JPS59214330A - phase synchronized circuit - Google Patents

Abstract

PURPOSE:To allow the phase of a voltage-controlled oscillator to follow up the phase of data easily by measuring the period of input data through a data period measuring circuit, setting the control voltage of the voltage-controlled oscillator when a data block is detected, and then inputting the data to a phase comparing circuit. CONSTITUTION:The data period measuring circuit 1 consists of a reference oscillator, counter, flip-flop and known logical circuit, and the interval between pull- in data added to the head and tail of a data block is measured by the reference oscillator and counter. The output of the data period measuring circuit 1 is inputted to an initial value voltage setting circuit 2 and converted into a proper voltage depending upon control voltage-frequency characteristics. This output is turned on and off under the control based upon the output of a delay circuit 4. The voltage of a loop filter 7 is set to this output voltage and a phase comparing circuit 6 becomes able to operate. Then, the voltage-controlled oscillator 5 outputs an oscillation frequency corresponding to the voltage of the loop filter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a phase synchronization circuit, and more specifically, for example, in data discrimination from a read signal of a magnetic tape device.
The present invention relates to a phase synchronization circuit that is convenient for data discrimination and that can extract data from a read signal by minimizing the pull-in time and maximizing the pull-in range.

[Background of the invention]

In conventional phase-locked circuits, synchronization data equal to the frequency to be processed is input in place of the data until the data is input to the phase comparator circuit, and the data is input when a data block is detected. ing. Therefore, if the frequency difference between the data and the synchronization data becomes large, there is a drawback that the voltage control excavator cannot follow the data.

[Purpose of the invention]

An object of the present invention is to easily make the phase of a voltage control excavator follow the data phase even if the data frequency deviates significantly from the frequency to be processed, and to shorten the time required for tracking. The purpose of this invention is to provide a phase-locked (b) path.

[Summary of the invention]

In order to achieve the above object, the phase locked circuit of the present invention uses a data period measuring circuit to adjust the period of input data in order to easily pull in the voltage controlled oscillator even when the data frequency deviates significantly from the expected frequency. The control voltage of the voltage control excavator is set at the time when a data block is detected based on the result, and the data is then input to the phase comparator circuit.
This allows the output of the voltage controlled oscillator to be easily drawn into and tracked by input data.

The details of the present invention will be explained below using examples.

[Embodiments of the invention]

(Configuration of an Embodiment FIG. 1 is a configuration diagram showing an embodiment of a phase synchronization circuit according to the present invention. DATA is input to a data period measurement circuit 1, a data block detection circuit 3, and a phase comparison circuit 6. The output of the data period measurement circuit 1 is input to the initial value voltage setting circuit 2, and the output of the block detection circuit 3 is input to the data period measurement circuit 1 and the delay circuit 4.The output of the delay circuit 4 is input to the initial value voltage setting circuit. 2 and the phase comparison circuit 6, the output of the initial value voltage setting circuit 2 is sent to the loop filter 7, the output of the loop filter 7 is sent to the voltage controlled oscillator 5, the output of the voltage controlled oscillator 5 is sent to the phase comparison circuit 6, the phase comparison circuit The output of 6 is input to a loop filter 7.

(2) The operational data period measuring circuit of the embodiment is composed of a reference oscillator, a counter, a flip-flop, and a known mechanical circuit, and includes a synchronization pull-in circuit that is added to the beginning and end of the data block. The data interval is measured by a reference oscillator and a counter. On the other hand, one flip-flop is used to synchronize the input from the block detection circuit 3 with the data, and this output is used to block input to the counter and freeze the creation result of the data period. The output of the data period measuring circuit 1 is input to the initial value voltage setting circuit 2, and is converted into an appropriate voltage determined from the control voltage versus frequency characteristic of the voltage controlled oscillator. This output is turned ON10 by the output of delay circuit 4.
FF is controlled. Initial value 'When the output of the voltage setting circuit 2 is turned on, this output voltage (the voltage of the loop filter 7) is set. The block detection circuit 3 is a circuit that checks the continuity of input data, and is The output is determined when there is continuous input data of The comparator circuit 6 becomes operational. The voltage controlled oscillator 5 outputs a rooting frequency corresponding to the voltage of the loop filter. The phase comparator circuit 6 connects the data and the voltage controlled oscillator 5.
The voltage controlled oscillator 5 is controlled via the loop filter 7 by comparing the 0 output. When the output of the data block detection circuit 3 is turned off, the output of the delay circuit 4 is also turned off, and a control voltage corresponding to the number of cycles Il of the head portion of the currently processed block is set and held in the loop filter 7.

FIG. 2 shows the relationship between the output signals of the above-mentioned valley elements.

〔Effect of the invention〕

As is clear from the above configuration, according to the present invention, a control voltage corresponding to the frequency of input data is forcibly set in the loop filter, so that the input frequency is far away from the frequency to be processed. Also, the output of the voltage controlled oscillator can be easily made to follow the frequency I of the input data. Hagi, since the loop filter retains the information of the previously processed block, the time required to set the control voltage can also be shortened.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a phase locked circuit according to the present invention, and FIG. 2 is a signal time chart showing the output relationship in the circuit of the above embodiment. 1...Data cycle measurement circuit 2...Initial value voltage setting circuit 3...Block detection circuit 4...Delay circuit 5...Voltage controlled oscillator 6...Phase comparison circuit 7...Loop filter substitute Akio Takabono, Patent Attorney

Claims (1)

[Claims] A circuit that checks the data interval at the beginning of the data block input to the phase comparator circuit, and an initial control circuit that determines the initial value of the voltage control excavator (l [4I) by the output of the check circuit. A phase synchronized circuit characterized by having a voltage setting circuit as an energizing port.