Question
What is the received signal level with a transmit power of 10 W (+40 dBm), a transmit antenna gain of 6 dBi, a receive antenna gain of 3 dBi, and a path loss of 100 dB?
Answer Options
- A) -51 dBm
- B) -54 dBm
- C) -57 dBm
- D) -60 dBm
Correct Answer: A
Explanation
The received signal level (P_{RX}) is calculated by adding the transmit power and all gains in the system, and then subtracting all losses. Since the values are given in dBm (for power) and dB (for gains and losses), they can be arithmetically summed or subtracted, simplifying the link budget calculation significantly.
The calculation involves summing the transmit power (+40 dBm), transmit antenna gain (+6 dBi), and receive antenna gain (+3 dBi), and then subtracting the path loss (-100 dB). The final received signal level is 40 + 6 + 3 - 100 = -51 dBm. This power level must then be compared to the receiver’s noise floor to determine the signal-to-noise ratio and hence the quality of the communication.
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