DMDVB20 LBST Satellite Modem
Theory of Operation
TM138 – Rev. 1.0
3-1
Theory of Operation
3
3.0 Modem Hardware
The modem is based on a two printed circuit card (minimum configuration) design with additional
optioned printed circuit cards available for additional features. The minimum configuration
consists of a Digital Baseband assembly, Tx L-Band assembly and RX L-Band Receiver
assembly. The optional printed circuit cards include a Turbo Codec printed circuit card an
optional data interface printed circuit card (refer to Appendix A). A block diagram of the Modem is
shown in Figure 3.1.
Figure 3-1. Block Diagram
3.0.1 L-Band Printed Circuit Card
The L-Band circuit cards consists of an analog modulation function, an analog complex down
conversion, and two wide-band digital synthesizers. The block diagram of the L-Band assembly
is shown in Figure 3-2.
In the modulator, analog in-phase (I) and quadrature (Q) signals are generated on the Digital
Baseband Printed Circuit Card, routed to the L-Band Printed Circuit Card, and modulated at the
desired frequency. The L-Band modulated signal is then passed through a microprocessor
controlled variable attenuator providing gain control of the output signal.
Summary of Contents for DMDVB20 LBST
Page 11: ...Table of Contents DMDVB20 LBST Satellite Modem xii TM138 Rev 1 0...
Page 14: ...DMDVB20 LBST Satellite Modem Introduction TM138 Rev 1 0 1 3...
Page 20: ...Installation DMDVB20 LBST Satellite Modem 2 6 TM138 Rev 1 0...
Page 36: ...Theory of Operation DMDVB20 LBST Satellite Modem 3 16 TM138 Rev 1 0...
Page 67: ...DMDVB20 LBST Satellite Modem User Interfaces TM138 Rev 1 0 4 31...
Page 73: ...Rear Panel Interfaces DMDVB20 LBST Satellite Modem 5 6 TM138 Rev 1 0...
Page 79: ...Maintenance and Troubleshooting DMDVB20 LBST Satellite Modem 6 6 TM138 Rev 1 0...
Page 88: ...DMDVB20 LBST Satellite Modem Technical Specifications TM138 Rev 1 0 7 9...
Page 90: ...Appendix A DMDVB20 LBST Satellite Modem A 2 TM138 Rev 1 0...
Page 97: ...DMDVB20 LBST Satellite Modem Appendix B TM138 Rev 1 0 B 7...
Page 100: ...DMDVB20 LBST Satellite Modem Appendix C TM138 Rev 1 0 C 3...
Page 107: ...DMDVB20 LBST Satellite Modem Appendix D TM138 Rev 1 0 D 7...