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US 5,293,420 AGranted
Ring trip circuit
AssigneeFujitsu Limited
InventorTakashi Nagato
Life of this patent
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Abstract
A first part for picking up a signal being proportional to a ringing tone signal transferred on a subscriber line; a second part for extracting an ac component from the thus picked-up signal; and a third part for receiving both the signals from the first and second parts and comparing, in level, these two signals to produce a ringer stop signal if the level difference therebetween becomes larger than a setpoint value, and thus, a conventional low-pass filter can be removed.
Claims10
A ring trip circuit comprising:
- a first means for picking up a signal that is proportional to a ringing tone signal transferred on a subscriber line;
- a second means for extracting an ac component from the thus picked-up signal;
- and
- a third means for receiving both the signals from said first and second means and comparing, in level, these two signals to produce a ringer stop signal if the level difference therebetween becomes larger than a setpoint value.
1 more element
Dependencies are inferred from the claim text.