JP3163621B2 - Clock frequency correction method for wireless terminal equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a wireless terminal device having a clock function.
The present invention relates to a clock frequency correction method for improving the time accuracy of the function.

[Related Art] An oscillation circuit unit such as a reference oscillation frequency generation circuit is incorporated in a wireless terminal device. However, when a clock function is added to the wireless terminal device, a separate oscillation circuit unit is additionally provided. It is necessary to provide a clock function oscillation circuit unit independently. That is, the circuits necessary for the main operation of the wireless terminal device, such as the reference oscillation frequency generation circuit, are activated and deactivated by turning the power of the device on and off.
This is because, although stopped, the clock function oscillation circuit section must always be operated even when the apparatus power is turned off.

[Problems to be Solved by the Invention] Generally, the above-described clock circuit for a clock function has a lower oscillation frequency accuracy than a reference oscillation frequency generating circuit section or the like in a wireless terminal device, thereby reducing cost. ing. For example, the clock frequency accuracy of the clock function oscillation circuit unit mounted on a personal computer is ± 20 PP at room temperature.
It is about M, and an error of about one minute occurs in one month.

The present invention has been made in view of such circumstances, and has as its object to provide a clock frequency correction method for a wireless terminal device that can improve the time accuracy of a clock function.

[Means for Solving the Problems] To achieve the above object, the invention according to claim 1 is
In a wireless terminal device including a reference oscillation frequency generation circuit unit and a clock function oscillation circuit unit for realizing a clock function, when the power is turned on, the reference oscillation frequency generation circuit unit included in the wireless terminal device generates the reference oscillation frequency. The clock frequency generated in the clock function oscillation circuit section is compared with a clock frequency generated in the clock function oscillation circuit section having a lower oscillation frequency accuracy than the reference oscillation frequency generation circuit, and based on the comparison result. And in the power-off state, the operation of correcting the clock frequency generated in the clock function oscillation circuit section is stopped.

The invention according to claim 2 is characterized in that, when the power is turned on, the clock frequency generated by the reception frequency measurement circuit unit built in the wireless terminal device and the clock function having lower oscillation frequency accuracy than the reference oscillation frequency generation circuit. In this method, the clock frequency generated in the clock oscillation circuit is corrected, and the operation of correcting the clock frequency generated in the clock function oscillation circuit is stopped in a power-off state.

[Operation] Since the present invention has the above-described configuration, the clock function can be performed in the power-on state by using the frequency of a clock (hereinafter, also referred to as a reference clock) generated by a reference oscillation frequency generation circuit or a reception frequency measurement circuit. Since the frequency of the clock (hereinafter, also referred to as a corrected clock) generated in the oscillator circuit for correction is corrected, the accuracy of the corrected clock frequency is improved as much as the accuracy of the reference clock.

On the other hand, in the power-off state, since the reference clock runs out, the correction operation is stopped, and deterioration of the accuracy of the clock generated in the clock function oscillation circuit is prevented.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention.

In the drawing, reference numeral 1 denotes a reference oscillation frequency generation circuit, and 2 denotes an oscillation circuit for a clock function, the former having higher accuracy of the clock oscillation frequency. The clock signals generated by the circuit units 1 and 2 are output to the frequency comparison circuit unit 3 and compared with the reference clock generated by the reference oscillation frequency generation circuit unit 1 in the circuit unit 3. The frequency comparison circuit unit 3 detects, by the comparison operation, how much the frequency of the clock to be corrected deviates from the frequency of the reference clock.
The detection result is output to the variable frequency dividing circuit unit 4 as a control signal. The variable frequency dividing circuit 4 corrects the output frequency of the clock function oscillation circuit 2 by the deviation of the clock to be corrected,
By operating the time counting circuit unit 5 with the clock signal,
The time is counted.

The above series of operations is performed only when the power is on.
That is, in the power-off state, since there is no output from the reference oscillation frequency generation circuit 1, the frequency of the clock to be corrected is directly detected as an error, and a normal correction operation cannot be performed. Therefore, when the power is off, the clock signal of the clock function oscillation circuit section 2 is output to the time counting circuit section 5 as it is to count the time.

FIG. 2 is a block diagram showing a second embodiment of the present invention, and FIG.
The figure is a block diagram showing a received wave frequency measuring circuit in the same block.

In the present embodiment, the wireless terminal device includes a receiving unit 7 and a circuit unit (received wave frequency measurement circuit unit) 8 for measuring the frequency of the received wave. Then, the received wave frequency measuring circuit 8 generates a reference clock, and the frequency of the reference clock is compared with the frequency of the clock to be corrected (output from the clock function oscillation circuit 2) by the frequency comparing circuit 3. The frequency comparison circuit 3 detects how much the frequency of the clock to be corrected deviates from the frequency of the reference clock, and outputs the detection result to the variable frequency dividing circuit 4 as a control signal. As in the first embodiment, the variable frequency dividing circuit 4 corrects the output frequency of the clock function oscillating circuit 2 and operates the time counting circuit 5 with the clock signal to count time.

Here, the reception wave frequency measurement circuit section 8 has a configuration as shown in FIG. That is, a received wave is input from the input terminal 11, the output of the local oscillation frequency circuit 14 and the received wave are combined by the mixer 12, and the intermediate frequency amplifier 13 amplifies the difference component of the frequency. Subsequently, the amplified signal is frequency-divided by the frequency divider 16 and output from the output terminal 18 as a reference clock.

In the figure, 15 is a discriminator, and 17 is a demodulation output terminal. The frequency of the received wave is generated by the base station device with high accuracy, and is usually ± 5 PPM or less in a wide temperature range from low to high (−20 ° C. to + 60 ° C.).

Accordingly, the reference clock frequency output from the output terminal 18 is more accurate than the clock frequency generated in the clock function oscillation circuit unit 2 in FIG.

Also in the second embodiment, the correction of the clock frequency output from the clock function oscillation circuit unit 2 is performed only when the power is on, and the correction operation is not performed when the power is off.

[Effects of the Invention] As described above, according to the present invention, when the wireless terminal device is powered on, the clock frequency generated by the clock function oscillation circuit unit is changed to the clock frequency from the reference oscillation frequency generation circuit unit with higher accuracy. Alternatively, the clock frequency of the clock function oscillation circuit section is corrected by comparing with the frequency of a received wave transmitted from a base station or the like, and thereby there is an effect that clock accuracy can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention, FIG. 2 is a block diagram showing a second embodiment of the present invention, and FIG. FIG. 3 is a block diagram illustrating a frequency measurement circuit. 1: Reference oscillation frequency generation circuit 2: Clock function oscillation circuit 3: Frequency comparison circuit 4: Variable frequency divider 5: Time counting circuit 7: Receiver 8: Received wave frequency measurement circuit 11: Input terminal 12: Mixer 13: Intermediate frequency amplifier 14: Local oscillation frequency circuit 15: Tiscriminator 16: Divider, 17: Demodulation output terminal 18: Output terminal

Claims (2)

(57) [Claims] 1. A wireless terminal device incorporating a reference oscillation frequency generating circuit portion and a clock function oscillation circuit portion for realizing a clock function, wherein when the power is turned on, the reference oscillation frequency built in the wireless terminal device is provided. A clock frequency generated by the clock generation circuit is compared with a clock frequency generated by the clock oscillation circuit having a lower oscillation frequency accuracy than the reference oscillation frequency generator. And correcting the clock frequency generated in the clock function oscillation circuit unit when the power is off. 2. A wireless terminal device having a built-in reception frequency measurement circuit portion and a clock function oscillation circuit portion for realizing a clock function, wherein a reception frequency measurement circuit built in the wireless terminal device when the power is turned on. The clock frequency generated in the clock function oscillation circuit is compared with the clock frequency generated in the clock function oscillation circuit having a lower oscillation frequency accuracy than the reference oscillation frequency generator, and the clock frequency generated in the clock function oscillation circuit is determined based on the comparison result. A clock frequency correction method for a wireless terminal device, comprising: correcting a clock frequency to be performed, and stopping a clock frequency generated by the clock function oscillation circuit unit when the power is off.