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Multifrequency Data Receiver

IP.com Disclosure Number: IPCOM000092361D
Original Publication Date: 1967-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Garcia, J: AUTHOR

Abstract

This portion of an electronic telephone system uses keyboard-type dialing in which each key causes transmission of a short pilot tone and then a number representative combination of two of seven tones. Only a few decoder units are used and a first one scans across all active lines until a pilot tone is detected on a line. This first decoder then latches to this line until the signals being transmitted are decoded into the appropriate numeral. In the meantime, a second decoder is scanning across the remaining active lines looking for a line carrying a pilot tone, etc.

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Multifrequency Data Receiver

This portion of an electronic telephone system uses keyboard-type dialing in which each key causes transmission of a short pilot tone and then a number representative combination of two of seven tones. Only a few decoder units are used and a first one scans across all active lines until a pilot tone is detected on a line. This first decoder then latches to this line until the signals being transmitted are decoded into the appropriate numeral. In the meantime, a second decoder is scanning across the remaining active lines looking for a line carrying a pilot tone, etc.

When a subscriber lifts phone 1 off hook 2, the status change is detected by a scanner in the CPU 3. The latter acts to connect the secondary of the subscriber's transformer 4 through switching matrix 5 to one of a group of tone transformers 6, thus sending the subscriber the dial tone from generator 7. A lead from the tone side of each tone transformer 6 goes into test matrix 8 controlled by commutator 9. Matrix 8 has one row lead for each transformer 6 and has a column lead for each of a group, here three, of number decoders 10. Commutator 9 is controlled by an address generator 11 to sequentially connect decoder 10 to transformers 6.

In this system, depression of a phone key sends out a short pilot signal followed by a combination tone. When decoder 10 detects the pilot signal, it stops commutator 9 from shifting its inputs. Then generator 11 starts a second and, if ne...