Equations (1) and (2) assume that all platforms are received at 

 the same level by the spacecraft. Where the signal levels of the 

 platforms as received at the spacecraft are not the same, as may 

 be the case when fixed and buoy platforms are received 

 simultaneously, the equation is slightly different. In this 

 case equation (1) becomes 



EIRP/„ 



' Channel 



W 



watts 



Z 

 a 



(X + 

 ^ a 



N ) 

 a' 



(watts per 

 channel ) 



(3) 



where 



W = EIRP in watts, as before 



X = number of channels received 



simultaneously at a given level, 

 and 



N = noise-to-signal ratio (expressed 

 as numeric) of those channels. 



The summation is taken over all the different power levels and their 

 respective noise-to-signal levels. 



Equation (2) or (3) can also be used when the satellite is trans- 

 mitting in low-power mode., as it will be during eclipse periods 

 beginning with GOES-2 satellite. In this case, the numerator is 

 0.4 watts (+26dBm) instead of 2.5 watts. 



68 



