If the antenna, ODU, and Forward Link parameters have been set correctly (see section 9.2.1 - Antenna
and ODU Parameter Configuration, and section 9.2.3 - Forward Link Parameters) and the IDU RX power
level is as specified above, the VSAT is ready to acquire the Forward Link:
1. If not already logged on, start the VSAT and login as installer (user = install, factory default
password = dvbrcs) after having seen the message Starting DVB interface.
2. Enter the CLI command dvb rx start to acquire the Forward Link.
3. The CLI message Forward Link up is displayed on the CLI output after successful acquisition of
the Forward Link.
The reader is referred to Appendix O for a description of the steps performed by the SatLink VSAT when acquiring
the Forward Link.
If the VSAT reports that RX tuning failed please check the following:
ODU parameter setting – section 9.2.1
Forward Link parameter setting – section 9.2.3
That the RX cable is properly connected to both the VSAT and the LNB
That the signal level in to the IDU is between -25 dBm and -65 dBm
That the antenna/ODU has been properly aligned (both antenna pointing and polarization adjustment
correct)
To ensure good performance (less than one error event at MPEG2-TS level per hour) for the Forward
Link, the SNR value, reported using the dvb rx show command, shall be verified to be at a minimum
level before line-up is completed. If, after repeated antenna/ODU alignment, the minimum SNR value is
not obtained, the system operator/service provider shall be contacted.
Non-rainy weather conditions will normally be required to obtain the minimum SNR value. If the
minimum SNR value has been provided by the system operator/service provider, the reported SNR shall
be verified against the provided value. If the minimum SNR value has not been provided by the network
operator, the minimum SNR value is found as follows:
For DVB-S2 CCM operation:
The minimum SNR value is specified in Table 12. However, this table does not account for any required
link margin to compensate rain fade attenuation.
For DVB-S2 ACM operation:
Check with the system operator/service provider what is the expected maximum MODCOD to be
received at each specific VSAT site and use Table 12 to find out what the minimum SNR is for that
MODCOD. The SNR values shown in Table 12 are valid for normal frames (64 kbit); for short frames
(16 kbit) add 0.2 dB to obtain the required minimum SNR.
Please keep in mind the following two facts:
1. The maximum MODCOD would be accomplish only during clear sky conditions
2. The maximum achievable MODCOD can change from site to site due to differences in downlink EIRP
(satellite coverage) and VSAT antenna size.
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