JP2553998Y2 - Radio tuning clock selection device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for selecting a radio-controlled timepiece which corrects time by receiving a time signal transmitted from a radio station or the like.

[0002]

2. Description of the Related Art A radio-controlled timepiece has a function of receiving a time signal of a predetermined frequency emitted from a radio station and performing a so-called zero return based on the received signal. Such a radio-controlled timepiece is provided with a channel selecting device using a frequency synthesizer or the like, and is configured to automatically select a channel on which a broadcast signal exists, and to receive a signal from the selected station. It is configured to perform a time adjustment operation based on the time.

As a channel selecting device for an AM radio wave, for example, a control signal is sent from a control circuit to a PLL synthesizer circuit to increase (or decrease) a local oscillation frequency value by one channel at a predetermined repetition cycle by one channel. In the receiving circuit and the PLL synthesizer circuit, the intermediate frequency (IF) level and the IF count value of the received AM wave are obtained and compared with preset values, and the IF level and the IF count value are within the set values. In some cases, it has been proposed to stop the output of a command signal on the assumption that a desired station has been selected (for example, see Japanese Patent Publication No. 2-2330). In a radio-controlled timepiece using this device, a time correction operation is performed based on the hour sound of an audio signal as a time signal included in a broadcast reception signal of a selected station.

[0004]

However, in the above-described conventional apparatus, when the electric field strength of a broadcast signal by a predetermined station is weakened due to noise or a change in weather, another station which should not be originally selected is selected. As a result, the selected broadcast signal has a problem that the audio signal as a time signal is not AM-modulated, and there is a problem that time cannot be corrected.

The present invention has been made in view of such circumstances, and has as its object to provide an apparatus for selecting a radio-controlled timepiece that can prevent erroneous selection with a simple configuration and realize highly accurate time correction. Is to do.

[0006]

In order to achieve the above object, the radio tuning timepiece selecting apparatus of the present invention provides a command signal for changing the value of the local oscillation frequency by one channel at a predetermined repetition period. Command signal generating means for generating, local oscillation signal generating means for generating a local oscillation signal of each channel based on the command signal, and converting a received signal to an intermediate frequency signal based on the local oscillation signal, Receiving means for extracting the time signal from the signal, an intermediate frequency signal level determining means for determining the level of the intermediate frequency signal and comparing it with a preset value, counting the frequency of the intermediate frequency signal, and Frequency counting means for comparing with the value, waveform shaping means for shaping the time signal into a pulse-like signal, and counting the number of pulses of the output signal of the waveform shaping means. Pulse number counting means, and when the intermediate frequency signal level is determined by the intermediate frequency signal level determining means to be equal to or higher than a set value, and when the frequency counted by the frequency counting means is within the set value, the command signal generating means Control means for stopping the output of the command signal by means of the clock section and, when the count value of the pulse number counting means at that time is within a preset range, correcting the time of the clock section.

[0007]

According to the present invention, a command signal for instructing the command signal generating means to set the local oscillation frequency to the frequency corresponding to the first channel is generated and output to the local oscillation signal generating means. The local oscillation signal generating means generates a local oscillation signal having a frequency corresponding to the command and outputs the signal to the receiving means. The receiving means receives, for example, an AM wave transmitted from an AM radio broadcasting station, converts the received signal into an intermediate frequency signal based on the local oscillation signal, and outputs the intermediate frequency signal to the intermediate frequency signal level determining means and the frequency counting means. At the same time, a time signal is extracted from the received signal, and the extracted time signal is output to the waveform shaping means.

In the intermediate frequency signal level determining means, the conversion level is compared with the set value, and the result is output to the control means. Similarly, the frequency counting means counts the intermediate frequency, compares the count value with the set value, and outputs the result to the control means. In the waveform shaping means, the time signal is shaped into a pulse-like signal and output to the pulse counting means. The pulse number counting means counts the number of pulses in the output signal of the waveform shaping means, and outputs the counted value to the control means. In the control means, when the determination result of the intermediate frequency signal level is equal to or more than the set value and the frequency counted by the frequency counting means is within the set value,
The output of the command signal by the command signal generation signal is stopped.
Then, when the count value of the pulse number counting means at that time is within the set range, the time of the clock section is adjusted.

[0009]

FIG. 1 is a block diagram showing an embodiment of a channel selecting device of a radio-controlled timepiece according to the present invention. In FIG. 1, 1 is an antenna unit, 2 is a local oscillator constant setting unit, 3
Is a receiving circuit, 4 is a PLL (Phase Locked Loop) synthesizer circuit, 5 is a waveform shaping circuit, 6 is an audio pulse counting circuit, 7 is a time signal detection circuit, 8 is a control circuit, 9 is a clock section, V _CC is a power supply voltage, SSW indicates a start switch.

The antenna unit 1 includes a variable capacitance diode D
1, configured by a capacitor C1, a resistance element R1, and coils L1 and L2, tuned to a broadcast wave transmitted from, for example, an AM radio broadcast station, and outputs a specific frequency band to the reception circuit 3.

The local oscillator constant setting unit 2 is composed of a variable capacitance diode D2, a capacitor C2, a resistance element R2 and a coil L3. In response, the receiving circuit 3 generates a local oscillation signal LS having a frequency corresponding to each channel.

The receiving circuit 3 converts the AM wave input from the terminal AMIN from the antenna unit 1 into an intermediate frequency signal IF based on the local oscillation signal LS generated at the terminal OSC, and the conversion level is higher than a preset value. In this case, a high-level “H” signal is output from the terminal IFV to the PLL synthesizer circuit 4 and the signal is output from the terminal IFF to 450 kHz.
Outputs of the intermediate frequency to the PLL synthesizer circuit 4, also outputs the terminal AFO, for example as shown in FIG. 2 (a), the audio signal S ₃ to the waveform shaping circuit 5. In addition,
As shown in FIG. 2, the sound signal as the time signal is such that, for example, a 440 Hz notice sound is transmitted at predetermined intervals (for example, 1 second intervals), and three waveforms are transmitted. .

[0013] PLL synthesizer circuit 4 receives a command signal S ₈ for changing one channel minute value of the local oscillation frequency from the control circuit 8 generates a local oscillator VCO voltage LV of level corresponding to the command Output from the terminal VOSC to the constant setting unit 2 of the local oscillator, and when a high-level signal from the receiving circuit 3 is received from the terminal IFL, the terminal I
Counting the intermediate frequency input from the FC, when in the range of IF count value is preset, and outputs a stop signal S ₄ for stopping the output of the command signal S ₈ to the control circuit 8. Further, the PLL synthesizer circuit 4 supplies the antenna tuning voltage AV to the antenna unit 1 from the terminal VANT.

[0014] The waveform shaping circuit 5 receives the audio signal S ₃ by the receiving circuit 3, as shown in FIG. 2 (b), and shaped into a pulse-shaped waveform having a predetermined width, the sound pulse count circuit as a signal S ₅ 6 And output to the time signal detection circuit 7. FIG.
FIG. 3 is a block diagram illustrating a configuration example of a waveform shaping circuit 5. FIG.
As shown in (1), it comprises an amplifier (AMP) 51, a low-pass filter (LPF) 52, a comparator (CMP) 53, an integrator 54, and a shaper 55. In such a configuration, for example, about 200mVp-p audio signal S ₃ of is amplified with a predetermined gain by the amplifier 51, f
After passing through a low-pass filter 52 of c = 1 kHz, a comparator 53 compares the threshold with a preset threshold TH (for example, 0.8 V). When the output of the low-pass filter 53 is equal to or larger than the threshold value TH, the output of the comparator 53 is input to the integrator 54 at a high level.
The integrator 54 is composed of, for example, an npn-type transistor, a resistive element and a capacitor. A high-level input of the comparator 53 causes a gradual discharge after a steep rise, resulting in a waveform falling rightward. 55, where it is shaped into a rectangular pulse waveform.

The sound pulse counting circuit 6 receives the output pulse signal S ₅ of the waveform shaping circuit 5 counts the number of pulses, and outputs a signal S ₆ indicating the counted number to the control circuit 8.

The time signal detection circuit 7 receives the output pulse signal S ₅ of the waveform shaping circuit 5, if detected the hour sound after detecting three times warning sound at intervals of one second, the time signal detection signal S ₇ Output to the control circuit 8.

When the start switch SSW is turned on, the control circuit 8 sets a plurality of values of the local oscillation frequency f (kHz) preset in accordance with the oscillation frequency of the station for a predetermined repetition cycle to select a station. And outputs a command signal S ₈ for raising (or lowering) one channel at a time. When receiving a signal S ₄ from the PLL synthesizer circuit 4, the output of the command signal S ₈ is stopped. When the output signal S ₆ indicates, for example, the count number “3”, and receives the output signal S ₇ of the time signal detection circuit 7, it is assumed that an audio signal has been received as a time signal consisting of a warning sound and an hour sound. and outputs a time correction signal S ₉ to the clock unit 9 to perform time correction to the hour. Also, after receiving a signal S ₄ from the PLL synthesizer circuit 4, the output signal S of the output signal count is "3" or less than the time signal detection circuit 7 S ₆ audio pulse counting circuit 6
_If the input of ₇ is not performed within a predetermined time after the input of the signal S ₄ , the command signal S _{8 is set} to P for the next tuning.
Output to the LL synthesizer circuit 4.

Next, the operation of the above configuration will be described with reference to the flowchart of FIG. After device initialization (S
1), the start switch SSW is set to ON (S2), the first channel is set in the control circuit 8, the command signal S ₈ for instructing to set the local oscillator frequency to the frequency of the channel corresponding Is PLL
The data is output to the synthesizer circuit 4 (S3).

[0019] In the PLL synthesizer circuit 4, receives a command signal S ₈ for changing the value of the local oscillation frequency from the control circuit 8 by one channel minute, local oscillator VCO voltage LV of level corresponding to the command is generated Terminal VOS
C outputs to the constant setting unit 2 of the local oscillator. In the local oscillator, the local oscillation signal LS is generated in the receiving circuit 3 in response to the local oscillation VCO voltage LV. At this time, an AM wave transmitted from an AM radio broadcast station received by the antenna unit 1 is input to the receiving circuit 3.

In the receiving circuit 3, the AM wave input from the antenna unit 1 input from the terminal AMIN is converted into the intermediate frequency signal IF based on the local oscillation signal LS generated at the terminal OSC, and the conversion level (IF level) is set in advance. It is determined whether the value is equal to or greater than the set value (S4). The audio signal S ₃ is output to the waveform shaping circuit 5 from the terminal AFO of the receiving circuit 3.

If it is determined in step S4 that the IF level is equal to or higher than the set value, the terminal IFV
, A high-level “H” signal is output to the PLL synthesizer circuit 4 and 450 kHz
Is output to the PLL synthesizer circuit 4.

When the PLL synthesizer circuit 4 receives a high-level signal from the receiving circuit 3 and receives an intermediate frequency, the input intermediate frequency is counted (IF count) (S5), and the IF count number is set in advance. A determination is made as to whether or not the current value is within the range including the set value (450 kHz)) (S6).

Further, the waveform shaping circuit 5, the audio signal S ₃ by the receiving circuit 3 is shaped into a pulse-shaped waveform having a predetermined width,
As the signal S ₅ is outputted to the audio pulse counting circuit 6 and the time signal detection circuit 7. The speech pulse counting circuit 6 receives the output pulse signal S ₅ of the waveform shaping circuit 5, the pulse count of is performed, the signal S ₆ indicating the count is output to the control circuit 8. The time signal detection circuit 7 receives the output pulse signal S ₅ of the waveform shaping circuit 5, if detected the hour sound after detecting three times warning sound at intervals of one second, time signal detection signal S ₇ controls circuit 8 Is output to

[0024] In step S6 described above, IF count value if it is judged to be within the predetermined value, the stop signal S ₄ for stopping the output of the command signal S ₈ is outputted to the control circuit 8. The control circuit 8, the stop signal S ₄ is input, the audio pulse counting circuit 6
Output signal to input S ₆ of the count value is within a predetermined range, for example, the count value is whether or not "3" determination is made (S7, S8).

In step S8, the count value is determined to be "3", and the output signal S
Upon receiving the _7, as having received the audio signal as a time signal consisting notice sound and the hour sound, time correction to the hour and outputs a time correction signal S ₉ to the clock unit 9 is performed (S9) .

It should be noted that in step S4 described above,
It is determined that the level has not reached the predetermined level,
In step S6, it is determined that the IF count value is not within the predetermined range, and the audio pulse count value is "3".
If it is determined not to be in control circuit 8 sets the following channel (S10), the command signal S ₈ for performing the next channel selection is output to the PLL synthesizer 4 circuit returns to the operation in step S4 , The above-described operation is repeated.

FIG. 5 is a diagram showing the frequency and audio pulse when using the apparatus shown in FIG. 1 to tune to NHK first and second AM broadcasts of the Japan Broadcasting Corporation (NHK) in seven major cities in Tokyo. It is a figure showing the relation with a number. In the figure, "-"
The portion indicated by the mark indicates a station that was not selected in the determination of the IF level and the IF count value, fL indicates the lowest value of the audio pulse, and fH indicates the highest value of the audio pulse.

As can be seen from FIG. 5, when realizing a device that corrects the time to the hour based on audio signals emitted from NHK first and second broadcasting stations in nearby prefectures including Tokyo, it is necessary to select an apparatus. The NHK 1st and 2nd Tokyo where a station is desired have an audio pulse of 3 to 11 Hz, and the station where no tuning is desired (no audio) has a frequency of “0” Hz or “20” Hz or more. Therefore, if a station that falls within the range of 1 to 15 Hz is selected, incorrect selection can be prevented with high accuracy.

As described above, according to the present embodiment,
A command signal S from the control circuit 8 to the PLL synthesizer circuit 4 for increasing (or decreasing) the value of the local oscillation frequency by one channel at a predetermined repetition cycle.
₈ is output, and the receiving circuit 3 and the PLL synthesizer circuit 4 determine the IF level and the IF count value of the received AM wave, compare them with the set values, and when they are within the set values, select a desired station. As a result, the output of the command signal S ₈ is stopped, and the audio signal S ₅ is output to the waveform shaping circuit 5.
After shaping into a pulse waveform by the voice pulse counting circuit 6
In counting the number of pulses, the pulse count value is configured to carry out the time correction of the clock unit 9 receives the time signal detection signal S ₇ when there is a station that fall within the set range, which includes the audio signal Only in such a case, it is possible to shift to the time correction operation, to prevent erroneous channel selection with high accuracy, and to achieve an accurate time correction.

In this embodiment, the waveform shaping circuit 5 and the time signal detection circuit 7 are provided separately, but both circuits can be shared. Further, although the set value of the determination target of the number of audio pulses is described as “3” in the present embodiment, it is needless to say that the set value is not limited to this.

[0031]

[Effects of the Invention] As described above, according to the present invention,
There is an advantage that erroneous channel selection can be prevented with a simple configuration and highly accurate time correction can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a channel selection device in a radio-controlled timepiece according to the present invention.

FIGS. 2A and 2B are diagrams illustrating a configuration example of an audio signal as a time signal, in which FIG. 2A is a diagram illustrating a transmission waveform example, and FIG. 2B is a diagram illustrating a pulse waveform after shaping of the waveform in FIG.

FIG. 3 is a block diagram illustrating a configuration example of a waveform shaping circuit according to the present invention.

FIG. 4 is a flowchart for explaining the operation of FIG. 1;

FIG. 5 is a diagram showing the relationship between frequency and the number of audio pulses when selecting NHK 1 and 2 which are AM broadcasts of seven major cities in Tokyo nearby prefectures using the apparatus of FIG. 1; .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna part 2 ... Local oscillator constant setting part 3 ... Receiving circuit 4 ... PLL synthesizer circuit 5 ... Waveform shaping circuit 51 ... Amplifier 52 ... Low-pass filter 53 ... Comparator 54 ... Integrator 55 ... Shaper 6 ... Audio pulse count circuit 7 ... time signal detection circuit 8 ... control circuit 9 ... watch part V _CC ... the power supply voltage SSW ... start switch

Claims (1)

(57) [Scope of request for utility model registration] An apparatus for selecting a radio-controlled timepiece that corrects the time of a clock section in response to a time signal transmitted from a broadcasting station, wherein the value of the local oscillation frequency is set for one channel at a predetermined repetition period. Command signal generating means for generating a command signal for changing; a local oscillation signal generating means for generating a local oscillation signal for each channel based on the command signal; and an intermediate frequency signal for receiving a signal based on the local oscillation signal. Receiving means for extracting a time signal from a received signal, intermediate frequency signal level determining means for determining the level of the intermediate frequency signal and comparing it with a preset value, and frequency of the intermediate frequency signal. Frequency counting means for counting the time signal and comparing with a preset value; waveform shaping means for shaping the time signal into a pulse-like signal; and output of the waveform shaping means. Pulse number counting means for counting the number of pulses of the signal; and when the intermediate frequency signal level is determined to be equal to or higher than a set value by the intermediate frequency signal level determination means, and the frequency counted by the frequency count means is within the set value. Control means for stopping the output of the command signal by the command signal generating means, and when the count value of the pulse number counting means at that time is within a preset range, performing time correction of a clock section. A radio tuning clock tuning device characterized by the following.