Nowadays, branching of wireless real time TV broadcasting to a digital format is the main event in television branch. Certainly, the wireless digital broadcasting has a set of advantages. However, even definitive deployment of a digital broadcasting in microwave range traditional for it can't provide full satisfaction of inquiries of the modern viewers. It is possible even to tell that this process was late in relation to growth of the modern consumer requirements of services already. First of all, it concerns quantity of broadcast programs which for an on-air broadcasting is much less, than it’s for a satellite and cable TV networks. In this case the broadcasting systems working in higher frequencies ranges, including those from them which for TV signals transmitting use others, except DVB-T/T2, broadcast standards to the aid can come. For the purpose of additional possibilities realization «ROKS» offers microwave broadcasting systems on the basis of technologies MMDS (2-11 GHz), MVDDS (11-15 GHz) which Ukrainian analog is broadcasting system MITRIS and also systems on the basis of technology LMDS (22 - 39 GHz). Features of architecture inherent in given systems promote achievement of high power and spectral efficiency and conformity to their highest ecological requirements.
For MMDS systems we recommend a proprietary architecture that allows you to use one powerful transmitter instead of few relatively low-power transmitters with the individual transmitters signals frequency division multiplexing in propagation medium possibility (the Ukrainian Patent № 54644). We also propose a new system architecture that allows you to eliminate areas of shading, resulting in transmitting signals to the multi-carrier TV system MMDS. The proposed co-channel repeaters are more efficient than traditional Gap Fillers (the Ukrainian Patent № 54275).
The architecture of system MVDDS offered by us (MITRIS) has shown rather useful ability to repeated relaying of a group signal without its regeneration. We patent system "MITRIS-CS" (the Ukrainian Patent № 24643) which is optimum for construction of broadcast networks that haves some of base stations, connected among themselves by means of RRLs.
In countries that are now in the communication infrastructure development process, constantly growing unsatisfied demand not only for the services of digital TV broadcasting, but, above all, on complex of services offered with the Internet. Demand for all services can be met simultaneously by using the fast deployable wireless multimedia systems which are both broadcast and information systems. The using of such systems are more efficiently in the economical and social aspects than the creation of separate broadcasting and information systems.
A common property of our multimedia systems is the use of modem equipment and CPE standard DOCSIS (with or without updating). With DOCSIS modems you can create an effective and very large information capacity system based on the compound MMDS + DOCSIS (2 -11 GHz) and MVDDS + DOCSIS (11 - 13 GHz).
A second factor that is common to all systems is their construction mostly around the sector antennas system thus increasing the information capacity of the system and quantity of it serves individual and corporate subscribers. In terms of function integration we have gone even further by combining broadcasting and information complex with an extensive video information gathering system. As a result of such combining was established patented UWMS-R system (the Ukrainian Patent № 54643) which were combined in Ku-band the functions of wireless broadcasting and information systems based on MVDDS + DOCSIS and professional video information gathering systems (video surveillance). In this system the first time in the world practice by using its own information system have been carried out remote management of subscriber receivers and transmitters of video information gathering posts and full monitoring of broadcast network allowing to continuously monitoring of each subscriber’s TV broadcasting signal quality using the services of the own information part.
Extremely high integration of functions, achieved in the UWMS-R, can bring to life the concept of "intelligent town". The overall data capacity of the information system using one WMTS DOCSIS in each of the 8 sectors is up to 328 Mbps and can be increased in proportion to the quality of the applied WMTS. The total capacity of the system broadcast part reaches 4.48 Gbps, and video information gathering system - up to 7.168 Gbps.
Despite the rapid development of wireless local networks, radio relay lines are not only doing looses its value, but their use has been enriched with new contents. Now they are increasingly working closely to the cellular networks, cable TV, and wireless broadcasting systems. RRLs today are a mandatory attribute of any advanced communications system. New applications require from RRLs even greater flexibility and variability of performances. If the normally RRS for each of the frequencies ranges, and even for each of the frequencies plans has consolidated structure consisting two main blocks - the block of the outer (ODU) and internal (IDU) installation, we are using in our design the division on many more modules. Only in this way in a small-scale production different applications can be adapted to numerous product requirements.
PJSC "ROKS" offers two basic types of RRS:
1. "ROS-2H-TV" is a RRS family developed in several bands with frequency plans, lying in the frequency range from 2 to 15 GHz. They are mainly designed to transmit a television programs multiplex or E1/E3 plesiochronous hierarchy signals. ODU and IDU are interconnected by coaxial cables to transfer signals on the standard intermediate frequencies 70 and 140 MHz. Types of modulation used - QPSK, 16QAM, 32QAM and 64QAM. For television signals receiving are using set top boxes standards DVB-S and DVB-C.
2. «ROKS-DTV» is a RRS family intended primarily for transmission of multi-frequency group signals consisting of several carriers, modulated by the multiplexes of digital TV programs. Therefore, the connection to the ODU and IDU is also made with coaxial cables but in the L -range. On the air data signals occupy the few frequency trunks arranged according to the RRL frequency plan in the frequency range from 10 to 20 GHz.
Video surveillance systems that are based on IP- network cameras and various IP-based local networks are currently the sales major hit in the wireless video surveillance offerings. As long as the network size (number of served cells) will not exceed a certain level - everything is running smoothly. But if on the basis of such decisions to try create a large network at the municipal level, once any major difficulties. These difficulties relate primarily to the insufficient capacity of existing and future local area networks and the relative symmetry of their traffic. Built on the basis of their network would be bulky (using thousands hubs) and difficult to manage, because it uses hundreds of command centers and involved hundreds of operators. The fact is that local networks were developed to transfer data to subscribers and from subscribers to central station and traffic is almost symmetrical. In video surveillance networks most of the video dates transmitted from the peripheral towards the central station and the amount of information to control video cameras and transmitters is negligible. In addition, in accordance with the purpose of the system requirements for quality professional network transmission of images is much higher.
We concluded that the use of local networks that not specifically designed for video surveillance signal transmission in professional video surveillance system is impractical.
In our system were realized the new design principles that will allow to implementing a system to ensure the signals transmitting from 1792 cameras. The transmitted signals have a broadcast quality (including HD signals). The total transmitting capacity of information system is 7.168 Gbps. These parameters have been achieved through the use of two levels of the system - the lower and upper. The lowest transmission level uses the L and S bands, the top – Ku-band.
All the cameras used in the system have remote control over the air.
TX Station of Multi-channel SFN
Multi-сhannel SFN with content transfer by RRLs consisting of the central station and base stations (remote transmitters) set in which base station the principle of frequency multiplexing in air
Is use and in which for the shaded sites of cells liquidation and a network cover zone expansion co-channel repeaters are used.
PJSC "ROKS" offers two new technical decisions which concern multi-channel networks architecture of a single frequency synchronous broadcasting network (multi-channel SFN) in which content transfer from the central station to set of base stations (remote transmitters) is carried out on RRLs.
The first of them is transmitting (base) station of a television and radio broadcasting network realized with channels multiplexing directly on air.
There are two standard variants of multi-channel transfer realization.
In the first variant the multi-channel signal is formed on IF and moves on the multi-channel transmitter which will convert it to the necessary radio frequency, gains, and transfers in the antenna.
In the second variant single-channel transmitters each of which converts and gains only one channel are used. Combining of the signals formed by single-channel transmitters in this case is carried out by means of the multiplexer consisting set of BPF (band pass filters) and ferrite circulators.
The first variant is easier in realization, but for a group signal transfer it demands unfairly high transmitter power, in particular, by transfer of several carriers in formats DVB-C or DVB-T. First, for reception signals with modulation QAM64 that is typical for these formats high enough level SNIR = 25 dB (for reception QPSK it is required SNIR = 10 -12 dB) is required. Secondly, QAM concerns modulations with signal amplitude changing from a symbol to a symbol. And such mode demands an additional stock on power of a signal for 10 dB, differently by transfer of a group signal appear intermodulation distortions. To avoid influence of intermodulation products, it will be necessary to choose the transmitter with the output power repeatedly exceeding total power of transmitted channels. Thus it is necessary to consider that cost of the transmitter with growth of its power sharply increases. The calculations made the company have shown that at use of standards DVB-C and DVB-T and a planned covering zone in radius 30 km group transmitters are economically expedient for using only for transfer of two-three carriers that is MPTS streams. At more channels quantity it is more favourable to use the single-channel transmitters intended for each carrier transfer.
Fig 1. Base Station of Multi-channel SFN Block Scheme.
Denotation per figure:
1. Omnidirectional Slot-hole Antenna.
2. Upconverter Block (BUC).
3. N-channels Crossover.
4. Channel Band Pass Filter (BPF).
5. N Transmodulator Block with Synchronization Schemes that Referenced on GPS Signal.
6. Receiving RRS Low Noise Downconverter (LNB).
7. Receiving RRS Antenna.
Nevertheless, the multiplexer applied at physical level, is expensive enough and complex in production. Besides, it inserts considerable dissipative losses (the signal power losses) and demands introduction in each channel path the group time delay corrector. Therefore in considered design it is offered to use a method of frequency multiplexing directly on air.
The offered principle can be realized in the base station assigned on 12 channels (digital packages) transfer in a bandwidth of 120 MHz (5.705 – 5.825 GHz). In it are used single-channel transmitters and slot-hole omni-directional antennas. The antenna system looks like the two-storey design which each floor represents a hexagon with the parties of meter length. In each corner of a hexagon the omni-directional antenna is placed. Thanks to the narrow orientation diagram in a vertical plane, the antennas placed at different levels practically don't influence against each other, but the signals radiated by antennas which are placed on one floor, not only are transmitted, but also are received by each of these antennas. The signals radiated by the adjacent antennas, will be perceived by output transmitters cascades as the signals reflected from the antennas and can cause instability of the amplifier. For struggle against this phenomenon it is offered to use the ferrite circulators providing an outcome in 20 dB and more.
The distance increase between antennas (the sizes of antenna system) is less effective. For each concrete case it is necessary to calculate a system optimum configuration by means of mathematical model. Nevertheless, the generic calculations show that application of frequency multiplexing on air allows using single-channel transmitter’s power more effectively, rather than at physical level multiplexers use.
The second technical decision used at multi-channel SFN design, represents a co-channels repeater.
New Principle of Gap Filler construction
Traditionally used in synchronous broadcasting networks the on-channel repeaters (Gap Fillers) are assigned on relaying only one channel DVB-T/H and consequently are inefficient in multi-channel SFN. In case of a content distribution network between the central station and set of base stations (remote transmitters) organization as the network of simplex RRLs working in higher frequencies range than a synchronous broadcasting network, within beams transferring RRSs (except 80 % of a Fresnel zone) it is possible to place repeaters receiving antennas which will receive and transmit signals in RRS used frequencies range. Unlike on-channel repeaters which receive, and transmit signals on frequency on which all network works, multi-channel repeaters take a signal from a radio relay line, and transfer to its subscribers as a broadcasting signal. Therefore it is necessary to consider them as co-channel repeater.
As on higher frequencies the relative bandwidth occupied with a group signal will be less, there is possible a design of the multi-channel repeaters working under standard DVB-S, instead of DVB-T/H. Thus in broadcasting network user's receivers of two types will be used: working in a multi-channel single frequency synchronous network and the receiving signals transmitted by co-channel repeaters. Such approach will allow in the conditions of a city with dense many-storey building and an abundance of the shaded sites to lower cost of repeating stations at the expense of repeaters quantity reduction, and on city suburbs where the distribution mode comes nearer to LOS, will allow on some of directions to expand a service zone of a network.
The given principle can be realized at content distribution network architecture in a range 11.7 – 12.2 GHz. In a 500 MHz band it is possible to place the same 12 channels with step of 40 MHz.
Use of the offered technical decisions will allow to construct an effective cellular broadcasting network, capable to transfer over 100 TV programs in which at the expense of co-channels repeaters use problems of the cells shaded sites liquidation are successfully solved and the network service zone can be increased on any directions.
Img. 2. The Shadow Zone Liquidation by Introduction in Network Co-channel Repeater.
Denotation per figure:
1,2 – Overlapping SFN Cells.
3 – Transmitting RRS.
4 – Receiving RRS.
5 – Receiving Antenna of Co-channel Repeater.
6 – Area in which Receiving Antennas of Relay Station Placing Excludes.
7 – Shadow Area.
8 – Obstruction (high storage).
9 – Co-channel Repeaters Block.
10 – Repeater Transmit Antenna.
11 – User’s Receiver of Second Type.
12 – User’s Receiver of First Type.
13 – Sector in which Signal that Transmitting by Repeater are Propagated.
Multimedia System UWMS-R
PJSC "ROKS" offers the new project – multimedia system UWMS-R which is the modernized variant of UWMS system. The same as and UWMS, UWMS-R is an interactive system MVDDS added with a gathering system that is able to collect the great video information volumes. The system represents the broadcasting-information complex intended for work in the close to LOS propagation conditions. It is capable to give complex service (quadruple play) which includes such functions:
- Really multi-program (over 100 TV programs) TV broadcasting;
- Bi-directional data transmission for high-speed Internet;
- Voice communication services (VoIP)’
- The diversity great volumes of a video information (video surveillance) gathering system.
All functions are carried out simultaneously. The system can be placed in operation stage by stage and is easily scaled. The most suitable to system functioning is the range of frequencies Ku.
As it is known, the range of frequencies Ku is boundary from the view point of rain influence on propagation channel quality. The sharp increase in propagation path losses which are caused by a rain begins with it. Therefore at design of system UWMS-R intended for work in regions with rain intensity 40 mm/hour and more to neglect losses in a rain it is impossible. For such intensity rain a propagation path loss will make about 2dB/km. That in such rain conditions to keep working power of system at a zone with radius 15 Km covering it is required to increase the transmitters power in it on 30 dB. For lack of a rain the signals powers accepted by remote stations receivers, will in addition increase on 30 dB that will demand essential increase in their dynamic range. The integrated dynamic range which can be calculated as the sum of difference levels of the signals, caused by distance change from the central station to separate user's station, and losses in a rain, will make more than 84 dB.
Fig. 1. The Block-scheme of UWMS-R.
Denotation per figure:
1 – The System Central Station.
2 – Subsystem of Video Information Gathering.
3 – User’s Stations.
4 – Central Station Segment.
5 – The Sector Antenna.
6 – Duplexer.
7 – BUC.
8 – LNB.
9 – Block of Converters.
10 – WMTS.
11 – Converter.
12 – Combiner.
13 – Commutator (Switch).
14 – Control and Monitoring Block Блок.
15 – Digital Platform.
16 – Power Divider Block.
17 – Combiner-Equalizer Block.
From this size 30 dB it is compensated for the account of user's receivers DVB-S (tuners DBS) AGC work, and 20 dB more – at the expense of application in system the user's antennas with various gain factors: with minimum for the user's stations located in a near zone around CS, and with maximum – for remote stations.
Remained 34 dB should be compensated for the account of amplifiers gain factor change in user’s stations radio-frequency blocks. It gives to an operator additional possibility for a broadcasting part of system monitoring and considerably facilitates installation and system service.
In the given design that a broadcasting part of system monitoring and adjustment of these gain factors is carried out by means of own information part of system data transmission network is essentially new.
Internet occurrence in houses of users allows to automating as much as possible housekeeping, thereby having realized the concept of "the intellectual house». Thanks to the broadest complex of services which system UWMS-R is capable to give, with its help the concept of "an intellectual town» in which all its inhabitants have an opportunity unlimited communication with each other and with the whole world, and local authorities bodies, public organizations and business structures operatively receive the information helping quickly to make of the correct administrative decision can be realized.
Fig. 2. User’s Station Block Scheme.
Denotation per figure:
1 – Antenna.
2 – iLNB.
3 – User’s Transeiver block.
4 – DBS Tuner.
5 – User’s Modem (CPE).
6 – Ortoplexer.
7,9,14 – Filters.
8 – LNA.
10 – Down converted Mixer.
11 – Local Oscillator.
12 – IF Amplifier with Gain Control.
13 – Upconvertion Mixer.
15 – IF Amplifier with Gain Control.
16 – Power Amplifier.
17 – Duplexer.
18 – Downconverter.
19 – Output Diplexer.
20 – Upconverter.
21 – Commutator (Switch).
22 – Control and Monitoring System Modem.
23 – Directed Coupler.
24 – Power Detector.
A variant of secondary content distribution network that provide signaling to remote multichannel SFN transmitters.
Now the society concerning many important everyday services becomes more and more dependent on exact time and frequency signals received by means of GPS system. First of all it concerns synchronization of SFN DTT transmitters. The problem consists what to create faults in reception of signals UTC (Coordinated Universal Time) which are transferred by system GPS very easily. Besides, system GPS is supervised by military bodies of the several countries. Thus, independence from GPS to become a determinative at a choice of new systems DTT. In this plan, possibility of the user’s current data distribution in a real time mode on optical or microwave networks looks very tempting.
In the process of the technical decision for a secondary distributive network of a mobile television broadcasting search as starting points such positions have been accepted:
1. The central station and remote transmitters intend for work as a part of multichannel SFN.
2. As a part of the Central Station there should not be adapters SFN (the devices intended for MIP injection) as shouldn't be present at the transport streams corresponding to separate multiplexes any additional signals of network synchronization and management.
3. Radio-frequency blocks of remote transmitters shouldn't contain any blocks of digital and analog signals processing, except amplifiers.
4. For synchronization of a multichannel single frequency network the signals received from GPS receivers or any other external precision sources of time and frequency reference signals shouldn't be used.
5. Transfer of a content from base stations to remote transmitters should be carried out on FO.
6. On FO network not digital signals in a format of IP or DVB packages but analog radio-frequency signals according to standard DVB-T/H should be transmitted.
7. Synchronization on frequency for the signals radiated by remote transmitters is reached because all of them are copies of the signals received on modulators outputs in each of N channels (N = to quantity of multiplexes) at the expense of what their frequencies completely coincide automatically.
8. Transfer time coincidence of COFDM symbols transferred by remote transmitters which correspond to each separate multiplex is reached because at use in a network of identical optical transmitters and receivers (FO TX and FO RX) and equal lengths of the optical cables connecting base station with remote transmitters, gets out for all cases to identical and equal length of the most extended FO line. At a choice of the same fibre-optical cables and use by transfer on an optical line of signals with identical length a delay in lines in this case will be equal. Those sections of cables which for the others FO lines are superfluous on length play a delay lines role for all optical signals transferred on a fibre-optical cable in a direction of the given transmitter. So the effect of simultaneous transfer corresponding to all N multiplexes of symbols COFDM without attraction for this purpose of any additional means is reached.
The “multichannel SFN” Base Station (see Fig. 1) receives an entering content in the form of N digital multiplexes which have a transport streams DVB-T/H format.
These transport streams pass all operation cycle in the modulators 1 which quantity is equal to channels quantity in network N, and modulate carrier for the purpose of DVB-T/H standard radio-frequency signals reception. Each multiplex is transferred on the own frequency. Signals of the everyone N modulated carriers divides on power on M parts by power divider 2, where M number to equally quantity of remote transmitters in a network. Each of M signals copies goes on the Block of optical transmitters 3 and arrives on inputs of separate optical transmitters 4 (FO TX) in which there is a modulation of optical signals on radiation intensity by a radio frequency signal directly. The complete sets of signals intended for transfer on separate optical cables consisting of many fibres (their quantity should be not less channels numbers in a network) optical cables 5 which connect Base station to remote transmitters set are formed from the optical signals geted by such way. Thus, given BS quite can carry out BS functions for multichannel SFN.
The optical signals which have come on the remote transmitter (see Fig. 2) on separate fibers of multichannel FO network 1 arrive on the optical receivers 3 which are a part of the optical receivers block 2. In optical receivers they are detected for the purpose of standard DVB-T/H radio-frequency signals receiving which are already ready for their transfer to an air. The given signals amplify on power by power amplifiers 4 and are radiated by antennas 5.
As amplifiers 4 (see Fig. 2) it is possible to apply intensifying modules of company TREDESS to separate channels signals gaining. TREDESS lets out the intensifying modules providing a number of output powers: 5; 10; 20 and 50 W. On level of an input signal the given modules will well be coordinated with output level of Televes company optical receivers (from -70dBm to – 20 dBm).
Each of channel’s amplifiers works on the omnidirectional antenna. At small channels quantity the antennas can be simply allocated on a vertical plane. At the expense of it their influence against each other is eliminated. At a considerable quantity of channels, i.e. in a case when to allocate all antennas on a vertical plane it is not possible, we recommend to use a patented method of multiplexing in space (the Patent of Ukraine № 54644, bul. № 22, 2010) at which some part of antennas can settle down in one plane.
A television reporting complex in a centimetric frequencies range. Complex appointment.
The centimetric range television reporting complex is intended for live video reporting carrying out from the cameras places in studio directly. Transfer of one usual quality (SD) digital TV signal meeting studio requirements Is supposed. Use in the transmitter and the receiver of a reporting complex the directed antennas demands the observance of a transfer mode close to LOS. Same necessity of reporting carrying out from any place in city boundaries (in a zone in radius to 20 Km) and a propagation mode that be in a microwave range (Ricean mode for which presence of the expressed direct beam and many smaller intensity reflected beams is characteristic) demands. That the system was steady in the conditions of a detained signal copies presence which are a consequence of a multibeam propagation mode the modulation COFDM is applied. The modulated signal parameters correspond to the standard of digital radio and TV broadcasting – DVB-T.
The advantages obtained at the expence of a sector antennas system application.
In a reception part of the reporting complex instead of omnidirectional antennas applied usually, the system of sector antennas is applied which the total diagram of an orientation also represents a cycle (see Fig. 2). The antenna system consists of four sector antennas with the width of a beam some exceeding 90 deg. For each of antennas the orientation diagram represents "the camomile" consisting of four partially overlaped petals.
To avoid shadowed from a tower construction on any of directions the omnidirectional antenna should be established at the top of a tower. It is no means always possible and very frequent - inconveniently. The system of sector antennas favourably differs that supposes any arrangement on a television center tower without danger blockage by a tower construction, without supposing thus distortion of the antenna system general orientation diagram.
The advantages scored at expense of Antenna Diversity receiver application.
It is known that at application of sector antennas system which work on four different receivers, there are difficulties with signal division on borders of the adjasent sectors. If in the receiver to apply simple switching of the received signals at such arrangement of the transmitter which is shown in Fig 2, there is an uncertainty. The signal in this case can be received both the antenna belonging to sector 1 and the antenna belonging to sector 2. In this case to reach reception unambiguity it is necessary to enter an additional criterion for division on sectors. Alternation of frequency channels or polarity can be such criterion. But the reporting transferring station can occupy any position concerning position in space of the antenna system orientation diagram petals and know nothing about in what of sectors it is. Necessity of switching or frequency, or polarization at transition from sector in sector strongly complicates transmitting station and complicates work of the operator. The good decision of a problem can be obtained for the application account in a receiving part of a complex the one four-input receiver working by principle Antenna Diversity (reception with antenna division by a principle of the maximum rating summation - SMR). Receiver Antenna Diversity working according to algorithm SMR, processes the signals simultaneously received by antennas of adjacent sectors. Application of the four-input receiver allows to accurately "sew" an orientation diagrams of four sector antennas, having obtained full analog of the ombidirectional antenna. Thus both the transmitting antenna and the receiving antenna remain directed that allows to reduce influence of the reflected signals and to get reliable signal reception arriving on any of directions.
It is known that at use «camera-back» transmitters which are usually equipped with omnidirectional antennas located directly over an operator head is exposed to influence power that continuously radiated by antenna. The power delivered by the transmitter in the antenna – to 1 W. Thus the power absorbed in basic by the operator head at the expense of dispersion in space round the aerial will be lowered only to 0.1 W. For a signal transmission on distance to 20 Km taking into account that the directed antenna of the transmitter will have gain factor 30 dB the transmitter power of 0.4 W is required. This power will be concentrated basically in a beamwidth 5-7 deg. Behind the antenna there will be only the power concerning a back petal of the orientation diagram which is less than power of the basic petal on 40-50 dB, i.e. all-14 dBm! It is absolutely safe mode for the operator. The difference in levels for two cases mentioned here makes, at least, 34 dB.
Structure of the reporting complex equipment (see Fig. 1).
The reporting complex consists of two basic parts:
1. Mobile reporting transmitting station.
2. Receiving station of the reporting complex.
The mobile transmitting station represents the two-mirror antenna (Cassegrain) equipped with a protective radio transparent cap on which the powerful upconverter (BUC) is fixed. The antenna and BUC are established on a tripod which assumes installation on the rigid horizontal basis (a surface of the earth or a roof of the house). The transmitting station antenna should be aimed at the antenna of receiving station which settles down on a television centre tower and looks like a sector antennas system. From a point of installation of transmitting station the tower of a television centre should be necessarily visible.
The antenna block has external execution and is connected to the internal block which modulator COFDM is. Modulator COFDM is executed in the case 1U intended for installation in a standard 19” Rack. The modulator carries out such functions:
1. Accepts standard PAL signals of audio/video, digitizes them and compresses according to standard MPEG-2.
2. Modulates by the transport stream gated from the compression encoder or from the outside on ASI bus carrier on one of different frequencies of UHF range.
1. Types of constellation: QPSK; QAM16; QAM64
2. Modulation error rate (MER)> 40dB
3. FEC 1/2; 2/3; 3/4; 5/6; 7/8
4. A guard interval: 1/4; 1/8; 1/16; 1/32
5. Mode IFFT: 2k
6. A radio channel bandwidth: 5, 6, 7 and 8 MHz
7. Signal level on a radio-frequency output> 100 dBmkV.
Modulator COFDM block incorporates with BUC by means of a coaxial cable on which on BUC supply voltage also is transferred. A power supplying of the mobile reporting stations is carried out from the storage battery or from an onboard network of the car.
The signal from the camera moves on one of device inputs.
The receiving station of a reporting complex has the block of external installation which consists of a sector antennas system ANT1 – ANT4 with the blocks of low noise converters established on them LNB1 - LNB4, and the internal block consisting from four–input Antenna Diversity receiver and professional tuner PBI 400. Receiver Antenna Diversity receiver accepts arriving on it from LNB1-LNB4 intermediate frequency signals and forms ASI - stream for transfer on tuner PBI. A power supplying of low noise converters is made from Antenna Diversity receiver on each of inputs.
The given technical decision allows to realizing the effective system intended for a direct signal transmission from the mobile reporting transmitting station on a television centre for realization reporting in online mode.