The purpose of this invention is to provide a kind of satellite TV system for trains, it can solve on the power issue, train of vibration problem that train is in operation, closed-circuit TV train various electrical equipment to the road interference problem of closed-circuit TV, the flexible connection problem between train.
The object of the present invention is achieved like this: satellite TV system for trains, comprise antenna, some output image equipment, it comprises that also the antenna input of satellite television receiving system, each compartment vision receiver, sound that satellite television receiver is sent here, vision signal select wherein one the tunnel through sound, video switcher, be modulated to intermediate frequency carrier, frequency conversion is a radio frequency again, pass through radio frequency cable, radioamplifier, coupler and splitter transmit distribution with TV signal with closed circuit form, arrive the antenna input of each picture receiver at last;
Described satellite television receiving system comprises antenna feed, antenna automatic control device, low noise amplifier, low-converter, the first intermediate frequency transmission cable, power device, satellite television receiver, video/audio distributing box, colored monitoring equipment, antenna The Cloud Terrace.
The present invention has following advantage: the invention solves the vibration problem that train is in operation, the power issue of closed-circuit TV train, on the train various electrical equipment to the road interference problem of closed-circuit TV, the flexible connection problem between train.
Describe embodiments of the invention in detail below in conjunction with accompanying drawing.
1) playout center
Railroad train satellite television playout center, by forming with the lower part, comprise sound, vision signal that video tape recorder, player, VCD, DCD, satellite television receiver are sent here, pick up camera, microphone and signal generator (test card signal), station symbol, with several signals through sound, video switcher, select wherein one the tunnel, be modulated to intermediate frequency carrier, frequency conversion is a radio frequency again, by radio frequency cable, radioamplifier, distributing box and splitter transmit distribution with TV signal with closed circuit form, arrive the antenna input of each compartment vision receiver at last.
Described satellite television receiving system comprises antenna feed, antenna automatic control device, low noise amplifier, low-converter, the first intermediate frequency transmission cable, power divider, satellite television receiver, video/audio distributing box, colored monitoring equipment; The antenna The Cloud Terrace; Antenna receives satellite TV signal and passes to low noise amplifier, be sent in the compartment by the intermediate frequency transmission cable through low noise amplifier processing and low-converter processing, tuner (outdoor unit) receiver, video, high-frequency signal is through high frequency distributor processes modulator, satellite television receiver is delivered to colored monitoring equipment with the satellite television received signal through high-frequency switcher, the antenna automatic control device delivered to measurement signal simultaneously by satellite television receiver, through measuring, the computing signal is delivered to actuating unit, automatic compensation satellite TV system for trains receiving wire direction ON TRAINS.
Because train is under steam, sometimes cross tunnel, mountain valley and high and steep mountains, and often braking or starting, therefore satellite television receiving antenna towards at any time, all require to make the main lobe of antenna can automatically aim at satellite direction all the time in any case, the antenna system of this automatic search and automatic tracking (comprising antenna-feedback system, antenna mounting and antenna automatic tracking control setup) utilizes this antenna system (interior dress global positioning receiver and digital compass).At first search satellite-signal, finish to the correct automatic tracking at satellite aximuth, the elevation angle and to the precise adjustment of polarizing angle by the antenna automatic tracking control setup again.
Described radioamplifier amplifies high-frequency modulation signal or directly transfers out by high frequency cable; Described distributing box is the distribution devices in the highfrequency transmission systems, and signal power is told equably; Described splitter is made up of transformer type directional coupler and distribution network.
Train TV intermediate frequency Modulation transmitter is delivered to the sound subcarrier frequency-shift keying with sound, frequency signal through amplifier, and sound subcarrier 6.5 megahertzes are carried out frequency modulation, carries out mixing with intermediate frequency carrier 37 megahertzes, obtains sound intermediate frequency 30.5 megahertz signals.Vision signal is added to that the video amplifier amplifies and clamp, is added to intermediate frequency modulator then, and 37 megahertz intermediate frequency carrier are carried out amplitude modulation.Modulated image intermediate frequency signal is through the vestigial sideband filter limited frequency range.Be added to the intermediate frequency out amplifier through the signal of vestigial sideband filtering and amplify, and mix mutually, obtain the image accompanying sound intermediate frequency signal with accompanying sound intermediate frequency signal.Image accompanying sound intermediate frequency signal and local oscillation signal carry out mixing by nonlinear device, and choose needed image sound accompaniment radiofrequency signal by bandpass filter.
Total system test, adjustment adopt television signal generator as signal source, are made up of color sync generator, coder, picture signal generator three parts.Can produce composite sync, mixed blanking, burst gating pulse, burst signals such as colour subcarrier.The function of video/audio automatic switchover device mainly as switching video/audio signal, is broadcasted usefulness to make image and sound.
The required source of AC 220v of cable TV on train system forms the direct supply on the Train Wheel shaft generator (48v nominal voltage) inversion with the thyristor inversion voltage stabilizer.The train of band generator car can direct color 220v source of AC, without the thyristor inversion voltage stabilizer.
2) high-frequency transmission and distribution system
High-frequency transmission and distribution system are made up of high frequency cable, radioamplifier, distributing box and splitter.High-frequency modulation signal input radioamplifier amplifies or directly transfers out by high frequency cable, and this high frequency coaxial cable is called the trunk main of transmission system.High-frequency signal is assigned to the antenna terminal of picture receiver through distributing box and splitter from trunk main.
When high-frequency signal transmitted in cable, its decrement was decided by the model of cable, the length of cable and the frequency of high-frequency signal etc.
Distributing box is the distribution devices in the highfrequency transmission systems, and signal power is told equably.For example train CATV playout center when being located at No. eight compartments, is selected S214-2 type distributing box for use, high-frequency signal can be divided into two-way, transmits to the 7#-9# both direction.Two kinds of distributing boxs are exported in two tunnel outputs and four tunnel that have that the cable TV on train system is commonly used.
Splitter is made up of transformer type directional coupler and distribution network.The distribution network of splitter is identical with distributing box.Effect is to give service main sub-fraction signal with trunk main medium high frequency signal allocation, supplies with picture receiver.All the other most of signals continue to transmit down along trunk main.Require the decrement of splitter and distributing box as far as possible little.
Radioamplifier is important components very in the closed-circuit TV.Because high-frequency signal is decayed in cable, splitter, distributing box transmission course, the signal that arrives vision receiver may be lower than desirable value 65dB~80dB), so need amplifier to amplify,, thereby on TV screen, obtain satisfied image so that picture receiver has enough signal levels.
3) receiving terminal
Receiving terminal is made up of colored receiver and terminating terminal, and the installation of satellite TV system for trains vision receiver is divided into the hard-seat coach, four kinds of mounting meanss such as carriage with semi-cushioned berth, soft berth sleeper and dining car.The two ends, hard-seat coach are imported and exported the top and are respectively adorned one of 22 inches vision receiver, and source of AC adopts thyristor inversion voltage stabilizer capacity 200VA.Have 14 inches colour TVs to be installed on the window top in each private room of soft berth sleeper, 600VA thyristor inversion voltage stabilizer is made source of AC.The carriage with semi-cushioned berth mounting means has two kinds: a kind of is identical with the hard-seat coach, and a kind of is identical with soft berth sleeper, and just two lattice are adorned 14 inches colour TVs temporarily earlier, another lattice attaching terminator, otherwise high-frequency signal can be reflected by open end, can make on the terminal TV set image ghost image to occur.Dining car is adorned 22 inches colour television sets.