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:
Oct. 13, 1998
Filed:
Feb. 10, 1997
Michel B Baylocq, Menlo Park, CA (US);
Space Systems/Loral, Inc., Palo Alto, CA (US);
Abstract
In a spacecraft having devices which are operative in plural modes, particularly an earth sensor operative in a north hemispherical inhibit mode, a south hemispherical inhibit mode, and a normal mode, a watchdog circuit* is employed to detect the presence of a mode command issued to the device. The command may be issued by a station on the earth, and communicated via a telemetry link to the spacecraft. The watchdog circuit may be part of a central processing unit (CPU) with a computer on board the spacecraft, the computer serving to perform various data processing operations for the mission of the spacecraft. The watchdog circuit stores the mode command and then repeats the command during a succession of repetitions. Thereby, in the event that the device, particularly the earth sensor, is momentarily disabled by an electrostatic discharge (ESD) event, wherein digital control circuitry of the earth sensor may shift the sensor to a different mode of operation, the next repetition of the mode command from the watchdog circuit reinstates the desired mode of operation. The watchdog circuit and the CPU are radiation hardened and may be enclosed by a Faraday shield to render them substantially impervious to the radiation.