General Information; Description Of The Tvm450/Tvm550; Description Of The Tvm550Ii/Tvm550Iis - Standard Communications TVM Series Owner's Manual

General Information

1 GENERAL INFORMATION
DESCRIPTION OF THE TVM450/S TVM550/S
The TVM450, TVM450S, TVM550, and TVM550S are rebroadcast-quality, phase-
locked loop (PLL)-synthesized, frequency-agile, community antenna television
(CATV) and cable system television-distribution modulators. The TVM450 models
range from 54 to 450 MHz, and the TVM550 models range from 54 to 550 MHz for
use in domestic systems.
Both modulators use an open-architecture circuit and chassis design that allows
system growth with multiple field configurations.
The TVM450/S and TVM550/S are designed to be the primary building blocks of
an intelligent CATV distribution system. At the heart of these modulators is
SCC's PLL-synthesized, dual-conversion up/down converter.
The conversion process uses SCC's high-level mixing, which eliminates out-of-band
noise floor and spurious emission problems. High-level mixing and superior design
allow the TVM450/S and TVM550/S to meet the NTC-7-recommended specifications
for a 550 MHz spectrum, without the use of external bandpass filters .
The TVM550/S and TVM550/S modulators use a unique nonvolatile microprocessor
tuning circuit. Available is an optional Composite IF Loop kit that allows the external
input of either aural, visual, or a composite IF signal through a special loop. An
alternate IF option is also available.
Channels are selected with a front panel rotary switch, and the modulators can
be set to only a legitimate output frequency. When a modulator is on line and the
frequency output is changed, a circuit mutes the RF output until the modulator
has locked onto the new output channel frequency.
Front panel potentiometers for varying video modulation, audio deviation, and
visual/aural carrier ratio have center detents. This type potentiometer allows the user to
leave the front panel controls in their center positions while properly adjusting receiver
outputs to the modulator's correct input levels. RF output is also controlled by a like
potentiometer. The user can adjust the satellite receiver, for 1.0 V p-p video and
0 dBm peak audio/Broadcast Television Standards Committee (BTSC) input levels,
without the use of expensive test equipment.

DESCRIPTION OF THE TVM550II/TVM550IIS

SCC's superior circuit construction is carried over from previous TVM models.
These new models differ from the preceding TVM550 models in that they sport a
much-improved power supply that reduces noise and improves reliability. The
TVM550II uses the CMA60 audio demodulator, while the TVM550IIS
incorporates an SCC DSG2000BD digital stereo audio demodulator.
TVM450/S/TVM550/S/TVM550II/TVM550IIS Owner's Manual Page 1-1