{
  "patent_number": "US 2266401",
  "country": "US",
  "title": "How Pulse Code Modulation Digitizes Analog Signals",
  "original_title": "Signaling system",
  "summary": "A foundational 1938 patent describing how to convert continuous sound waves into a stream of digital numbers for transmission.",
  "what_it_does": "This patent describes the process of Pulse Code Modulation (PCM). It works by sampling an analog signal—like a human voice—at regular intervals and assigning a numerical value to the amplitude of the signal at each point. These numbers are then transmitted as a series of pulses, which can be reconstructed back into the original sound wave at the receiving end. This method allows for clearer communication because the digital pulses are easier to filter from noise than a continuous analog signal.",
  "what_it_does_not_cover": [
    "Does not cover the specific hardware circuitry used in modern microprocessors.",
    "Does not cover analog-to-digital conversion methods that do not use pulse modulation.",
    "Does not cover data compression algorithms like MP3 or AAC."
  ],
  "filed": "1938-06-09",
  "granted": "1941-12-16",
  "expires": "1958-12-16",
  "status": "expired",
  "holder": "International Standard Electric Corp ",
  "holder_url": "https://patentbrief.org/company/international-standard-electric-corp",
  "inventors": [
    {
      "name": "Reeves Alec Harley",
      "url": "https://patentbrief.org/inventor/reeves-alec-harley"
    }
  ],
  "times_cited": 181,
  "tags": [
    "telecommunications",
    "semiconductors"
  ],
  "abstract": null,
  "url": "https://patentbrief.org/patent/us/2266401/pcm-pulse-code-modulation-reeves",
  "markdown_url": "https://patentbrief.org/patent/us/2266401/pcm-pulse-code-modulation-reeves/md",
  "google_patents_url": "https://patents.google.com/patent/US2266401",
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}