In telemetry, what does receiver sensitivity refer to?

• A. The minimum signal level required to demodulate reliably.
• B. The maximum tolerable noise level.
• C. The difference between transmitter and receiver frequencies.
• D. The threshold for error-free decoding.

Answer: (A)

The idea being tested is how weak a received signal can be for the system to still work reliably. In telemetry, receiver sensitivity is the minimum input signal level needed for the demodulator to operate and recover the data with the required reliability, typically defined for a specific data rate and modulation (often expressed in terms of a target bit error rate).

Think of it this way: if the incoming signal is strong enough, the receiver can separate the signal from the noise and make correct decisions about the data. As the signal gets weaker, noise starts to overwhelm it, and the chances of errors in the recovered data rise. Sensitivity captures the point where the receiver just meets the specified performance, meaning below that level the performance would no longer meet the target.

This isn’t about how much total noise the system can tolerate in a broad sense, nor about how far apart the transmitter and receiver frequencies are. It’s specifically about the smallest signal level at the input that still allows reliable demodulation for the given conditions. And while you’ll see BER targets used rather than truly zero-error decoding, the essence is the same: the minimum signal power at the input required to achieve the desired reliability.