Minimum Detectable Signal Calculator

The Minimum Detectable Signal (MDS) Calculator finds the weakest signal a radio receiver can reliably detect — a critical figure in radar, wireless communications, and RF system design. Enter your receiver's bandwidth, noise figure, operating temperature, and required Signal-to-Noise Ratio (SNR) to get the MDS in dBm. Secondary outputs include thermal noise power and receiver sensitivity in watts.

Hz

The bandwidth of the receiver in Hz

dB

The noise figure of the receiver in dB

K

Operating temperature in Kelvin (room temperature ≈ 290K)

dB

Required SNR for signal detection in dB

Results

Minimum Detectable Signal (MDS)

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Thermal Noise Power

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Sensitivity

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Frequently Asked Questions

What is minimum detectable signal (MDS)?

MDS is the lowest power level of a signal that can be detected by a receiver above the background noise. It represents the sensitivity threshold of the receiver system.

How does bandwidth affect receiver sensitivity?

Larger bandwidth increases thermal noise power, which reduces sensitivity (higher MDS). Narrower bandwidth improves sensitivity by reducing the noise floor.

What is the relationship between noise figure and MDS?

Higher noise figure degrades receiver sensitivity, resulting in a higher (worse) MDS value. A 1 dB increase in noise figure directly increases MDS by 1 dB.

Why is temperature important in MDS calculations?

Temperature affects thermal noise power. Higher temperatures increase thermal noise, which degrades sensitivity and increases MDS. Standard calculations use 290K (room temperature).

What SNR should I use for different applications?

Typical SNR requirements: analog voice (10-12 dB), digital data (6-10 dB), radar detection (13-15 dB). Higher SNR provides better signal quality but requires stronger signals.

How does MDS relate to receiver range?

Better sensitivity (lower MDS) allows detection of weaker signals, extending communication range. A 3 dB improvement in MDS roughly doubles the communication range.

What units are used for MDS?

MDS is typically expressed in dBm (decibels relative to 1 milliwatt). Lower dBm values indicate better sensitivity (ability to detect weaker signals).

Can MDS be improved in existing receivers?

MDS can be improved by reducing noise figure (better LNA), narrowing bandwidth, cooling the system, or using external low-noise amplifiers at the antenna.