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NRZ vs. Manchester Encoding

Run the NRZ vs. Manchester Encoding MicroSim Fullscreen

About This MicroSim

s:

This MicroSim is built with p5.js and is width-responsive, so it adapts to the width of the page or container it is embedded in.

How to Use

Use the controls in the panel below the drawing area to explore the concept. Adjust the sliders, toggle the options, and step through the stages to see how each change affects what is shown.

Specification

The full specification below is extracted from Chapter 5: The Physical Layer.

Type: microsim
**sim-id:** nrz-vs-manchester-encoding<br/>
**Library:** p5.js<br/>
**Status:** Specified

Build an interactive MicroSim that lets students enter a bit pattern and see the resulting voltage waveform under NRZ and Manchester encoding side by side.

Canvas: 920 px wide by 520 px tall, responsive down to 360 px. A 100 px control panel sits below.

Layout:

- A text input box at the top accepts a bit string (e.g., "10110001") with a default of "10110001".
- Below the input, two stacked oscilloscope-style displays:
  - Top trace labeled "NRZ Encoding": a horizontal voltage axis with discrete levels (low and high). The waveform follows the bit pattern directly — high for 1, low for 0 — with no transitions during a run of identical bits.
  - Bottom trace labeled "Manchester Encoding": the same bit pattern, but each bit period contains a mid-bit transition. A 1 is a low-to-high transition; a 0 is a high-to-low transition.
- A vertical dashed line indicates each bit boundary, and a small numeric label above shows which bit (0/1) is being encoded in that period.

Interactivity:

- The user can edit the bit string and the waveforms update live.
- Toggle "Add noise": injects small random voltage offsets and shows how the receiver's decision threshold (a horizontal dashed line at the midpoint) tolerates the noise. Manchester's transition-based decoding is shown to be more robust because the receiver is comparing levels just before and after the mid-bit transition.
- Toggle "Long run of zeros": replaces the input with "00000000" and highlights how NRZ produces a flat line with no clock recovery, while Manchester continues to provide a transition each bit period.

Visual style:

- Voltage traces in honey amber on a slate grid background.
- Bit boundaries as thin vertical lines.
- Decision threshold as a horizontal dashed line in white.

Learning objectives:

- (Bloom — Understanding) Students explain why Manchester encoding always provides at least one transition per bit period.
- (Bloom — Analyzing) Students compare the bandwidth efficiency and clock-recovery properties of NRZ vs. Manchester.
- (Bloom — Evaluating) Students judge which encoding is appropriate for a given combination of distance, noise, and clock-recovery requirements.

Implement in pure p5.js with the existing MicroSim CSS theme. The waveform display should be responsive and remain readable at 360 px wide.

Iframe Embed Code

You can add this MicroSim to any web page by adding this HTML:

<iframe src="https://dmccreary.github.io/networking/sims/nrz-vs-manchester-encoding/main.html"
        height="502px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Learning Objective

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Bloom Taxonomy Level

Understand

Suggested Classroom Use

  1. Predict — Ask students to predict the behavior before they interact.
  2. Explore — Have students manipulate the controls and observe the results.
  3. Explain — Ask students to explain, in their own words, what they observed and how it connects to the physical layer.

References