JPH03284052A - Method and apparatus for phase synchronizing control - Google Patents

Abstract

PURPOSE:To attain accurate information transmission reception through the use of a low accuracy clook by comparing a measured time of the low accuracy clock with a measured time of a high accuracy clock and calculating the error of the measured time by the low accuracy clock and correcting the measured time and applying phase synchronizing control based on the clock resulting from the correction. CONSTITUTION:A CPU 1 forming a microcomputer for a facsimile equipment or the like together with a ROM 2 and a RAM 3 or the like counts a low accuracy clock and a high accuracy clock from crystal oscillators 4, 6 respectively to measure the time, the result of both measurements is compared and the measured time error by the low accuracy clock is calculated to correct the measured time. Then the clock corresponding to the result of correction is used and the phase synchronization with an external clock for other facsimile equipment or the like and the transmission reception of facsimile information or the like is implemented accurately without making the constitution complicated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a phase synchronization control method and apparatus for facsimiles and the like.

Conventional technology In general, conventional facsimile machines have a dedicated high-precision clock in order to synchronize the modem installed in the sending facsimile and the modem installed in the receiving facsimile at the beginning of transmission and reception. In addition, a CPU with a built-in high-precision clock is provided to perform line synchronization when receiving image data, and a high-precision clock dedicated to the image sensor is also provided.

In such a facsimile, when receiving a modulated signal of image data transmitted from the other party's facsimile using Group 2 communication, a predetermined time required for one line is measured using a high-precision clock built into the CPU. Based on this measurement result, line synchronization with respect to the modulation signal of the received image data is performed.

Here, the above-mentioned group 2 communication means, as shown in FIG. This is a communication method in which the data received from the previous facsimile is directly input to the thermal head pulse applying section as image data. However, the above-mentioned modem is a device that transmits a signal obtained by modulating transmission data to the modem of the other party's facsimile machine, and also demodulates the signal transmitted from the other party's facsimile machine and converts it into received data (hereinafter the same shall apply). ).

On the other hand, there is group 3 communication as a communication method different from the above. This group 3 communication is as shown in Figure 9.
The image data read by the image sensor is encoded by the encoding means and output to the modem as transmission data, and the received data inputted to the modem from the recipient's facsimile is thermally encoded as image data by the decoding means. This is a communication method that inputs to the head pulse application section.

However, when performing line synchronization with the modulation signal of image data received by the modem, group 3 communication does not require a highly accurate clock signal.

Problems to be Solved by the Invention In the case of such a facsimile, especially in the case of a facsimile that performs Group 2 communication, a CPU with a built-in high-precision clock, a high-precision clock dedicated to synchronous control of the modem, and a dedicated clock dedicated to the image sensor are required. Accurate transmission and reception of image data cannot be performed unless different high-precision clocks (oscillators), such as high-precision clocks, are provided for each type of processing.

Furthermore, since a plurality of expensive high-precision clocks are provided, the manufacturing cost of the device increases.

Means for Solving the Problems The invention according to claim 1 includes a measurement time comparison step of comparing a measurement time using a low-precision clock with a measurement time using a high-precision clock, and a method based on the comparison result of the measurement time comparison step. a measurement error calculation step of calculating an error in the measurement time by the low-precision clock; a measurement time correction step of correcting the measurement time by the low-precision clock based on the calculation result of the measurement error calculation step; and the measurement time. The present invention is comprised of a phase synchronization control step for performing phase synchronization control with an external clock signal based on the clock signal as a result of the correction in the correction step.

Further, the invention according to claim 2 provides a first clock formed by a low-precision oscillator, a second clock formed by a high-precision oscillator, a time measured by the first clock, and a second clock formed by a high-precision oscillator. measurement time comparison means for comparing the time measured by the second clock; measurement error calculation means for calculating the error in the time measured by the first clock based on the comparison result by the measurement time comparison means; and the measurement error calculation means. A measurement time correction means for correcting the measurement time by the first clock based on a calculation result by the measurement time correction means, and a phase synchronization control with an external clock signal based on a clock signal as a correction result by the measurement time correction means. It consists of a phase synchronization control means.

By making corrections based on the comparison between the time measured by the low-precision clock and the time measured by the high-precision clock, the clock signal from the low-precision clock has the same accuracy as the clock signal from the high-precision clock. Since the clock signal resulting from this correction is used to perform phase synchronization control with an external clock signal, it is possible to accurately transmit and receive information using a low-precision clock.
Furthermore, the manufacturing cost of the device can be reduced by minimizing the number of high-precision clocks.

Embodiment An embodiment of the present invention will be explained based on FIGS. 1 to 7. The actual phase synchronization control device is installed in a facsimile machine. As shown in FIG. 1, this facsimile includes a CPU 1 connected to a ROM 2 and a RAM 3 to form a microcomputer.
The PUI includes a low-precision crystal oscillator 4 as a first clock, an image sensor 7 connected to a high-precision crystal oscillator 6 as a second clock via a frequency divider 5, and the crystal oscillator 7. A modem 8 connected to an oscillator 6, a thermal head 9, and a motor drive circuit 12 connected to a recording paper motor 10 and a document motor 11 are connected. However, the modem 8 generally requires a high-precision oscillator to be connected due to its specifications.

In such a configuration, the CPUI controls the output of the thermal head 9, the recording paper motor 10, and the document motor 11, manages the reading of the image sensor 7, and controls the modem 8. , the image data of the reading result and a reading start signal for each line are input.

On the other hand, this facsimile machine transmits and receives image data using group 2 communication.

Generally, Group 2 communication is a communication method that employs the vestigial sideband amplitude modulation-phase modulation method specified in the CCITT T.3 recommendation.

When transmitting and receiving image data using this group 2 communication, a tonal procedure is performed between this facsimile machine and the other party's facsimile machine, as shown in FIG.

In other words, the facsimile on the sending side of image data is
The signal, LC3 signal (line adjustment signal), and fading signal are transmitted to the receiving facsimile in the above order.

However, as shown in Figure 3, a fading signal is defined as a no-carrier part with no amplitude (approximately 159 m5ec) and a full-carrier part with amplitude (approximately 8 m5ec) in l units (1
/6sec) was transmitted for about 6 seconds.

In addition, the above-mentioned message signal is transmitted in units of one line (1/6 sec) of image data, and as shown in Figure 4, the message signal is transmitted in the white part of one line of the image to be transmitted. It is formed by a corresponding full carrier portion and a no carrier portion corresponding to the black portion.

Then, the facsimile on the receiving side that receives the GC signal, the LC8 signal (line adjustment signal), and the fading signal recognizes that the facsimile on the transmitting side is compatible with Group 2 communication.

Furthermore, if the receiving facsimile succeeds in phase synchronization with the transmitting facsimile based on the above-mentioned fading signal, it transmits a CFR signal to the transmitting facsimile to respond that it is ready for reception.

After receiving the 200FR signal, the sending facsimile confirms that the transmission of the CFR signal has been completed, and then transmits a message signal (image data) to the receiving facsimile.

Here, when the receiving facsimile performs phase synchronization with the transmitting facsimile, it searches for the starting point of the carrier wave based on the above-mentioned fading signal, and based on the starting point of the carrier wave, the starting point of one line, That is, it is necessary to judge the timing to set the left edge of the document.

As shown in FIG. 5, the starting point of this l line is 1/1 period, which is one period from the starting point discovered based on the fading signal (the moment when phase synchronization with respect to the fading signal from the sending facsimile is successful). 6 (see)
This is the virtual point after counting an integer multiple of , and this is the virtual starting point.

That is, from the starting point discovered by the CPU based on the fading signal (n-1) x 166.7 (ms) (hereinafter 1/
6 (sec) to 166. 7 (ms))
A message signal is detected after the elapse of nX 166.7 (Ink), and reception of the message signal is started with the time after the elapse of nX 166.7 (Ink) set as the starting point of the first line of image data.

In such a facsimile, the above-mentioned 166,
The signal with a period of 7 (ms) uses the CPU clock, and if there is an error in this signal, the left edge of the image will shift in the main scanning direction. You will need something like this.

On the other hand, in this embodiment, since a low-precision crystal oscillator 4 is used as the CPU clock, the measurement time comparison means compares the clock produced by the crystal oscillator 4 with the clock produced by the crystal oscillator 6. comparison process), and find the error.

For example, if the crystal oscillator 4 is used and a calculated time of 2 seconds is set on the timer, the value will be different from the value of the crystal oscillator 6 (accurate 2 seconds) due to an error in the crystal oscillator 4. The difference between the value of the crystal oscillator 6 and the value of the crystal oscillator 4 is ΔT(
μs), one line (to be exact, 166, 666
(ms) ) per error Δt (μs) is as follows.

Based on this calculation formula, the measurement error calculation means calculates the error Δdirect μs) per line (measurement error calculation step).

Furthermore, using this calculation result, the measurement time correction means corrects the error of the crystal oscillator 4 (measurement time correction step). Based on this correction result, the phase synchronization control means calculates (n-1)X(166,7(ms)-Δ
Phase synchronization is performed after t (μs) x 10-” (ms) has elapsed as a virtual starting point (phase synchronization control step).

Furthermore, in order to measure the error ΔT (μs) caused by the crystal oscillator 4, only 2 to 3 seconds of unused period of the CPU timer are required. As shown in FIG. 7, this time is used during the GI double signal transmission period in the receiving facsimile, and during the GC signal transmission period in the transmitting facsimile.

In this way, by performing correction based on the comparison between the measurement time by the low-precision crystal oscillator 4 and the measurement time by the high-precision crystal oscillator 6, the clock signal from the crystal oscillator 4 is The clock signal has the same accuracy as the clock signal, and the clock signal resulting from this correction is used to perform phase synchronization control with the other party's facsimile.
Information can be transmitted and received accurately using the low-precision crystal oscillator 4, and the manufacturing cost of the device can be reduced by minimizing the number of high-precision crystal oscillators.

Effects of the Invention As described above, the invention according to claim 1 includes a measurement time comparison step of comparing a measurement time using a low-precision clock with a measurement time using a high-precision clock, and a method based on the comparison result of this measurement time comparison step. a measurement error calculation step of calculating an error in the measurement time by the low-precision clock; a measurement time correction step of correcting the measurement time by the low-precision clock based on the calculation result of the measurement error calculation step; and the measurement time. and a phase synchronization control step of performing phase synchronization control with an external clock signal based on the clock signal as a correction result of the correction step. a first clock formed by a clock, a second clock formed by a high-precision oscillator, and a measurement time comparison that compares the measurement time by the first clock and the measurement time by the second clock. means, a measurement error calculation means for calculating an error in the time measured by the first clock based on the comparison result by the measurement time comparison means, and a time measured by the first clock based on the calculation result by the measurement error calculation means. A clock signal with low precision By making corrections based on the comparison between the time measured by the clock and the time measured by the high-precision clock, the clock signal from the low-precision clock becomes one that has the same accuracy as the clock signal from the high-precision clock. Since the clock signal resulting from the correction is used to perform phase synchronization control with an external clock signal, information can be sent and received accurately using a low-precision clock, and the number of high-precision clocks is not required. By minimizing this, it is possible to reduce the manufacturing cost of the device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the hardware configuration in an embodiment of the present invention, FIG. 2 is a block diagram showing a tonal procedure, FIG. 3 is a block diagram showing a fading signal, and FIG.
The figure is a block diagram showing a message signal, and Figure 5 is a block diagram showing the process from when a fading signal is transmitted until phase synchronization is performed when a high-precision oscillator is used.
Figure 6 is a block diagram showing the process from when a fading signal is transmitted until phase synchronization is performed when a low-precision oscillator is used to correct the error, and Figure 7 shows the clock correction execution timing. FIG. 8 is a block diagram showing the flow of data in group 2 communication, and FIG. 9 is a block diagram showing the flow of data in group 3 communication. 4...First clock, 6...Second clock output
Requester Tokyo Electric Co., Ltd.

Claims (1)

[Claims] 1. A measurement time comparison step of comparing a measurement time using a low-precision clock with a measurement time using a high-precision clock, and a measurement using the low-precision clock based on the comparison result of this measurement time comparison step. a measurement error calculation step that calculates a time error; a measurement time correction step that corrects the measurement time using the low-accuracy clock based on the calculation result of this measurement error calculation step; A phase synchronization control method comprising a phase synchronization control step of performing phase synchronization control with an external clock signal based on a clock signal. 2. A first clock formed by a low-precision oscillator, a second clock formed by a high-precision oscillator,
measurement time comparison means for comparing the measurement time by the first clock and the measurement time by the second clock; and calculating an error in the measurement time by the first clock based on the comparison result by the measurement time comparison means. measurement error calculation means; measurement time correction means for correcting the measurement time by the first clock based on the calculation result by the measurement error calculation means; 1. A phase synchronization control device comprising: phase synchronization control means for performing phase synchronization control with a clock signal.