Signal Processing Calculators
13 free calculators with formulas and worked examples.
Filter design (Butterworth, Chebyshev), ADC SNR, FFT bin resolution, Johnson noise, BER vs SNR, PLL loop filter, and sampling/Nyquist calculators.
Filter Designer
Design passive Butterworth and Chebyshev LC ladder filters up to order 10. Calculate component values for low-pass, high-pass, and band-pass topologies. Free, instant results.
Nyquist Sampling
Calculate Nyquist sampling rate, oversampling ratio, and aliasing frequency. Verify your ADC sampling meets the Nyquist criterion and determine data rate. Free, instant results.
SNR
Calculate signal-to-noise ratio, noise floor, receiver sensitivity, and dynamic range for RF systems. Analyze your signal chain performance. Free, instant results.
ADC SNR & ENOB
Calculate ADC signal-to-noise ratio, ENOB, and SFDR with aperture jitter effects. Analyze converter performance for data acquisition design. Free, instant results.
FFT Resolution
Calculate FFT frequency bin resolution, Nyquist range, time record length, and scalloping loss. Design spectral analysis parameters for DSP systems. Free, instant results.
Johnson-Nyquist Noise
Calculate thermal noise voltage, power, and spectral density for any resistor. Determine Johnson-Nyquist noise floor for low-noise circuit design. Free, instant results.
AM Modulation Index
Calculate AM modulation index: m = (Amax − Amin) / (Amax + Amin). Computes sideband amplitudes, bandwidth (2 × fm), power efficiency, and flags overmodulation (m > 1).
FM Modulation Index
Calculate FM modulation index, Carson's rule bandwidth, and SNR improvement over AM. Determine Bessel bandwidth for FM transmitter design. Free, instant results.
Oversampling & Noise Shaping
Calculate SNR improvement from oversampling and noise shaping for sigma-delta ADCs. Determine effective bits gained from higher OSR. Free, instant results.
Filter Order Calculator
Calculate minimum filter order for Butterworth, Chebyshev, and elliptic designs. Determine order from passband ripple and stopband attenuation specs. Free, instant results.
PLL Loop Filter
Design a type-2 second-order PLL passive loop filter. Calculates time constants, capacitor and resistor values for target loop bandwidth and phase margin.
BER Calculator
Free BER calculator for BPSK, QPSK, 8PSK, 16-QAM. Enter Eb/N0 to instantly compute bit error rate. Compare modulation schemes and optimize link performance.
Quantization Noise
Calculate ADC quantization noise, SQNR, ENOB, and noise spectral density. Analyze dynamic range for analog-to-digital converter design. Free, instant results.
About Signal Processing Calculators
Signal processing transforms, filters, and analyzes signals to extract information, reduce noise, or prepare data for transmission. In electronics, this spans analog filter design (setting bandwidth and roll-off before ADC sampling), digital filter implementation (FIR/IIR in DSP or FPGA), and system-level metrics like SNR, BER, and dynamic range.
The Nyquist theorem sets the fundamental sampling constraint: a signal must be sampled at more than twice its highest frequency component to avoid aliasing. Anti-aliasing filters must attenuate signal content above the Nyquist frequency before the ADC. Filter order determines the sharpness of the roll-off: a 4th-order Butterworth provides 80 dB/decade, while a Chebyshev trades passband ripple for steeper skirts.
ADC dynamic range is characterized by ENOB (effective number of bits) and SFDR (spurious-free dynamic range). Johnson noise sets the thermal noise floor: a 50 Ω source at room temperature generates −174 dBm/Hz, which limits sensitivity regardless of amplifier sophistication. Oversampling improves SNR by 3 dB per octave of oversampling ratio — a cheap way to gain resolution in low-bandwidth applications.
PLL loop filter design connects the phase detector output to the VCO control input, setting loop bandwidth and phase margin. Narrow loop bandwidth rejects VCO phase noise but amplifies reference spurs; wide bandwidth does the opposite. The PLL loop filter calculator designs 2nd and 3rd order passive filters for charge-pump PLLs using the standard Fractional-N architecture.