The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 03, 1978
Filed:
Aug. 17, 1976
Louis W Champan, Kent, WA (US);
Arthur T Perkins, Bellevue, WA (US);
Melco, Bellevue, WA (US);
Abstract
A rotary dial signal processing circuit and an automatic selecting circuit for combining the rotary dial signal processing circuit with a Touch-Tone digital decoding system. The rotary dial signal processing circuit includes means to interpret line signals as to on/off hook condition, dial pulsing, and completion of a dial pulse sequence. This includes estimation of the time durations of specific signal levels. Thus, for a dial pulse the off-hook signal input goes low for 33-90 ms, causing an appropriate system response; there is no system change for a low input signal of less than 25 ms; a low input signal of over 95 ms is interpreted as on-hook, and causes reset; a high input signal of over 150 ms is interpreted as completion of the dial sequence (timeout). The rotary dial signalling processing circuit counts the sensed dial pulses and provides a 4-bit output code which is compatible with the Touch-Tone code. This processing circuit also provides timing signals for the rotary dial/Touch-Tone interface and timeout logic. The rotary dial/Touch-Tone combining circuit buffers key timing outputs of the rotary dial signal processing circuit and renders them compatible with the Touch-Tone counterparts; it also establishes priority as to the rotary dial and Touch-Tone outputs. This circuit multiplexes the rotary dial and Touch-Tone timing signals and also multiplexes the rotary dial signal data and the Touch-Tone data into a common latch device for ultimate transmission to the associated transfer ready group or digit relay tree, as appropriate, and for generation of the ring timeout function.