Comtech EF Data Radyne DM240XR, Installation And Operation Manual

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DM240XR High-Speed Digital Modulator AutoEQ™ Interface Operation Guide
MN-DM240XR– Revision 12 D–2
This signal is transmitted to the satellite, and received (Satellite Loop-Back) by the DM240XR
AutoEQ™ input at the L-Band downlink frequency. The AutoEQ™ calibration mode will
demodulate the received signal, and automatically calculate the required pre-distortion parameters
for the Satellite Link.
This information is read by the DM240XR modulator where the new pre-distort values are
programmed into the outbound carrier, resulting with the required pre-distortion of the TX output.
Upon successful completion of the calibration cycles, the DM240XR will automatically return to
the programmed outbound signal (such as DVB-S2) with the proper pre-distortion for the satellite
loop per the selected symbol rate, roll off and transponder frequency. If any parameters are
changed affecting Symbol Rate or Roll off, AutoEQ™ must be re-calibrated to the new
parameters. At any time, AutoEQ™ can be enabled or disabled.
The DM240XR is capable of retaining 32 AutoEQ™ satellite loop pre-distortion values, which
can be useful for systems requiring relocation to different transponders or Satellites. Once the
applicable transponder is calibrated, the calibration information can be stored in memory for use
now or in the future. All storage locations can be renamed by the user to correspond with the
identification of the transponder, and recalled for operational use.
Figure 1 AutoEQ™ Satellite Loopback