Systems and methods for performing automatic frequency control are provided. Instead of relying on individual frequency tuners for each channel of a multi-channel receiver system, the present subject matter uses a single frequency tuner for receiving each channel of the multi-channel receiver system. A locked demodulator may be designated as a reference demodulator and frequency offset values associated with the reference demodulator may be applied to other demodulators of the multi-channel receiver. These frequency offset values may be used by individual demodulators of each channel for correcting corresponding frequency offsets.

A network interface for use within a distributed antenna system, the network interface including circuitry configured to: receive a downlink digital communication signal from an external device external to the distributed antenna system, wherein a reference clock is embedded in the downlink digital communication signal; generate a master reference clock for the distributed antenna system using the reference clock embedded in the downlink digital communication signal; convert the downlink digital communication signal into a downlink signal; communicate the downlink signal toward a remote antenna unit within the distributed antenna system; and wherein the distributed antenna system is configured to distribute the master reference clock to various components of the distributed antenna system to keep the various components of the distributed antenna system locked to a single clock, wherein the various components of the distributed antenna system include the remote antenna unit.

A network interface for use within a distributed antenna system, the network interface including circuitry configured to: receive a downlink digital communication signal from an external device external to the distributed antenna system, wherein a reference clock is embedded in the downlink digital communication signal; generate a master reference clock for the distributed antenna system using the reference clock embedded in the downlink digital communication signal; convert the downlink digital communication signal into a downlink signal; communicate the downlink signal toward a remote antenna unit within the distributed antenna system; and wherein the distributed antenna system is configured to distribute the master reference clock to various components of the distributed antenna system to keep the various components of the distributed antenna system locked to a single clock, wherein the various components of the distributed antenna system include the remote antenna unit.

A distributed antenna system (DAS) includes: a base station network interface; and a remote antenna unit communicatively coupled to the first base station interface, the remote antenna unit including an antenna. The remote antenna unit configured to: receive a radio frequency band signal from a subscriber unit; convert the radio frequency band signal into a data stream; and communicate the data stream with the first base station network interface. The first base station network interface is configured to: convert the data stream or a signal derived from the data stream into a communication signal, wherein a mater reference clock is distributed between various components of the DAS to keep the various components of the DAS locked to a single clock; and communicate the communication signal and the master reference clock to an external device, the external device configured to lock its clock to the master reference clock.

A distributed antenna system (DAS) includes: a base station network interface; and a remote antenna unit communicatively coupled to the first base station interface, the remote antenna unit including an antenna. The remote antenna unit configured to: receive a radio frequency band signal from a subscriber unit; convert the radio frequency band signal into a data stream; and communicate the data stream with the first base station network interface. The first base station network interface is configured to: convert the data stream or a signal derived from the data stream into a communication signal, wherein a mater reference clock is distributed between various components of the DAS to keep the various components of the DAS locked to a single clock; and communicate the communication signal and the master reference clock to an external device, the external device configured to lock its clock to the master reference clock.

A near field radio-frequency identification (RFID) probe includes a probe tip comprising a resonant coil configured to communicate with an RFID compatible device at a predetermined resonant frequency. The near field RFID probe further includes a plurality of switch capacitor networks each comprising a capacitor and an RF switch, wherein switching the plurality of switch capacitor networks changes the capacitance of the resonant coil, thereby changing the resonant frequency of the resonant coil. The near field RFID probe further includes a probe control module configured to adjust the resonant frequency of the resonant coil to maintain the predetermined resonant frequency by switching the switch capacitor networks responsive to detecting that the resonant frequency of the resonant coil has deviated from the predetermined resonant frequency.

A near field radio-frequency identification (RFID) probe includes a probe tip comprising a resonant coil configured to communicate with an RFID compatible device at a predetermined resonant frequency. The near field RFID probe further includes a plurality of switch capacitor networks each comprising a capacitor and an RF switch, wherein switching the plurality of switch capacitor networks changes the capacitance of the resonant coil, thereby changing the resonant frequency of the resonant coil. The near field RFID probe further includes a probe control module configured to adjust the resonant frequency of the resonant coil to maintain the predetermined resonant frequency by switching the switch capacitor networks responsive to detecting that the resonant frequency of the resonant coil has deviated from the predetermined resonant frequency.

A pet monitoring device (101) for monitoring a sub-dermal RFID microchip (103), the pet monitoring device comprising: a wearable item (1) bearing 1 to 5 turns of electrical conductor (7) wound circumferentially to form a wearable item resonator; and an RFID reader (9) attachable and detachable to said wearable item, wherein said RFID reader comprises: a driving circuit (1100) comprising a primary inductance (Lp) inductively coupled to said wearable item when said RFID reader is attached to said wearable item; a secondary inductance (Ls) and resonance capacitor (Cs) conductively coupled to said wearable item when said RFID reader is attached to said wearable item, wherein the secondary inductance and resonance capacitor form the wearable item resonator with said electrical conductor, wherein the wearable item resonator comprises a circuit (1004) to automatically adjust said resonance capacitor to compensate for a size of said wearable item when fitted to said pet; wherein the driving circuit is operable to drive the wearable

Methods, apparatus, systems and articles of manufacture are disclosed to measure a resonant sensor based on detection of group delay. An example apparatus includes a modulation manager configured to query the resonant sensor with a modulated signal including a frequency; and a resonance determiner configured to determine a resonance frequency of the resonant sensor based on a group delay associated with the resonant sensor and the frequency.

Methods, apparatus, systems and articles of manufacture are disclosed to measure a resonant sensor based on detection of group delay. An example apparatus includes a modulation manager configured to query the resonant sensor with a modulated signal including a frequency; and a resonance determiner configured to determine a resonance frequency of the resonant sensor based on a group delay associated with the resonant sensor and the frequency.