Specifications

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DMD20/20LBST Universal Satellite Modem Theory of Operation

MN-DMD20-20LBST Revision 14 3–39

3.15.9 Carrier-in-Carrier Commissioning and Deployment

Prior to commissioning a Carrier-in-Carrier link, it is critical that the link is fully tested in non

Carrier-in-Carrier mode and all system issues including external interference, antenna pointing,

cabling, SSPA backoff are resolved. Only after the link is robust, should the user attempt turning

on Carrier-in-Carrier.

The following procedure is recommended for Carrier-in-Carrier commissioning and deployment:

Step

Procedure

Turn ON the carrier at Site A. Carrier from Site B is OFF. CnC function is OFF at

both sites.

 Using a spectrum analyzer, measure Co+No/No at the input to the modem

at Site A.

 Using a spectrum analyzer, measure Co+No/No at the input to the modem

at Site B.

 Measure/record Eb/No at Site B. Make sure there is sufficient margin to

account for CnC.

 Measure/record Receive Signal Level (RSL) at Site B.

Turn OFF the carrier at Site A. Turn ON the carrier at Site B. CnC function is OFF at

both sites.

 Using a spectrum analyzer, measure Co+No/No at the input to the modem

at Site A.

 Using a spectrum analyzer, measure Co+No/No at the input to the modem

at Site B.

 Measure/record Eb/No at Site A. Make sure there is sufficient margin to

account for CnC.

 Measure/record RSL at Site B.

Using Co+No/No readings calculate PSD ratio at Site A and Site B. If it is not within

specification, make necessary adjustments to bring it within specification and repeat

measurements in Step (1) and (2).

 Also verify that the RSL is within spec.

Now without changing the transmit power levels, turn ON both the carriers (on the

same frequency) and turn CnC ON.

 Measure/record Eb/No at Site A and B.

 Measure/record RSL at Site A and B.

 Now compare Eb/No in presence of 2 over lapping carriers with CnC with

Eb/No when only 1 carrier was ON. Eb/No variation should be within spec

for that modulation, FEC and PSD ratio.

The test can be repeated for different PSD ratio and Eb/No.