Abstract: Embodiments of systems and methods for implementing multi-channel tuners are generally described herein. Other embodiments may be described and claimed.

Abstract: Embodiments of systems and methods for implementing multi-channel tuners are generally described herein. Other embodiments may be described and claimed.

Abstract: Techniques are described that can be used to reduce interference in a desired channel by one or more other channels. A radio includes a level detect logic that is responsive to both the frequency offset and amplitude of undesired signals and sets the gain applied to received signals based on the offset frequency and determined amplitude of undesired signals. For example, detection of a signal amplitude in an interfering signal in a channel adjacent to the desired channel may be made. Detection of a signal amplitude in an interfering signal in a channel other than the adjacent channel and desired channel may also be made. Based on detection of one or more interfering channel, a gain of an input signal may be adjusted. Interference arising from at least spectral re-growth of noise and clipping noise may be reduced.

Abstract: Techniques are described that can be used to reduce interference in a desired channel by one or more other channels. A radio includes a level detect logic that is responsive to both the frequency offset and amplitude of undesired signals and sets the gain applied to received signals based on the offset frequency and determined amplitude of undesired signals. For example, detection of a signal amplitude in an interfering signal in a channel adjacent to the desired channel may be made. Detection of a signal amplitude in an interfering signal in a channel other than the adjacent channel and desired channel may also be made. Based on detection of one or more interfering channel, a gain of an input signal may be adjusted. Interference arising from at least spectral re-growth of noise and clipping noise may be reduced.

Abstract: A pulse generator is provided for generating pulses with a selectable variable width and/or delay. The pulse generator comprises an oscillator and a selecting arrangement for selecting how many of a first group of delay elements are connected in series for delaying the oscillator signal. Identical delay elements are connected in series to form a second group. A measuring circuit repeatedly measures the delay provided by the second group, for example providing output pulses whose width or duration is equal to the delay. A reference pulse generator generates a series of reference pulses, each of which is a predetermined fraction of the oscillator period. A control circuit compares the measurement and reference pulses to generate an error signal that is fed back to timing delay control inputs of all the delay elements such that the widths of the measurement and reference pulses are made substantially equal to each other.

Abstract: A frequency changer for a radio frequency tuner and a tuner incorporating such a frequency changer are provided. The frequency changer comprises a mixer comprising a plurality of mixing stages. The output signals of these stages are supplied without relative phase shift to a summer, for example, in the form of a common load arrangement. The inputs of the stages are connected together to form a signal input of the mixer. Commutating signal inputs of the mixing stages received from the local oscillator are of the same frequency, but of different phases. The commutating signals are square or rectangular waves.

Abstract: A quadrature frequency changer comprising first and second mixers and a local oscillator and a tuner and modulator including the quadrature frequency changer are provided. The local oscillator provides first and second commutating signals which are nominally in phase-quadrature and includes an arrangement for changing the phase of the first commutating signal by 180° to provide a third commutating signal. The first mixer comprises first and second mixing stages for mixing an input signal with the first and second commutating signals and a summer for summing the mixer stage output signals. The second mixer comprises third and fourth mixing stages for mixing the same or a different input signal with the second and third commuting signals and a summer for summing the third and fourth mixer stage output signals.

Abstract: A variable signal delaying circuit comprising an analog delay line having a control input for controlling the variable delay. A phase detector compares the input and output signals of the delaying circuit and supplies an output signal to a charge pump and integrator. A pulse stream generating arrangement produces pulse streams of different pulse widths and pulse control logic controls a selector for selecting any one of the pulse streams. In a first mode of operation, the control logic monitors the charge pump/filter output and selects the pulse stream which minimizes change in the output. The selection is fixed and the output of the charge pump/filter is then supplied as a correction signal to the control input of the analog delay line. Such an arrangement may be used to maintain minimum phase imbalance in I and Q signal paths of a quadrature frequency converter.

Abstract: A radio frequency tuner includes a first quadrature frequency changer, I and Q filters which are electronically adjustable, and a second quadrature frequency changer. During alignment of the filters, an alignment controller connects a test tone generator to the input of the frequency converter and the generator supplies a sequence of test tones of different accurately known frequencies. The amplitude of the resulting signals at the output of one of the filters is measured by a level detector. The controller compares the measured levels with a desired frequency response and adjusts the filter accordingly. The controller then causes the generator to supply a sequence of two test tones of different frequencies and a differential phase detector measures the phase difference between the output signals of the mixers of the second frequency changer.

Abstract: A radio frequency tuner comprises one or more tracking filters ahead of at least one frequency changer. A controller has a filter alignment mode and a reception mode. Each filter has one or more resonant networks comprising an inductance and a switched capacitor network which is digitally controlled for selecting the network resonant frequency. In the alignment mode, the controller determines the difference between the nominal and actual capacitances of the network for achieving a known resonant frequency in order to determine a correction factor for the capacitor network. The correction factor is then used during normal reception by the tuner.

Abstract: A frequency changer arrangement is provided for a radio frequency tuner. The arrangement comprises a first quadrature frequency changer for converting a desired input channel to zero or near-zero intermediate frequency in-phase and quadrature signals. These signals are filtered by low pass filters, whose turnover frequencies may be varied so as to vary the intermediate frequency bandwidth. A second quadrature frequency changer upconverts the filtered signals and supplies these to a summer. The resulting output intermediate frequency is determined by the frequency of commutation signals in the second frequency changer so that the output intermediate frequency may be continuously varied to allow any desired frequency to be selected.

Abstract: A tuner is provided for permitting independent reception of a plurality of channels from a multiple channel radio frequency input signal. A first analog converter of the upconverter type block-converts the radio frequency band to an intermediate frequency band. Several second analog frequency converters, such as quadrature ZIF downconverters, are independently controllable for independently selecting respective channels for reception from the intermediate frequency band at the output of the first converter. Each of the second converters converts the respective selected channel to the desired intermediate frequency. A voltage-driven interface is provided between the first converter and the second converters.

Abstract: A radio frequency tuner is provided having inputs for receiving signals in common or overlapping frequency ranges from distribution networks. Each input is connected to a respective first converter, for example performing upconversion to a first intermediate frequency above the RF frequency ranges of the incoming signals. The first frequency changers are arranged to be active one at a time. The outputs of the first frequency changers are supplied to a second frequency changer which performs downconversion on the output signal of the active first converter to convert a selected channel from one of the distribution networks to a second intermediate frequency. Sufficient RF isolation may therefore be provided without requiring mechanical switching components such as RF relays.

Abstract: A single conversion tuner comprises an image reject downconverter and a plurality of tracking RF bandpass filters ahead of the downconverter for providing image rejection. The downconverter comprises first and second mixers which mix the signal from the filters with quadrature commutating signals from a commutating signal generator. The mixer outputs are filtered by first and second roofing filters and the filtered signals are summed in a summer amplifier. The roofing filters may be off-chip inductance/capacitance filters.

Abstract: A radio frequency tuner is provided for selecting for reception a channel from a broadband multiple channel radio frequency signal supplied to its input. The tuner comprises an upconverter which performs frequency upconversion to a frequency range above the highest frequency of the broadband signal. This is followed by an image-reject downconverter which converts the selected channel from the upconverter to near-zero intermediate frequency.

Abstract: A digital terrestrial tuner has an RF input connected to a filter arrangement, whose output signal is supplied to a zero intermediate frequency frequency changer. The filter arrangement comprises a plurality of signal paths of different frequency responses. The signal paths are selectable one at a time for insertion between the tuner input and the frequency changer. At least one of the signal paths comprises a non-tracking filter which provides attenuation of out-of-band signals so as to reduce harmonic mixing caused by harmonics of the frequency changer commutating signal or by harmonics of spurious signals at lower frequencies.

Abstract: A tuner arrangement is provided comprising one or more tuners. Each tuner has two or more frequency changers, each comprising a mixer and a local oscillator. A controller controls the local oscillators in response to receipt of a channel select request. The controller determines the nominal frequencies of the local oscillators for tuning the selected channel and then performs a calculation to determine whether any beat frequencies between harmonics greater than the first harmonic of the local oscillators lie within the frequency band at the tuner output occupied by the selected channel. If so, the controller shifts the local oscillator frequencies so as to move the potentially interfering products outside the utilised band and then tunes the local oscillators appropriately.

Abstract: A multiple conversion tuner comprises a plurality of cascade-connected frequency changers, each of which comprises a mixer and a local oscillator. The tuner also comprises a local oscillator frequency selecting circuit which controls the frequencies of the local oscillators. The frequencies are controlled so that the final mixer 10 converts a desired signal to the final intermediate frequency and so that the frequency band occupied by the desired signal at the output of each mixer is within the passband of the following intermediate frequency part of the tuner. The local oscillator frequencies are also chosen so that there is no signal of unacceptably large level in the frequency band of the desired signal at the final intermediate frequency resulting from mixing of an undesired signal with harmonics higher than the first harmonic of the local oscillator signals.