LABORATORY 29 · ELECTRONICS & COMMUNICATION

Direct Sequence Spread Spectrum (DSSS) and Jamming Margin / Processing Gain

Spread a narrow-band digital baseband signal using high-rate pseudo-noise (PN) Gold codes, measuring processing gain (G_p) in dB across code chipping rates from 100 kcps to 1000 kcps. 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.

MEASURED PROCESSING GAIN G_P—

RF INSTRUMENTATION TELEMETRY

Ready to sample with Log Chipping Ratio = 5.5 log(cps).

Log Chipping-to-Bit Ratio log₁₀(R_c)5.5 log(cps)Set Log Chipping Ratio (log(cps))

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

Adjust Log Chipping Ratio, 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.

DSSS & Processing Gain Telecommunication Workstation

Provides regulated RF/baseband excitation, precision impedance-matched test fixtures, and low-noise interconnection for maximal length sequences, anti-jamming margin & code division multiple access (cdma).

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 dsss & processing gain.

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

Delivers calibrated, low-phase-noise continuous-wave and modulated carrier signals to establish log chipping ratio 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.

Spread a narrow-band digital baseband signal using high-rate pseudo-noise (PN) Gold codes, measuring processing gain (G_p) in dB across code chipping rates from 100 kcps to 1000 kcps. Standardized parameter settings: 5.0, 5.2, 5.4, 5.6, 5.8, 6.0 log(cps).

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.
Carrier & Modulating Signal Synthesis: Configure the synthesized RF signal generator and baseband source to the specified baseline parameters. Calibrate the log chipping ratio using the precision digital multimeter and oscilloscope.
Systematic Telemetry Acquisition & Setpoint Stepping: Increment the log chipping ratio systematically across the experimental range (5.0 to 6.0 log(cps)), logging the resulting measured processing gain g_p after signal settling.
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.
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.
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 DSSS & Processing Gain mathematical scaling.

LINEAR REGRESSION FIT · y = mx + b

G_p = 10.0000 · log10(R_c) - 40.0000

#	Log Chipping-to-Bit Ratio log₁₀(R_c) (log(cps))	Measured Processing Gain G_p (dB)	Log chipping rate log10(R_c)	Processing gain G_p (dB)

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 DSSS & Processing Gain, the primary dependent variable measured is:

Question 2: The mathematical relationship governing DSSS & Processing Gain 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.

Spread a narrow-band digital baseband signal using high-rate pseudo-noise (PN) Gold codes, measuring processing gain (G_p) in dB across code chipping rates from 100 kcps to 1000 kcps.

G_p = 10.0000 · log10(R_c) - 40.0000

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