Patent record
US4532509
Communication system having timer controlled field stations
| Assignee | Federal Signal Corporation |
|---|---|
| Filed | 1974-11-18 |
| Granted | 1985-07-30 |
| Status | expired term |
| Est. term end | 2002-07-30 |
| Fee lapse date | — |
| CPC codes | G06Q40/04 |
Dates on the curated countdown pages are USPTO-adjusted expiration dates (verified against USPTO/Google Patents legal-status data as of July 2026, including patent-term adjustment); they still assume maintenance fees keep being paid, and are not a legal determination. Dates in the searchable database are raw patent-term math (20 years from filing, or the older 17-from-grant rule) that ignores adjustments, extensions, and terminal disclaimers. This is not legal advice.