Abstract: A phase frequency detector-based high-precision feedback frequency measurement apparatus and method: a Field Programmable Gate Array (FGPA) roughly measures a frequency fx of a measured time-frequency pulse by an equal-precision frequency measurement method; a Direct Digital Synthesizer (DDS) automatically synthesizes a frequency fx? according to the fx roughly measured by the FPGA; the fx and the fx? are sent to a phase frequency detector for performing phase frequency detection and then sent to the FPGA after passing through a charge pump, a low-pass filter circuit, and an (Analogue-to-Digital) A/D converter; the FPGA processes a frequency difference obtained by the phase frequency detector and then transmits the processed frequency difference to the DDS to form a negative feedback frequency measurement system so that the DDS continuously adjusts the fx? according to a frequency difference measurement result until the output of the DDS is stable.

Abstract: A phase frequency detector-based high-precision feedback frequency measurement apparatus and method: a Field Programmable Gate Array (FGPA) roughly measures a frequency fx of a measured time-frequency pulse by an equal-precision frequency measurement method; a Direct Digital Synthesizer (DDS) automatically synthesizes a frequency fx’ according to the fx roughly measured by the FPGA; the fx and the fx’ are sent to a phase frequency detector for performing phase frequency detection and then sent to the FPGA after passing through a charge pump, a low-pass filter circuit, and an (Analogue-to-Digital) A/D converter; the FPGA processes a frequency difference obtained by the phase frequency detector and then transmits the processed frequency difference to the DDS to form a negative feedback frequency measurement system so that the DDS continuously adjusts the fx’ according to a frequency difference measurement result until the output of the DDS is stable.

Abstract: A system and method for correlating personal identifiers with corresponding online presence are disclosed. A particular embodiment includes providing, by use of a data processor, a user interface to enable a user to specify a person or personal identifier of interest; producing search terms associated with the person or personal identifier of interest; using the search terms in a search query to obtain related search results collected from a plurality of content sources; filtering the search results to obtain information indicative of a plurality of profile sources; using the information indicative of a plurality of profile sources to obtain related profiles collected from a plurality of profile sources; filtering the related profiles to obtain a set of matching profiles; and reporting information on the person or personal identifier of interest and links to the corresponding matching profiles to the user.