Initial Measurements; Initial Performance Measurements, Hub Canceller Disabled - Teledyne QMultiFlex-400 Installation And Operating Handbook

QMultiFlex-400™ Installation and Operating Handbook
Mod & Coding
Tx FEC Code Rate
Tx FEC Frame Size
Rx FEC Code Rate
Rx FEC Frame Size
Carrier
Tx Spectral Roll Off
Rx Spectral Roll Off
Table 8-3 – Remote QFlex-400 Example Configuration
In addition, set Point to Multipoint mode within all remote Modems: Navigate to the Edit >
IP > Advanced page and scroll down to the Point to Multipoint Operation field and set to
Point to Multipoint
Note: Any parameters omitted from the tables are disabled.
8.3.3

Initial Measurements

These initial measurements are performed to ensure the hub carrier can be received by
each of the intended remotes and each remote, in turn, can be received by the hub prior to
the hub canceller being enabled.

8.3.3.1 Initial Performance Measurements, Hub Canceller Disabled

Enable the Hub outbound carrier and take a performance snapshot of the links in terms of
the Es/No of the hub OB carrier as received by each remote. Record within the table below.
Configure one of the demodulators within the Hub Modem to receive its own transmit carrier
off satellite. This may mean reducing the transmit carrier to be below 40Msps if a large
outbound carrier is being used (40Msps is the maximum symbol rate for each individual
demodulator). Remember to reduce the Tx power too, if reducing symbol rate! Then, with
a Hub demod locked to its own transmit carrier, ensure the Rx carrier offset frequency falls
within the Rx demodulator carrier offset search range, which is fixed at +/-20kHz. If this is
not the case, adjust the modem's Rx carrier frequency, accordingly. The reason for this is
as follows:
The in-bound Rx carrier center frequencies (there could be 2 to 14 of them) are independent
of the centre frequency of the received echo, which the canceller must suppress. So, when
it comes to ensuring that the Rx carrier offset frequency reported by one of the demods
when locked to the echo is less than ±20kHz, any correction has to be made to the Paired
Carrier "Rx Carrier Frequency" entry field. So, for example, when Paired Carrier is disabled
and the Tx uplink carrier is enabled. We configure one of the demods to receive and
synchronise to its own transmission. We note the Rx carrier offset frequency. Let's say the
carrier offset frequency is -57.329kHz away from the 140MHz we were expecting it to be.
Tx Rate Control
Tx Data Rate
Tx Clock Source
Rx Service
Rx Rate Control
Rx Symbol Rate
Tx Modulation
Rx Modulation
Tx Freq Band
Tx Carrier Freq
IF Output Power
Modem Carrier
Rx Freq Band
Rx Carrier Freq
Data / Symbol Rate
120k – 60Mbps
Internal / Tx Clk In / Rx Ref
DVB-S2/X / Fastlink / Closed Net
Data / Symbol Rate
150k – 50Msps
QPSK/8PSK/16APSK/32APSK
Numerous, refer to Datasheet
Normal / Short
QPSK/8PSK/16/32/64APSK
Numerous, refer to Datasheet
Normal / Short
IF / L-Band
50 – 180MHz
5/10/15/20/25/35%
0 to -25dBm
On / Off
IF / L-Band
50 – 180MHz
5/10/15/20/25/35%
8-9
Data Rate
2Mbps
Internal
DVB-S2X
Symbol Rate
10Msps
QPSK
3/5
Normal
8PSK
23/36
Normal
IF
136MHz
10%
-20.3
Initially Off
IF
140MHz
10%