2223820

Information

• Patent Grant
• 2223820

• References
• Source

• Patent Number

  2,223,820

• Date Filed

  Not available

• Date Issued

  Tuesday, December 3, 1940
  84 years ago

• CPC

  • H04L21/02 - at the transmitting end

• US Classifications

  • 178 - Telegraphy
  • 370 - Multiplex communications