M7/M7L/M7LT Modular Satellite Modem
Maintenance
M7/M7L/M7LT - Rev. 0.05
3-103
saturation but should be several dB above the nominal operating point for margin, e.g. -10.0
dBm.
9. Set the
< Mod: IF - AUPC Min Level>
parameter to the desired level. Determine the value
for this parameter by calculating the minimum power that is allowed to prevent the link from
dropping below the operating threshold but should be several dB below the nominal
operating point for margin, e.g. -15.0 dBm.
3.10.1.1.2.
Site 1 AUPC Setup
1. Set the
<Intf: MCC Mode>
parameter to “Full Access”. Please note that this will interrupt the
link from A to B until the B modem is set to the same settings.
2. Set the
<Intf: MCC Send Rate Limit>
parameter to
“0.500 kbps” or higher.
3. Set the
<Intf: MCC Send Address>
and
<Intf: MCC Rcv Address>
parameters to “2” for
this example. The setting of this address can be any address between 1 and 254 but must
match the
<Demod: IF AUPC Remote MCC Address>
setting of the modem at Site A.
4. Set the
<Demod: IF AUPC Remote Path>
to “Out MCC Port”.
5. Set the
<Demod: IF AUPC Remote MCC Address>
to “1” for this example. The setting of
this address can be any address between 1 and 254 but must match the
<Intf: MCC Send
Address>
and <
Intf: MCC Rcv Address>
parameter settings of the modem at Site B.
6. Set the
<Mod: IF AUPC Mode>
to “Enabled”.
7. Set the
< Mod: IF - AUPC Eb/No>
to the desired value, e.g. 7.0 dB.
8. Set the
< Mod: IF - AUPC Max Level>
parameter to the desired level. Determine the value
for this parameter by calculating the maximum power that is allowed to prevent the link from
saturation but should be several dB above the nominal operating point for margin, e.g. -10.0
dBm.
9. Set the
< Mod: IF - AUPC Min Level>
parameter to the desired level. Determine the value
for this parameter by calculating the minimum power that is allowed to prevent the link from
dropping below the operating threshold but should be several dB below the nominal
operating point for margin, e.g. -15.0 dBm.
The PtP link should now be operating and using bidirectional AUPC that will adjust both transmit
output power levels in order to keep the distant end receive Eb/No constant. Alarms will be generated
if the transmit level reaches either the max or min level attempting to maintain proper receive Eb/No.
The exact settings required can be further adjusted to account for the type of fading expected. For
example if in a tropical environment with sudden heavy showers you may want to allow more power
margin.
3.10.2. AUPC Local Mode
In AUPC Local operation no external or mux overhead Eb/No return channel is required. However,
the modem at the broadcast transmit site must be a full duplex modem and the demodulator must be
set up to receive the broadcast carrier from the satellite.
Local AUPC must consider some potential sources for error in the operation of a local only AUPC
function:
1. The demodulator providing the Eb/No reference is at the same location of the modulator,
which will cause
a ‘double’ fade when there is a fading event on the broadcast site.
2. The fade on the transmit carrier will be slightly different than the fade on the received carrier
at the same site due to the different satellite frequencies.
3. The antenna sizes in a broadcast network will typically have significant differences between
the transmit site and any of the receive sites. This antenna size difference will cause a
difference in the absolute Eb/No readings from the demodulators. The accuracy of the Eb/No
reading may be different at the higher Eb/No readings, i.e. >10dB, when compared to the
lower Eb/No readings, i.e. <7dB.
