What is the link margin in a system with a transmit power level of 10 W (+40 dBm), a system antenna gain of 10 dBi, a cable loss of 3 dB, a path loss of 136 dB, a receiver minimum discernable signal of -103 dBm, and a required signal-to-noise ratio of 6 dB?
Answer+8dB
Start with +40 dBm transmit power, add 10 dB antenna gain, subtract 3 dB cable loss and 136 dB path loss: received level is -89 dBm. A -103 dBm MDS plus 6 dB required SNR means -97 dBm is required, leaving an 8 dB margin.