NEC transmitters for digital TV

By Susumi Tanaka

Most recently the NEC Corporation begins to produce some new transmitting units for digital television broadcasting.

The DTU-31 transmitter is a leader of the NEC line. It falls into Versatile II series of universal UHF transmitters with water-cooling. The particularity of this unit is a availability of high effective broadband solid-state power amplifier with output LDMOS transistors. Besides, the transmitter is provided by built-in power source.

The compact amplifying modules allow realizing a monitoring and remote control with RS-485 interface. They are provided by special circuits intended for the protection from overheat, excess of reflected power level, rising of power supply voltage, current overloading, as well as from supplying network voltage fall below than permissible level.

In transmitter exciter the technology of phase noise revealing is applied. Besides, it includes the frequency synthesizer, the circuits for digital processing and correction, and provided by possibility of up transformations in the whole frequency band.

DTU-31 have a function to adaptive digital correction that provides the stability of the digital signal transmission. This model, either as all other units from Versatile II series, contains the server blocks, allowing to operator to trace remotely the quality of the transmission in browser window in PC, connected to Internet. This allows to reduce the costs on maintenance of the transmitter since enables to realize from one centre the parameter monitoring and adjustment of transmitting units.

DTU-31 digital transmitter

The transmitters of DTU-50 series are provided by air cooling. The power of these units lies within range from 1 to 5 kW. These quite new transmitters, which will be launch in line production at the end of this year. They are the units of high compactness.

One more NEC transmitter series is TVD-MPA series (by power from 50 to 200 W). This is the second generation of low output NEC transmitting units, under development of which the features, got in the first generation unit, were improved. The transmitters by power from 100 to 200 W consist of corresponding number of the 50 W modules. In a case of a failure there is the possibility to replace the failed module without transmitter switching out, i. e. in “hot swapping” mode.

Besides, in NEC arsenal there is the compact DM-3000A unit by 1U size, comprising DVB-T exciter and modulator.

Material is provided by NEC