MADS System
Microwave Adaptable Distribution System
OVERVIEW
MADS is specific category of TV transmitter which is distributing TV signal by microwave transmitter. The difference between MADS and standard television transmission is in used band which is 12GHz for MADS and 50-900MHz for UHF/VHF TV transmitters. Microwave distribution system is most advanced system for transmission of TV services now. MADS system is in fact linear converter which is able to convert IF frequencies to 12GHz band with almost every modulation scheme (AM, FM, QPSK, QAM, OFDM). Most suitable for MADS application is DVB-S standard with QPSK modulation. This combination can offer with regards to bandwidth up to 16 TV services in one MADS multiplex. Also is important that at customers side (receiving side) is necessary only one receiving antenna for family house or dozens of flats where is possible to use actual TV cabling. This technology will then have influence also to city look where are no big antenna systems on the roofs needed any more. By microwave links and satellite transponders is possible to feed this MADS system which can then offer TV services in locations where was impossible to receive them or possible only with poor quality. MADS system is also designed for cable networks where can be used as cable network gap filler or main distribution system for cable networks. Cable network can be also fully replaced by MADS so citizens can have similar program offer without need to any expensive cable network. If owner of MADS network is city itself there is also no need for pay TV, all services can be for free. There is also possibility to encrypt transmitted services and thus make pay TV with MADS system. System is also able to broadcast info channel with videotext informations and capable of teletext broadcasting.
MADS SYSTEM TV TRANSMITTER
MADS transmitter is able to broadcast up to 16 TV services to one antenna system with radiation angle 40 - 170°. Transmitter with integrated system is installed inside waterproof box which can be directly installed to rod. In case of indoor installation is wall material with good dielectric parameters required. Technology for receive and processing of input feeds can be installed separately.
RECEIVER UNIT
Customer is able to receive MADS TV services on regular TV receiver with MADS receiver set. Configuration of this set vary depending on distance from receiver to MADS transmitter. Up to 1 km is possible to use only small horn antenna for distance over 1km is parabolic antenna needed. Size of parabolic antenna can be precisely defined for every distance by measurement but generally Ø 60 cm is enough up to 6km. Also free sign of view is required for best receiving performance.
Technical parameters
| Input IF | 70 MHz-1,3 GHz | Output Frequency | 11,7 GHz - 12,56 GHz |
|---|---|---|---|
| Output Power | 5-1000 mW/channel | ||
| Input Impedance | 50 Ω | Output Impedance | 50 Ω |
| Modulation | given by IF | ||
| Number of TV services | 1-16 | Frequency Stability | ± 500Hz |
| Power Supply | 230 V ±10% | Power Consumption 15W at | 100 mW/channel |
| Polarization | H or V | Input Connector | N |
| Radiated Beam Width | 40-170° in horizontal view | Radiated Beam Height | 10° in vertical view |
| Operation Temperature | -20 to +50°C |
TX Dimmensions |
560x320x180 mm |
ADVANTAGES SUMMARY FOR MADS SIGNAL DISTRIBUTION
- Easy, fast and low cost integration
- Low cost receiving set
- System can be upgraded later up to 16 TV services
- International frequency coordination is not required
- Missing TV services can be easily broadcasted to wide area
- Number of free frequencies with robust signal
- Possibility to broadcast own informational TV service with high ratings
- Possibility to use retransmitters on same frequency without need for SFN network for areas without free sign of view to main transmitter
SCHEMATIC DESCRIPTION OF MADS INSTALLATION IN CITY
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