Flux locked loop
US4004217A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 31, 1975 |
| Grant date | Jan 18, 1977 |
| Priority date | — |
| Expiry date | Oct 31, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R33/0356
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A flux locked loop, employing a squid in connection with the production of the locked-loop error signal, includes circuitry which renders the locked loop more immune to disturbance inputs such as a ground-loop noise and interference transients and which facilitates a scale factor adjustment of a sub-carrier drive signal for the squid. To minimize ground-loop noise disturbance effects, a portion of the circuitry in the feedback path of the locked loop includes a voltage-responsive converter circuit arrangement providing a current-drive feedback signal for coupling to the squid. To minimize interference transient disturbance effects, a portion of the circuitry in the forward path of the locked loop includes a circuit arrangement having a non-linear transfer characteristic defining opposed substantial attenuation regions separated by a generally linear gain region. To facilitate adjustment of the scale factor to a desired value, a portion of the circuitry provides for an open-loop operation in which a test-mode oscillating signal is coupled to the squid along with an operating-mode modulation drive signal. This causes a heterodyning process to take place such that the frequency spectr…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.