Telephonic communications – Supervisory or control line signaling – Signal reception at substation
Patent
1996-12-05
1998-08-18
Zele, Krista
Telephonic communications
Supervisory or control line signaling
Signal reception at substation
379142, 379252, 379373, 379377, H04M 100, H04M 157
Patent
active
057968152
ABSTRACT:
A communications device is presented which is able to detect a ring signal without the need for dedicated ring signal detection circuitry. The communications device includes a hookswitch coupled between a telephone line and a communications circuit. In an open mode of the hookswitch, an electrical resistance of at least 25 megohms exists between two switch terminals of the hookswitch, and the communications circuit is essentially disconnected from the telephone line at d.c. A capacitor positioned between the switch terminals of the hookswitch couples a.c. signals from the telephone line to the communications circuit when the hookswitch is in the open mode. A DSP of the communications circuit performs ring signal detection when the hookswitch is in the open mode using electrical power provided by a power supply. The input impedance of the communications circuit is substantially equivalent to a series combination of an inductance and a resistance. The series combination of the capacitor and the equivalent inductance and resistance of the input impedance of the communications circuit effectively forms an R-L-C highpass filter. The value of the capacitor is operably chosen such that: (i) the amplitudes of 20 Hz ring signals are reduced to below a 1.0 Vp-p maximum allowable input voltage range of common analog-to-digital converters, and (ii) the amplitudes of a.c. signals at Caller ID frequency shift keying frequencies of 1,200 Hz and 2,200 Hz are not increased or attenuated to a degree which would impair Caller ID circuit operation.
REFERENCES:
patent: 5483577 (1996-01-01), Gulick
patent: 5655011 (1997-08-01), Brown
patent: 5680447 (1997-10-01), Diamond et al.
patent: 5694465 (1997-12-01), Apfel
patent: 5699418 (1997-12-01), Jones
patent: 5699419 (1997-12-01), Ardon
Tussing et al., Application Note entitled, "The Application of a Telephone Tone Ringer as a Ring Detector," Motorola Telecommunications Device Data, 1985, pp. 3-66.
MC34012-1, MC34012-2 & MC34012-3 Data Sheet from Motorola Telecommunications Device Data, 1985, pp. 2-201 through 2-207.
Mitel Corporation CMOS MT8843 Product Data Sheet, Issue 3, Apr. 1996, pp. 5-1 through 5-22.
Mitel Corporation MSAN-164 Product Data Sheet, Issue 1, Oct. 1996, pp. 5-1 through 5-18.
Guercio David J.
Xie Zheng-yi
Advanced Micro Devices , Inc.
Saint-Surin Jacques M.
Zele Krista
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