A measuring device serves to determine an active channel from a plurality of channels of known frequencies. In this context, it comprises a processor (11) which, in turn, comprises a transform unit (20). This transform unit (20) is embodied to transform the signal which contains the active channel or a signal (30) derived from this signal into a signal in the frequency domain (31). The processor (11) further contains a detection unit (28), which is embodied to detect the active channel in the signal in the frequency domain (31).

A method of performing alternate frequency switching in a radio includes tuning the radio to a primary frequency. A candidate alternate frequency is identified. It is determined whether the candidate alternate frequency is a third order inter-modulation artifact. Tuning is switched from the primary frequency to the candidate alternate frequency only if it is determined in the determining step that the candidate alternate frequency is not a third order inter-modulation artifact.

Disclosed is an integrated circuit for a near-field radio, including an oscillator configured to output a carrier frequency, an inductor capacitor (LC) tank antenna circuit configured to resonate at a resonance frequency, a frequency measuring circuit configured to measure the resonance frequency of the LC tank antenna circuit and compare the resonance frequency to the carrier frequency, and a controller to adjust the frequency of the LC tank antenna circuit to the carrier frequency.

The invention relates to a method for radio communication using one or more tunable antennas and an antenna tuning apparatus, and to an apparatus for radio communication using one or more tunable antennas and an antenna tuning apparatus. An apparatus for radio communication of the invention comprises: 4 antennas, each of the antennas being a tunable passive antenna; a radio device; an antenna tuning apparatus having 4 antenna ports, each of the antenna ports being coupled to one of the antennas through a feeder, the antenna tuning apparatus having 4 radio ports, each of the radio ports being coupled to the radio device through an interconnection; and a tuning control unit, the tuning control unit receiving a tuning instruction generated automatically within the apparatus for radio communication, the tuning control unit delivering a plurality of tuning control signals to the antenna tuning apparatus and to the tunable passive antennas.

Disclosed here is an interactive audio system and a method of operating the same. In one embodiment, the interactive audio system comprises a processor and a receiving module for receiving a radio frequency (RF) carrier signal associated with a broadcast station. The audio system further comprises a memory storing computer-executable instructions, where the processing module is configured to access and execute the computer-executable instructions to perform a set of acts. The acts include shifting a frequency associated with the received RF carrier signal to an intermediate frequency (IF). The acts include demodulating the frequency shifted portion of the RF carrier signal associated with the broadcast station, the demodulation resulting in an output signal. The acts further include extracting an embedded data from the demodulated output signal. The acts further include serving the embedded data in conjunction with the demodulated audio signal.

The invention relates to a method for radio communication using multiple antennas and localization variables, and to an apparatus for radio communication using multiple antennas and localization variables. An apparatus for radio communication of the invention comprises: 4 antennas, the 4 antennas forming an antenna array; a radio device; a sensor unit estimating a plurality of localization variables; an antenna tuning apparatus having 4 antenna ports, each of the antenna ports being coupled to one of the antennas through a feeder, the antenna tuning apparatus having 4 radio ports, each of the radio ports being coupled to the radio device through an interconnection; and a tuning control unit, the tuning control unit receiving a tuning instruction generated automatically within the apparatus for radio communication, the tuning control unit delivering a plurality of tuning control signals to the antenna tuning apparatus.

Methods and circuitry for calibrating inductive-capacitive resonant circuits are disclosed. An example of the circuitry includes an inductive-capacitive (L-C) resonant circuit operable to receive signals in response to induced electromagnetic signals transmitted on a carrier frequency. A demodulator has a signal source and is operable to demodulate signals generated by the L-C resonant circuit. Switching circuitry is operable to inject signals generated by the signal source into the L-C resonant circuit during a calibration mode. The calibration mode is for adjusting the capacitance in the L-C resonant circuit to tune the L-C resonant circuit to the carrier frequency.

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 method of performing alternate frequency switching in a radio includes tuning the radio to a primary frequency. A candidate alternate frequency is identified. It is determined whether the candidate alternate frequency is a third order inter-modulation artifact. Tuning is switched from the primary frequency to the candidate alternate frequency only if it is determined in the determining step that the candidate alternate frequency is not a third order inter-modulation artifact.

A Domino circuit for impedance tuning circuit can include a first node and a second node, and an inductance circuit including an inductor and a first switch connected in series such that the inductor is connected to the first node and the first switch is connected to the second node. The inductance circuit can further include a second switch implemented between ground and a third node between the inductor and the first switch, such that the inductance circuit is capable of providing a series inductance path between the first and second nodes or a shunt inductance path between the third node and the ground.