Apparatus for accurately timing an event relative to clock signals
US4408895A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 30, 1981 |
| Grant date | Oct 11, 1983 |
| Priority date | — |
| Expiry date | Oct 30, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG04F10/04
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The apparatus gives an indication of the location in time between two successive clock signals of an event to be timed. Such an event may be the arrival of a laser pulse at a satellite. An integrator circuit (C84) is charged by a relatively high charging current from a first current generator (66) during the period of time between the event and the next clock signal. The integrator circuit is then discharged by a smaller current of opposite sign from a second current generator (80). The ratio of the charge and discharge currents "stretches" the inter clock pulse time interval to a length that can be measured by counting clock pulses as the integrator discharges. For this factor to be useful, it is essential that the charging current remains constant during charging and from one charging occasion to the next. This is achieved by keeping the generator (66) generating current constantly and by diverting the current through an integrator circuit by-pass (R78) when not integrating. Switching is done using two transistors (Q71 and Q72) that are as identical as possible, and independently controlled in phase opposition. The by-pass current is detected and used to regulate the generator (6…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.