The VM2551 is a vestigial sideband, agile modulator with synthesized visual and aural carriers and a full +55 dBmV output level.
Designed to accept composite NTSC video and audio inputs from a satellite receiver, video server, off-air demodulator, DVD player, VCR, or similar source, the VM2551 features front panel video and audio over-modulation indicators and level controls to permit easy setup of modulation levels.
The use of frequency synthesis provides complete frequency agility in the range of 54 to 550 MHz using off-air or CATV (STD, IRC, or HRC) channel plans. In compliance with FCC regulations, channels that fall in specified aeronautical bands feature automatic frequency offset.
The use of a superior SAW filter in the IF circuitry allows adjacent channel operation when used with other modulators or signal sources. A composite IF loop following the SAW filter and before signal conversion to the final RF output channel allows the insertion of scrambling equipment or an IF switch to provide switchover for EAS operation.
If required, the audio preemphasis may be defeated to allow use with a baseband stereo encoder or the normal internally generated aural carrier can be disabled and an externally sourced 4.5 MHz signal can be applied to the rear panel input.
These features, combined with a carefully designed low distortion output stage, provide reliable and economical performance in an adjacent channel +55 dBmV cable television or private cable environment.