Tektronix MTM400 Manuel d'utilisateur télécharger pdf (Page 174)

Interface Configuration and Interpretation

3-130 MTM400 MPEG Transport Stream Monitor User Manual

Configurations: This dialog box provides an option to recall a number of settings

configuration files; for example, prestored transponder

parameters. The configuration files are created and stored in the

MTM400. To select a configuration file, highlight the required

name in the list.

Tuner Frequency (kHz):

This value is the center frequency of the IF channel to be

received (that is, after downconversion in the LNB where

applicable). Any frequency can be entered; there is no need to

follow a channel plan. The frequency resolution is determined

by the tuner step size of 1 MHz.

Symbol Rate (kBaud):

This value is the symbol frequency (Baud rate) of the signal to

be received, over a range of 1 to 30 MBaud. You need to enter

the symbol rate to a typical accuracy of 1000 ppm to ensure

successful lock.

Modulation Format:

The card supports a number of modulation formats: Turbo FEC

8PSK, Turbo FEC QPSK, DVB QPSK and Digicipher ™ II.

Enter the appropriate format and puncture rate (also known as

the code rate) into the modulation dropdown dialog box. A Scan

function is also provided, allowing automatic acquisition if the

precise code rate is not known.

LNB Power: The QPSK/8PSK card incorporates a regulated power supply for

control of a LNB (Low Noise Block) or similar equipment. The

supply voltage, using the drop-down dialog box, is selectable

between Off (default), 13V and 18V. The output current is

limited to 200 mA maximum, and is foldback limited to a low

value in the event of an overload.

LNB 22kHz Tone:

A 22 kHz tone is provided for control of an LNB (Low Noise

Block) or similar equipment. The tone, using the drop-down

dialog box, is selectable between Off (default) or On.

Front End Lock

If full lock is acquired onto the channel and it is receiving the

signal correctly, the Front End Lock (FEL) indicator will light

up green. When a signal is present but no lock is achieved, the

indicator is red. When no signal is found, the indicator is gray.

BER The Bit Error Rate ahead of the FEC is displayed.

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Tektronix MTM400 Manuel d'utilisateur Page 174