CN101521811A - Synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network - Google Patents
Synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network Download PDFInfo
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Abstract
The invention relates to a synchronous monitoring self-healing system for broadcast signals of a railway television single-frequency network in the technical field of information, which comprises a TS packet monitoring and counting module, a synchronous information packet monitoring module, a signal synchronizing phase-demodulation module, a signal synchronizing state control module and an RAM read control module. The system monitors occurrence interval of synchronous information packets in TS stream, and resets or adjusts cache RAM read addresses according to the presence of synchronous error or the severity of error. The system can ensure the synchronization of the signals of the railway television single-frequency network, can automatically make a synchronous transmitting station dropping out of the single-frequency network caused by signal synchronizing error due to the opacity of a distribution link to reenter the single-frequency network, improves the stability of the single-frequency network, achieves unattended operation of the synchronous transmitting station, is simple to achieve, has extremely low cost, and is quite suitable for the synchronous transmitting stations in remote areas with severe environments.
Description
Technical field
The present invention relates to the synchro system in a kind of areas of information technology, particularly relate to a kind of synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network.
Background technology
The railway TV monochromatic network system is a system that reasonable application prospect is arranged.The benefit of single frequency network maximum is saved frequency spectrum resource exactly, makes things convenient for frequency spectrum planning.The railway system is a system independently comparatively speaking, introduces single frequency network in railway TV, and it is possible carrying out that the same channel in the same set of program whole nation covers on the railway line in the whole nation, and does not also conflict with existing industrial system.One of key technology of railway TV monochromatic network is exactly the synchronous of single frequency network.Mainly be divided into synchronously the synchronous of three parts: Frequency Synchronization, time synchronized and signal Synchronization.All be to tend to the overall time dissemination system that uses GPS such on the Frequency Synchronization universal significance; The method of time synchronized be to use carry time synchronization information promptly " the synchronizing information bag " of " the time mark stabs " calculate emission delay and carry out synchronously.
For signal Synchronization, important one side is to guarantee for becoming same frame after the framing in the same synchro transmitter of TS stream in single frequency network with different delayed time, promptly so-called " frame synchronization phase place (FrameSync Phase) " is the same (referring to ATSC A/110B Synchronization Standard forDistributed Transmission, Revision B).So an importance of signal Synchronization guarantees that exactly synchro transmitter becomes frame synchronization.Realize the one-tenth frame synchronization at each synchronized transmissions station, a framing reference point (frame synchronization head in other words) and synchronization mechanism will be arranged.
Find the technical literature that European Telecommunications StandardsInstitute delivered in June, 2004 (Technical Specification) " DigitalVideo Broadcasting (DVB) through literature search to prior art; DVB mega-frame for Single Frequency Network (SFN) synchronization ", the technology of a kind of time and signal Synchronization has been proposed in this article, be specially: the data that send in each second are integrated into a huge frame, and each huge frame is set up a MIP (huge frame initialization bag).As the reference synchronization point, STS i.e. " the time mark stabs " is carried in MIP the inside, indicates the transmitting time of current reference point at adaptive end, and this time numerical value adjustment algorithm that will be used to delay time is accordingly carried out synchronously.And in the MIP bag position that the pointer that points to next huge frame is determined next reference point is set.Its deficiency is: this mode has only been investigated TS stream framing reference synchronization point one time between resetting for twice, do not consider the mistake change of the opaque reference synchronization point that causes of distribution link.The distribution link is a data link between single frequency adapter and the synchronizer, this link in general the error rate lower (the IF loop error performance such as national satellite television standard GB/T17700-1999 regulation will reach QEF, promptly 10
-10～10
-11), good error performance makes the people be difficult to discover the influence to signal Synchronization that distribution link zone of opacity comes easily.But in actual Project Realization, the situation of channel error code and unexpected error can cause the change of the framing reference synchronization point of TS stream.Such as, the distribution link is a satellite link, can in TS stream, insert the TS standard null packet for adaptive channel speed in the satellite link, these standard null packet will be removed in the single frequency network synchronizer, in case but occur error code in the channel, make sky bag mistake originally become the non-NULL bag, then synchronizer can't normally delete it, sends but be used as normal TS bag.This just is equivalent to insert a TS bag without foundation in TS stream, modulates so in the back after the framing, and this synchronized transmissions station of makeing mistakes will generate with the different frame in synchronized transmissions station on every side, and promptly signal is asynchronous.
The time of the existing general mono-frequency network system that can look into and signal synchronizing system adopt above-mentioned way to realize basically.Its system is embodied as: in the single frequency network synchronizer, passing by the TS that comes from adapter via distribution chain flows to into time-delay buffer memory RAM, enter monitoring of synchronizing information bag and processing module simultaneously, monitoring of synchronizing information bag and processing module are found after the synchronizing information bag, send sync packet synchronous enabled (hereinafter to be referred as " synchronous enabled ") and " the time mark stabs " to the time-delay control module, the time-delay control module run into synchronous enabled in, during according to " the time mark stabs " calculating TS curtain coating, and read control module forward delay interval enabling signal to RAM according to this time-delay, RAM reads control module according to the delayed startup signal enabling that the time-delay control module produces, and the TS that reads among the RAM flows to back level output.Simultaneously, also comprise reseting module in the system, can reset other modules.
Consider the weak point of top system, should be detected signal Synchronization.If adopt the i.e. method of " catch------trackings---reacquisition " synchronously of traditional frame synchronization means, then can not be fully up to expectations under the single frequency network application.Such as the reference synchronization point of DVB-T single frequency network, ATSC single frequency network and ADTB-R single frequency network interval about 1 second is arranged all,, will introduce the time-delay in several seconds if use the conventional frame synchronization means.
If the situation that certain base station accesses single frequency network often appears in railway TV monochromatic network,, also to consider the normal problem of launch point of recovering even if do not consider do not having to need the people on the train to come notification signal to lose under the condition of return path.In the laying of railway, run into mountains and rivers through regular meeting, the river, complex environments such as desert, under such environment, the launch point of setting up Attended mode is inappropriate, cost is high too, still has problem on the cost if build the network of unified control base station.
Summary of the invention
The objective of the invention is at the deficiencies in the prior art, a kind of synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network is provided, be applied in the railway TV monochromatic network, can monitor the signal lock-out automatically, and, guarantee that railway TV monochromatic network is in the signal Synchronization state by the self-healing mechanism recovery.
The present invention is achieved by the following technical solutions, the present invention includes: TS bag monitoring counting module, synchronizing information bag monitoring modular, signal Synchronization phase demodulation module, signal Synchronization status control module and RAM (random access memory) read control module.Wherein:
Described TS bag monitoring counting module, this module be input as TS stream after adjusting through time-delay and the zero clearing of synchronizing information bag monitoring modular output enables, be output as the TS stream that offers synchronizing information bag monitoring modular and the TS that offers signal Synchronization phase demodulation module wrapped count value.This module is responsible for monitoring the TS stream of input and is carried out TS bag counting, and count value is offered signal Synchronization phase demodulation module, gives synchronizing information bag monitoring modular after TS is flowed to, and enables to carry out counter O reset according to the zero clearing of synchronizing information bag monitoring modular.
Described synchronizing information bag monitoring modular, the TS stream that is input as the output of TS bag monitoring counting module of this module is output as the synchronous enabled and TS bag monitoring counter zero clearing of the synchronizing information bag of signal Synchronization phase demodulation module and enables.This module is responsible for monitoring the TS stream of input, in case find the synchronizing information bag, then exports the synchronous enabled and TS bag monitoring counter zero clearing of synchronizing information bag and enables.
Described signal Synchronization phase demodulation module, the synchronizing information bag that is input as the output of synchronizing information bag monitoring modular of this module is synchronous enabled monitors the count value of counting output with the TS bag, and module is output as the signal Synchronization phase difference value.The signal calculated locking phase amount of deflection in the time of the synchronous enabled appearance of synchronizing information bag, signal Synchronization phase demodulation module offers the synchronous regime control module with this difference.In the adapter of monochromatic network broadcast, inserting the synchronizing information bag in the TS stream is regular and is known, the number of due TS bag also is known and definite between two synchronizing information bags, the signal Synchronization phase difference value is exactly in the time of the synchronous enabled appearance of synchronizing information bag, due TS bag number between the TS bag count value of current TS bag monitoring counting module output and two the synchronizing information bags is subtracted each other as the signal Synchronization phase difference value, give subsequent module this difference.The TS bag count value of current TS bag monitoring counting module output is greater than between two synchronizing information bags during due TS bag number, the signal Synchronization phase difference value be on the occasion of.The TS bag count value of current TS bag monitoring counting module output is less than between two synchronizing information bags during due TS bag number, and the signal Synchronization phase difference value is a negative value.
Described signal Synchronization status control module, the signal Synchronization phase difference value of the synchronous enabled and signal Synchronization phase demodulation module output of the synchronizing information bag that is input as synchronizing information bag monitoring modular output of this module, module are output as the reset enable that offers outside reseting module and offer signal Synchronization that RAM reads control module and correct and enable and the signal Synchronization phase difference value.This module is carried out state transitions according to the signal of input, and output signal correction synchronously enables and the signal Synchronization phase difference value.
Described signal Synchronization status control module is carried out work as a state machine according to state transitions, and all states of synchronous regime control module comprise, initial condition, operating state and overflow status, and concrete state transitions mode is:
Enter initial condition after resetting, run into the synchronous enabled operating state that enters;
Run into synchronous enabledly in the operating state, and signal phase difference≤M then continues to stay operating state, and output signal is corrected synchronously and enabled and the signal phase difference;
Run in the operating state synchronous enabled, and the signal phase difference M, then transfer to overflow status, and output reset enable;
After resetting, module is transferred to initial condition automatically from overflow status.
Wherein, M is determined by the capacity of time-delay buffer memory RAM, the signal Synchronization phase deviation of its meaning for correcting under situation about not resetting under the prerequisite that is unlikely to overflow at time-delay buffer memory RAM.
Described RAM reads control module, and the signal Synchronization that is input as the generation of signal Synchronization status control module of this module is corrected and enabled and the signal Synchronization phase difference value.This module comprises that also correction enables to read the address renewal according to signal Synchronization except that finishing normal RAM read functions.When the signal Synchronization correction enabled to occur, a few bit address numerical value of reading expression TS bag ordinal number in the address that RAM is current and the addition that the signal Synchronization phase difference value has symbol were as the renewal of reading the address of RAM.This wherein, a few bit address numerical value of reading expression TS bag ordinal number in the address that RAM is current are meant: the storage of TS bag is stored according to the TS bag among the RAM, a RAM has been divided into several subregions (BANK), TS bag of each subregion storage, RAM reads that there are several bit representations front in the address is the address sequence number of subregion in other words of subregion, the address of the subregion that a few bit address numerical value of expression TS bag ordinal number just are meant.With the signal Synchronization phase difference value addition of symbol is arranged, specifically be meant when signal Synchronization phase difference value when being positive, add the absolute value of signal Synchronization phase difference value, when the signal Synchronization phase difference value for negative the time, deduct the absolute value of signal Synchronization phase difference value.
The invention has the beneficial effects as follows: can so that railway TV monochromatic network guarantee automatically under working properly and correct two prerequisites of time synchronized algorithm of GPS that in a single day single frequency network makes mistakes and can get back to synchronous regime fast by time-delay adjustment, and also can solve by system reset for nonadjustable timing error.The present invention can recover the almost any signal Synchronization mistake except that the hardware error of system own, can resist the mistake that can't predict.The present invention has reduced human cost, has improved system reliability, and implementation is succinct, and cost is very low, even needs cost hardly, only need cheap monitoring module is installed or carry out software upgrading at synchronizer.
Description of drawings
Fig. 1 is the time and the signal synchronizing system block diagram of common mono-frequency network system.
Fig. 2 is a general implementation system block diagram of the present invention.
Fig. 3 is the operating state transition diagram of the general synchronous regime control module of implementing of the present invention.
Fig. 4 is the system block diagram that the present invention implements in ADTB-R SFN system.
Fig. 5 is the operating state transition diagram of the synchronous regime control module implemented in ADTB-R SFN system of the present invention.
Fig. 6 is the block diagram of reading the address adjusting module of the time-delay buffer memory RAM that implements in ADTB-R SFN system of the present invention.
Embodiment
Below in conjunction with accompanying drawing embodiments of the invention are elaborated: present embodiment is being to implement under the prerequisite with the technical solution of the present invention, provided detailed execution mode and concrete operating process, but protection scope of the present invention is not limited to following embodiment.
As shown in Figure 1, existing mono-frequency network system is (typical, such as ADTB-R SFN system) time and signal synchronizing system be: pass by the TS that comes from adapter via distribution chain and flow to into time-delay buffer memory RAM16, enter monitoring of synchronizing information bag and processing module 12 simultaneously, monitoring of synchronizing information bag and processing module are found after the synchronizing information bag, write control module 15 to RAM and send sync packet synchronous enabled (hereinafter to be referred as " synchronous enabled "), send synchronous enabled and " the time mark stabs " to time-delay control module 13, the time-delay control module 13 run into synchronous enabled in, during according to " the time mark stabs " calculating TS curtain coating, and read control module 14 forward delay interval enabling signals to RAM according to this time-delay, RAM reads the delayed startup signal enabling that control module 14 produces according to time-delay control module 13, and produce time-delay buffer memory RAM read to enable and read the address, and RAM writes control module and writes according to synchronous enabled generation and enable and write address.Module 12,13,14,15 can reset by reset signal generation module 11 simultaneously.
As Fig. 2, general implementation method of the present invention is to be made up of five submodules: TS bag monitoring counting module 203, synchronizing information bag monitoring modular 202, signal Synchronization phase demodulation module 201, signal Synchronization status control module 204 and RAM read control module 208.
TS bag monitoring counting module 203.Module be input as TS stream after adjusting through time-delay and the zero clearing of synchronizing information bag monitoring modular 202 outputs enables, be output as the TS stream that offers synchronizing information bag monitoring modular 202 and the TS that offers signal Synchronization phase demodulation module 201 wrapped count value.The function of module is the TS stream of monitoring input and carries out TS bag counting, count value is offered signal Synchronization phase demodulation module 201, to give synchronizing information bag monitoring modular 202 after the TS flow direction, and enable to carry out counter O reset according to the zero clearing of synchronizing information bag monitoring modular 202.
Synchronizing information bag monitoring modular 202.The TS stream that is input as 203 outputs of TS bag monitoring counting module of module is output as the synchronous enabled and TS bag monitoring counter zero clearing of the synchronizing information bag of signal Synchronization phase demodulation module 201 and enables.The function of module is the TS stream of monitoring input, in case find the synchronizing information bag, then exports the synchronous enabled and TS bag monitoring counter zero clearing of synchronizing information bag and enables.
Signal Synchronization phase demodulation module 201.The synchronizing information bag that is input as 202 outputs of synchronizing information bag monitoring modular of module is synchronous enabled monitors the count value of counting 203 outputs with the TS bag.Module is output as the signal Synchronization phase difference value.The function of module is the signal calculated locking phase amount of deflection in the time of the synchronous enabled appearance of synchronizing information bag, and this difference is offered synchronous regime control module 204.In the adapter of monochromatic network broadcast, inserting the synchronizing information bag in the TS stream is regular and is known, the number of due TS bag also is known and definite between two synchronizing information bags, the signal Synchronization phase difference value is exactly in the time of the synchronous enabled appearance of synchronizing information bag, and due TS bag number between the TS bag count value of current TS bag monitoring counting module 203 outputs and two the synchronizing information bags is subtracted each other the numerical value that obtains.The TS bag count value of current TS bag monitoring counting module 203 outputs is greater than between two synchronizing information bags during due TS bag number, this value on the occasion of.Otherwise instead then.
Signal Synchronization status control module 204.The signal Synchronization phase difference value that the synchronizing information bag that is input as 202 outputs of synchronizing information bag monitoring modular is synchronous enabled and signal Synchronization phase demodulation module 201 is exported of module.Module is output as the reset enable that offers reset signal generation module 205 and offers and reads signal Synchronization that RAM reads control module and correct and enable and the signal Synchronization phase difference value.The function of module is to carry out state transitions according to the signal of importing, and output signal correction synchronously enables and the signal Synchronization phase difference value.
The operation principle of signal Synchronization status control module 204 is, as a state machine, carries out work according to state transitions, concrete condition mode as shown in Figure 3,
Enter initial condition after resetting, run into the synchronous enabled operating state that enters.
Run into synchronous enabledly in the operating state, and signal phase difference≤M then continues to stay operating state, and output signal is corrected synchronously and enabled and the signal phase difference.
Run in the operating state synchronous enabled, and the signal phase difference M, then transfer to overflow status, and output reset enable.
After resetting, module is transferred to initial condition automatically from overflow status.
Wherein, M is determined by the capacity of time-delay buffer memory RAM, the signal Synchronization phase deviation of its meaning for correcting under situation about not resetting under the prerequisite that is unlikely to overflow at time-delay buffer memory RAM.
RAM reads control module 208, module.The signal Synchronization that is input as 204 generations of signal Synchronization status control module of module is corrected and is enabled and the signal Synchronization phase difference value.The concrete function of module is except that finishing normal RAM read functions, also comprise: when the signal Synchronization correction enables to occur, a few bit address numerical value of reading expression TS bag ordinal number in the address that RAM is current and the addition that the signal Synchronization phase difference value has symbol are as the renewal of reading the address of RAM.This wherein, a few bit address numerical value of reading expression TS bag ordinal number in the address that RAM is current are meant: the storage of TS bag is stored according to the TS bag among the RAM, a RAM has been divided into several subregions (BANK), TS bag of each subregion storage, RAM reads that there are several bit representations front in the address is the address sequence number of subregion in other words of subregion, the address of the subregion that a few bit address numerical value of expression TS bag ordinal number just are meant.With the signal Synchronization phase difference value addition of symbol is arranged, specifically be that worthwhile signal Synchronization phase difference value is when being positive, add the absolute value of signal Synchronization phase difference value, when the signal Synchronization phase difference value for negative the time, deduct the absolute value of signal Synchronization phase difference value.
The present invention can be applied among the ADTB-R SFN.ADTB-R SFN is that a cover is with the different railway TV system of DVB-SFN, the distribution link is a satellite link, its Frequency Synchronization has adopted more optimal GPS synchronized algorithm, and use SIP bag (package head format is hexadecimal 476015) to carry out time synchronized, and differ 4160 TS bags (the SIP bag also is a kind of special TS bag) between the adjacent SIP bag as the synchronizing information bag.
Fig. 4 is the realization block diagram of the present invention in ADTB-R SFN synchronizer, than general embodiment block diagram 2 of the present invention, except being embodied as SIP, sync packet monitoring and processing module 206 monitor processing module 406, sync packet monitoring modular 202 is embodied as SIP monitoring modular 402, also having RAM to read control module 208 is embodied as RAM and reads address generating module 408, RAM reads address adjusting module 412 and RAM reads to enable outside the generation module 411, and realization and the general embodiment of the present invention in ADTB-R SFN do not have more difference.
Specific embodiments in the present embodiment is:
1. determine the numerical value of M.Because the time-delay buffer memory RAM size in the ADTB-R SFN system is 2048 subregions, each subregion can be deposited a TS bag, and promptly the RAM capacity is 512KB.Consider the time delay of satellite distribution link and the setting of system maximum delay, each base station has maximum about about 1800 TS bags needs buffer memory, also is that M can be set to more than 100 at most, considers engineering allowance and actual application environment, and M is made as 10.The operating state transfer of synchronous regime control module of the present invention like this can be embodied as Fig. 5.
2.SIP the operation principle of monitoring modular 402 is embodied as, when TS bag monitoring module monitors is passed to SIP detection module 402 to the TS bag and it, module 402 will judge that the packet header of this TS bag is that SIP packet header is 471560, if, think that then this bag is the SIP bag, otherwise instead then.
Be embodied as RAM and read address generating module 408 3.RAM read control module 208, RAM reads address adjusting module 412 and RAM reads to enable generation module 411.RAM reads address that address generating module 408 produces will read to receive after the address adjusting module 412 reading on the address port of time-delay buffer memory RAM by RAM.
4.RAM read realization schematic diagram such as Fig. 6 of address adjusting module 412.The address that RAM reads address generating module 408 generations is divided into two-way, one the tunnel directly connects gate 62, one the tunnel connects adder 61, adder 61 and gate 62 are subjected to signal Synchronization and correct the control that enables, adder 61 links to each other with the signal Synchronization phase difference value again simultaneously, the output result links to each other with gate 62, and adder 61 has the add operation of symbol.Signal Synchronization is corrected and is enabled when effective, adder work, and gate 62 is output as the signal that adder 61 is come.Signal Synchronization is corrected and is enabled when invalid, and adder is not worked, and gate 62 is output as the signal of directly not coming through module 61.
5. finish after preceding four, put up system according to Fig. 4.Its operation principle is equal to the general operation principle of foregoing the present invention, and other module of present embodiment of not making specified otherwise does not all need to change in this embodiment.
By such method, present embodiment has reached the purpose that signal Synchronization is monitored: in case find that signal Synchronization is unusual, then assert the signal lock-out, then utilize the difference adjustment of signal Synchronization phase place to send to the time-delay of the TS bag of ADTB modulators modulate.Very big for some differences, can't adjust the situation of solution, link signal is cut off or the long period is distributed situations such as link degradation such as distribute, and the strategy of taking to reset guarantees that synchro transmitter reenters single frequency network.Thus, in whole single frequency network, the launch point of lock-out can not appear continuing, and such launch point will to around launch point produce can't self-healing strong jamming.
The present invention has passed through design, realization and the laboratory tests checking of FPGA in the above embodiments, test result shows, thereby the present invention has solved up hill and dale in the present embodiment and cannot recover after the signal lock-out to cause the synchronized transmissions point overlapping on every side of makeing mistakes not receive TV signal and problem that can't self-healing in going.
Claims (7)
1, a kind of synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network is characterized in that comprising: TS bag monitoring counting, the monitoring of synchronizing information bag, signal Synchronization phase demodulation, signal Synchronization status control module and RAM read control module, wherein:
TS bag monitoring counting module, its zero clearing that is input as through TS stream after the time-delay adjustment and the output of synchronizing information bag monitoring modular enables, the TS bag count value that is output as the TS stream that offers synchronizing information bag monitoring modular and offers signal Synchronization phase demodulation module, the TS stream of this module monitors input also carries out TS bag counting, count value is offered signal Synchronization phase demodulation module, to give synchronizing information bag monitoring modular after the TS flow direction, and enable to carry out counter O reset according to the zero clearing of synchronizing information bag monitoring modular;
Synchronizing information bag monitoring modular, it is input as the TS stream of TS bag monitoring counting module output, being output as the synchronous enabled and TS bag monitoring counter zero clearing of the synchronizing information bag of signal Synchronization phase demodulation module enables, the TS stream of this module monitors input, in case find the synchronizing information bag, then export the synchronous enabled and TS bag monitoring counter zero clearing of synchronizing information bag and enable;
Signal Synchronization phase demodulation module, this synchronous enabled bag with TS of synchronizing information bag that is input as the output of synchronizing information bag monitoring modular is monitored the count value of counting output, be output as the signal Synchronization phase difference value, this module is the signal calculated locking phase amount of deflection in the time of the synchronous enabled appearance of synchronizing information bag, and this difference is offered the synchronous regime control module;
The signal Synchronization status control module, it is input as the signal Synchronization phase difference value that the synchronizing information bag is synchronous enabled and signal Synchronization phase demodulation module is exported of synchronizing information bag monitoring modular output, being output as reset enable and offering reads signal Synchronization that RAM reads control module and corrects and enable and the signal Synchronization phase difference value, this module is carried out state transitions according to the signal of input, and output signal correction synchronously enables and the signal Synchronization phase difference value; RAM reads control module, and its signal Synchronization that is input as the generation of signal Synchronization status control module is corrected and enabled and the signal Synchronization phase difference value, and this module comprises that also correction enables to read the address renewal according to signal Synchronization except that finishing normal RAM read functions.
2, synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network according to claim 1, it is characterized in that, described signal Synchronization phase demodulation module, when the synchronizing information bag is synchronous enabled when occurring, due TS bag number between the TS bag count value of current TS bag monitoring counting module output and two the synchronizing information bags is subtracted each other as the signal Synchronization phase difference value, give subsequent module this difference.
3, synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network according to claim 1 and 2, it is characterized in that, described signal Synchronization phase demodulation module, when the synchronizing information bag is synchronous enabled when occurring, the TS bag count value of current TS bag monitoring counting module output is greater than between two synchronizing information bags during due TS bag number, the signal Synchronization phase difference value be on the occasion of; The TS bag count value of current TS bag monitoring counting module output is less than between two synchronizing information bags during due TS bag number, and the signal Synchronization phase difference value is a negative value.
4, synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network according to claim 1, it is characterized in that, described signal Synchronization status control module, as a state machine, carry out work according to state transitions, all states of synchronous regime control module comprise, initial condition, operating state and overflow status, and the state transitions mode of synchronous regime control is:
Enter initial condition after resetting, run into the synchronous enabled operating state that enters;
Run into synchronous enabledly in the operating state, and signal phase difference≤M then continues to stay operating state, and output signal is corrected synchronously and enabled and the signal phase difference;
Run in the operating state synchronous enabled, and the signal phase difference M, then transfer to overflow status, and output reset enable;
After resetting, module is transferred to initial condition automatically from overflow status;
Described M determines by the capacity of time-delay buffer memory RAM, is illustrated in the signal Synchronization phase deviation that can correct under situation about not resetting under the prerequisite that time-delay buffer memory RAM is unlikely to overflow.
5, synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network according to claim 1, it is characterized in that, described RAM reads control module, when the signal Synchronization correction enables to occur, a few bit address numerical value of reading expression TS bag ordinal number in the address that RAM is current, with the signal Synchronization phase difference value addition of symbol is arranged, as the renewal of reading the address of RAM.
6, synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network according to claim 5, it is characterized in that, a few bit address numerical value of reading expression TS bag ordinal number in the address that described RAM is current are meant, the storage of TS stream is stored according to the TS bag among the RAM, a RAM has been divided into several subregions, TS bag of each subregion storage, RAM reads that there are several bit representations front in the address is the address sequence number of subregion in other words of subregion, the address of the subregion that a few bit address numerical value of expression TS bag ordinal number just are meant.
7, synchronous monitoring self-healing system for broadcast signals of railway television single-frequency network according to claim 5, it is characterized in that, described and signal Synchronization phase difference value has the addition of symbol, be meant when signal Synchronization phase difference value when being positive, add the absolute value of signal Synchronization phase difference value, when the signal Synchronization phase difference value for negative the time, deduct the absolute value of signal Synchronization phase difference value.
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| CN102104474A (en) * | 2009-12-22 | 2011-06-22 | 大唐移动通信设备有限公司 | Clock detecting method and device |
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| CN102104474A (en) * | 2009-12-22 | 2011-06-22 | 大唐移动通信设备有限公司 | Clock detecting method and device |
| CN102104474B (en) * | 2009-12-22 | 2014-10-29 | 大唐移动通信设备有限公司 | Clock detecting method and device |
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