EP0180155B1 - Radio-controlled watch - Google Patents

Abstract

A radio controlled timepiece includes a radio receiver for demodulating a transmitted signal on which time and date information has been encoded. A pulse sequence is derived from the transmitted radio signal which is used to drive the stepping motor which advances the hands of a standard display timepiece. If unfavorable reception conditions exist, then the stepping motor will not be driven smoothly and the poor reception will be readily apparent from the irregular movement of the clock hand. A switch is provided to allow the stepping motor to be normally driven by a pulse sequence output of a standard time keeping circuit. A comparator compares the time displayed on the face of the timepiece with the time information encoded on the radio signal and, if the displayed time deviates from the actual time, the frequency of the pulse sequence from the time keeping circuit is adjusted to correct the displayed time.

Description

The invention relates to a radio clock according to the preamble of claim 1.

Such a radio clock, equipped with a power reserve in the form of its own clock circuit (and also called "autonomous" because of this internal timing), is described in the contribution by H. Effenberger "Microprocessor-controlled radio clock with analog display" in the volume of the report on the 4th Darmstadt Colloquium "FUNKUHREN" (1983), edited by Prof. W.Hilberg, pp. 104-109. It is a pointer watch with devices for detecting the position of the hands and for automatically correcting the hands from any momentary false indication. When starting up such a watch (eg after replacing its battery), the hands, driven by stepper motors from the internal clock circuit, are first rotated to a reference position in rapid traverse. They then remain stationary in this until the radio receiver has received coded time information from which it was able to decode the applicable current time. The fact that the hands stand still in a defined reference position (usually in the 12 o'clock position) is an unmistakable sign for the viewer that this position of the pointer does not currently represent a time display - it is therefore actually not necessary Effenberger also provided an illuminated display of the fact that such a synchronization process is currently taking place. Finally, when the current impending time is decoded without doubt from the received and demodulated pulse sequences (the so-called time telegrams), the receiver is switched off again in order to relieve the battery supply. That decoded point in time is a numerical value which is transferred to a comparator of a microprocessor as a setpoint for the angular position. This causes the pointers to come out of the internal Clock circuit driven and rotated to the angular positions that correspond to the display of that numerically predetermined time. The hands move again in rapid traverse, from which even the layperson realizes that during this directional run from the previous reference position it is not yet a time display, but only the (rotary) movement there. As soon as the currently correct display position is finally reached, the pointers are then moved (again by the internal clock circuit) so that the viewer now has the normal display of a pointer clock in front of them. After a certain operating time of the clock, the receiver is temporarily switched on again to receive new absolute time information, and the processor compares the numerical value decoded therefrom with the current pointer angle position; which, however, has no effect if the time is correct for the pointer movement (and thus for the viewer). Only in the event of a difference (i.e. in the case of a currently incorrect time display) is this quickly corrected using the internal clock circuit. After that, the clock runs autonomously again when the receiver is switched off, meaning that it continues clocked correctly.

The DCF radio transmission of such time-telegrams, binary-coded and transmitted every minute, is explained in the article "Watches controlled by radio" by M.Schlegel in VDI-Nachrichten No.3 (Jan.1977): An RF signal in the long-wave spectrum is experienced every second a modulation in the form of an amplitude reduction of either shorter or longer duration. The start of a new minute, and thus of the next binary-coded time telegram, is marked by a minute mark (in the form of an amplitude reduction missing for the 59th second of each cycle). The correspondingly received and demodulated sequence of long and short receive pulses in minute intervals (with regard to the minute just ahead) represents the complete binary coding of the current time from the minute information onwards. This is shown in more detail in the article "The Coded Time Transmission According to DCF 77" by JRWonnay in volume 26 (1975) of the yearbook of the German Society for Chronometry (section J pages 1-20); where also the in the case of decoding at the receiving end, it is possible to check whether the decoded numerical value is correct time information or incorrect information based on local or external interference. The latter is ignored, so it is not used for pointer angle control. If, on the other hand, the decoded numerical value is recognized as valid, it is read directly from a digital clock for digital time display, while for a clock that displays electromechanically (for example by means of pointers), it is the target position in the above-mentioned angular position comparator for checking and correcting the pointer position is handed over.

This passed time information is therefore a mere numerical value. The second grid of the coding on the transmission side is therefore no longer contained in it. If necessary, continuous seconds information must be generated separately by the receiver, synchronized with the current minute mark and enumerated. The stepper motor controls for corrective (rapid traverse) or time-keeping (normal gear) pointer movement can therefore not be carried out from the decoded time information, but the generic clock is equipped with the autonomous internal clock circuit.

If, after commissioning the clock, when the receiver is temporarily switched on again later (for checking and, if necessary, for correcting the current time display), the current time information cannot be uniquely decoded from the demodulated pulse sequence due to any faults, then the current position of the hands is not checked at all instead - the clock continues to run with its internal time-keeping advance. This bridging mode, with a lack of plausible radio time information for non-radio-controlled pointer time display, is provided in the generic radio clock (according to Effenberger) by an LED blocking signal. Such light signals may be common in an electro-optically indicating digital watch, but in the dial of a stylistically balanced pointer watch design they appear as foreign objects, namely as extremely disruptive. And such an indicator in the form of the blocking signal light, which does not go out again during a longer fault is not particularly motivating for the technical layperson who has put this watch of the latest technology in the room; Rather, he is disappointed with the praised new technology: especially when he wants to put the radio clock into operation, but only achieves that the hands still run correctly in their reference position, but because there is no decodable reception (i.e. no current time information to set the Pointer time display) then stand still in this starting position - the lighting of the blocking lamp is no longer a consolation for the consumer, especially since it does not convey anything understandable to him about the reason for the apparent malfunction.

In relation to such a state of the art, it is therefore necessary, in the case of a common, generic pointer time display, without the need for additional display means which are foreign to the species (in particular physiologically or aesthetically disruptive) and which nevertheless provide information which can also be interpreted by the layperson as to whether (in particular at the start of operation) the radio reception of the coded time information is either disturbed or regular (and will therefore soon lead to the correct pointer position).

Already in DE-A-3 015 312, a sequence of digits that is meaningless in the event of reception disturbances, or even a representation of the time pulse reception by flashing light-emitting diodes, is rejected as confusing or in any case disturbing. On the other hand, it is considered more sensible and customer-friendly to output physical comparison information for such disturbed reception situations. This is based there on an electronic comparison of the demodulated receive pulses with standard pulses specified in the watch on the receive side. The viewer of the watch is thus provided with numerical information about the current reception quality, possibly together with a threshold indicator which must be clearly exceeded so that error-free reception of demodulable absolute time information can be expected over a sufficient period of time. So if the radio clock is set up so unfavorably that there is no sufficient reception for a correction of the current time display possible - display If the quality indicator is too low, then the receiving antenna built into the radio clock must be oriented or positioned differently in order to be able to decode the current time and correct the display on it. However, such a digital quality code display in a consumer radio watch with a pointer time display is also unreasonable per se, because it disturbs a balanced dial design even more than the aforementioned light-emitting diodes; and for the layperson this reception indicator number display is also without the desirable meaningfulness, rather deterrent.

Also not a generic radio clock with pointer time display is the radio clock with digital display according to the building instructions of R. Goessler "micro computer controlled radio clock in mini format" in FUNKSCHAU 1979 booklet 14 (S.839-842), 15 (S.891- 895), 16 (p.959-962) 17 (p.1027-1029 and 18 (p.1081-1083). Not for the consumer who looks at the watch display, but for the manufacturer (and maybe later for the Service technician), a light-emitting diode is connected to the comparator output in the interior of the kit as a reception adjustment aid or for troubleshooting. If, taking into account the current antenna orientation, the receiver setting has already been optimized and after a longer observation period, an even flashing sequence has finally occurred The purpose is to continue with the rest of the circuit adjustment (loc. cit. page 962, left and right column) In the radio clock circuit, this adjustment aid is of course no longer visible from the outside - it is therefore neither intended nor suitable for transmitting quality of reception information to the consumer. If, on the other hand, such a continuously flashing light-emitting diode were to be visible from the outside in the case of a pointer time display, then it would again represent the foreign body in the dial, which has otherwise been rejected as optically disturbing. Any suggestion of a received signal indicator that is compatible with the design of a balanced pointer time display can therefore also be found in this proposal by a separate internal auxiliary signal transmitter, even retrospectively, neither in terms of task nor even as a solution approach.

A comparable to the second blinker, but acoustic presentation is known in a digitally displaying radio clock according to GB-A-2 019 054, where (in addition to visual error display) an acoustic signal generator (which is also used as an alarm signal generator when an alarm signal is reached) from the time decoder predetermined wake-up time) can be activated briefly, for example, at the beginning of each second. Of course, this is an even more unpleasant nuisance for the environment than a constant or even intermittent light signal; why - and also to reduce the power requirement from the battery - this acoustic impulse radiation can be switched off (and thus of course ineffective)!

On the other hand, a radio-controlled clock of the generic type or even of the generic type is no longer at all if no complete, i.e. coded, current time information is transmitted via radio and evaluated in the autonomously timed clock for occasional control and, if necessary, for adjusting the angle of the pointer will; but if, according to the old technology of the clock networks, only advance pulses for the advancement of a non-autonomous time display are transmitted, as described, for example, by G. Krug "radio remote controlled clocks" in "clocks and jewelry" Vol.9 / No.2 (1971) p. 57-59. Such an advance remote control is at most relatively fail-safe insofar as no absolute time information has to be decoded in the clock. If, however, there is an error message (e.g. when the watch is started up with the randomly given hand position, or later due to a transmission impulse that has failed due to transmission, and also after every change from summer time to winter time), the display is then incorrectly clocked; because automatic display correction is not possible there because there is no absolute time information, or even only current pointer position information. Therefore, the problem does not arise here of signaling the absence of decodable absolute time information to be received for correction.

This also applies to the other watch remote control, which is an autonomous watch but lacks the transmission of one decodable absolute time information is also not a radio-controlled clock of the generic type: if - for example according to US-A 4 315 332 - the known radio time signal is received in an expected period and then in the event of a current display deviation the display shows the nominal time specified (usually the beginning of an hour or a day). EP-A2-0 042 913 also provides for a correction of the internal time base used to date in accordance with the currently occurring display deviation from the nominal time - the application of such corrective measures to a radio-controlled clock of the generic type is expressly rejected there! Again, this nominal time synchronization is only relatively immune to interference insofar as only the occurrence of the synchronization time mark is demodulated, but it is not necessary to decode absolute time information. However, if, for example during commissioning or due to an accumulating fault, the catch range specified in the clock in terms of circuitry is too far from the actual time, then the broadcast synchronization mark can no longer be received and the time display will continue to run incorrectly in the future. A possible indicator about the quality of the radio signal to be received would also be irrelevant here, since even in good reception conditions, the missed signal is of no use. In addition, depending on the system, a correction of a limited deviation in the minute display can take place, but not a correction of the hour display. The clock will therefore continue to run incorrectly if, for example, the correct minute but an incorrect hour is displayed at the start of operations or after every change from summer time to winter time. For this time change constellation, the last cited document provides for the special effort of an additional, computer-controlled date clock, which stops the hands of the clock for one hour or lets it advance by one hour in rapid traverse to the time change even in the case of different calendar data to be preprogrammed each year Understand the display - which is completely independent of the reception of the radio time signal as well as the correctness of the current display before or after such functional intervention. Therefore, the problem underlying the invention does not arise here either. Of course, even with such additional calendar intervention, the Current standstill or the current rapid traverse - in so far as during commissioning and as with the correction process on a generic pointer radio clock - a clear indication for the viewer that there is currently no valid pointer time display, but that an adjustment process is taking place. On the other hand, the longer standstill of the time display required only for the transition to winter time, according to this prior art, can be considerably more irritating, namely if the layperson is currently not prepared for this operating case, which occurs only once a year. However, these two special operating modes of the time changeover are not significant for the quality of radio reception, because the time changeover here is not radio-controlled.

To a certain extent, it is a mixed operation (albeit also alien to the genus) if, according to H.Schreiber "Control of a usage watch by time signal transmitter" (FUNKSCHAU 1977 issue 2 pages 95-96 and issue 3 pages 73-74) the output pulses of an autonomously timed clock circuit Control of a pointer-stepper motor are compared with the output pulses of a multivibrator which in itself is running too fast, but which in turn is synchronized to regulate the gear from the second modulation of any time transmitter carrier. Depending on the current movement of the clockwork, a slight acceleration or deceleration of the movement control is derived from this phase comparison, depending on the current movement of the clockwork, as this can be seen in the millisecond range. If the sequence of seconds received via radio fails, the multivibrator continues to run at its natural frequency, which results in a beat mode with briefly alternating lead and lag periods of the factory. The time display is therefore not touched, and it always stays on time even on average regardless of the actual reception conditions. In any case, the consumer does not notice the lack of clock reception when looking at the dial. On the other hand, if for some reason the time display is incorrect (like when the watch was started with an arbitrary current hand position), then this cannot be corrected by undisturbed reception of the seconds markers, since yes (contrary to the principle with the generic clock) no absolute time information received and no pointer position detection is operated. The current reception quality is again completely irrelevant for the consumer even with this prior art, which is why no indication of the problem solved according to the invention can be derived from this either.

US Pat. No. 4,316,274 neither relates to the problems underlying the invention nor to a solution contributing to the invention. There it is a matter of signaling that the capacity of the battery of a conventional watch is running low without losing the continuous time display but by means of this continuous time display. This is expressed there by switching to an unusual but still time-keeping rhythm instead of the usual step-by-step rhythm for time display (e.g. with second increments of the second hand), for example by only switching the second hand every two seconds advances two seconds. The function of the clock with its internally controlled time display is therefore fully retained. Only the time resolution of this time display is coarsened on an unchanged basis of the internal time-keeping circuit

In a generic radio clock according to the unpublished but priority EP-A1-0 172 069, the display control takes place in the manner of clock networks via cable from a mother clock, but with the special features that the mother clock itself can be radio-controlled by a reference clock and that only incremental pulses are now transmitted in the conventional way, rather than coded absolute time information. These are converted into digital pointer display setpoint angle information so that a drive operating in start-stop mode (i.e. not as a quasi-continuous stepper motor) is switched on until its output shaft has reached the angular position corresponding to the setpoint display specification. Until the next cable transmission of absolute time information from the mother clock, the pointer movement is then continued from an internal time-keeping circuit. If the radio control of the mother clock from your reference clock is disturbed, then the cable control for the time display is not affected - the mother clock may go wrong, so that the remote display (corresponding to our radio clock in terms of function) is set incorrectly, but this is not signaled to the viewer. Under these circumstances, even at the start of operation, there is no notification as to why the time display may not start at the correct time. This threatens to make consumers misunderstand the new watch technology.

The generic radio clock (according to Effenberger) is only equipped with an hour and a minute hand, which are moved independently of each other from the internal clock circuit via their own pulse-driven clock stepper motor. This allows the circuitry outlay for the detection of the respective pointer movement through its reference position (for the pointer position feedback that is used in one electronic counter) to be kept relatively low and, for each pointer separately (i.e. without excessive rotational speed stress on the pointer mechanism), the computer-controlled display corrections (e.g. from the initial position at the start of operation) to the currently decoded absolute time by means of temporarily faster clocking from the internal clock circuit in rapid traverse perform. Incidentally, Effenberger mentions that the computer control also allows the operation of a second hand; but without it being recognizable from this note, with which motor and according to which information (the current second is no longer contained in the time information decoded for the pointer position correction, that is to say purely numerically available) an additional second hand should then be driven. Also not quite understandable is the reference to the possibility of continuing to operate the hands if the time information from the sequence of the minute marks is not fully decodable (before the start of each code cycle) - because after the first position correction at the start of operation, the hands will continue to be used for so long internal time-keeping circuit moves until a pointer position check can be carried out again based on a currently decoded absolute time information.

In recognition of the shortcomings shown, the invention has for its object to design a generic radio clock in such a way that a simple indicator of the reception quality of the pulse train to be decoded with a comparatively little additional technical expenditure for the pointer time display that is already present, functionally and organically in a consumer radio clock can be included in such a way that it can easily be conveyed to the layperson whether regular radio reception is currently being given at the start of operation (which will soon lead to the setting of the pointer display, which is typical for a generic radio clock, to the current point in time from any malposition); or whether reception is too disturbed when the radio clock is currently set up for decoding radio information suitable for display correction.

The object is achieved in that the generic radio clock is equipped with a reception indication according to the characterizing part of claim 1.

This solution therefore dispenses with irritating, at least less meaningful and, above all, disruptive dial design electro-optical displays; and it does not drive the effort for a quantitative assessment and numerical representation of the signal quality of received and yet to be decoded radio signals, which are of interest only for the person skilled in the art. Instead of this - regardless of the time display or in addition to it - according to the present invention, an indicator pointer, referred to here as the present, is at least temporarily directly from the not yet decoded by means of its pulse stepping motor (not for the correction movement or for timely display from the internal clock circuit, but instead) Pulse sequence of the received time telegram switched on. Since this pulse sequence occurs regularly in the second grid (with suppression of the 59th pulse of a full minute), the indicator pointer introduced according to the invention (at the start of operation without displaying current time information or even performing a display correction run) becomes undisturbed in reception conditions rhythmically familiar second step sequence moves. This undisturbed pointer advance therefore only serves to make the regular reception of discrete (usable for decoding) pulses clear. And so this additional (indicator) pointer movement can also be easily interpreted by the layperson, if necessary, to the effect that the radio clock is now working normally. So he recognizes that their time display, in the case a display that differs from the actual time, will set the correct time display at the next comparison time.

If, on the other hand, the reception of the coded time information is disturbed, either pulses fail, or pulses occur in a faster or irregular sequence than according to the second cycle. Both lead to an unusual movement of the pointer that deviates from the sequence of steps in a second; and even the layperson can recognize without a doubt that there are disturbed reception conditions. In the result, this applies even more when there is no second-hand movement because no pulses can be picked up and demodulated by the receiver. In any case, such a movement of the pointer, which is not regular with regard to the rhythm of the seconds, also makes it readily apparent to the layperson among the consumers that the current time display is not secured and will also not be corrected for the foreseeable future. He can then z. B. try to possibly improve the reception conditions by changing the spatial layout of the radio clock until this connection of the demodulated receive pulses to the switching of the relevant pointer after the start of operation switches to the time-keeping circuit as soon as a first complete time information is decoded, and for the time comparison as well provided for display correction. If at this point there are regular demodulated pulses arriving every second and the seconds hand of a watch is selected as the reception indicator, the consumer may not even notice the changeover of the hand advance from the (except for the missing 59th pulse) the second clock of the demodulated ones Receive pulses on the (uninterrupted) second cycle of the time-keeping circuit; he is therefore not possibly, unnecessarily, irritated by this measure.

If, on the other hand, clearer information about this switching process is sought in the case of undisturbed reception conditions, it is more expedient to select one as an indicator pointer that is normally not moved every second, e.g. the minute or hour hand of the watch controlled by its own motor.

Switching the control of the pointer stepper motor in question from the demodulated receive pulses to the time-keeping device can be advantageous - especially if it is a matter of realizing the decoding of the time information and determining and tracking the displayed time by means of a microprocessor - in a circuit-technical connection with the decryption circuit and the comparator for the time information transmitted via radio coding.

Additional alternatives and further developments as well as further features and advantages of the invention result from the further claims and from the following description of a preferred implementation example for the solution according to the invention, which is sketched in a simplified manner as a block diagram and limited to the essentials.

In the case of a radio clock, a radio receiver 1 with a radio frequency part 3 connected to an antenna 2 (for example a ferrite coil), this demodulator 4 and output amplifier 5 connected downstream supplies a square-wave pulse train 6 with a pulse repetition frequency of 1 Hz, which is encoded within one by means of binary pulse length coding Minute contains complete time and date information (not considered in the drawing).

If an undisturbed pulse sequence 6 has been received for at least one complete minute, the information about the current point in time can be detected therefrom by means of a decryption circuit 7 and with the current time display, in the form of the position of hands 8 in front of the minute track on the dial 9 of a clock, in a comparator 10 can be compared, which is supplied by a pointer position detector 11 (on the basis of, for example, rotary angle meters or incremental actuators).

The pulse train 6 passing a threshold stage 12 controls (in the example shown: with its differentially positive edges) the dynamic changeover input 13 of a bistable reversing circuit 14, at the outputs of which are inverted with respect to one another, 6 H potential and L potential change in the rhythm of the pulse train . If necessary, it can be useful to connect amplifiers 15 to these outputs, which can also be part of a pole-changing bridge circuit.

In any case, the control coil of a bipolar single-phase clock stepping motor 16, which is placed over the outputs of the bistable circuit 14 or the amplifier 15, thereby alternately has precisely the signal sequence which leads to the succession of rotation steps by half a revolution, and accordingly via a gear coupling 17 leads to the step-by-step movement of a pointer (here the second hand 18) by one-second steps if the pulse sequence 6 emitted by the radio receiver 1 is actually undisturbed, that is to say with a pulse repetition frequency in the second grid.

If, on the other hand, this pulse sequence 6 is disturbed (in the form of failing or interrupted individual pulses), then the movement of the pointer used for the reception indication (here the second hand 18) can be seen without further ado because it is not the familiar, uniform one Executes step movement in the angular second cycle, but eg jumps uneasily.

Preferably, a switchover device 19 is provided for the control of the stepping motor 16, via which - as just described - the pulse train 6 is passed from the radio receiver 1 to the reversing circuit 14 as soon as the overall arrangement, or at least the radio receiver 1 after a break in operation is put into operation; for example by means of an operating switch 20, or for example as a result of the use of a power source 21 (for example a battery). As a result, a set input 23 for the switching device 19, possibly via a trigger circuit 22 for triggering a set pulse driven for this switching of the pulse train 6 on the reversing circuit 14. At the start of operation, the progression of the indicator pointer 18 therefore only actually indicates the passage of time in a second pattern when an undisturbed pulse sequence 6 is received. As soon as the decryption circuit 7 has decoded the time information from it, the switchover device 19 is switched via its reset input 24 to receive the time-keeping pulses 25 from a time-keeping device 26, that is to say to a clock-second cycle; in which from now on (until the next break in operation of the radio clock), for example, a second hand 18 is switched on. However, the time-keeping pulses can also temporarily have a higher frequency, for example, if the comparator 10 detects a deviation between the time indicated by the pointer 8 and the current time decoded by the decoding circuit 7.

In the interest of clarity, the block diagram shown does not take into account the fact that it may be more expedient to provide separately controlled stepping motors 16 on the one hand for the second hand 18 and on the other hand for the hour and minute hands 8 and to control them separately from the comparator 10; in order to enable a quick adjustment of the position of the hands 8 without having to rotate the second hand 18 unduly quickly via a gear coupling. Such separate motors 16 also make it possible to select the minute or even the hour hand 8 as the reception indicator pointer; in this case, the function of the switching device 19 would include separating the indicator motor 16 from the received pulse train 6 and applying the time-keeping pulse train 25 to the clock drive circuit.

Claims (5)

1. A radio-controlled clock, which is equipped with a self-sufficiently working time-keeping mechanism (26), as well as with a display mechanism for items of absolute time information received by radio, in which respect this display mechanism comprises a stepping-motor-operated time display with at least one hand for the representation of the time of day, which is correctable by the absolute items of time information received by radio, by there being obtained from the actually received absolute items of time information by demodulation a pulse train (6) and from this by decoding a signal representing the actual absolute item of time information, in which respect this pulse train (6) obtained by demodulation from the said actually received items of time information has missing or interrupted pulses if disturbed reception conditions prevail, characterised in that a stepping motor (16) of the said stepping-motor-operated time display for the movement of one of the said hands of the display mechanism upon commencement of operation of the clock is controllable by the pulse train (6) obtained by demodulation from the said actually received items of time information and after that, when at least one actual absolute item of time information has been decoded, from pulses (25) of the self-sufficiently working time-keeping mechanism (26), in which respect first of all after commencement of operation the hand movement tracing back to this pulse train (6) obtained by demodulation from the said actually received items of time information but still not decoded serves as reception indication for the disturbed or else the normal reception of the said absolute items of time information.
2. A radio-controlled clock according to patent claim 1, characterised in that the said one hand serving for the reception indication is the seconds hand (18) of the display mechanism.
3. A radio-controlled clock according to patent claim 1, characterised in that the said one hand serving for the reception indication is a hand of the display mechanism which is normally not moved in the seconds rhythm.
4. A radio-controlled clock according to one of the preceding patent claims, characterised in that a switch-over mechanism (19) is provided, which upon commencement of operation of the clock switches through the pulse train (6) obtained by demodulation from the said actually received items of time information to that stepping motor (16) the hand of which serves for the reception indication, until a decoding circuit (7) for decoding of the actual absolute item of time information contained in the pulse train (6) sets the switch-over mechanism (10) back onto stepping-motor control from the self-sufficiently working time-keeping mechanism (26).
5. A radio-controlled clock according to one of the preceding patent claims, characterised in that the said stepping motor (16) of the hand which is intended for the reception indication is connected between the inverted outputs of a bistably working reversing circuit (14) which is controllable alternatively with the pulse train (6) obtained by demodulation from the said actually received items of time information or else with a train of pulses (25) from the self-sufficiently working time-keeping mechanism (26).

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