JOHN ALEXANDER
Massage Therapy at Maple Ave, Vienna, VA

4254414, Mar 3, 1981

Mar 22, 1979

6/023043

Thomas T. Street - Springfield VA
John I. Alexander - Vienna VA

The United States of America as represented by the Secretary of the Navy - Washington DC

G08B 1700

340627

A fire detection system which includes an environmental sampling assembly upled to a programmable digital processor for detecting a threat of fire and reducing the occurrences of false alarms in a changing environment. The sampling assembly comprises a network of air ducts, a chamber, two sensors, and an exhaust fan. The processor includes two analog-to-digital (A/D) converters, a multiplexed digital summer, short and long-term storage mediums, a signal magnitude comparator, logic circuitry, and a timing generator. The fan continuously draws ambient air through the air ducts and the chamber. Sensors within the chamber sample the air. If the sensors detect particulates of combustion in the air, the sensors provide electrical signals of varying amplitudes, which amplitudes depend on the number and sizes of the particulates being sampled, to the A/D converters of the processor. One of the sensors also feeds its signals to the fan motor for increasing the speed of the fan, thereby clearing the chamber and drawing air through the chamber at a faster rate for a more vigorous sampling of the environment. The processor may be programmed to suit a specific environment.