3562791

Information

• Patent Grant
• 3562791

• References
• Source

• Patent Number

  3,562,791

• Date Filed

  Not available

• Date Issued

  Tuesday, February 9, 1971
  53 years ago

• CPC

  • H04M9/10 - with switching of direction of transmission by voice frequency
  • H03G1/0035 - using continuously variable impedance elements
  • H03G1/0047 - using photo-electric elements
  • H03G1/0082 - using bipolar transistor-type devices
  • H03G3/30 - in amplifiers having semiconductor devices
  • H03G3/301 - the gain being continuously variable
  • H04M1/6033 - for providing handsfree use or a loudspeaker mode in telephone sets
  • H04M9/08 - Two-way loud-speaking telephone systems with means for suppressing echoes or otherwise conditioning for one or other direction of traffic

• US Classifications

  • 379 - Telephonic communications