Receiver Sensitivity
The minimum signal level a receiver can detect at a specified data rate and error rate — a critical link budget parameter.
What is Receiver Sensitivity?
Receiver sensitivity (often written as S_min or simply "sensitivity") is the minimum input signal power, in dBm, at which a receiver can reliably demodulate and decode a signal at a specified performance standard — typically a target bit error rate (BER) or packet error rate (PER).
More negative sensitivity means a more sensitive receiver. A receiver with −105 dBm sensitivity can detect signals 100,000 times weaker than one with −55 dBm sensitivity. Sensitivity is determined by three fundamental factors: the thermal noise floor, the receiver's noise figure, and the minimum SNR required by the modulation and coding scheme.
In link budget calculations, receiver sensitivity is the lower boundary that received signal power must exceed to establish a functional link. The margin between received power and sensitivity is the fade margin.
Why Does It Matter?
- In a free-space path loss model, a 3 dB sensitivity improvement increases range by about 1.41×. Doubling range requires approximately 6 dB additional link budget.
- Sensitivity varies with channel bandwidth — wider bandwidth channels have higher (less negative) noise floors
- Sensitivity is modulation-dependent — higher-order modulations (256QAM) require much higher SNR and thus have worse sensitivity
- LNA (Low Noise Amplifier) placement before the receiver significantly improves effective sensitivity
- Sensitivity limits determine the maximum range a link can achieve for a given EIRP and path loss
Quick Receiver Sensitivity Calculator
Formulas Used by LinkBudgetPro
\(-174\) dBm/Hz = thermal noise density at 290 K · \(B_{\text{Hz}}\) = channel bandwidth in Hz
Shannon-derived minimum SNR for target rate \(R\) [b/s], bandwidth \(B\) [Hz], \(N_s\) spatial streams
Receiver sensitivity: minimum received signal power to achieve the target data rate
Parameter Explanation
| Parameter | Symbol | Unit | Description |
|---|---|---|---|
| Bandwidth | BW | Hz / MHz | Channel bandwidth — wider channels raise the noise floor |
| Noise Figure | NF | dB | Receiver noise added above thermal floor. LNA: 1–3 dB, typical radio: 5–12 dB |
| Required SNR | SNR_min | dB | Minimum SNR needed by the modulation/coding scheme |
| Thermal noise floor | N₀ | dBm/Hz | −174 dBm/Hz at 290 K (room temperature) |
| Noise floor | N | dBm | Total noise power in the channel: N₀ + 10·log₁₀(BW) + NF |
| Receiver Sensitivity | S_min | dBm | Minimum detectable signal = noise floor + required SNR |
| Spatial Streams | N_s | — | Number of MIMO spatial streams = min(Tx antennas, Rx antennas) |
Worked Example
Calculate receiver sensitivity for a 10 MHz channel, 6 dB noise figure, targeting 20 Mbps data rate with 1 spatial stream:
When Should You Use It?
- Selecting radios — compare sensitivity specs when choosing between different radio modules or platforms
- Calculating from first principles — when no datasheet is available, compute sensitivity from bandwidth and NF
- Rate vs. range trade-offs — higher data rates require better SNR, reducing sensitivity and thus range
- LNA evaluation — quantify how much a low-noise amplifier improves effective sensitivity
- MIMO planning — understand how spatial streams affect sensitivity in MIMO configurations
Related Calculations
- Noise Figure Calculator — how noise figure affects the receiver noise floor
- Shannon Capacity — theoretical max throughput and minimum SNR for a given rate
- Fade Margin Calculator — link headroom above receiver sensitivity
- dBm ↔ Watt Conversion — convert sensitivity between dBm and linear power
- RF Documentation Index — all RF engineering reference pages
Calculate receiver sensitivity from bandwidth and noise figure in the full RF link budget calculator.
Open Full RF Link Budget Calculator