Receiver capable of receiving radio signals in a preferred state at all times
AssigneeAlps Electric Co., Ltd.
InventorYukio Ohtaki
Life of this patent
Estimating the term…
Abstract
A receiver has an adder for output intermediate-frequency signals of a plurality of receiving blocks, a demodulator for an added intermediate-frequency signal, adjustable reference-signal generator for supplying phase-shifted reference signals to the PLL circuits of the plurality of receiving blocks, and a plurality of switches. The switches are controlled when power is first supplied to the receiver such that the frequency-divided reference signals to the PLL circuits are in phase with one another. The adjustable reference-signal generator, upon tuning on power, is set in the phase-shift adjusted state stored immediately before previously turning off the power.
Claims15
A receiver comprising:
- a plurality of receiving blocks, each receiving block having an antenna, a frequency mixer that frequency-converts a reception signal received at the antenna, a local oscillator that supplies a local oscillation signal to the frequency mixer, a PLL circuit that sets an oscillation frequency of the local oscillator, and an intermediate-frequency circuit that selects an intermediate-frequency signal out of an output frequency-mixed signal of the frequency mixer;
- an adder that adds together output signals of the plurality of receiving blocks;
- a reproduction processor that reproduces an output added signal of the adder;
- an adjustable reference-signal generator that:
- supplies phase-shifted reference signals respectively to the PLL circuits of the plurality of receiving blocks, and
- adjusts a phase shift of the reference signals such that, upon power being first supplied to the receiver, the reference signals are set to an initial phase-shift adjusted state that was stored immediately before turning off power to the receiver previously and, during steady state operation, output signals of the plurality of receiving blocks have the same phase;
- and
- a plurality of switches connected between the respective PLL circuits and the adjustable reference-signal generator, switch-on times of the switches controllable such that the reference signals frequency-divided by the respective PLL circuits have the same phase upon power being first supplied to the receiver.
An OFDM signal receiver comprising:
- a plurality of receiving blocks, each receiving block having an antenna, a frequency mixer that frequency-converts an OFDM signal received at the antenna, a local oscillator that supplies a local oscillation signal to the frequency mixer, a PLL circuit that sets an oscillation frequency of the local oscillator, and an intermediate-frequency circuit that selects an intermediate-frequency signal out of an output frequency-mixed signal of the frequency mixer;
- an adder that adds together an intermediate frequency signal outputted from the plurality of receiving blocks;
- an analog-digital converter that converts an added intermediate-frequency signal outputted from the adder into a digital signal;
- an OFDM demodulator that OFDM-demodulates the digital signal;
- a phase-shift amount controller connected to the OFDM demodulator to set an amount of phase-shift of the adjustable reference-signal generator such that a demodulated signal of the OFDM demodulator has a power of at least a predetermined value and power dispersion of the demodulated signal is minimized, wherein the phase-shift amount controller includes a power detector that detects the power of the demodulated signal of the OFDM demodulator and a power dispersion detector that detects the dispersion of the demodulated signal of the OFDM demodulator.
A method of maximizing output signal power while minimizing signal dispersion of a receiver when power is first supplied to the receiver after power to the receiver has been terminated, the method comprising:
- storing an initial phase-shift adjusted state of an adjustable reference-signal generator immediately before power to the receiver has been terminated;
- supplying phase-shifted reference signals to PLL circuits of a plurality of receiving blocks of the receiver via the adjustable reference-signal generator when power is supplied to the receiver;
- adjusting a phase shift of the reference signals such that when power is first supplied to the receiver after power to the receiver has been terminated the reference signals are set to the initial phase-shift adjusted state;
- controlling reference signals frequency-divided by the PLL circuits to have the same phase upon first supplying power to the receiver;
- and
- adjusting a phase shift of the reference signals such that output signals of the receiving blocks have the same phase during steady state operation.
Dependencies are inferred from the claim text.