4-1
SECTION 4 OPERATION - HOW TO USE THE 3ST
TRANSMITTER
4.1 INTRODUCTION
This section provides detailed operation of the 3ST Transmitter.
Included are detailed descriptions of the various displays of the
selected modes of operation.
4.2 STEALTH SWEEP START-UP PROCEDURE
The Model 3ST Transmitter is quite flexible with regard to sweep
insertion, in that the sweep level relative to the other carriers is not
extremely critical. A key principle to keep in mind is that the trans-
mitter measures the levels of the video and audio carriers simulta-
neously to the receiver. It also measures its own injected sweep
carrier. In order to do this, the sweep must be injected prior to the tap
which samples the system signal for the transmitter's measurements
(see diagram below).
Combining
Network
Stealth Transmitter
IN
OUT
DC a
DC b
System
Stealth
Receiver
IN
Sweep insertion is prior to sampling of system levels by 3ST Transmitter
The Model 3ST's output may be injected as shown above, using a
directional coupler at the output of the combining network, or it may
even be injected at an input to the combining network. With an
output level set such that the sweep is 15 dB below video carrier level,
good response measurements can be made without interference to
subscriber TV pictures.
