KWS Electronic VAROS 109, Руководство пользователя

Страница: 16 / 60

Chapter 6 - Measuring range
10911 V01.06
16
6.2 DVB-S mode
Using this mode, QPSK-modulated DVB-S signals can be received and measured.
6.2.1 Symbol rate input
You must set the corresponding symbol rate before receiving a DVB-S signal. The instrument offers
the operator five preset symbol rates for rapid input. Select
MODE -> Symbol rate
to use one of the
five preset symbol rates. Use the
Up/Down
arrow keys to select the required symbol rate. The new
symbol rate is selected when you press
ENTER
. Press
->
to change the preset symbol rate between
2,000 and 45000 kBd (2.000 – 45.000 MSym/s). The default symbol rates are 27500, 22000, 5632,
4000 and 2400
kBd.
6.2.2 Scan
Use this function to search the entire satellite frequency range (910 – 2.150 MHz) for DVB-S signals
whose symbol rates correspond to the value that is currently set in the instrument. During the search,
the instrument alternates between the currently set symbol rate and the first two preset symbol rates.
This means that the instrument scans the satellite range with a maximum of three different symbol
rates.
Start the scan by tuning the measuring receiver to a frequency at which the scan should begin (see
“Frequency input”). Pressing
ENTER
begins the process, as indicated by the “SCAN” message in the
frequency window. When the instrument finds a transponder, the scan is halted and the measuring
receiver measures the frequency found. Stop the scan by pressing a number key, the
Up
or
Down
keys, or the
ESC
key.
During the scan, the instrument also detects DVB-S and DVB-S2 signals and switches the measuring
receiver to the relevant operating mode.
Note:
In the UNICABLE and JESS operating mode the scan function is deactivated.
6.2.3 DVB-S parameters
The parameters are shown in the parameter window. If the measuring receiver is tuned to a
frequency (see “Frequency input”), the DVB-S channel decoder attempts to synchronise with the
signal that is present; this activity can be traced using the “SCAN” message in the parameter
window.
The measuring receiver attempts to synchronise to the DVB-S signal that is present using the set
symbol rate. If this is not successful, all of the preset symbol rates are set one after another.
If a QPSK signal with the set symbol rate is present, the channel decoder locks and
LOCKED
is
displayed in the instrument's parameter window.
Otherwise, the
UNLOCKED
message is shown. This may be caused by the following: none of the set
symbol rates fit; the receive level is too low; there is too much noise in the signal; or there is no DVB-
S signal at this frequency.