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Vector Signal Analyzer Online Simulator


Professional Virtual VSA | Engineering Education Portal

Virtual Vector Signal Analyzer (VSA)

System-Level RF Signal Analysis & Verification

Instrument Controls

Format: I, Q (one per line)

Measurement Results

RMS EVM: 0.00 %

Peak EVM: 0.00 %

PAPR: 0.00 dB

Sample Count: 0

Constellation Diagram

CCDF (Power Stats)

Mathematical Background & Theory

1. Vector Signal Representation

Modern wireless communication uses complex modulation. A signal is represented as a vector in the complex plane:
S(t) = I(t) + jQ(t)

Where I is the In-phase component and Q is the Quadrature component. The Constellation Diagram plots these points over time to visualize signal quality.

2. Error Vector Magnitude (EVM)

EVM is a measure used to quantify the performance of a digital radio transmitter or receiver. It represents the difference between the measured symbol and the ideal symbol.

EVM(%) = √ [ Σ|Smeas,n - Sideal,n|² / Σ|Sideal,n|² ] × 100

3. CCDF and PAPR

The Complementary Cumulative Distribution Function (CCDF) is critical for Power Amplifier (PA) design. It shows the amount of time a signal spends at or above a given power level relative to its average power.

  • PAPR (Peak-to-Average Power Ratio): High PAPR (typical in OFDM) requires expensive, linear amplifiers to avoid clipping.
  • The X-axis of the CCDF shows the power level (dB) above average.
  • The Y-axis shows the probability (percent of time).

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