M7/M7L/M7LT Modular Satellite Modem Maintenance
M7/M7L/M7LT - Rev. 0.05 3-81
3.7.8. Using the M7L/LT Receive RF Frequency Feature
The M7L (and M7LT) can be tuned to any frequency between 950 to 2150 MHz in 1 Hz increments.
The modem can display the actual satellite RF frequency being received at the LNB input. To enable
this feature simply supply the <Demod: LNB – LO Frequency> parameter with a value other than
“0”. When the value set here is equal to the LNB’s LO frequency then the modem can automatically
compute the RF frequency at the LNB input.
The M7L/LT modems will also set the proper spectrum for high side or low side LO. If the LNB has a
Low side LO, the spectrum is not inverted and the <Demod: LNB – Rcv Spectrum> setting would
typically be set for “Non-Inverted”.
NOTE: After entering a new <Demod: LNB – LO Frequency> parameter the modem requires a new
Receive IF frequency input to recalculate the proper input frequency setting.
To return to using the L-Band IF frequency setting, simply enter a value of “0” into the <Demod: LNB
– LO Frequency> parameter.
Common LO frequency for the 3.7 to 4.2 GHz C-Band range is 5150 MHz (high side LO), while a
common LO for the 11.7 to 12.2 GHz Ku Band range is 10750 MHz (low side LO).
3.7.9. Using the M7LT BUC Control
The M7LT offers features related to the control and use of an outdoor Block Up Converter (BUC)
BUC Power Control – The M7LT contain an internal BUC power supply and internal power relay
to control application of power to the L-Band transmit cable under front panel or remote control.
The modem can also read the voltage and current being applied to the transmit cable.
Transmit Frequency Control – When the BUC Local Oscillator or LO frequency is entered into
the <Mod: BUC – LO Frequency> parameter, the <Mod: IF – Frequency> parameter requires
entry of transmit frequency at the actual satellite uplink RF frequency. To return to using L-Band
IF frequencies set the <Mod: BUC – LO Frequency> parameter to “0”.
BUC Transmit Gain – The <Mod: BUC – Xmt Gain> parameter is used to set the desired gain
of the BUC.
BUC Transmit Level Max – When the <Mod: BUC – Xmt Level Max> parameter is set, the
M7LT will provide an alarm if the output level exceeds the setting.
BUC FSK Remote M&C – When the <Mod: BUC – FSK Remote M&C> parameter is “Enabled”,
the M7LT provides the ability to control a ‘smart BUC’ from the front panel or remotely via the
control interface.
3.7.10. Using the M7LT LNB Control
The M7LT offers features related to the control and use of an outdoor Low Noise Block Down
Converter (LNB).
Receive Frequency Control – When the LNB Local Oscillator or LO frequency is entered into
the <Demod: LNB – LO Frequency> parameter the <Demod: IF – Frequency> parameter
requires entry of receive frequency at the actual satellite downlink RF frequency. To return to
using L-Band IF frequencies set the <Demod: LNB – LO Frequency> parameter to “0”.
LNB Power Control – The M7LT contain an internal LNB power supply and internal power relay
to control application of power to the LNB’s receive output cable under front panel or remote
control. The voltage applied can be chosen for either 18VDC or 13 VDC. The modem can also
read the voltage and current being applied to the receive cable.
3.7.11. Carrier Acquisition Parameters
The modem has two main modes and several programmable receive carrier acquisition parameters
available. These parameters control the initial acquisition of a carrier and reacquisition of a carrier
that has been removed and reapplied.
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