3639692

Information

• Patent Grant
• 3639692

• References
• Source

• Patent Number

  3,639,692

• Date Filed

  Not available

• Date Issued

  Tuesday, February 1, 1972
  53 years ago

• CPC

  • H04M19/08 - Current supply source at substation
  • H04M19/04 - ringing-current generated at substation
  • H04Q5/245 - Circuit arrangements in which for one subscriber low frequency speech and/or signalling signals proceed on the line, while for the other subscriber the low frequency speech and/or signalling signals are modulated upon a high frequency carrier signal

• US Classifications

  • 370 - Multiplex communications
  • 379 - Telephonic communications