2206538

Information

• Patent Grant
• 2206538

• References
• Source

• Patent Number

  2,206,538

• Date Filed

  Not available

• Date Issued

  Tuesday, July 2, 1940
  85 years ago

• CPC

  • H04Q3/0016 - Arrangements providing connection between exchanges
  • H04Q1/453 - in which m-out-of-n signalling frequencies are transmitted
  • H04Q5/06 - Signalling by amplitude or polarity of dc

• US Classifications

  • 379 - Telephonic communications