Mark A Kilcommons

US Patent:

51172194, May 26, 1992

Filed:

Jan 30, 1990

Appl. No.:

7/472225

Inventors:

Lee D. Tice - Bartlett IL
Todd W. Fritz - Jackson MI
Mark A. Kilcommons - Berwyn IL

Assignee:

Pittway Corporation - St. Charles IL

International Classification:

G08B 2600

US Classification:

340518

Abstract:

A smoke and fire detection system wherein a central controller transmits data to remote transponders on a voltage supply line by pulse code modulation (PCM) of the supply voltage, and the transponders communicate with the controller by pulse width modulated (PWM) current pulses over the voltage supply line. A transmitter in the controller supplies a nominal operating voltage to the transponders and transmits a data word comprising a plurality of data bits to the transponders over the line. The transmitter generates each data bit by switching the voltage supplied to the line from the nominal operating voltage to a first voltage corresponding to a first logical level or a second voltage corresponding to a second logical level. A decoder in each transponder derives the transmitted data word. The decoder detects each data bit by detecting the transition from the nominal voltage to the first or second voltage, and the decoder determines the logical level of each bit by measuring the transmitted voltage level immediately after detecting the transition.

US Patent:

49164325, Apr 10, 1990

Filed:

Oct 21, 1987

Appl. No.:

7/111811

Inventors:

Lee D. Tice - Bartlett IL
Todd W. Fritz - Jackson MI
Mark A. Kilcommons - Berwyn IL

Assignee:

Pittway Corporation - Northbrook IL

International Classification:

G08B 2600
G05B 2302

US Classification:

340518

Abstract:

A smoke and fire detection system wherein a central controller transmits data to remote transponders on a voltage supply line by pulse code modulation (PCM) of the supply voltage, and the transponders communicate with the controller by pulse width modulated (PWM) current pulses over the voltage supply line. A transmitter in the controller supplys a nominal operating voltage to the transponders and transmits a data word comprising a plurality of data bits to the transponders over the line. The transmitter generates each data bit by switching the voltage supplied to the line from the nominal operating voltage to a first voltage corresponding to a first logical level or a second voltage corresponding to a second logical level. A decoder in each transponder derives the transmitted data word. The decoder detects each data bit by detecting the transition from the nominal voltage to the first or second voltages, and the decoder determines the logical level of each bit by measuring the transmitted voltage level immediately after detecting the transition.