CN101772152A - Method for synchronizing common-frequency simulcasting communication - Google Patents
Method for synchronizing common-frequency simulcasting communication Download PDFInfo
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- CN101772152A CN101772152A CN201019087025A CN201019087025A CN101772152A CN 101772152 A CN101772152 A CN 101772152A CN 201019087025 A CN201019087025 A CN 201019087025A CN 201019087025 A CN201019087025 A CN 201019087025A CN 101772152 A CN101772152 A CN 101772152A
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Abstract
The invention provides a method for modulating and synchronizing an overlapping area in a common-frequency simulcasting communication system in the field of radio communication. In the method, when an auxiliary transmitting base station corresponds to each main transmitting base station, modulating signal delay time to be performed is arrayed into a modulating signal delay length table and the modulating signal delay length table is stored in the auxiliary transmitting base station. When the main transmitting base station transmits a signal, the main transmitting base station transmits the number of the main transmitting base station to the auxiliary transmitting base station. After receiving the number of the main transmitting base station, the auxiliary transmitting base station inquires the modulating signal delay length table to acquire a delay length value and delays a voice signal according to the value. The delay length value in the delay length table is calculated in advance according to a position relation between the base stations and the property of a base station device. The base station digitalizes a modulating signal, stores the modulating signal in a temporary storage and realizes modulation delay by reading the delay length at a fixed time and converting the delay length into the modulating signal. The method realizes modulation synchronization on the premise of not relying on a time service; and the reliability is superior to the prior art.
Description
Technical field
The present invention relates to a kind of radio communication technology, relate to a kind of in the common-frequency simulcasting communication system specifically and realize intersecting the synchronous method of area of coverage modulation.
Background technology
The analog radio communications system is called radio intercom system again.Usually, the scope that covers when system is wider, and intrasystem intercom is at a distance of far away excessively, to such an extent as to when signal can not directly be passed on, then set up the base station by near the higher place the area of coverage and come signal is carried out relay.The process of analog communication base station relay is: receive the radio wave (being called upward signal) that intercom sends, demodulation obtains speech (or low speed data), send into transmitter and send (being called downstream signal), all intercoms in its coverage can both be received in the mode of broadcasting.Because the base station is based upon the place that helps radio propagation, for example on high-lager building or the high mountain top, so it can receive the small-signal that distant place intercom transmits, its radio wave of sending also can be transferred to place far away simultaneously.Therefore, by the relay of base station, the coverage of analog radio communications system can be more wide than not adopting the base station relay.
Along with society to the improving constantly of emergent communicating requirement, also more and more higher to the requirement of the coverage of analog radio communications system.The coverage of a base station mainly is subjected to the influence of radio wave propagation characteristic, can not accomplish infinity.When needs cover large areas, cover with regard to a plurality of base stations of needs.For the area of coverage from a base station, speech is delivered to the area of coverage of other base station in the communication system, usually the way of taking be by a base station when carrying out aforementioned relay, send one the tunnel specially at other signal of base station, after other base station receives this road signal, give intercom in the own area of coverage its relay again.This other signal of base station that sends to specially is called link signal; Send the base station of link signal, be called the main base station of sending out; Receive link signal and give the base station of the intercom in the own area of coverage, be called from sending out a base station with its relay.In most of analog radio communications system, each base station all both can be used as the main base station of sending out, and can be used as again from sending out a base station; But at the same time, can only have a master to send out the base station, corresponding, at this moment other base station all is from sending out the base station.
Because radio frequency is day by day crowded, and do not wish to change when mobile frequency in communication system, people wish that usually all base stations all adopt identical frequency.But, may have the overlapping area of coverage between the base station.In the overlapping area of coverage, intercom can be received the signal of two or more base station broadcasts simultaneously, if these signals adopt identical nominal frequency, just might influence each other, and causes the reduction speech that intercom can't be good.The reason of speech of causing well reducing mainly contains two:
(1) though the nominal frequency of base station is identical, can have error, this will produce beat in the receiver of intercom, if the low frequency signal that beat produces just in time falls within the passband of audio frequency amplifier, people just can hear howling.
(2) owing to stand from sending out the station from main sending out, from different from send out the intercom of standing the path of process different, the needed time of radio propagation is also just different; Main send out the link signal that send at station, after send out the station and transmit, when the arrival intercom, the voice signal of its modulation just has phase difference through different.Through the intercom demodulation, the audio frequency of out of phase meeting mutual superposition causes serious distortion.
Layout by rational adjustment base station can reduce the overlapping area of coverage, eliminates the situation in a place of overlapping covering simultaneously, the above base stations of 3 and 3 substantially.But the situation of 2 overlapping coverings in base station is inevitably, otherwise, just must allow the distance between the base station far away as far as possible, the place of covering will appear not having in a large number like this.In order to eliminate the influence of the overlapping area of coverage, people have proposed to have the solution of three key elements by research:
(a) tranmitting frequency of each base station is identical as far as possible, and its error will make the frequency of Beat Signal be lower than the low-limit frequency of audio frequency passband.
(b) signal of each base station, its voice modulation phase place are wanted consistent or the difference of special setting are arranged, make in the center of overlapping covering, and the signal that comes from two base stations, the phase place of its modulation is consistent as far as possible.Make the method for phase modulation unanimity, be called method for synchronous.
(c) system will judge the quality of upward signal, allows receive that the best base station of upward signal becomes the main base station of sending out, and its signal is all transmitted in other base station.
Above-mentioned solution is called for short with frequently successively, synchronously, with broadcasting, in radio communication field general designation common-frequency simulcasting technology, adopt the radio communications system of this technique construction to be called the common-frequency simulcasting communication system.The theoretical foundation of relevant common-frequency simulcasting communication system has in following document comparatively comprehensively and discusses:
(1) beam greatly: " the common-frequency simulcasting system group network is realized Study on Technology ", University Of Tianjin's master thesis, 2006.
(2) Chen Jian: " based on the exploitation of the trunking mobile communication simulcasting system of DSP ", Beijing University of Post ﹠ Telecommunication's master thesis, 2004.
But above-mentioned document is not all mentioned the specific implementation of method for synchronous.In the Chinese patent prospectus 200610037084.1, can utilize gps clock to come the signal calculated retardation though mentioned, thereby adjust synchronously, not mention and specifically how to calculate and adjust.It may be noted that the employing gps clock, for communication system, in fact is exactly " outside " signal that has utilized native system to have no right to control, in case this " outside " signal interrupts, communication system will be subjected to serious adverse effect.
Summary of the invention
Task of the present invention provides a kind of character according to common-frequency simulcasting communication system itself, postpone to realize the synchronous method for synchronous of overlapping area of coverage speech modulation signal by speech, this method does not rely on " outside " signals such as gps clock, and reliability is better than prior art.
According to radio propagation prediction, delimit the center of the overlapping area of coverage to base station overlay area.The meaning of the center of the overlapping area of coverage is meant in this position, adjacent two signal of base station, and intensity equates and is maximum.The voice signal phase shifts that causes according to the geographical position and the base station itself of above-mentioned center, base station, calculating is for i base station (this base station), signal is sent to needed time of center of the overlapping area of coverage that this base station relates to from other any one base station j, with T
IjExpression.This time is divided into two parts, and first radio wave is propagated the needed time aloft, uses t
IjExpression; It two is signals during through the base station relay, if any Synchronous Processing is not done to modulation signal in the base station, the phase shifts that cause modulation signal base station itself the reduced value of equivalent time, with t
Ij' expression.Have:
T
ij＝t
ij+t
ij′
The radio range of related overlapping area of coverage center is s from j base station to i base station in order
Ij, have:
Wherein, s
IjCan measure from map according to radio-ray path, c is a velocity of radio wave, can be by light velocity value.
The translation method of phase shifts and time: the phase shifts that makes base station itself cause to signal is Δ φ, and this numerical value is relevant with the frequency of speech, and under physical condition, unified is test frequency with the comparatively responsive 1KHz pure tone of people's ear.The chopping phase potential difference of the signal that base station receiver is sent in test and the signal that sends from base station transmitter is Δ φ value, unit for spend (°).So:
Calculate all T of whole communication system
Ij, get with wherein the longest one compare, the identical or longer time is that the benchmark of system postpones T
0:
T
0≥|T
ij|
MAX
So, i base station is at the time of delay that need carry out the voice signal of sending from j base station:
ΔT
ij＝T
0-T
ij
With Δ T
IjThe modulation signal that is stored in i base station postpones in the lengths table, when the link signal of sending j base station (the main station of sending out) is received in this base station, immediately voice signal is carried out length and equals Δ T
IjDelay.When each base station all postponed by this rule, the speech phase modulation of whole each overlapping area of coverage of communication network had just kept unanimity, and had all postponed T than main station link modulation
0
As a special case of above-mentioned principle, if the main base station of sending out also will be near transmission downstream signal, that is also serve as local covering task, need so the modulation of downstream signal is postponed.It is Δ T that order postpones length
j, the needed time of center of the intersection area of coverage that a main signal of base station relates to oneself is t
j, have:
ΔT
j＝T
0-t
j
For each base station, t
jFix, so the Δ T of each base station
jFix.
In actual communication systems, often a base station relates to two or more overlapping areas of coverage, only in this way could form on a large scale, continuous covering.In this case, for a base station, the distance that arrives each overlapping area of coverage may be inconsistent, so s
IjJust not unique yet, can't obtain Δ T
Ij, the solution that the present invention proposes is as follows:
Consider that generally speaking the center between very approaching adjacent two base stations, the center of the overlapping area of coverage is so when a base station occurring and relate to the two or more overlapping area of coverage, make the phase modulation of base station down just passable synchronously.At this moment, s
IjDefinition become the radio range of j base station to i base station.T
IjDefinition become for i base station, signal is sent to this base station and sends the needed time by this base station from other any one base station j.
The main station of sending out must tell that from sending out the station specifically be the link that send at which station, thereby could determine that the occurrence of j checks in and how long postpone from sending out the station.The way that the present invention adopts is to unique numbering of each base station assigns, and this numbering is exactly j or has one-to-one relationship with j, mainly sends out the initial a period of time that stands in the transmitting chain signal, at first sends the numbering of oneself.Stand in when receiving link signal from sending out, earlier the numbering that transmits in the link signal to be read, before obtaining this numbering fully, can modulation not postponed earlier; After obtaining numbering, postpone lengths table according to numbering inquiry modulation signal immediately, perhaps determine j according to numbering earlier, inquire about modulation signal again and postpone lengths table, and, begin delay modulation signal according to the delayed data that checks in.It is all very little to transmit needed data volume of numbering and transfer rate, can utilize any low speed data transmission means that is applicable to analog communication system, for example waits and transmits with the known dual-tone multifrequency of industry, frequency shift keying.
Each base station all has a modulation signal that is applicable to this base station to postpone lengths table, and this table embodies j and Δ T
IjOne-to-one relationship, be equivalent to and embody main station numbering and the Δ T of sending out
IjOne-to-one relationship.This table is stored in the synchronizer of developing according to the principle of the present invention's announcement in the base station.For the digital signal processor of being made up of the computer of microprocessor or other type, this table is stored in its database.For other various forms of synchronizers, postpone lengths table and embody j and Δ T as long as can store modulation signal in any way
IjOne-to-one relationship, all can adopt method for synchronous of the present invention.
In synchronizer of the present invention, the delay of voice is to rely on digital signal processor to realize.Before voice are sent to digital signal processor, at first voice signal is converted to data by analog/digital converter (A/D).These data push in the built-in or plug-in high-speed data memory temporary by digital signal processor.Through Δ T
IjAfter time, digital processing unit comes out data read again, sends in the digital/analog converter (D/A) and is reduced to speech, launches by transmitter.
The sampling rate of A/D converter should satisfy the requirement of nyquist sampling theorem, the processing speed of digital processing chip (comprising data storage) and D/A converter should be able to be competent at by above-mentioned sampling rate adopt the Processing tasks of data, device is selected for use with programming should reduce uncertain delay error and various distortion as far as possible.Obviously, this is the design principle that each various equivalent modifications is all known, and the method that satisfies this principle also is known, does not need lay special stress on.Meeting under the prerequisite of this design principle, can select any A/D, D/A chip and digital processing unit for use.
It is noted that in design during synchronizer, should do taking into full account the phase error that A/D, D/A and digital processing unit may cause, and be revised.A kind of feasible way is, synchronizer is installed in the base station, is provided with simultaneously that to postpone be 0, with the Δ φ that records under this state as calculating Δ T
IjFoundation.
For the communication system that the center chain way station is arranged, no matter which station an in fact main station is, signal all will be forwarded to from sending out the station through the center chain way station, that is time-delay length is not subjected to the main influence of sending out the station, only need according to the center chain way station with just can determine from the radio range of sending out between standing.For this simple scenario, can not transmit the main station of sending out and number, and by the delay of fixing from a station.
Because disclosed method is determined time of delay according to the signal delay amount of communication system itself, and utilize the delay lengths table of base station stored, according to the main difference of sending out the station, the speech that indivedual definite each base station should be carried out postpones, thereby has realized that under the prerequisite of disobeying outer time service fully overlapping area of coverage speech is synchronous.
Description of drawings
Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.
Accompanying drawing 1 is the signal flow graph of typical common-frequency simulcasting communication system
Accompanying drawing 2 is s
IjMeasurement mapping example
Accompanying drawing 3 is the block diagrams according to the synchronizer of the principle composition of the present invention's announcement
Embodiment
Fig. 1 is the signal flow graph of typical common-frequency simulcasting communication system, and it has described the signal flow of a common-frequency simulcasting communication system that is made up of n base station.Caller intercom A sends calling, is transmitted to the intercom B in this base station overlay area after it is amplified in base station 1, sends wireless link signals simultaneously.This link signal all can be received until base station n in base station 2, and they are transmitted to intercom C, D in the own area of coverage.Obviously, the propagation path of the signal process that intercom B, C, D are received is different, if without Synchronous Processing, the time that speech arrives is just inconsistent.What Fig. 1 was expressed is a kind of typical situation.Because the base station is based upon on the higher position usually, so in the ordinary course of things, the wireless link signals of all base stations all can be gone directly.If can not go directly, can in position carry out the link relay, the way of relay is that industry is known.It should be noted that if link signal has passed through relay, calculating s
IjThe time, should calculate distance and summation piecemeal; Calculating t
IjIn ' time, relay stations also should be taken into account.
Fig. 2 is s
IjMeasurement mapping example, what its was described is in the common-frequency simulcasting communication system that is made up of 4 base stations, for asking for s
IjThe measurement mapping of being carried out.The position of base station 1～4 is known, and they are marked in the drawings according to the mode that helps accurate measuring distance, for example is indicated in the topographic map that chi is drawn to scale.Among Fig. 2, great circle is represented the coverage of base station, and the overlapped place of circle is the overlapping area of coverage, and four black squares are represented overlapping area of coverage center 5, and the field intensity of promptly adjacent two base stations equates and maximum point.A represents the distance of base station 1 to the overlapping area of coverage center between the base station 1,2, b represents the distance of base station 1 to the overlapping area of coverage center between the base station 1,3, d represents the distance between the base station 1,2, and m represents the distance between the base station 1,4, and k represents the distance between the base station 2,3.No matter be the scope or the center of the area of coverage, can try to achieve by the way of radio-wave propagation prediction, actual measurement.
According to the announcement of the present invention to General Principle, for base station 1, signal from the base station 2 propagate into it intersection area of coverage center the path of process be:
S
12=d+a or b
In this example, for this base station that two and the above overlapping area of coverage are arranged, unless a=b can't obtain unique S
12, can't look after each overlapping area of coverage respectively.At this moment should take to allow the synchronous way of modulation of all base station down signals, so:
S
12Distance=d between the=base station 1,2
S
13Distance between the=base station 1,3
S
14Distance=m between the=base station 1,4
S
21Distance=S between the=base station 2,1
12
S
23Distance=k between the=base station 2,3
S
24Distance between the=base station 2,4
S
31Distance=S between the=base station 3,1
13
S
32Distance=k between the=base station 3,2
S
34Distance between the=base station 3,4
S
41Distance=m between the=base station 4,1
S
42Distance=S between the=base station 4,2
24
S
43Distance=S between the=base station 4,3
34
Further, can be according to s
IjCalculate Δ T
Ij, with a Δ T from a base station
IjLine up one to one from sending out all the main base station numberings of sending out that to get in touch the base station with this, just obtain this from sending out the delay lengths table of base station.
Fig. 3 is the block diagram according to the synchronizer of the principle composition of the present invention's announcement.
The speech and the low speed data mixed signal of the output of base station link receiver at first enter the numbering decoder, separate voice-and-data, data decode is obtained the main base station numbering of sending out send digital signal processor to, give A/D conversion circuit with pure speech.Digital signal processor is according to the main base station numbering of sending out, the corresponding delay length of inquiry in postponing the lengths table memory, the voice data in the buffer is transferred in extension according to delay length, to send into D/A conversion circuit through the voice data that postpones, be converted to voice signal, pass through level translation again, be sent to transmitter and send to intercom.
According to the represented signal flow of Fig. 3, those skilled in the relevant art can select suitable chip with same function and circuit arbitrarily for use, thereby design the synchronizer that is suitable for various application scenarios.
Claims (2)
1. the method for synchronous of a common-frequency simulcasting communication, comprise by to the in addition different delay of the modulation signal of different base station to realize intersecting the synchronous method of area of coverage modulation, it is characterized in that:
Have the modulation signal that weaves in advance to postpone lengths table from sending out base station stored, this table record has corresponding to each main when sending out base station, and this is from sending out the time of delay that the base station should apply modulation signal;
The main base station of sending out to the numbering that sends oneself from a base station, from sending out the base station according to the main numbering of sending out the base station, is inquired about modulation signal and is postponed lengths table, and modulation signal is postponed accordingly after the emission beginning.
2. the method for synchronous of common-frequency simulcasting communication according to claim 1, it is characterized in that basis of compilation that modulation signal postpones lengths table comprise signal from main send out the station be delivered to the overlapping area of coverage the entire path of process total time that need consume; Does not carry out when synchronous the base station, and the modulating signal phase that circuit caused changes, and converts to the time to count in above-mentioned total time.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102136861A (en) * | 2011-01-20 | 2011-07-27 | 哈尔滨侨航通信设备有限公司 | Diversity reception method for simulcasting system |
| CN102572715A (en) * | 2012-02-14 | 2012-07-11 | 北京市万格数码通讯科技有限公司 | IP network-based method for realizing simultaneous broadcasting |
| CN102932909A (en) * | 2012-10-08 | 2013-02-13 | 科立讯通信股份有限公司 | Digital common frequency broadcasting system and wireless judgment and synchronization method |
| WO2017118115A1 (en) * | 2016-01-08 | 2017-07-13 | 中兴通讯股份有限公司 | Pdt common-frequency simulcast group establishment method, communication method, related device and system |
| CN111711535A (en) * | 2020-06-03 | 2020-09-25 | 广州维德科技有限公司 | Multi-standard integrated communication system |
-
2010
- 2010-02-11 CN CN201019087025A patent/CN101772152A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102136861A (en) * | 2011-01-20 | 2011-07-27 | 哈尔滨侨航通信设备有限公司 | Diversity reception method for simulcasting system |
| CN102136861B (en) * | 2011-01-20 | 2013-12-18 | 哈尔滨海能达科技有限公司 | Diversity reception method for simulcasting system |
| CN102572715A (en) * | 2012-02-14 | 2012-07-11 | 北京市万格数码通讯科技有限公司 | IP network-based method for realizing simultaneous broadcasting |
| CN102932909A (en) * | 2012-10-08 | 2013-02-13 | 科立讯通信股份有限公司 | Digital common frequency broadcasting system and wireless judgment and synchronization method |
| WO2017118115A1 (en) * | 2016-01-08 | 2017-07-13 | 中兴通讯股份有限公司 | Pdt common-frequency simulcast group establishment method, communication method, related device and system |
| CN111711535A (en) * | 2020-06-03 | 2020-09-25 | 广州维德科技有限公司 | Multi-standard integrated communication system |
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Application publication date: 20100707 |