2299821

Information

• Patent Grant
• 2299821

• References
• Source

• Patent Number

  2,299,821

• Date Filed

  Not available

• Date Issued

  Tuesday, October 27, 1942
  82 years ago

• CPC

  • H04Q1/4535 - with an additional signal transmitted for voice protection

• US Classifications

  • 379 - Telephonic communications
  • 361 - Electricity: electrical systems and devices