95.5 x 106, = NV(2) = log-1(82.2/10) = 166 x 106, = C/No = 1/[(10-6/95.5) + (10-6/166)] = 1/(0.016 x 10-6) = 62.5 x 106= = 77.96 dB. This is the carrier-to-noise ratio in 1 Hz of bandwidth. To derive C/N for a particular RF bandwidth, use the following formula: C/N =C/N0-10 log BWHz. = - CONCEPTS IN TRANSMISSION TRANSPORT Suppose the example system had a 1.2-MHz bandwidth with the C/No of 77.96 dB. What is the C/N ? C/N = 77.96 dB 10 log(1.2 x 106) = 77.96 - 60.79 = 17.17 dB. 9.3.6.4 Uplink Considerations. A typical specification for INTELSAT states that the EIRP per voice channel must be +61 dBW (example); thus, to determine the EIRP for a specific number of voice channels to be transmitted on a carrier, we take the required output per voice channel in dBW (the +61 dBW in this case) and add logarithmically 10 log N, where N is the number of voice channels to be transmitted. For example, consider the case for an uplink transmitting 60 voice channels: +61 dBW + 10 log 60 = 61 + 17.78 = +78.78 dBW. If the nominal 50-ft (15-m) antenna has a gain of 57 dB (at 6 GHz) and losses typically of 3 dB, the transmitter output power, Pt, required is EIRPdBW =Pt+Gant-line lossesd where Pt is the output power of the transmitter (in dB/W) and Gant is the antenna gain (in dB) (uplink). Then in the example we have +78.78 dB W = Pt+53-3 - 3, Pt = +24.78 dB W = 300.1 W. 9.3.7 Digital Communication by Satellite There are three methods to handle digital communication by satellite: TDMA, FDMA, and over a VSAT network. TDMA was covered in Section 9.3.5.2 and VSATs will be discussed in Section 9.3.8. Digital access by FDMA is handled in a similar fashion as with an analog FDM/FM configuration (Section 9.3.5.1). Several users may share a common transponder and the same backoff rules hold; in fact they are even more important when using a digital format because the IM products generated in the satellite TWT high-power amplifier (HPA) can notably degrade error performance. In the link budget, once we calculate C/No [Eq. (9.24)], we convert 