Larcan Inc T1000U ユーザーズマニュアル

Unit 1 – Introduction

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2. General Technical Descriptive:

2.1. IF Modulator (for transmitter):

This is the input module. It is a professional audio and video modulator. The audio and video

signals are applied to their respective input for the modulation process in IF (41 to 47 MHz]. The audio
and video input impedances are 600 balanced Ohms and 75 unbalanced Ohms, respectively.

2.1.1. Video processing:

The video signal passes through linearity correction circuits and then is applied to the 45.75

MHz video modulator. There are Synchronizing Separation circuits that generate the auxiliary outputs
to “Automatic Circuits”. The video signal is also applied to a group delay predistortion circuit.

2.1.2. Audio processing:

The Mono-audio signal or stereo base band is applied to the module and modulates a 41.25

MHz audio carrier.

2.1.3 Module output:

Both carriers, audio and video modulated (41.25 and 45.75 MHz), are applied to the “Vestigial

Side Band Filter” (SAW Filter). At the output there is a circuit to control the IF output level.

2.2. UHF UP Converter:

2.2.1. Introduction:

This module converts an IF frequency signal into an UHF band channel, keeping its

characteristics and the same bandwidth.

2.2.2. IF filter and AGC amplifier (for transposer):

The IF amplifier and filter module establish the adequate bandwidth for the input signal and

supply the gain in this signal, keeping the level constant through an AGC loop.

2.2.3. Technical Descriptive:

The 2

UHF converter has an oscillator controlled by PLL (Phase Locked Loop Integrated

Circuit), which frequency is selected through the DIP switch from the Oscillator control board. When
the modulated signal in IF is received in the 2

converter, it is filtered and applied to a mixer. The

result of this mixing is filtered (channel filter) and supplied to the following modules of the equipment,
in the selected channel.