shown in frame 68, carry out of short duration the waiting (for example 1 millisecond) that carrier wave is obtained at frame 70.Then, determine whether (frame 72) has realized carrier lock.If not, those thick and/or thin DAC are scanned to attempt to realize carrier lock by this microprocessor ambiguity scope of crossing over.
In case the realization carrier lock determines whether (frame 74) has realized that Wei Te is than synchronously.If not, this wetby decoder will attempt to use its canonical algorithm to weigh synchronously until realizing (frame 75) synchronously.If can not realize Wei Te than synchronously, this CTL loop is not also successfully recaptured and is got.Requirement turns back to full rate scanning (" rescanning ") to realize carrier lock.Under these circumstances, fast quick-recovery is not implemented.
In case Wei Te takes place than synchronously, determines whether (frame 76) has realized that Reed one Saloman is synchronous.If not, this RS decoder will be attempted to weigh synchronously in a kind of mode of routine.In case realize that RS is synchronous, all the mode that the FEC locking can a kind of routine is followed.
The laboratory tests of described method show the many improved performance of obtaining restoration methods that has previous.This test comprises per 10 seconds and disturbs CW carrier wave (from standard carrier 10MHz) insertion to reach 5 milliseconds time period with one.This interference will make CTL lose locking.In the time more than 90%, recovery is that successful and visible influence is limited to some macro block.
Illustrated among Fig. 5 that another kind of carrier wave recaptures access method.This method may be faster than the method among Fig. 4, has the time that loop still less purifies, and be applicable to section transition time usually.
The CTL loop filter condition of related description with Fig. 4 also must be satisfied among the embodiment in Fig. 5. Frame 80,82,84,86,88,90,92,94 and 96 among Fig. 5 corresponds respectively to 60 among Fig. 4,62,64,66,68,70,72,74 and 76.But, when carrier lock is lost, shown in frame 92, loop purifies to be engaged (supposes that a counting is below a predetermined value, shown in frame 100,102,104) be shorter than time among Fig. 4 embodiment (for example 1 millisecond but not 20 milliseconds), after it, CTL loop BW is set (frame 88) and is allowed to obtain 1 millisecond (frame 90).If do not obtain, this process repeats to reach maximum predetermined value until carrier lock realization or event counter.Use this method, the transition of very short (for example 1 millisecond) is recovered quickly and the transition of growing (for example 15 milliseconds) also can be resumed.Shown in frame 85, this counter was reset to zero before first loop purifies.
Be appreciated that now and the invention provides a kind of fast quick-recovery one modulator-demodulator that is used for, for example instantaneous method and apparatus of losing of the carrier wave that receives in satellite or the ground communication modulator-demodulator.This modulator-demodulator comprises a carrier tracking loop path filter, and its voltage is guided a predetermined value in one " introducing window " so that the frequency change minimum when this loop is cleaned.When a transition took place, this carrier tracking loop path filter was cleaned a time period that is about this transition length.In case this transition in the past and this purifying step be done, this carrier tracking loop is activated, and attempts to introduce the frequency and the phase place of the carrier wave of reception.This track loop is remained in this introducing window so that " purification " and then the method for " startup " provide the program of fast quick-recovery to be shown that the method that the transition situation of prior art is recovered carried out significant improvement.The present invention is applicable to and simulated and digital two kinds of phase-locked loops (PLL) receiver modulator-demodulator of carrying out.
Although invention has been described in conjunction with various preferred embodiments.Load is appreciated that can make many remodeling and variation under the prerequisite that does not break away from the scope of the present invention that is defined by the following claims.
Claims (16)
1, a kind of instantaneous method of losing that is used to the carrier wave that recovers to receive includes step:
Carrier tracking loop with a loop filter is provided;
Detect the appearance of a transition situation of the described carrier tracking loop of influence;
In response to described detection step, described loop filter is purified the expection length that is dependent on described transition situation and a fixed time period;
The voltage of forcing described loop filter in described purifying step towards a predetermined value so that when described loop filter is cleaned, any variation minimum in the frequency of described carrier tracking loop; And
Make described carrier tracking loop after described purifying step has finished, attempt to draw in the frequency and the phase place of described carrier wave.
2, according to the method for claim 1, also include step:
Manage to make this loop filter remain on described predetermined value through a guiding step.
3, according to the method for claim 1 or 2, wherein:
Described carrier tracking loop with loop bandwidth BW work, reached before described purifying step
After finishing described purifying step, use described loop bandwidth BW to start this carrier tracking loop.
4, according to the method in preceding arbitrary claim, wherein said detection step detects the appearance of described transition situation according to an error signal.
5, according to the method for claim 4, wherein said error signal by one forward error correction circuit be provided.
6, according to the method for claim 5, wherein said error correction circuit forward is after carrier track and bit timing are lost, and the weight that begins described carrier tracking loop and described carrier wave is synchronous.
7, according to the method in preceding arbitrary claim, wherein said pressure step was carried out continuously in the operating period of described carrier tracking loop.
8, a kind of instantaneous device of losing that is used to recover a carrier wave that receives comprises:
Carrier tracking loop with a loop filter;
Checkout gear is used to detect the appearance of a transition situation that influences described carrier tracking loop;
Purifier is used in response to described checkout gear, and described loop filter is purified the expection length that is dependent on described transition situation and a fixed time period;
Forcing device is used for when described loop filter just is being cleaned, the voltage of forcing described loop filter towards a predetermined value so that when described loop filter is cleaned, any variation minimum in the frequency of described carrier tracking loop; And
Enabled device is used to make described carrier tracking loop to attempt to draw in the frequency and the phase place of described carrier wave after described purifying step has finished.
9, device according to Claim 8 also comprises:
Guiding device is used for following the tracks of operating period normal, guides described loop filter voltage lentamente in a preset range and do not lose locking.
10, a kind of instantaneous device of losing that is used to recover a carrier wave that receives comprises:
Carrier tracking loop with a loop filter and oscillator;
One error-corrector forward, described error-corrector forward provides an error signal when a transition situation of the described carrier tracking loop of influence occurring; And
One processor is coupled with in response to described error signal, and described loop filter is purified the expection length that is dependent on described transition situation and a fixed time period;
The voltage of the described loop filter of described processor monitors, and control described oscillator with when this loop filter just is being cleaned, keep described loop filter voltage in a preset range, thereby make when described loop filter is cleaned any variation minimum in the frequency of described carrier tracking loop.
11, according to the device of claim 10, wherein said processor at the described oscillator of the operating period of described carrier tracking loop continuous control so that described loop filter voltage is remained in the described preset range.
12, according to the device of claim 10 or 11, wherein:
Described loop filter response in described processor to set up a bandwidth of described carrier tracking loop; And
Described processor is controlled described loop filter so that this bandwidth is turned back to a predetermined value after this filter is cleaned.
13, a kind of method that is used to follow the tracks of a carrier wave that receives includes step:
Carrier tracking loop with a loop filter is provided; And
Guiding loop through being associated with described carrier tracking loop forces this loop filter to one to be scheduled to the loop output voltage values.
14, according to the method for claim 13, also include step:
Detect the appearance of a transition situation of the described carrier tracking loop of influence;
In response to described detection step, described loop filter is purified the expection length that is dependent on described transition situation and a fixed time period;
Force described loop filter in described purifying step towards described predetermined loop output voltage values so that when described loop filter is cleaned, any variation minimum in the frequency of described carrier tracking loop; And
Make described carrier tracking loop after described purifying step has finished, attempt to draw in the frequency and the phase place of described carrier wave.
15, a kind of device that is used to follow the tracks of a carrier wave that receives comprises:
Carrier tracking loop with a loop filter and oscillator;
One guiding loop is associated to force this loop filter to one to be scheduled to the loop output voltage values with described carrier tracking loop.
16, according to the device of claim 15, also comprise:
One error-corrector forward, described error-corrector forward provides an error signal when a transition situation of the described carrier tracking loop of influence occurring; And
One processor is coupled with in response to described error signal, and described loop filter is purified the expection length that is dependent on described transition situation and a fixed time period;
The voltage of the described loop filter of described processor monitors, and control described oscillator with when this loop filter just is being cleaned, force described loop filter voltage to described predetermined loop output voltage values, thereby make when described loop filter is cleaned any variation minimum in the frequency of described carrier tracking loop.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98123596 CN1222008A (en) | 1997-11-06 | 1998-11-06 | Method and apparatus for fast recovery from loss of lock in phase locked loop |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60/064666 | 1997-11-06 | ||
| CN 98123596 CN1222008A (en) | 1997-11-06 | 1998-11-06 | Method and apparatus for fast recovery from loss of lock in phase locked loop |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1222008A true CN1222008A (en) | 1999-07-07 |
Family
ID=5228260
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 98123596 Pending CN1222008A (en) | 1997-11-06 | 1998-11-06 | Method and apparatus for fast recovery from loss of lock in phase locked loop |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1222008A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101998028B (en) * | 2009-08-13 | 2012-08-29 | 承景科技股份有限公司 | Carrier wave tracking system and method |
-
1998
- 1998-11-06 CN CN 98123596 patent/CN1222008A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101998028B (en) * | 2009-08-13 | 2012-08-29 | 承景科技股份有限公司 | Carrier wave tracking system and method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5970397A (en) | Method for the frequency correction of multicarrier signals and related apparatus | |
| CA2169551C (en) | Apparatus and method for maximizing frequency offset tracking performance in a digital receiver | |
| EP0311973A2 (en) | Quotient phase-shift processor for digital phase-licked-loops | |
| US5539355A (en) | Frequency-shift-keying detector using digital circuits | |
| CN1398455A (en) | Digital phase-locket loop | |
| WO1999027671A1 (en) | Orthogonal frequency division multiplexing receiver where fft window position recovery interlocks with sampling clock adjustment and method thereof | |
| EP0311972A2 (en) | Auto-threshold / adaptive equalizer | |
| US5524126A (en) | Symbol timing recovery using fir data interpolators | |
| CN1078838A (en) | The carrier recovery processor of qam television signal | |
| GB2331210A (en) | Timing recovery in vestigial sideband modulation | |
| CN1222008A (en) | Method and apparatus for fast recovery from loss of lock in phase locked loop | |
| JPH10502790A (en) | Data slicer | |
| EP0817418B1 (en) | Method for the frequency correction of multicarrier signals and related apparatus | |
| KR100290857B1 (en) | apparatus for recovering clock in digital TV | |
| EP0801486B1 (en) | Carrier recovery in a multicarrier receiver | |
| KR20040046168A (en) | Symbol timing synchronous apparatus and method, and symbol Timing recovery apparatus for multi-level modulation scheme | |
| EP1039711B1 (en) | Digital demodulator | |
| JP2000049763A (en) | Receiver, automatic frequency correction device and communication equipment | |
| KR960010494B1 (en) | Hdtv receiver | |
| US5475714A (en) | DC removal circuit for digital signal | |
| JPS63178642A (en) | Carrier extracting circuit | |
| KR100290869B1 (en) | apparatus for detection frequency off-set sign of demodulation | |
| CN1144416C (en) | Double-pilot frequency clock-restoring method and device in digital transmission | |
| JP4332966B2 (en) | PLL selection control method for television broadcast and PLL selection control device for television broadcast | |
| KR20010010342A (en) | Apparatus of timing recovery using interpolation filter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |