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:
Jan. 18, 1977
Filed:
Oct. 31, 1975
Robin P Giffard, East Palo Alto, CA (US);
S.H.E. Corporation, San Diego, CA (US);
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 spectrum of the electrical signal does not contain frequency components at or near the frequency of the test-mode oscillating signal under circumstances in which the modulation drive signal has been adjusted to the desired value.