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Digital Satellite Receivers


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CompuSat represents digital receivers in exactly the same way as it represents analog receivers, which means that you access the receiver's details in its monitor screen from the CompuSat front panel, and in the transponder database that CompuSat manages for you.

Changing channels is automatic because CompuSat uses the transponder values stored in its database, as described in Tuning a Digital Channel.
You can access the receiver's monitor screen by clicking the silver tuning knob in the receiver's display on the CompuSat front panel. The monitor screen allows you to manually control all of the digital parameters of the receiver, as described in Using the Receiver Monitor.
The CompuSat transponder database contains all of the information used to tune the receiver to a digital channel, so switching channels is fully automatic, as described in Using the Transponder Database.
You can also use digital macros to quickly change the basic digital parameters; this is useful when dealing with ad hoc transponders or transponders that are only used occasionally, as described in Using Digital Macros.


Tuning a Digital Channel

To tune a digital channel, click the receiver’s transponder pick list and select the desired channel as shown here:

Selecting a digital channel

When you select a channel to tune, CompuSat displays the channel change confirmation window:

Confirming a digital channel change

Once you confirm the change, the receiver is tuned to receive the desired signal. Once the receiver locks on a digital stream, the Eb/No display for the receiver turns green to let you know the stream is locked in, and the Eb/No changes to reflect the current signal.


Using the Receiver Monitor for Fine Tuning

CompuSat creates a receiver monitor screen for each receiver in your configuration; you can use this screen to review or modify the digital tuning parameters.

To access the monitor screen for a receiver, click the silver tuning knob in the receiver's display on the CompuSat front panel. Here's a typical receiver monitor screen:

Receiver monitor screen

The controls available on a receiver's monitor screen is specific to the receiver model.

Using the Transponder Database

You can modify the database that Image Communications, LLC provides for use with CompuSat.

To view the settings for any channel, open the transponder database by selecting Database/Transponder Tuning Data from CompuSat's Database menu, as shown here:

Calling up the transponder database

CompuSat displays the transponder database. For example:

The transponder database

To display tuning parameters for a transponder, select the satellite and transponder. CompuSat displays the name of the transponder to the right of its number and label. The label above the OK button shows where (in which database) the transponder is stored: this can be the factory database, your custom database, or a customized version of a factory-defined transponder.

Digital Channel Labels

CompuSat uses the following conventions for the digital channel labels:

Single carrier per channel (SCPC) signals are identified as slots.

When a transponder has multiple slots defined, and each has its own center frequency, these are referred to as SCPC channels. Each SCPC channel can have its own tuning parameters, and can occupy a specific portion of the transponder’s bandwidth.

Typically, when a transponder is sliced into multiple SCPC channels ,the channels are labeled
Slot A through Slot n.
Multiple carrier per channel (MCPC) signals are identified as services.

When a transponder has multiple services defined, and each has the same center frequency, these are referred to as MSCP channels. Each MCPC channel in a given stream has the same tuning parameters except for the stream selection.

Typically, when a transponder that is used as a MCPC transponder, the channels are labeled
Srvc 1 through Srvc n.

All digital transponders also have various other turning parameters such as symbol rate, data rate, FEC, and modulation type. These are all represented in the transponder database and are set when a digital channel is tuned.

Split Transponders in the Factory Database

The Factory Database provided by Image Communications, LLC, defines transponder selections for many popular digital services. CompuSat appends a label to the transponder number for channel names. These names are defined in the split transponder labels. For example, SCPC channels are labeled with Slot A type designators, and MCPC channels are defined with Srvc 1 type designators. Transponder labels also include D01 (Digital 01) type labels when a transponder is divided many ways.

To set the default labeling style for split transponders, follow these steps:

1. Display the Preferences screen by clicking Preferences in CompuSat's Configuration/Preferences menu, as shown here:
Selecting Preferences

2. CompuSat displays the Preferences screen.
The Preferences screen
3. Click Split Transponder Labels in the Preferences screen. CompuSat displays the Split Transponder labels screen:
The split transponder labels screen
4. Click the Set Default CompuSat Labels button.


Adding Channels to the Database

You can add digital transponders to your custom database. Follow these steps:

1. Click Transponder Tuning Data in CompuSat's Database menu. CompuSat displays the
Transponder Tuning Data screen:
  Transponder tuning data

2. Select the satellite and transponder to which you want to add the digital transponder.
3. Click Split Transponder at the top of the transponder tuning screen.
4. Select the label for the new channel.

At this point, you've created an exact copy of the original transponder.
5. Click Rename Transponder at the top of the transponder tuning screen.
6. Enter a descriptive name for the new transponders, and enter the correct input frequency.
  Repeat this for all required slots or services.


Using Digital Macros

You can use digital macros to quickly switch the basic digital parameters when using an ad hoc channel.

To access a digital macro, click the Eb/No field on any digital receiver display in the CompuSat front panel, then select the macro from the list that's displayed:

Selecting a digital macro

When you select a macro to use, CompuSat displays the digital macro changes confirmation window:

Confirming a digital macro

Adding a New Digital Macro

To add a macro, follow these steps:

1. Click Macro Preferences in CompuSat's Configuration/Preferences menu. CompuSat displays the digital macro definition screen, as shown here:
Defining a digital macro
2. Highlight an unused macro number in the vertical number list.
3. Enter a descriptive name for the macro. For example, WB Full would be a good descriptive name for tuning in the Warner Brothers Full Transponder.
4. Enter the data rate and FEC of the service.

Any questions? Call Image Communications, LLC @941-322-2534

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