Page 376 - Satellite Communications, Fourth Edition

356 Chapter Twelve

TABLE 12.1 Atmospheric Absorption Loss and Satellite Pointing Loss for Cities and
Communities in the Province of Ontario
Satellite antenna pointing loss, dB
Atmospheric absorption
Location dB, summer 1 /4 Canada coverage 1 /2 Canada coverage

Cat Lake 0.2 0.5 0.5
Fort Severn 0.2 0.9 0.9
Geraldton 0.2 0.2 0.1
Kingston 0.2 0.5 0.4
London 0.2 0.3 0.6
North Bay 0.2 0.3 0.2
Ogoki 0.2 0.4 0.3
Ottawa 0.2 0.6 0.2
Sault Ste. Marie 0.2 0.1 0.3
Sioux Lookout 0.2 0.4 0.3
Sudbury 0.2 0.3 0.2
Thunder Bay 0.2 0.3 0.2
Timmins 0.2 0.5 0.2
Toronto 0.2 0.3 0.4
Windsor 0.2 0.5 0.8

SOURCE: Telesat Canada Design Workbook.

that the antenna misalignment losses have to be estimated from sta-
tistical data, based on the errors actually observed for a large number
of earth stations, and of course, the separate antenna misalignment
losses for the uplink and the downlink must be taken into account.

12.3.4 Fixed atmospheric
and ionospheric losses
Atmospheric gases result in losses by absorption, as described in Sec.
4.2 and by Eq. (4.1). These losses usually amount to a fraction of a deci-
bel, and in subsequent calculations, the decibel value will be denoted by
[AA]. Values obtained for some locations in the Province of Ontario,
Canada, are shown in Table 12.1. Also, as discussed in Sec. 5.5, the ion-
osphere introduces a depolarization loss given by Eq. (5.19), and in sub-
sequent calculations, the decibel value for this will be denoted by [PL].

12.4 The Link-Power Budget Equation
As mentioned at the beginning of Sec. 12.3, the [EIRP] can be consid-
ered as the input power to a transmission link. Now that the losses for
the link have been identified, the power at the receiver, which is the
power output of the link, may be calculated simply as [EIRP]
[LOSSES] [G ], where the last quantity is the receiver antenna gain.
R
Note carefully that decibel addition must be used.