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US 4,010,328 AGranted
Out-of-band signaling method and apparatus to adapt payphones to telephone systems
AssigneeThe Anaconda Company
InventorRonald F. McGuire
Life of this patent
Estimating the term…
Abstract
An out-of-band signaling method and apparatus are provided to facilitate the adaptation of payphones to telephone systems, as for example subscriber carrier systems. Part of the speech band is made unavailable to the subscribers and is employed for signaling DC line conditions from one end of the telephone system to the other.
Claims17
Applique circuitry for adapting a telephone system to operate with a paystation, comprising
- a. a first hybrid transformer connectible with said paystation,
- b. a second hybrid transformer connectible with the telephone system,
- c. a voice frequency transmit branch connected between certain coils of said first and second transformers, and including a first low pass filter to limit transmit voice frequencies to a selected band with an upper cut-off frequency f.sub.1,
- d. a voice frequency receive branch connected between other coils of said first and second transformers and including a second low pass filter, and
- e. signaling circuitry connected between said first transformer and said voice frequency transmit branch at a location between said first filter and said second hybrid transformer to transmit signal tones above f.sub.1.
2 more elements
Central office circuitry for adapting a telephone system to operate with a paystation, comprising
- a. a primary hybrid transformer connectible with the central office to which a subscriber terminal is remotely connected,
- b. a secondary hybrid transformer connectible with a central office terminal to which the paystation is remotely connected,
- c. a voice frequency transmit branch connected between certain coils of said transformers, and including a primary low pass filter to limit transmit voice frequencies to a selected band with an upper cut-off frequency f.sub.1,
- d. a voice frequency receive branch connected between other coils of said transformers and including a secondary low-pass filter, and
- e. signaling circuitry connected between said primary transformer and said voice frequency transmit branch at a location between the primary filter and the secondary transformer to transmit signal tones above f.sub.1.
2 more elements
Dependencies are inferred from the claim text.