3557319

Information

• Patent Grant
• 3557319

• References
• Source

• Patent Number

  3,557,319

• Date Filed

  Not available

• Date Issued

  Tuesday, January 19, 1971
  54 years ago

• CPC

  • H04Q1/4465 - the same frequency being used for all signalling information

• US Classifications

  • 379 - Telephonic communications
  • 327 - Miscellaneous active electrical nonlinear devices, circuits, and systems