Page 437 - Satellite Communications, Fourth Edition

Interference 417

From Eq. (13.10),

[I 1 ] 60 9 25 196
222 dBJ

From Eq. (13.12),
[I 2 ] 50 25 9 200

216 dBJ

From Eq. (13.11),
[ T E ] 222 228.6

6.6 dBK or T E 4.57 K

From Eq. (13.13),
[ T S ] 216 228.6

12.6 dBK

From Eq. (13.17),
[ T S E ] 6 12.6

6.6 dBK or T S E 4.57 K

The resulting equivalent noise-temperature rise at the earth-station E receive
antenna output is 4.57 4.57 9.14 K.

13.4.4 Coordination criterion
CCIR Report 454–3 (1982) specifies that the equivalent noise-temperature
rise should be no more than 4 percent of the equivalent thermal noise
temperature of the satellite link. The equivalent thermal noise temper-
ature is defined in the CCIR Radio Regulations, App. 29.
As an example, the CCIR Recommendations for FM Telephony allows
up to 10,000 pW0p total noise in a telephone channel. The abbreviation
pW0p stands for picowatts at a zero-level test point, psophometrically
weighted, as already defined in connection with Table 13.1. The 10,000-
pW0p total includes a 1000-pW0p allowance for terrestrial station inter-
ference and 1000 pW0p for interference from other satellite links. Thus
the thermal noise allowance is 10,000 2000 8000 pW0p. Four per-
cent of this is 320 pW0p. Assuming that this is over a 3.1-kHz band-
width, the spectrum density is 320/3100 or approximately 0.1 pJ0p
(pW0p/Hz). In decibels, this is 130 dBJ. This is output noise, and to