Transmitters from TV Broadcasting Systems Company

TV Broadcasting Systems Company has been developing and manufacturing TV and radio broadcasting transmitters since 1991. All transmitters have the Ministry of communications and informatization (Electrosvyaz system) standard certification.

One of the accents of the TV Broadcasting Systems Company transmitters is their block design, each block being a stand-alone, complete unit. All transmitters' blocks are designed in 19" frames and placed in a standard box or rack of 36U...42U. Typical transmitters' blocks are signal conditioner (exciter); amplifying blocks for 20, 50, 100, 200, 300, and 500 W; input/output devices' block of two types (for summating power of both two and four amplifying blocks); switching block (for automatic/semi-automatic switching of primary and stand-by transmitters); and also network block.

Transmitters' block design allows automatic reservation of most power loaded units (power amplifiers), convenient transportation and easy putting in operation, as well as high maintainability (i.e. quick replacement of single blocks and units), and gradual transmitters' power growing by replacing or attaching additional amplifying blocks.

All transmitters have common display and sound signal amplification.

Amplifiers' carrier frequencies are formed by coherent method of synthesizing frequencies from one frequency of the reference generator, whose function is perfumed by high-stable Giazint-M (DMW transmitters) and Fialka (MW transmitters) crystal oscillators. Schematic solution allows easy applying carrier frequency shift. Synthesis of all operating frequencies is realized by using chips of frequency synthesizers having Motorola digital control pipe. The digital operating is fully monitored by a micro controller of Atmel company.

Linear and harmonic distortion correctors are provided for compensation of display signal distortions emerging in the conditioner's channels. The characteristics of display signal sidebands, required by state-established technical standards, are formed by surface acoustic wave filter. Modulator's output signal (peak power) level is stabilized automatically with the help of automatic power regulation scheme.

Power amplifiers of TV transmitters base on several amplifying blocks: A100, A200, A300, and A500 with output power of 100, 200, 300, and 500 W respectively. The base amplifying blocks are fully autonomous: they have their own secondary power feeder, control and safety systems, and cooling system. Output stages base on the Philips field transistors. The blocks' nominal output power is 20 mW. In DMV band the blocks are spanned by the automatic power control system, allowing supporting necessary output power during input power fluctuation within ±6 dB, the blocks' output stages being load-isolated by ferrite isolators. Thanks to high linearity and good frequency characteristics, amplifying blocks do not bring evident distortions into the amplified TV signal. This allows excluding complex setting of the transmitter (conditioner-power amplifier) both in its manufacturing and exploitation.

Standard version's amplifiers with output power of up to 500 W (TVA-100, TVA-200, TVA-300, TVA-500) are of single-block type. Actually, these are appropriate base blocks with in-built output channel filters. Power amplifiers of 1 and 2 kW (TVA-1, TVA-2) base on summation of A500 base power amplifying blocks, contain two or four A500 blocks and a block of input/output devices. The block of input/output devices has the following functions: dividing input channel to several channels with necessary phasing and allowance for waste, summating output powers of the base amplifying blocks, and indicating general parameters of the transmitter.

Power amplifiers of up to 1 kW are also designed according to the scheme of summating powers of two base semi-set blocks in cases of advanced requirements to the amplifiers' no-failure operation without a stand-by set.

Transmitter's blocks have a developed indication system, allowing quickly evaluating transmitter's operability and identifying its defect.

Efir radio broadcasting transmitters series are designed for organization of radio broadcasting within 65.9...74 MHz band (for polar modulation system) and within 87.5...108 MHz (for pilot-signal system) in stereo mode with up to 4,000 MHz output power. The transmitters' engineering parameters comply with 13924-80 state-established technical standards. The block of conditioning radio signal, corresponding to the required broadcasting system, forms a complex stereo signal on the fixed band frequency with output power of 0,5 W. Quick tuning of frequency of certain spacing within one of the bands is possible. Power amplifiers' design is similar to that of TV power amplifiers.

Transmitter may operate at unattended areas. In this case transmitter may be started up by injection of the control external signal or by injection of the video signal to the modulator input.

Transmitters may be completed with:

• 100% stand-by capable of automatic switching onto a reserve transmitter;
• remote control and monitoring system;
• TV demodulator and TV signal generator;
• antenna-feeder device.

Provided by TV Broadcasting Systems Company.

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