Communication Systems

Communication-systems calculations spanning noise and link budgets, digital modulation and detection, analog modulation, information theory, and filter frequency response: decibel and dBm conversion, free-space path loss, full link budgets with margin, thermal noise and noise figure, Shannon capacity, BER over AWGN, Eb/N0 relationships, AM and FM parameters, and first- and second-order filter Bode response. Every calculator states its convention explicitly — dB as a power ratio, one-sided noise PSD, the Q-function form used — because in this field a silent convention mismatch changes the numbers.

Decibel & dBm Converter

Convert between linear ratios, dB, dBm, and watts, or cascade stage gains and losses to a running power level.

Free-Space Path Loss (Friis) Calculator

Free-space path loss from frequency and distance, and received power from transmit power, antenna gains, and losses.

Link Budget Calculator

Received power and link margin from transmit power, antenna gains, feed losses, path loss, and receiver sensitivity.

Thermal Noise & Noise Figure Calculator

kTB thermal noise power, noise power spectral density, noise temperature from noise figure, and the receiver noise floor.

Shannon Channel Capacity Calculator

Shannon–Hartley capacity C = B·log₂(1+SNR) — solve for capacity, required SNR, or required bandwidth.

BER vs Eb/N0 Calculator (AWGN)

Theoretical bit error rate for BPSK, QPSK, and coherent BFSK over an AWGN channel, with the waterfall curve.

SNR / Eb/N0 / Es/N0 Converter

Convert between SNR, Eb/N0, and Es/N0 given bits per symbol, symbol rate, and bandwidth — the classic source of dB bookkeeping errors.

AM Modulation Calculator

Modulation index, sideband power, total power, and transmission efficiency for standard full-carrier AM.

FM Parameters & Carson Bandwidth Calculator

FM modulation index and Carson's rule bandwidth from peak frequency deviation and modulating frequency.

RC/RL First-Order Filter Calculator

Cutoff frequency, magnitude, and phase of first-order RC and RL low-pass and high-pass filters, with the Bode plot.

Second-Order (RLC) Filter Calculator

Resonant frequency, Q, bandwidth, and damping for second-order low-pass, high-pass, and band-pass responses, with the Bode plot.