3671939

Information

• Patent Grant
• 3671939

• References
• Source

• Patent Number

  3,671,939

• Date Filed

  Not available

• Date Issued

  Tuesday, June 20, 1972
  53 years ago

• CPC

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

• US Classifications

  • 340 - Communications: electrical
  • 379 - Telephonic communications