Electronics & Communication / BFSK Modulation & PLL
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LABORATORY 12 · ELECTRONICS & COMMUNICATION

Binary Frequency Shift Keying (BFSK) Tone Separation and Phase-Locked Loop (PLL) Demodulation

Generate orthogonal BFSK waveforms using dual VCO excitation, evaluate modulation index, and measure demodulated PLL error voltage across tone frequency shifts. Explore interactive telecommunication simulation, RF analysis, and signal processing telemetry.

ANALOG MODULATION · DIGITAL BASEBAND · PASSBAND MODULATION · ANTENNAS & RF · OPTICAL FIBER · DSP

Your virtual electronics & communication engineering laboratory.

PLL DEMODULATED PEAK-TO-PEAK BEAT VOLTAGE V_PLL—
RF INSTRUMENTATION TELEMETRY

Ready to sample with Tone Frequency Shift = 20.0 kHz.

20.0 kHz
Excitation locked to low-phase-noise synthesized reference oscillator.

Adjust Tone Frequency Shift, then execute telecommunication RF/baseband acquisition.

Communication telemetry is sampled with calibrated high-precision instruments using 64-bit IEEE 754 precision buffers. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity modulation, channel, and spectral analysis.

Communication engineering assumptions and boundary limits

Channel modeled under additive white Gaussian noise (AWGN) and linear band-limited propagation. Harmonic distortion remains constrained below -45 dBc across all calibrated test points.

Laboratory apparatus & testing equipment.

BFSK Modulation & PLL Telecommunication Workstation

Provides regulated RF/baseband excitation, precision impedance-matched test fixtures, and low-noise interconnection for sunde's continuous phase fsk, carson's rule for fsk & phase error tracking.

6.5-Digit True-RMS Digital Multimeter (Keysight / Fluke)

Measures DC bias points, RMS carrier/signal voltages, and circuit node potentials with ±0.0035% baseline accuracy.

Four-Channel Digital Storage Oscilloscope (200 MHz, 2 GSa/s)

Captures high-frequency RF envelopes, baseband eye diagrams, constellation patterns, and transient responses for bfsk modulation & pll.

Synthesized Vector RF Signal Generator (9 kHz – 3 GHz)

Delivers calibrated, low-phase-noise continuous-wave and modulated carrier signals to establish tone frequency shift conditions.

High-Dynamic-Range RF Spectrum Analyzer (9 kHz – 3.6 GHz)

Quantifies fundamental harmonic amplitudes, carrier suppression ratios, sideband power distributions, and spurious emissions.

Matched 50-Ohm Coaxial Interconnects & Attenuator Set

Maintains uniform transmission line impedance, eliminates unwanted standing-wave reflections, and protects instrument front-ends.

FOLLOW THE METHOD

A reason behind every step.

Generate orthogonal BFSK waveforms using dual VCO excitation, evaluate modulation index, and measure demodulated PLL error voltage across tone frequency shifts. Standardized parameter settings: 5.0, 10.0, 18.0, 25.0, 32.0, 40.0 kHz.

  1. Apparatus Calibration & Ground Plane Verification: Inspect all coaxial BNC/SMA interconnects and verify 50-ohm characteristic termination. Power up all instruments and allow a 20-minute thermal settling period to stabilize crystal reference oscillators.
  2. Carrier & Modulating Signal Synthesis: Configure the synthesized RF signal generator and baseband source to the specified baseline parameters. Calibrate the tone frequency shift using the precision digital multimeter and oscilloscope.
  3. Systematic Telemetry Acquisition & Setpoint Stepping: Increment the tone frequency shift systematically across the experimental range (5.0 to 40.0 kHz), logging the resulting pll demodulated peak-to-peak beat voltage v_pll after signal settling.
  4. Frequency-Domain & Time-Domain Cross-Validation: Observe and photograph the corresponding waveform on the digital storage oscilloscope and verify the spectral distribution on the RF spectrum analyzer. Verify that harmonic distortion remains below -45 dBc.
  5. Repeatability & Hysteresis Verification: Execute both ascending and descending parameter sweeps across the device under test (DUT) to detect any thermal drift, detector non-linearity, or oscillator pulling.
  6. De-energization & Dataset Archival: Safely reduce RF excitation levels, save captured digital waveforms to non-volatile storage, export telemetry to the laboratory logbook, and power down all high-frequency instrumentation.
YOUR NOTEBOOK · 0 OBSERVATIONS

Turn measurements into telecommunication engineering insight.

See a complete example report ↗

Points are your recorded observations. The solid regression line validates BFSK Modulation & PLL mathematical scaling.

LINEAR REGRESSION FIT · y = mx + b
V_pll = 0.0800 · Δf
#Mark/Space Frequency Deviation Δf (kHz)PLL Demodulated Peak-to-Peak Beat Voltage V_pll (V)Mark/space deviation Δf (kHz)Demodulated PLL voltage V_pll (V)

No readings yet. Execute a communication trial and record it.

CHECK YOUR UNDERSTANDING

Explain what the communication metrics mean.

Question 1: In the experimental investigation of BFSK Modulation & PLL, the primary dependent variable measured is:

Question 2: The mathematical relationship governing BFSK Modulation & PLL is modeled as:

Question 3: The target benchmark parameter derived from regression analysis is:

Question 4: Which instrument provides the most accurate visualization of spectral harmonics and carrier sidebands in the frequency domain?

THEORY AND ELECTROMAGNETIC CONTEXT

Electronics & Communication Engineering background & physical principles.

Generate orthogonal BFSK waveforms using dual VCO excitation, evaluate modulation index, and measure demodulated PLL error voltage across tone frequency shifts.

V_pll = 0.0800 · Δf

Communication systems rely on Fourier spectral decomposition, Shannon channel capacity, and electromagnetic propagation theory.