Modulators are intended for carrier frequency formation and TV-signal frequency translation (image and sound) to necessary TV- channel frequency.
Modulators are used in TV-transmitters, cable TV systems, MMDS and other systems of TV-signal transmitting.
Carries out:
- stabilization of sound and image carrier frequencies by the synthesizers based on the thermos-tatted frequency oscillator;
- forming of signal with single side band by the SAW filter;
- stabilization of output signal level;
- indication of video signal absent;
- indication of over modulation of audio signal;
- high amplitude and frequency linearity of the section;
- correction of amplitude non- linearity of power amplifier of the TV-transmitters;
- balanced input for audio signal.
SPECIFICATIONS
| Image | Sound | |
| Frequency range | 20…6C106 Hz | 20…14C103 Hz |
| Modulation type | amplitude | frequency |
| Nominal level of input signal | 1V(at Rinp=75 Ohms) | 0,75V(at Rinp=600 Ohms) |
| Input signal levels range | 0,5…1,5 V | 0,25…1,75 V |
| Signal/noise ratio | 60 dB | 60 dB |
| Amplitude frequency characteristics unevenness of video signal | ±0,2 dB |
| Output signal to channel intermodulation products ratio | 60 dB |
| Non-linearity of carrier frequency: | |
| -in VHF range | ± 50 Hz |
| -in UHFrange | ± 200 Hz |
| Power supply | (220± 20) V |
| Operating temperature range | 5…450С |
| HF signal output level at Rloading=50/75 Ohms | 0,3…3 V |
MODULATORS FOR TV-TRANSMITTERS
