US 6,553,083 B1Granted

Frequency control and orthogonal detection circuit and FSK receiver

AssigneeKokusai Electric Corporation

InventorHisashi Kawai

Life of this patent

Estimating the term…

Loading patent…

Abstract

The present invention is a frequency control and orthogonal detection circuit and a FSK receiver capable of reducing a circuit size and control of VCO appropriately. The orthogonal detection circuit and the FSK receiver of the present invention include a delay circuit, a decoder for decoding the direction of rotation, and a first integral electric discharging circuit to detect the direction of rotation of the signal point of a signal received. There is also a second delay circuit, an XOR circuit, an adder, and a second integral electric discharging circuit to detect a rotation of the signal point of a signal received. The decision circuit decides a symbol on the basis of them. The AFC circuit controls the frequency of a signal outputted by the VCO in comparison with an ideal signal outputted by the standardizing circuit.

Claims10

Dependent claims

An orthogonal detection circuit comprising:

a decoder of rotation direction localizes a quadrant of a IQ plane having a signal point expressed by I phase component being same component and Q phase component being an orthogonal component of a received signal and a delayed signal of the received signal, and a signal outputted by a voltage controlling oscillator and outputs a difference between the value of the quadrant in the received signal and the value of the quadrant in the delayed signal,
a portion of synchronizing outputs a synchronized signal for every 1 symbol time,
a first integral electric discharge circuit integrates and outputs the difference of values of quadrants that are inputted from the decoder of rotation direction for 1 symbol time according to the synchronized signal,
a portion of detection of crossing over I axis detects that the signal point crossed the I axis in the IQ plane and outputs a signal of detection of crossing over the I axis,
a portion of detection of crossing over Q axis detects that the signal point crossed the Q axis in the IQ plane and outputs a signal of detection of crossing over the Q axis,
an adder adding the signal of detection of crossing over the I axis inputted from the portion of detection of crossing over the I axis to the signal of detection of crossing over the Q axis inputted from the portion of detection of crossing over the Q axis to output an axis crossing signal,
a second integral electric discharge circuit integrating the axis crossing signal inputted from the adder for 1 symbol time according to the synchronized signal to output an integral signal,
a reversing circuit reversing the code of the integrated result in the second integral electric discharge circuit to output,
a selector circuit selecting and outputting the output of the second integral electric discharge circuit, when an input from the first integral electric discharge circuit is plus, and selecting and outputting the output of the reversing circuit, when the input from the first integral electric discharge circuit is minus, and
a frequency control portion controlling a frequency of the signal outputted by a voltage control oscillator according to a signal inputted from the selector circuit.

7 more elements

An FSK receiver having an orthogonal detection circuit comprising:

a decoder of rotation direction localizes a quadrant of a IQ plane having a signal point expressed by I phase component being same component and Q phase component being an orthogonal component of a received signal and a delayed signal of the received signal, and a signal outputted by a voltage controlling oscillator and outputs a difference between the value of the quadrant in the received signal and the value of the quadrant in the delayed signal,
a portion of synchronizing outputs a synchronized signal for every 1 symbol time,
a first integral electric discharge circuit integrates and outputs the difference of values of quadrants that are inputted from the decoder of rotation direction for 1 symbol time according to the synchronized signal,
a portion of detection of crossing over I axis detects that the signal point crossed the I axis in the IQ plane and outputs a signal of detection of crossing over the I axis,
a portion of detection of crossing over Q axis detects that the signal point crossed the Q axis in the IQ plane and outputs a signal of detection of crossing over the Q axis,
an adder adding the signal of detection of crossing over the I axis inputted from the portion of detection of crossing over the I axis to the signal of detection of crossing over the Q axis inputted from the portion of detection of crossing over the Q axis to output an axis crossing signal,
a second integral electric discharge circuit integrating the axis crossing signal inputted from the adder for 1 symbol time according to the synchronized signal to output an integral signal,
a reversing circuit reversing the code of the integrated result in the second integral electric discharge circuit to output,
a selector circuit selecting and outputting the output of the second integral electric discharge circuit, when an input from the first integral electric discharge circuit is plus, and selecting and outputting the output of the reversing circuit, when the input from the first integral electric discharge circuit is minus, and
a frequency control portion controlling a frequency of the signal outputted by a voltage control oscillator according to a signal inputted from the selector circuit.

7 more elements

Dependencies are inferred from the claim text.