Software zur Simulation der Amplitudenmodulation (Amplitude Modulation Simulation Software)

Software zur Simulation der Amplitudenmodulation, geschrieben in Java (This software simulates amplitude modulation and is written in Java)

Functioning Logic

The software simulates AM signals, processes them through modulation, demodulation, and analysis, and supports time- and frequency-domain operations.

• Signal Representation:
  • Stores time array, message, carrier, modulated, demodulated signals, and frequency spectrum.
  • Uses high sampling rate (e.g., 44.1 kHz) for digital accuracy.
  • Manages data for all AM variants.
• Signal Processing:
  • Executes modulation, demodulation, noise addition, and spectrum computation.
  • Dynamically updates signals based on parameters (e.g., message frequency fm, carrier frequency fc, modulation index m).
  • Applies digital filters for demodulation and variant-specific processing.
• Visualization:
  • Plots time-domain signals (message, carrier, modulated, demodulated).
  • Computes frequency-domain spectra via Fast Fourier Transform (FFT).
  • Supports real-time signal animation and dynamic spectrum updates.
• Analysis:
  • Calculates Total Harmonic Distortion (THD) from harmonic peaks in FFT spectrum.
  • Computes Signal-to-Noise Ratio (SNR) by comparing signal and noise power.
  • Visualizes harmonics and noise in frequency plots.
• Data Export:
  • Exports signal data to CSV files for external use.

The software is modular, with components handling signal generation, processing, and analysis.

Simulation and Modeling

The software models AM signals in time and frequency domains, simulating realistic signal behavior. Key aspects are:

• Time-Domain Simulation:
  • Signal Generation:
    • Message: m(t) = Am * sin(2 * pi * fm * t), with amplitude Am, frequency fm.
    • Carrier: c(t) = Ac * cos(2 * pi * fc * t), with amplitude Ac, frequency fc.
  • Modulation:
    • DSB-AM: s(t) = Ac * [1 + m * m(t)] * cos(2 * pi * fc * t), m is modulation index.
    • DSB-SC: s(t) = Ac * m(t) * cos(2 * pi * fc * t), no carrier.
    • SSB: Transmits one sideband (upper/lower).
    • VSB: One sideband plus partial other sideband.
    • QAM: Two signals on orthogonal carriers.
  • Demodulation:
    • Envelope detection: Rectify and low-pass filter.
    • Coherent detection: Multiply with carrier, then filter.
  • Animation: Updates plots at ~60 FPS for continuous signal simulation.
• Frequency-Domain Simulation:
  • Spectrum:
    • FFT transforms signals to show peaks at fm, fc, and sidebands (fc ± fm).
  • Dynamic Updates:
    • Spectra adjust in real-time with parameter changes.
  • Filtering:
    • Low-pass for demodulation, band-pass for SSB/VSB.
• Modeling:
  • Discrete-time signals with sampling frequency fs >> 2 * (fc + fm).
  • Noise as additive white Gaussian noise (AWGN) with adjustable amplitude.
• Variants:
  • DSB-AM: Carrier + sidebands.
  • DSB-SC: Sidebands only.
  • SSB: Single sideband.
  • VSB: Sideband + vestige.
  • QAM: Quadrature modulation.

Utilization of Algorithms

• Fast Fourier Transform (FFT):
  • Purpose: Generates frequency spectra for visualization, THD, SNR.
  • Algorithm: Cooley-Tukey FFT, O(N log N) complexity.
  • Used in: SpectrumAnalysisFFT, TotalHarmonicDistortion.
• Digital Filtering:
  • Low-pass: Removes high frequencies in demodulation (e.g., Butterworth).
  • Band-pass: Isolates sidebands in SSB/VSB.
  • Algorithm: FIR or IIR filters via DSP methods.
• Modulation/Demodulation:
  • Modulation: Time-domain multiplication per AM equations.
  • Demodulation: Envelope (rectify + filter) or coherent (carrier multiply + filter).
  • Algorithm: Optimized for real-time processing.
• Noise Generation:
  • AWGN via Gaussian random numbers.
  • Algorithm: Box-Muller transform.
  • Purpose: Channel noise for SNR.
• THD Calculation:
  • Formula: THD = sqrt(V2^2 + V3^2 + ... + Vn^2) / V1, V1 is fundamental, V2-Vn are harmonics.
  • Algorithm: Peak detection in FFT, power summation.
• SNR Calculation:
  • Formula: SNR = 10 * log10(Psignal / Pnoise), Psignal and Pnoise from frequency bands.
  • Algorithm: Power integration in FFT spectrum.
• Animation:
  • Incremental signal updates at 16 ms intervals (~60 FPS).
  • Algorithm: Efficient signal computation and rendering.

Physics Models

• AM Signal:
  • Carrier amplitude varies with message.
  • DSB-AM: s(t) = Ac * [1 + m * cos(2 * pi * fm * t)] * cos(2 * pi * fc * t).
  • Spectrum: Peaks at fc, fc ± fm.
• Signals:
  • Message: m(t) = Am * sin(2 * pi * fm * t), e.g., fm = 1 kHz.
  • Carrier: c(t) = Ac * cos(2 * pi * fc * t), e.g., fc = 10 kHz.
  • Physics: Electromagnetic wave modulation.
• Noise:
  • AWGN models thermal noise, zero mean, variable variance.
  • Physics: Random signal fluctuations.
• Demodulation:
  • Envelope: Rectification + filtering.
  • Coherent: Carrier synchronization + filtering.
  • Physics: Baseband signal recovery.
• Spectrum:
  • Power distribution across frequencies.
  • Physics: Fourier decomposition into sinusoids.
• THD:
  • Measures distortion from harmonics.
  • Physics: Nonlinear effects at integer multiples of fundamental.
• SNR:
  • Signal quality vs. noise.
  • Physics: Power ratio for communication performance.

Screenshots