Signal Processing SW

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Real-Time Input Validator Using JavaScript

Introduction In modern web applications, validating user input in real-time is a key aspect of user experience. For developers working with digital systems, communication protocols, or binary data, ensuring that users enter valid bits (0s and 1s) is crucial. In this tutorial, we will create a Real-Time Bit Input Validator using HTML, CSS, and JavaScript , which checks for valid binary input and even-length sequences instantly without needing to submit a form. <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Real-Time Input Bit Validator</title> <style> body{ font-family: Arial, sans-serif; background:#f4f6f9; margin:40px; } .container{ max-width:600px; margin:auto; background:white; padding:30px; border-radius:8px; box-shadow:0 3px 12px rgba(0,0,0,0.1); } h1{ co...

Cross-Spectrum Explained (with MATLAB)

Cross-Spectrum: Concept and Mathematics The cross-spectrum measures the frequency-domain correlation between two signals, showing how the signals relate in magnitude and phase at each frequency. For two discrete-time signals x[n] and y[n] , the cross-spectral density is defined as: S xy (f) = X(f) · Y * (f) X(f) = FFT{x[n]} → Fourier transform of x[n] Y(f) = FFT{y[n]} → Fourier transform of y[n] Y*(f) → Complex conjugate of Y(f) |S xy (f)| → Magnitude shows correlation strength at each frequency ∠S xy (f) → Phase shows relative phase difference Cross-spectrum is widely used in: Beamforming Coherence analysis Direction-of-arrival estimation (DoA) Identifying frequency-dependent relationships between signals MATLAB Code Example This MATLAB example demonstrates the cross-spectrum between two sinusoidal signals with a phase difference: %% Cross-Spectrum Demonstration clc; clear; clo...

MATLAB 2D/3D Beamforming Simulation with Cross-Spectrum Analysis for Antenna Arrays

MATLAB Code %% 2D Conceptual + Electronically Steered Beamforming clc; clear; close all ; %% PARAMETERS Fs = 1000; % Sampling frequency [Hz] T = 1/Fs; % Sampling period t = 0:T:1-T; % 1-second time vector f_sig = 50; % Signal frequency [Hz] %% SIMULATE ANTENNA SIGNALS p = sin(2*pi*f_sig*t); % Reference signal (antenna p) vx = 0.8*sin(2*pi*f_sig*t + pi/6); % vx antenna vy = 0.6*sin(2*pi*f_sig*t + pi/4); % vy antenna %% NORMALIZE SIGNALS pnor = p / max(abs(p)); vxnor = vx / max(abs(vx)); vynor = vy / max(abs(vy)); %% PASSIVE ROTATION (Conceptual Beamforming) I1 = real(fft(pnor) .* conj(fft(vxnor))); I2 = real(fft(pnor) .* conj(fft(vynor))); theta = 360 * atan(sum(I2)/sum(I1)) / (2*pi); % degrees vc = vxnor * cosd(theta) + vynor * sind(theta); resultant_passive = pnor + 2*vc; %% ELECTRONICALLY STEERED BEAM theta_steer = 60; % Desired steering angle in degrees lambda = 1; % Normalized wavelength d = 0.5*lambda; ...

FSPL Online Simulator

Free Space Path Loss (FSPL) Calculator Compute FSPL in dB, linear scale, and wavelength with multiple units and optional received power. Inputs Distance: km m miles Frequency: Hz kHz MHz GHz Transmit Power (dBm): Tx/Rx Gains (dBi): Calculate FSPL Results FSPL(dB): -- FSPL(linear): -- Wavelength λ: -- meters Received Power Pr: -- dBm Example Calculation f = 3500 MHz, d = 1 km FSPL(dB) = 20 log₁₀(1) + 20 log₁₀(3500) + 32.44 = 0 + 70.88 + 32.44 = 103.32 dB

RLC Online Simulator

Advanced RLC Simulator Inputs Circuit Type: RLC Series RLC Parallel R (Resistive) L (Inductive) C (Capacitive) RL Series RC Series LC Series R (Ω): L (H): C (F): f (Hz): V rms (V): Calculate Frequency Sweep Plot Phasor Diagram Workflow and Mathematical Principles 1. User Input The simulator collects the following inputs: Circuit type (R, L, C, RL, RC, LC, RLC series, RLC parallel) Resistance (R in Ω) Inductance (L in H) Capacitance (C in F) AC Source frequency (f in Hz) AC Source voltage (V rms in V) 2. Reactance Calculations Inductive Reactance: X L = 2πfL Capacitive Reactance:...

Cutoff Frequency (including RC, RL, and RLC Circuit)

Cutoff Frequency 1. Definition The cutoff frequency ( f c ) is the frequency at which the output of a circuit drops to a specific fraction of its maximum value: Voltage or current drops to 70.7% of the maximum (1/√2 ≈ 0.707) In decibels: this corresponds to the −3 dB point 2. Cutoff Frequency Formulas a) RC Filter RC Low-Pass: f c = 1 / (2πRC) RC High-Pass: f c = 1 / (2πRC) b) RL Filter RL Low-Pass: f c = R / (2πL) RL High-Pass: f c = R / (2πL) c) Series RLC Circuit For a series RLC circuit, the resonant frequency is: f 0 = 1 / (2π√(LC)) The −3 dB cutoff frequencies (lower and upper) are: f L = f 0 - R/(4πL) f H = f 0 + R/(4πL) Bandwidth: BW = f H - f L = R / (2πL) 3. Step-by-Step RC Low-Pass Example Given: R = 1 kΩ = 1000 Ω C = 0.1 μF = 0.1 × 10⁻⁶ F Cutoff frequency: f c = 1 / (2πRC) f c = 1 / (2π × 1000 × 0.1 × 10⁻⁶) ≈ 1591 Hz Interpretation: Frequencies below 1.591 kHz pass mostly unaffected; a...

Series RLC Circuit Impedance

Impedance of a Series RLC Circuit 1. Series RLC Circuit Components R = Resistance (Ω) L = Inductance (H) C = Capacitance (F) All components are in series, so the same current flows through each. 2. Impedance Definition The total impedance Z is the opposition to AC current , combining resistance and reactance: Z = R + j(XL - XC) j = √-1 (imaginary unit) XL = 2πfL (inductive reactance in Ω) XC = 1/(2πfC) (capacitive reactance in Ω) f = AC frequency in Hz 3. Magnitude of Impedance |Z| = √(R² + (XL - XC)²) 4. Phase Angle φ = tan⁻¹((XL - XC)/R) φ > 0 → circuit is inductive φ φ = 0 → resonance (XL = XC) 5. Step-by-Step Calculation Example Given: R = 10 Ω L = 0.1 H C = 100 μF = 100 × 10⁻⁶ F f = 50 Hz Step 1: Reactances XL = 2πfL ≈ 31.42 Ω XC = 1/(2πfC) ≈ 31.83 Ω Step 2: Net Reactance X = XL - XC = 31.42 - 31.83 = -0.41 Ω Step 3: Impedance Magnitude |Z| = √(R² + X²) = √(10² + (-0....

Counters: Ring, Johnson, Decade, and Ripple

Counters: Ring, Johnson, Ripple, and Decade 1. Ring Counter Definition: A ring counter is a shift register where the output of the last flip-flop is fed back to the input of the first flip-flop. Operation: Only one flip-flop is "1" at a time, circulating a single 1 around the ring. Number of Bits: Can be any number of flip-flops (common example: 4-bit). States (4-bit example): 1000 → 0100 → 0010 → 0001 → 1000 ... 2. Johnson Decade Counter (Twisted Ring Counter) Definition: A Johnson counter is a ring counter with inverted feedback: the inverted output of the last flip-flop is fed to the first flip-flop. Number of Bits: Usually 4 bits for a Johnson decade counter. States (4-bit example): 0000 → 1000 → 1100 → 1110 → 1111 → 0111 → 0011 → 0001 → 0000 ... It cycles through 10 unique states (hence "decade"). 3. Ripple Counter (Asynchronous Counter) Definition: A ripple counter is an asynchronous binary counter...

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