F-Term-List

H04M3/02-3/06@Z;19/00-19/08,100

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PURPOSE AND EFFECTS

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. Improved speech quality

. . Noise removal

. . . In-phase noise removal

. . . Elimination of noise from the power supply

. . Prevention of reduction of the level of the speech-signal

. . . Measures to prevent magnetic saturation

. Improved reliability

. . Prevention of malfunction

. . Circuit protection

. . Measures for power failures (e.g., commercial power supplies)

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. Economization

. . Circuit sharing

. . Power consumption reduction

. Simplification, miniaturization, and integration

. Load reduction

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USES

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. Digital telephone sets

. Multi-function telephone sets

. Public telephone sets

. Party-line telephone sets

. Photoelectric telephone sets

. Magnetic telephone sets

. Circuit termination devices

. Time sharing switching systems

. Space sharing switching systems

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COMPONENTS

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. Photocouplers

. Thyristors

. Zener diodes

. Direct current to direct current (DC-DC) converters

. Current mirror circuits

. Variable resistance circuits

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STATUS OF THE SUBSCRIBER LINE

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. Line currents

. Line voltage

. Line and median point potentials

. Line resistance

. On- and off-hook status

. Direct current (DC) polarity

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SUPPLY OF SPEECH CURRENT FROM SWITCHING SYSTEMS

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. Use of current sources

. . Variable current values

. Use of voltage sources

. . Variable voltage values

. Direct current polarity inversion

. Current supply circuit start or stop

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TYPES OF SIGNALS THAT ARE SUPPLIED FROM SWITCHING SYSTEMS

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. Ringing signals

. Ringback tones

. Dial tones

. Holding tones

. Howler tones

. Busy signals

. Forecast, pay warning, and interruption tones

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GENERATION, SENDING, AND CONTROL OF SIGNALS THAT ARE SUPPLIED FROM SWITCHING SYSTEMS

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. Generation of analog signals

. . Use of memory

. Generation of digital signals

. . Pulse-code modulation (PCM) signals

. . Addition of information for audible signals

. Signals sent from trunks

. . Insertion into time slots

. Signals sent from subscriber circuits

. Signals sent by voice-analysis synthesis systems

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. Intermittent pattern control

. Frequency and tone control

. Signal level control

. Outgoing timing control

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DIRECT-CURRENT TELEPHONE SET CIRCUITS

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. Hook signals and hook signal generation circuits

. Current supply circuits that use station power supplies

. . Power supply switching

. . . business power supply-station power supply

. . . Battery-station power supply

. . Chargeable current-supply circuits

. . Circuit start and stop control

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RING-TRIP CIRCUITS

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. Use of low-pass filters (LPF) for removal of ringing signals

. Line current and line voltage analog-to-digital (A/D) conversion

. Conversion into pulse waveforms

. Detection multiple times

. Stopping of ringing signals

5K037	DEVICES FOR SUPPLY OF SIGNAL CURRENT
	H04M3/02 -3/06@Z;19/00-19/08,100