CN207664989U - Digital tv ground broadcasting - Google Patents

Abstract

The utility model discloses a kind of digital tv ground broadcastings, the system includes at least one transmitter, the transmitter includes sequentially connected first filter circuit, the first prime amplifying unit and power amplifier unit, wherein, the transmitter is used to launch from aerial reception digital television terrestrial broadcasting network signal and after handling it, depending on the signal value for area, landform and the received signal that first filter circuit is obtained based on the frequency of received signal and the power of the transmitter and quantity cover as needed.The utility model uses low power transmitter, reduces the selection requirement to launch point, therefore can be with flexible arrangement launch point.In addition, filtered and amplification signal carries out supplement transmitting in protection interval, main covering signal blind zone can be repaired.

Description

Digital tv ground broadcasting

Technical field

The utility model is related to digital television terrestrial broadcasting technical fields, more particularly to digital tv ground broadcasting.

Background technology

In digital TV ground, wired, satellite transmission schemes, digital terrestrial television transmission system environment is the most complicated, Also it is concerned because its technology requires highest, audient is wide.The standard of ground system has United States advanced television systems committee (ATSC), European Digital Video terrestrial broadcasting (DVB-T) and Japanese Terrestrial Integrated Services Digital Broadcasting (ISDB-T).1999 I State sets up DTV research and development and industrialization key special subjects and sets up national digital TV leading group, clear autonomous formulation technology Standard.For the specific standards of China Digital TV application, it is proposed within 2006 China Digital TV ground standard DTMB.

Terrestrial DTV transmits national standard in the formal implementation on the 1st of August in 2007.2008,8 Olympic Games cities were opened Logical digital terrestrial television.

2016, the whole nations national standard DTMB covering plan, promote DTMB top box of digital machines, DTMB digital moving-tvs, Surface wave receives handheld device, 9 cun of DTMB mobile digital TVs, DMB-TH ground wave digital televisions and hand-portable DTMB movements The development of the receiving device of the Suresh Kumars such as TV.

The wireless digitizing covering engineering of central broadcast TV programme covers national 31 provinces, municipalities and autonomous regions, municipalities directly under the Central Government, removes More than 2500 a radio and television backbone transmitting stations, also Guangxi, Qinghai more than 500 50 watts of small-powers mend point station, be related to altogether 6200 multi-section transmitters.

Center covering engineering terrestrial DTV frequency planning scheme is related to the existing ground launch station in each province, radio relay broadcasting station It stands and mends some stations and amount to 3117, the principle (individual stations are 1 transmitter) of two transmitters is distributed according to each station, The amount total of transmitter 6230.The project type of transmitter can be divided into 2 classes：One kind is transformation property, the i.e. hair of the frequency point It penetrates machine and central program is broadcasted using DTMB modes originally, to meet the television program transmission requirement of center covering engineering, it is necessary to right Transmitter undergoes technological transformation, and amounts to 384；Another kind of is newly-built property, that is, needs to carry out frequency used in the frequency point New planning simultaneously buys new DTMB transmitters, and amounting to 5846, (578 transmitters in wherein Guangxi have particular/special requirement not yet to recruit Mark).This frequency planning carries out frequency assignment planning mainly for 5846 newly-built transmitters.

Networking mode uses high-power, high mountain transmitting station station structure at present.Distance is remote between base station, is influenced by topography and geomorphology Bigger and networking is complicated.There are many signal interference regions in network.Moreover, building, which blocks, generates many signal blind zones. In addition, there are certain requirements to launch point because transmission power is high, between the base stations there may be the gap of many overlay areas, Even there are many areas that can not be capped at all.On the basis of existing resource and technical solution, improve difficult.

Utility model content

In order to solve the above technical problems, the utility model provides a kind of digital tv ground broadcasting, with supplement DTMB signals cover, the free existing overlay areas DTMB of elastic extension.

The embodiments of the present invention provide a kind of digital tv ground broadcasting, which includes at least one hair Machine is penetrated, the transmitter includes sequentially connected first filter circuit, the first prime amplifying unit and power amplifier unit, wherein institute Transmitter is stated for launching after handling from aerial reception digital television terrestrial broadcasting network signal and to it, described first filters The face that wave circuit is obtained based on the frequency of received signal and the power of the transmitter and quantity cover as needed Depending on the signal value of product, landform and received signal.

In one embodiment, the transmitter can also include sequentially connected second filter circuit, the amplification of the second prime Unit and switch unit, the switch unit are connected between the first filter circuit and the first prime amplifying unit, so as to Between connection and the second filter circuit and the first prime amplifying unit between one filter circuit and the first prime amplifying unit Connection switches over, and second filter circuit is obtained based on the frequency of received signal.

In one embodiment, the transmitter can be that power emits equipment from 8 milliwatts to 50 watts of small-power, and single-point covers Lid range is from 5 meters to 20 kilometer.

In one embodiment, the first filter circuit and the second filter circuit may each comprise low-pass filter and high-pass filtering Device decays 3dBm hereinafter, inhibiting 30dBm or more for non-targeted signal for echo signal.

In one embodiment, the first prime amplifying unit and the second prime amplifying unit may each comprise low noise amplification Device.

The advantageous effect of said program is：Since transmitter power is small, distance is close between base station, so to launch point Selection require it is low, can be with flexible arrangement launch point.Furthermore filtered and amplification signal carries out supplement hair in protection interval It penetrates, main covering signal blind zone, the free existing overlay areas DTMB of elastic extension can be repaired.

The advantages of the utility model additional aspect, will be set forth in part in the description, partly will be from following description In become apparent, or recognized by the practice of the utility model.

Description of the drawings

Fig. 1 is the principle model figure according to the filter circuit of the utility model one embodiment；

Fig. 2 is the structural schematic according to the transmitter 10 of the utility model one embodiment；

Fig. 3 shows a specific example of filter circuit 110 in Fig. 2；

Fig. 4 is the structural schematic according to the transmitter 40 of another embodiment of the utility model；

Fig. 5 gives a kind of showing for the construction method of digital tv ground broadcasting according to the utility model embodiment Meaning property flow chart；And

Fig. 6 shows the allocation plan of the transmitter of the broadcast system according to an example.

Specific implementation mode

In view of problems of the prior art, a kind of thinking emitting networking using small-power is inventors herein proposed.This Utility model be one kind in DTMB networks, with small-power emit supplementary signal and networking technology.Design filter circuit processing Airborne electromagnetic wave controls small insertion loss, filters out useful signal, then designs low power transmitting equipment, believes in reflection The networking of small-power multi-point transmitting is realized in number protection interval that can receive.

DTMB (Digital Television Terrestrial Multimedia Broadcasting) is digital electricity Depending on the english abbreviation of ground multimedia broadcast.In DTMB systems, using the modulation of time-domain synchronization OFDM (OFDM) Mode supports the data transmission in 8MHZ bandwidth.Protection interval is added between each symbols of the OFDM in subcarrier, reduces code Between interfere, can support mobile communication well.As long as the time difference of unlike signal is less than protection interval, would not constitute dry with frequency It disturbs.

According to the utility model embodiment 1, a kind of digital tv ground broadcasting is provided, which includes at least one A transmitter.The transmitter includes sequentially connected filter circuit, prime amplifying unit and power amplifier unit.Wherein, transmitter Launch after handling from aerial reception digital television terrestrial broadcasting network signal and to it, the filter circuit is based on being received The frequency of signal and obtain and area, landform and received signal that the power of transmitter and quantity cover as needed Depending on signal value.

The transmitter of the present embodiment is that power emits equipment from 8 milliwatts to 50 watts of small-power, and single-point coverage area is from 5 meters To 20 kilometers.For example, low-noise amplifier may be used in prime amplifying unit, two-stage or multistage work(may be used in power amplifier unit Rate amplifier.Since distance is small between base station, the transmitting signal of all base stations and their reflection signal are all in the protection of terminal In interval.Therefore, the selection of launch point is easy, flexible arrangement.

In one embodiment, filter circuit in such a way that 5 rank high-pass filters are combined, is come using 5 rank low-pass filters Realize narrow-band filtering.Out-of-band interference point inhibits to arrive 50dBm 30.Its principle model figure is as shown in Figure 1.

Fig. 2 is the structural schematic according to the transmitter 10 of the utility model one embodiment.As shown in Fig. 2, transmitting Machine 10 includes sequentially connected filter circuit 110, prime amplifying unit 130 and power amplifier unit 140.Filter circuit 110 includes low Bandpass filter 111 and high-pass filter 112, to realize that bandwidth is, for example, the narrow-band filtering of 8MHz.Filter circuit 110 is according to each Ground frequency point designs, it is desirable that decays 3dBm hereinafter, inhibiting 30dBm or more for non-targeted signal for echo signal.

Beijing area uses tri- DTMB frequency points of 626MHz, 666MHz and 674MHz, Fig. 3 to show filter circuit in Fig. 2 110 are applied to a specific example of Beijing area.In Fig. 3, resistance R0, capacitance C1 to C6 and inductance L1 and L2 constitute low Bandpass filter 111, resistance R1, capacitance C6 to C11 and inductance L3 and L4 constitute high-pass filter 112.Wherein, resistance R0 Resistance value is 75 Ω, and the capacitance of capacitance C1 to C5 is respectively 2pF, 100pF, 2.2pF, 3.3pF and 3.3pF, the appearance of capacitance C6 to C11 Value is respectively 2.2pF, 2.7pF, 3.6pF, 1.5pF, 1.8pF and 4.7pF, the inductance value of inductance L1 and L2 be respectively 12nH and 10nH。

Filter circuit 110 in above-mentioned example is analog filter, it will be understood by those skilled in the art that filter circuit 110 can also use digital filter, write program by the memory to digital filter, so that it may realize various filtering work( Energy.

It is preceding after the filtering for the filtered circuit of digital television terrestrial broadcasting network signal 110 that antenna receives in Fig. 2 Grade amplifying unit 130 amplifies, to meet requirement of subordinate's power amplifier to incoming level.In order to reduce noise, ensure the linear of signal Degree, prime amplifying unit 130 are, for example, low-noise amplifier LNA, and power amplification is 16dBm or so.Power amplifier unit 140 can be adopted With AB class linear amplifiers, such as lateral diffusion metal oxide semiconductor (i.e. LDMOS) device, to meet OFDM for power amplifier Linear, stability and dynamic range etc. high requirement, the letter for specifying power (such as 300mW) is exported from power amplifier unit 140 Number launch to antenna.According to actual conditions, those skilled in the art can further increase final stage power amplifier and be attached thereto Bandpass filter, to export the radiofrequency signal of maximum 50W.

In addition, transmitter 10 may include the power supply and monitoring unit of power supply to the device, to realize long-haul telemetry and monitoring. Further, transmitter 10 may include the directional coupler being connect with power amplifier unit 140, to couple incident, reflection signal Go out for monitoring.

Fig. 4 is the structural schematic according to the transmitter 40 of another embodiment of the utility model.In Fig. 4, the first filtering Circuit 410, the first prime amplifying unit 430 and power amplifier unit 440 can be with filter circuit 110, the prime amplifying units in Fig. 2 130 and power amplifier unit 140 it is identical, omit detailed description thereof herein.For example, the first prime amplifying unit 430 and power amplifier list Member 440 can realize the gain of 30dB jointly, and the condition of this parameter is 1dB compression point measured values.

Transmitter 40 further includes the second filter circuit 420, the second prime amplifying unit 450, power governor 460 and switching Unit 470.Second filter circuit 420 and the second prime amplifying unit 450 can respectively with before the first filter circuit 410 and first Grade amplifying unit 430 is identical.Switch unit 470 is, for example, to switch, when control switch unit 470 makes aerial radiofrequency signal via the When two filter circuits 420, the second prime amplifying unit 450 and power governor 460 are input to the first prime amplifying unit 430, Two level amplification can be carried out to signal.Compared to the situation that signal is transmitted from the first filter circuit 410, the work(of signal can be improved Rate and linear.In practical applications, it when monitoring that the level attenuation of radiofrequency signal is larger or breaks down, can grasp manually Make switch unit 470 and realize switching, to ensure the stability of system.

Power governor 460 can be arranged in overflow in order to prevent, be, for example, adjustable attenuator, can make signal Decay 0dB, 3dB, 6dB or 9dB.It will be appreciated by those skilled in the art that circumferential work can also temporarily be used between two-stage amplification Rate adjuster is adjusted.

In the digital tv ground broadcasting of above-described embodiment, filter circuit frequency signal-based and obtain, and Depending on the signal value of area, landform and the signal that the power and quantity of transmitter cover as needed.That is, first Aerial signal is tested, obtain features such as the frequency of echo signal, intensity in network and requires supplementation with the area in the region of signal, root It is believed that number Frequency Design filter circuit, design transmitter further according to the intensity of the area and signal and Combining with terrain situation Power and quantity.The transmitter of the present embodiment is that power emits equipment from 8 milliwatts to 2 watts of small-power.Utilize this system structure The Network stretch built uses existing aerial radiofrequency signal, it is not necessary to the signal source of transmitting be provided separately, therefore can reduce into This.Filtered and amplification signal carries out supplement transmitting in protection interval, can supplement the covering of DTMB signals, freely elasticity Extend the existing overlay areas DTMB.

Digital tv ground broadcasting in above-described embodiment uses low power transmitter, is wanted to the selection of launch point Ask low, therefore can be with flexible arrangement launch point.In addition, since power is small, frequency can be adjusted flexibly.

On the other hand, the utility model provides a kind of construction method of the digital tv ground broadcasting of embodiment 1, The executive agent of this method can be server.The construction method includes the following steps：

S10 tests and analyzes aerial signal, obtains the frequency of echo signal and signal value in network and requires supplementation with letter Number region area；

S20 designs filter circuit based on the frequency of echo signal；

S40 designs the work(of transmitter according to the area and the signal value of the echo signal and Combining with terrain situation Rate and quantity, to obtain the radio frequency overlay network that covering requires supplementation with the region of signal.

Fig. 5 gives a kind of showing for the construction method of digital tv ground broadcasting according to the utility model embodiment Meaning property flow chart.In step S511, composed using frequency spectrograph test airborne electromagnetic wave frequency.In step S512, for electromagnetic spectrum It is analyzed, obtains the frequency of echo signal in network, other non-targeted signals in intensity and signal-to-noise ratio numerical value and frequency band Frequency and intensity, while obtaining requiring supplementation with the area in the region of signal.

Next, in step S521, filter circuit is designed according to frequency spectrum.It is required that filter circuit decays for echo signal 3dBm for non-targeted signal hereinafter, inhibit 30dBm or more.In step S522, it is filtered throwing plate, welding and the tune of circuit Examination, and test its performance.Hereafter, process proceeds to step S523, for the performance of filter circuit whether meet index request into Row judges.For example, whether the cutoff frequency of test filter circuit, insertion loss, passband filter line, stopband attenuation etc. meet predetermined want It asks.If meeting index request, process proceeds to step S541.Otherwise, process returns to step S521, adjusts filter circuit The parameter of structure and/or internal components, a time design of iteration.

In step S541, set according to the intensity of the area and echo signal that are obtained in step S512 and Combining with terrain situation Count the power and quantity of transmitter.

In this step, the area, landform and the signal value design small-power transmitting domain that cover as needed.For example, for The building structure that volume is 30 meters * 30 meters * 30 meters, the power for designing transmitter are 300mW, and number is set up using individual transmitter Word television terrestrial broadcasting system.

In typical covering design model, single emission point is used in the range of 10,000 square metres, the work(of 300mW is installed Rate equipment.Fig. 6 shows the allocation plan of the transmitter of the broadcast system according to an example.In Fig. 6, a=100 meters, b=50 Rice.As shown in fig. 6, using 9 or more launch points P, each launch point P in the range of 90,000 square metres uses a 300mW Emit equipment, to one network for covering 90,000 square metres by 9 or more launch points of composition.Due to the power of each launch point P It controls in 300mW, therefore other regions in non-point region and non-coverage in network coverage are generated Electromagnetic interference very little.

For extreme terrain, building structure etc., in a launch point coverage area being likely to occur local signal is shielded The case where.In order to solve the problems, such as this, rational position can be chosen and increase a launch point.As shown in fig. 6, the upper right side in figure A launch point P is increased in high mountain region, to realize in target coverage area the network for being an all standing.This networking side Formula is not present in high-power network, solves the problems, such as that same frequency net can not be mended a little.

Then, in step S542, throwing plate and the networking debugging of transmitter is carried out, actual effect is tested.If target area The intensity of interior electromagnetic wave signal reaches pre-provisioning request, and target area is completely covered, and design is completed.Otherwise, process returns To step S541, the power and/or quantity of transmitter are adjusted according to measurement result, with polishing signal power and/or eliminate signal Blind area.

In the utility model embodiment, the signal of each launch point is homologous, synchronous, same-phase radiofrequency signal, that is, With frequency net signal.But (have signal when mending point high tower strong signal but exist with the nonsynchronous situation of frequency), it may be used small Range power compresses, the bad signal section in critical zone to solve high tower signal.

The utility model at least has the advantages that compared with the prior art

First, the airborne electromagnetic wave pollution range of network consisting is small, and electromagnetic pollution is small in network's coverage area.

Second, the launch point selection of networking requires low, the common-frequency network of the easy multiple exit point of composition.

Third, Network stretch use existing aerial radiofrequency signal, it is not necessary to the signal source of transmitting be provided separately, reduce Cost.

In several embodiments provided herein, it should be understood that embodiments described above is only to illustrate Property, disclosed device and method may be implemented in other ways.The unit illustrated as separating component can be or Person, which may not be, to be physically separated, that is, and each functional unit in each embodiment of the utility model can integrate, Can physically exist alone, can also be during two or more units are integrated in one unit.

Although the embodiments of the present invention have been shown and described above, it is to be understood that above-described embodiment is Illustratively, it should not be construed as a limitation of the present invention, those skilled in the art are in the scope of the utility model It is interior to modify, replace and modification to above-described embodiment.

Claims (5)

1. a kind of digital tv ground broadcasting, which includes at least one transmitter, and the transmitter includes connecting successively The first filter circuit, the first prime amplifying unit and the power amplifier unit connect, which is characterized in that the transmitter from the air for connecing It receives digital television terrestrial broadcasting network signal and launches after handling it, first filter circuit is based on received signal Frequency and obtain and area, landform and received signal that the power of the transmitter and quantity cover as needed Depending on signal value.

2. system according to claim 1, which is characterized in that the transmitter further includes sequentially connected second filtered electrical Road, the second prime amplifying unit and switch unit, the switch unit is connected to the first filter circuit and the amplification of the first prime is single Between member, so as between the first filter circuit and the first prime amplifying unit connection and the second filter circuit and the first prime Connection between amplifying unit switches over, and second filter circuit is obtained based on the frequency of received signal.

3. system according to claim 1 or 2, which is characterized in that it is small from 8 milliwatts to 50 watts that the transmitter is power Power emitting device, single-point coverage area is from 5 meters to 20 kilometer.

4. system according to claim 2, which is characterized in that the first filter circuit and the second filter circuit are including low pass Filter and high-pass filter decay 3dBm hereinafter, inhibiting 30dBm or more for non-targeted signal for echo signal.

5. system according to claim 2, which is characterized in that the first prime amplifying unit and the second prime amplifying unit are equal Including low-noise amplifier.