Comtech EF Data DMD-2050E - Manual (Page 92)

DMD2050E Universal Satellite Modem Theory of Operation
MN-DMD2050E Revision 2 3–50
Leased bandwidth
Almost all satellite operators charge for the Leased Bandwidth (LBW). Leased Bandwidth or
Leased Resource is the greater of the Allocated Bandwidth and Power Equivalent Bandwidth.
For example, if a carrier requires 3 MHz of Allocated BW and 4.5 MHz of PEB, the Leased
Bandwidth is 4.5 MHz
Power Spectral Density (PSD)
Power Spectral Density (PSD) is the signal power per unit bandwidth: dBW / Hz or dBm / Hz
For example: Signal power = 20 dBm
Signal bandwidth = 500 kHz
PSD = 20 – 10 *log (500 * 1000)
= -36.99 dBm / Hz
PSD Ratio
PSD ratio is the ratio of power spectral density of the interfering carrier and the desired carrier. If
looking at the 2 carriers side-by-side on a spectrum analyzer:
Eb/No
Ratio of Energy per bit (Eb) to Noise density (No): Unit is dB
C/N
Carrier Power (C) to Noise (N) ratio: Unit is dB
C/No
Carrier Power (C) to Noise Density (N
o
) ratio: Unit is dBHz
Co+No/No
Carrier Density (C
o
) + Noise (N
o
) to Noise Density (N
o
) ratio: Unit is dB