Chapter 3 Operation; Theory Of Operation; Functional Summary - Wegener UNITY4650 User Manual

Digital media receiver/decoder

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Table Of Contents

Table of Contents

This chapter provides an overview of Unity 4650 operation, details of controls

and indicators, the alarm/warning system, and user interface details.

3.1 Theory of Operation

Functional

If an L-band receiver card is installed, the Unity 4650 accepts carriers in that

summary

band from an external antenna LNB and then demodulates and extracts the

transmitted MPEG transport stream. If an ASI transport card is installed, the

U4650 accepts ASI transport from a terrestrial source and likewise extracts the

transmitted MPEG transport stream. In either case, if the stream is scrambled

and the unit is properly authorized, it applies the descrambling algorithm to

regenerate that stream as it appeared at the multiplexer in the uplink compres-

sion system. The U4650 then decompresses the components of a selected pro-

gram and provides the audio, video, and/or data services for output. In

addition, the U4650 may also supply high-speed routing of IP data (sent

through the satellite link) to a connected LAN.

If the Pro Option is installed, the U4650 can accept a composite video input as

a timing reference and align its output video frames to that reference. This pro-

cess is called genlock. In addition to genlock, the Pro Option provides the

unit's video and both audios (ports 1 and 2) encapsulated in digital format as a

single output on a coaxial jack. This is the unit's SDI output.

As needed, the U4650 also provides auxiliary functions such as re-insertion of ver-

tical blanking interval data (e.g. closed captioning) in the video outputs (both ana-

log and digital). Figure 3.1 presents a logical block diagram of U4650 operation.

Available logical outputs from the U4650 include:

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