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Line Decoding

Digital information can be encoded as a digital signal. Choice of line code depends on requirements, medium, and equipment. The simplest mapping assigns voltage levels to binary 0 and 1; more complex codes improve performance.

Common codes:

NRZI (Non return to zero, inverted): Two modes:

NRZI (Transition occurs for a one): A 1 causes a level transition; a 0 does not. Example: "110100110" with initial 1 → "011000100".

NRZI (Transition occurs for a zero): A 0 causes a transition; a 1 does not. Example: "001011001" with initial 1 → "011000100".

Manchester: A mid-bit transition every bit period. Three modes:

Manchester (Thomas): High-to-low is 1; low-to-high is 0. Example: "0010110010" → "01 01 10 01 10 10 01 01 10 01".

Manchester (IEEE802.3): High-to-low is 0; low-to-high is 1. Example: "0010110010" → "10 10 01 10 01 01 10 10 01 10".

Differential Manchester: Always a mid-bit transition; a transition at the bit start means 0, otherwise 1. Example: "0011101011" → "10 10 01 10 01 01 10 10 01 10".

Biphase Mark: Each bit becomes two halves (1 → 01/10, 0 → 00/11) with a mandatory end-of-bit inversion. Example: "0010110010" → "11 00 10 10 10 11 01 00 10 10".

Miller: Used in RFID. A 1 transitions mid-bit; a 0 holds level, with a transition between consecutive 0s. Example: "0010110010" → "11 00 01 11 10 01 11 00 01 11".

Modified Miller: Idle stays high; a 0 pulses at the start, a 1 mid-bit; a 0 immediately after a 1 does nothing. Example: "1011001010":

Modified Miller

Modified Miller encoding example

Wrong Format or Data Rate yields decode failure; with Auto-Detect Data Rate checked, the manual rate field is disabled (Disable). For channel-prefix differences, see Settings.

Decode Settings

Decode Settings

Line Decoding Decode Settings
  • Channel: Assign the signal channel.
  • Format: Select the line code. Default: NRZI (Transition occurs for a one).
    • NRZI (Transition occurs for a one)
    • NRZI (Transition occurs for a zero)
    • Manchester (Thomas)
    • Manchester (IEEE802.3)
    • Differential Manchester
    • Biphase Mark Decode
    • Miller
    • Modified Miller
  • Show Unknown: Show unknown data. Field enabled (Enable) when checked. Default: cleared.
  • Show Bus: Show bus data. Field enabled (Enable) when checked. Default: cleared.
  • Auto-Detect Data Rate: Auto-detect the data rate; when checked, the manual Data Rate field is disabled (Disable). Default: checked. Manual placeholder text: 1 MHz.

Result

Line Decoding Result

Line Decoding decode result