| 摘要 |
The present invention relates to a device which is to be used in conjunction with key telephone systems, as for example, intercom systems. More particularly, the invention consists of a device for decoding the pulse output from rotary dial telephones, indicating which digit has been dialed and selectively signalling the called party. Special features include acceptance of a wide range of pulse speeds and ratios with decoding immunity to the initial hookswitch closure and the last opening. The latter permits the digit "1" to be used, providing for an additional signal function. A decoding matrix operates a relay tree with provisions for either single or two-digit codes. The device is intended for use in key telephone systems which include rotary dial telephones.
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