Comtech EF Data CDM-570AL - Estimate PSD Ratio from Satmaster

CDM-570A/570AL Satellite Modem with Optional Packet Processor
Revision 5
DoubleTalk Carrier-in-Carrier Option G–22 MN-CDM570A
G.5.2.2 Estimate PSD Ratio from Satmaster
G.5.2.3 Use a Spectrum Analyzer to Estimate PSD Ratio
You can also estimate PSD Ratio or CnC Ratio by using a Spectrum Analyzer capable of
integrating the signal power in a given bandwidth.
• CnC Ratio (in dB) = Power
C1
(in dBm) – Power
C2
(in dBm)
• PSD Ratio (in dB) = (Power
C1
– 10 log BW
C1
(in Hz)) – (Power
C2
– 10 log BW
C2
(in Hz))
= CnC Ratio – 10 log (BW
C1
/ BW
C2
)
If the two carriers have same Symbol Rate / Bandwidth, then the CnC Ratio is same as the PSD
Ratio.
Carrier A to B
Carrier B to A
CnC Ratio
± 2.46 dB
PSD (Carrier A->B)
= 24.34 – 10 * log(2.3441 x 10
-6
)
= – 39.36 dBW/Hz
PSD (Carrier B->A)
= 21.88 – 10 * log(2.3441 x 10
-6
)
= – 41.82 dBW/Hz
PSD Ratio
± 2.46 dB