Defining Signal-to-Noise Ratio

The Signal-to-Noise Ratio (SNR) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to the noise power, often expressed in decibels (dB).

If the noise environment is too aggressive, the receiver cannot distinguish between data pulses and random interference, leading to packet loss and retransmissions.

The Shannon-Hartley Theorem

This fundamental theorem tells us the absolute maximum data rate (Channel Capacity) of a communication link given its bandwidth and SNR.

• C: Channel capacity (bits per second)
• B: Bandwidth of the channel (Hz)
• SNR: Signal-to-Noise Ratio (linear power ratio)

Impact on Latency and Jitter

Low SNR doesn't just reduce speed—it introduces latency. When a packet is corrupted due to noise, the transport layer (TCP) must wait for a timeout and request a retransmission. This 'Retransmission Penalty' is a primary driver of unpredictable Jitter in real-time systems.

Mastering SNR is the key to achieving Five Nines Reliability in enterprise infrastructures.