JPH02275392A - Synchronous clock device using tv broadcasting signal - Google Patents

Abstract

PURPOSE:To generate a correct time signal by conducting initial synchronization periodically by a time signal contained in TV broadcasting wave signals and by executing synchronization monitoring and synchronization control at an interval of a short time by a picture signal. CONSTITUTION:A TV wave from a broadcasting station is led to an amplifier 102 through an antenna 101, amplified therein to be at a required level and inputted to a band-pass filter 103 and a sync signal separator 111. When a correct-time sound is contained in signals inputted to the band-pass filter 103, it is extracted and inputted to the next pulse generator 104, and a pulse generated in the generator 104 on receiving said signal is led to a frequency divider 107 of a clock device 105. Meanwhile, the frequency of a clock pulse other than the one of a correct time is always corrected by a picture sync signal contained in TV broadcasting waves extracted from outputs of the amplifier 102 by the sync signal separator 111. According to this constitution, there occurs no disorder in a time signal when forced synchronization with exact correct-time casting is executed once a day.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a TV broadcast signal synchronized clock device, and in detail, T.
The present invention relates to a TV broadcast signal synchronization clock device that uses various signals included in a TV broadcast signal to obtain accurate synchronization.

(Prior Art) In order to improve the accuracy of a time device, it is necessary to periodically correct deviations using reference time information, and conventionally, the hourly time signal of radio broadcasting has been used as time information.

Conventionally, this method includes a circuit that extracts the hourly sound of the hour signal included in AM or FM broadcast radio waves, and uses this signal to forcibly synchronize the clock device to the fixed time. .

An example of this type of device is shown in Fig. 4, which consists of an antenna 1, an hourly synchronized pulse generator 2, and a clock device 3. The system extracts the hour signal sound, determines the hour on the hour once a day from this signal, and forcibly synchronizes the time signal generated from the clock device with the hour.

Furthermore, the hourly sound synchronized pulse generator 2 includes a high frequency amplifier 2.
-1, bandpass filter 2-2 and pulse generator 2-3
The hourly signal is extracted from the radio broadcast signal, a pulse is generated, and the pulse is output to the next clock device 3.

The clock device 3 also includes a frequency divider 3-8 that divides the frequency of the pulse signal from the pulse generator 2, a crystal oscillator 3-2 that generates a pulse that becomes an input clock signal of this frequency divider, and the frequency divider 3-8. It consists of a time counter 3-3 that counts signals from -1 to generate a time signal, and a display 3-4 that displays the time generated by this time counter.

However, since such conventional synchronized clock devices are forced to synchronize with the base value once a day at a predetermined time, a sudden change in the time signal value occurs at the moment of this synchronization operation. However, this method has the disadvantage that the time interval is temporarily and drastically disrupted.

That is, if the time value of this clock device deviates significantly from the time signal of the radio broadcast, this deviation will be corrected all at once, and the time intervals before and after the deviation will become irregular.

The time difference X (tl in a general clock device is
If forced synchronization is not performed, it is expressed by the following equation.

X m = (at”/21+y, shi+Sy, (t
) dt...(1) However, a: Long-term frequency stability of the crystal oscillator y5 = Initial frequency setting error of the crystal oscillator y, (tl: Short-term frequency stability of the crystal oscillator In this equation, the rate of the clock is expressed on a long-term scale. If you look at it, the third of the above formula
The short-term frequency stability of the crystal oscillator in the first term can be ignored, and the long-term frequency stability (frequency age grade) of the crystal oscillator in the first term is particularly problematic.

Figures 5 and 6 show the degree of disturbance in the progress in conventional clock devices, and the time interval shift when forced synchronization is performed varies depending on the polarity and magnitude of the value of a. There is.

That is, as shown in Fig. 5, the deviation is positive when a>0,
If a x 0, it will be negative, and the smaller the absolute value of a, the smaller the deviation will be.

(A), (B), and (C) in FIG. 6 correspond to those in FIG. 5, respectively, and ΔX (t) is the deviation.

(Objective of the Invention) The present invention has been made in view of the circumstances described above, and it is possible to always maintain accurate time information without sudden fluctuations in time values and with easily obtainable time information. It is an object of the present invention to provide a TV synchronized clock device capable of generating a time signal.

(Summary of the Invention) In order to achieve this object, the present invention utilizes relatively easily obtained TV radio waves, first uses a time signal included in 'v broadcast radio waves as an initial synchronization signal, and then During short intervals, the rate of the clock device is synchronized with the image signal synchronization signal of the TV broadcast radio wave, and after the TV broadcast ends, the relative deviation of the rate of the clock device with respect to the TV image synchronization signal, which was accumulated during reception of the TV broadcast, is It is characterized by synchronously controlling the clock device based on the average value of the fluctuation trend.

In general, TV broadcast radio waves generate an image synchronization signal based on a signal from a highly accurate frequency source such as a rubidium oscillator, so if this image synchronization signal is extracted, a time signal with an extremely high M degree can be obtained. (Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a synchronized clock based on the present invention.
02 is a high frequency amplifier, +03 is a band pass filter for extracting the hourly sound of the time signal, +04 is a pulse generator, and the signal is a clock device! Guided to 05.

The clock device +05 uses a crystal oscillator [phase] + as before.
06, frequency divider 107, time counter 108 and display 1
Further, a phase comparison processor 20 is added, to which a part of the output of the amplifier +02 is connected via a synchronization signal separator 111.

To explain the operation in this configuration, the TV from the broadcasting station
? The It wave is guided to the amplifier lO2 via the antenna lot, amplified to a required level, and input to the bandpass filter 103 and the synchronizing signal separator 111.

Among these, if the signal input to the band pass filter 103 contains an hour tone, it will be extracted and input to the next pulse generator 104, and in response to this signal, it will be generated by the pulse generator. Frequency divider 1 whose pulse is clock device +05
Guided to 07.

Compulsory correction of the time signal of the clock device 105 based on the once-a-day hourly signal derived in this way is the same as the conventional one, but at the same time, the amplifier 102
T extracted by the synchronization signal separator II+ from the output of
The clock pulse frequency other than on the hour is constantly corrected by the image synchronization signal included in the V broadcast radio waves.

This correction is performed by dividing the signal from the synchronizing signal separator I11 by 75
The output of 1o7 is compared in the phase comparison processor 110, and the phase comparison processor +1
A control signal is output from 0 to the frequency divider 107.

Specifically, the pulse from the crystal oscillation Hxo6 is passed through the frequency divider 1.
07, the image synchronization signal is converted to a 1 second clock and extracted by the synchronization signal separator 11.1.
This is a 1 second clock, and the frequency division timing of the frequency divider is controlled so that the phase difference between the two is always constant.

Furthermore, since TV broadcasting is not always carried out 24 hours a day, when there is no broadcasting, the time signal is corrected as follows.

In other words, the phase comparison processor +10 has a function of statistically processing the phase processing results during V broadcasting, and calculates the trend of the rate of the crystal oscillator or frequency divider output signal in the device, in other words, The tendency of the time signal of device n to advance or lag is memorized, and after the end of the TV broadcast, synchronization maintenance pulses are outputted to the frequency divider +07 periodically or as needed based on this stored information. ing.

According to the above-mentioned means, the output clock of the frequency divider is corrected at short intervals as shown in Figs. 2 and 3, so that sudden locking and locking occur when correcting the hour as in the conventional method. A stable time signal can always be generated without phase correction.

(Effects of the Invention) As explained above, according to the present invention, T
Since the clock signal is constantly corrected by the image synchronization signal of the V broadcast radio wave, there is no sudden disturbance of the time signal when forcedly synchronizing with the accurate hourly time signal once every - day.

In addition, since the time can be corrected based on information stored through statistical processing of the tendency of the time device to lag or advance during TV broadcasting, it is possible to generate accurate time signals in the same way even after the TV broadcast ends. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the time device of the present invention, FIGS. 2 and 3 are diagrams showing the synchronization state and output waveform in the embodiment of the present invention, and FIG. 4 is a block diagram of a conventional time device. The block diagrams of FIGS. 5 and 6 are diagrams showing the synchronization state of the gate and the waveform of the output signal. 101...TV broadcast receiving antenna 102...High frequency amplifier 103...Band pass filter 104.
... Pulse generator 105 ... Clock device 105 10
6...Crystal oscillator 107...Division period IO2...
Time counter 109...Display device 110...Phase comparison processor [11...Synchronization signal separator patent applicant Toyo Tsushinki Co., Ltd.

Claims (2)

[Claims] (1) Initial synchronization is performed periodically using a time signal included in a TV broadcast radio signal, and synchronization monitoring and synchronization control are performed at short intervals using an image synchronization signal of the TV broadcast signal. TV broadcast signal synchronized clock device. (2) The TV broadcast signal synchronized clock device according to claim (1), wherein when the TV broadcast signal cannot be received, synchronization is ensured using statistically processed data obtained up to that point.