Comtech EF Data DMD-2050E - Manual (Page 72)

DMD2050E Universal Satellite Modem Theory of Operation
MN-DMD2050E Revision 2 3–30
• The ratio of power spectral density is normally less than 11 dB;
• CnC operates with modems – not modulators only or demodulators only .
In addition, to minimize ‘false’ acquisition, observe the following:
• Use of IESS-315 V.35 Scrambler is highly recommended;
• Keep the search delay range as narrow as possible – once the modem has reported the
search delay, narrow the search delay range to the nominal reported value +/- 5 ms – for
example, if the modem reported delay is 245 ms, narrow the search range to say 240 – 250
ms.
• Use external data source (e.g. Firebird) or internal BER tester when testing Carrier-in-Carrier
performance.
• To prevent self-locking in case the desired carrier is lost, it is recommended that the two
carriers have some configuration difference – for example, use different settings for Spectrum
Inversion.
3.11.4 System Functionality and Operational Considerations
Figure 3-10 illustrates a conventional, full duplex satellite link where two carriers are placed in
non-overlapping channels.
Figure 3-14. Conventional FDMA Link