Note: Descriptions are shown in the official language in which they were submitted.
I 1~7619
This invention relates to a method of and a device for
adjusting a clock by a time mark. The clock can be a digital clock
or a clock indicating in quasi-analog manner with the help of a
stepping motor, and that -- apart from the first installation or
a service -- it never needs an adjustment, even after a long opera-
tional period during which a time mark is missing, and does not
have a distinguishable speed- or rate deviation. The clock according
to this invention works accurately under extreme interference and
is power-saving.
The term "self-contained" radio-clock in this disclosure
means an automatically working radio-clock which is independent of
a manual adjusting process. The term "time mark" denotes a part
of a modulation envelope that is transmitted by wire or wirelessly
to indicate the time reference signal given by a transmitter.
The term "radio-cloçk" denotes a clock receiving the time
mark.The term "clock radio" denotes a clock with a radio set.
The known methods of adjusting radio-clocks can be divid-
ed into three categories: l. synchronization, 2. triggering,
3, demodulation and direct indication of a coded time information.
For all these methods there are numerous variations and circuits
including the necessary backup time, and a great number of publi-
cations are available. The first category includes analog or
digital clocks whose internal time base is constantly or partly
corrected in relation to a received reference frequency by means
of automatic frequency control or phase comparison, as e.g. describ-
ed by Tetzner, Karl: "Funksynchronisierte Uhren" in: Funkschau
1976, vol. 15, p. 623 (Franzis-Verlag M~nchen, Federal Republic
of Germany) or by Marti, Raymond: "Selbsttatige und fortlaufende
Zeiteinstellvorrichtung einer Uhr'l in German published patent
application (Auslegeschrift) DE-AS 1,773,406. There are also
applications known that derive the time base of the clock from
.~ ~
6 ~ 9
1 the carrier frequency of one (or several) transmitter(s). In
this case an additional change-over to a second time base is re-
quired (backup time), as described by Schreiber, Herrmann:
"Steuerung einer Gebrauchsuhr durch Zeitzeichensender" in Funk-
schau 1977, vol. 2, p. 96 and vol. 3, p. 137 (Franzis-Verlag
Munchen, Federal Republic of Germany). The second category in-
cludes digital clocks that work independently with a varying
amount of accuracy and that are set at nominal value at a fixed
time (mostly 0 o'clock) by means of a time mark, as e.g. describ-
ed by Beck, J.: "Korrekturautomatik f~r Digitaluhren" in Elektor
1974, vol. 7, p. 79 (Elektor Verlag GmbH Gangelt, Federal Republic
of Germany). The third category divides into two methods: 3.1
the time code transmitter is constantly received, as e.g. describ-
ed by Weiss, Reinhard: "Uhrzeit- und Norma'frequenzempfanger f~r
DCF 77 mit Gangreserve" in: Funkschau 1976, vol. 22, p. 964
(Franzis-Verlag M~nchen, Federal Republic of Germany), 3.2 the
ti~ code transmitter only temporarily serves for adjusting the
radio-clock, as e.g. described by Prof. Dr.-Ing. Hilberg, Wolfgang:
"Funkuhr-Einstellung" in the published German patent application
(Offenlegungsschrift) DE-OS 2,715,096: in this case, the switch-
ing-on of the receiver is dependent on the rate of the clock, and
the exceeding of the backup time is indicated; or the method of
Mukaiyama, Fumiakai, Suwa, Nagano: "Automatisches Korrekturverfahren
fur eine elektronische Uhr", according to the published German
patent application (Offenlegungsschrift) DE-OS 2,539,224, where
the codedly transmitted time information serves as correction value
for the digital clock at optional instants. The third category
also includes receivers, e.g. television sets, that are not radio-
clocks primarily but indicate the correct time after pressure on
a push-button, as e.g. developed by AEG-Telefunken and described
-- 3 --
1 1 67~9
1 in the magazine "Elektrotechnik" vol 6, 1972, p. 29 (Vogel-Verlag
KG, Wurzburg, Federal Republic of Germany) and under the title:
"Kunftig nur noch Atomzeit". Parallel to these there are various
time measuring methods that define the rate of a clock by means
of a transmitter signal and eliminate it by special provisions,
as e.g. described by Maire, Bernard, Marin: "Elektronisches Zeit-
messgerat mit automatischer Korrektur der Gangabweichung" in the
published German patent application (Offenlegungsschrift) DE-OS
2,851,223; in this case, the rate of a clock in second steps is
manually measured by means of a time mark over a long time interval,
and then stored; the clock automatically corrects its stored rate
within the next, same time intervals as long as a new correction
invitation is signalized to the set user.
The methods mentioned have different advantages and dis-
advantages of which only the disadvantages to be emphasized are
enumerated here: as to the 1st category: relatively long turn-on
time of the receiver, which raises the susceptibility and the re-
quired energy; relatively short backup time; no self-contained
operation in the original sence. As to the 2nd category: re-
latively inexact time indication after a longer missing time mark,because the rates of the subsequent, not corrected time intervals
add up continuously; triggering is at 0 o'clock (counter reset)
which makes it impossib~e to tune out interferences occurring
regularly at that time. As to the 3rd category: a time code
transmitter with a sufficient field intensity must be receivable
which presupposes relatively elaborate and expensive receiving
devices; the decoder circuits are relatively elaborate; the
mounting of quasi-analog indicating clocks is not possible. Be-
sides the manual operation, the aforedescribed time measuring
method has the disadvantage that the rate of the clock reaches a
~ 1 ~7649
1 relatively high value before correction begins.
A general object of the present invention is to over-
come the aforementioned disadvantages. More particularly, an ob-
ject of this invention is to provide a fourth category of radio-
clocks which presents a combination of a time measuring method
for the rate of the clock with an automatic adjusting process
typical for radio-clocks, the result of which is a self-contained
operation.
According to the method of this invention, the rate
deviation of the clock is measured both as to its magnitude and
its direction by means of a time mark with defined equal time in-
tervals, the deviation is stored and then used for the correction
of the rate and the oscillator frequency of the clock. The turn-
ing-on of the time signal receiver, the fixing of the lock-in
range for the time mark, as well as the decoding of the time mark
is also performed by this oscillator frequency. In spite of a
very short turn-on time of the time-signal receiver, the lock-in
range must be chosen wide enough to ensure that the time mark is
within the limit value, even under the worst operational condi-
tions. After a missing time mark, a false measurement and falsecorrection is inhibited. In this case, the aforementioned correc-
tion is performed with the latest values stored, the result of
which is a high backup time. Furthermore, the method has been
worked out to be ~pplicable for various clock installations. In
this case, the master clock can, among other things, be regarded
as amplifier stage for the time mark, providing all slave clocks
with an amplified time mark. Provided that there is a uniform
time-signal transmitted by all radio and TV stations, time code
stations and master clocks, the time-signal receiver can auto-
matically adjust to the transmitter with the highest field in-
1 1 67649
1 tensity, and can select another transmitter after repeated miss-
ing time mark. Likewise a displacement of the time-signal receiv-
er into commercial radio and TV sets is possible, so that the al-
ready existing receiving device can be used by the radio-clock as
well.
The invention presents the following advantages:
1. the maximum rate can be kept smaller than the display resolu-
tion; 2. the backup time is very high; 3. the method can be
applied to digital clocks as well as to quasi-analog indicating
clocks; 4. the time-signal receiver is turned on periodically for
very short moments, the result of which is a very high freedom
from interference and 5. energy economy; 6. the correction of the
indicated value need not necessarily be at 0 o'clock; 7. the method
can be applied to clock installations; 8. at the clock manufactur-
ing the oscillator alignment can be avoided.
Provided a uniform time-signal which can be established
and transmitted by far less problematically than a coded time
information, further advantages can be provided: 9. the decoder
circuits are laid out comparatively simple and can be produced in
large numbers of pieces; 10. it is possible to displace the time-
signal receiver into commercial radio and TV sets, so the already
existing receiving device for this equipment can be useful for the
radio-clock as well moreover the radio-clock can be produced more
cheaply; 11. the time-signal receiver can be produced less expensive-
ly than a receiver for coded time information because 11.1 a larger field
intensity can be counted on (receiver locks in place to transmitter with
highest field intensity); 11.2 the decoder circuit is more simple;
11.3 higher demodulation distortion is admissible; 11.4 the power
supply can be smaller.
I 1 67649
1 - The novel features which are considered characteristic
for the invention are set forth in particular in the appended
claims. The invention itself, however, both as to its construc-
tion and its method of operation, together with additional objects
and advantages thereof, will be best understood from the following
description of preferred embodiments when read in connection with
the accompanying drawing.
FIG. 1 shows in a flow chart the method of this inven-
tion;
FIG. 2 shows in a block diagram the functional sequence
of FIG. l;
FIG. 3 shows the time diagram of the indication correc-
tion;
FIG. 4 shows a block diagram of the time-signal receiv-
er;
FIG. 5 shows schematically a complete concept of the
radio-clock according to this invention;
FIG. 6 shows the application of the time-signal receiv-
er in commercial radio and television sets;
FIG. 7 shows the principle of function of a clock in-
stallation according to the invention;
FIG. 8 shows schematically another embodiment of the
clock installation according to the method invented; and
FIG. 9 shows an example of an appropriate time-signal
for the method of this invention.
The flow chart in FIG. 1 shows the time sequence of the
most important signal conducting lines of the block diagram in
FIG. 2. These signal conduits are denoted by encircled reference
numerals corresponding to thoee in FIG. 2. This block diagram is
intended merely for illustrating the function of this invention
~ ~ 67~'~9
1 and in practice is substituted by a computer program. The rate of
the clock 49 is determined by the frequency stability of the os-
cillator 30. In order to measure this rate, a comparison with a
supposedly "correct" time interval must be possible. As there is
no absolutely correct time scale, the basis for clock applications
has to be the legal time transmitted by non-uniform time-signals by
radio and television stations and time code transmitters. The
following disclosure supposes, however, that a uniform automatical-
` ly evaluable time-signal is transmitted by all radio and television
stations, so that the method described here can fully take effect.
The clock is put into operation by means of the switch f
that turns on the start automatic 48 and the time-signal receiver
45. In case the clock is in operation it can be stopped by means
of the stop-pushbutton e. For quasi-analog indication clocks, the
hand setter is set to the time reference or held at that position.
The next time mark 3 or 5 gets into the clock via the start auto-
matic 48 and adjusts all registers -- according to the time re-
ference given -- to the desired value, and starts the time counter.
Now the clock 49 works automatically without any influence of the
transmitter with the accuracy of its quartz-oscillator until the
arrival of the subsequent time mark 3 or 5. Parallel to the first
time mark 3 or 5 received, the quiescent is produced via the reset
; path of the start automatic: the flip-flop 47 is reset via the
OR-gate 41~ which interlocks the time mark output of the AND-gate
46; the clock counter 40 is brought to 0 and the flip-flop 38 is
brought to a rest position via an OR-gate 36, so that clock signal
1 cannot get into a clock counter 40 via an AND-gate 39; a switch-
ing-on stage 43, 44 of the time-signal receiver 45 is brought to
the "off"-position via an OR-gate 35; further, the registers in
the adjusting logic 31 are set to the desired value, and the con-
-- 8
1 3 67649
1 ten~s of the memory for sign 23 and of the memory for difference
time 26 are brought to 0. A short time later~ the time-signal
receiver 45 and the start-automatic 48 are turned off by means of
the switch f which ends the start. A temporal preselection signal
1 of the clock 49 turns on the time-signal receiver 45 via the
switching-on stage 43, 44, (e.g. after 23 h. / 59 min. / 50 s.)
and opens the AND-gate 39 by means of the flip-flop 38, so that
clock signal 1 can get into the clock counter 40. The next in
time signal 2 is given by the clock counter 40, and releases the
time mark output of the time-signal receiver 45 via the flip-flop
47 and the AND-gate 46, resets the registers in the difference
time measuring stage 24 and in the priority logic 21, and releas-
es via the AND-gates 22, 25 the carry of information from prior-
ity logic 21 and difference time measuring stage 24 to the memory
for sign 23 ane the memory for difference time 26. The priority
logic 21 now accepts the time mark 3, 5, or the periodic pulse 4
from the clock counter 40. In case the periodic pulse 4 arrives
before the time mark 5, thereiis a positive sign in the priority
logic 21 (the signàl for the memory for sign e.g. has the poten-
tial H); in the opposite case, there is a negative sign by difini-
tion (the signal for the memory for sign e.g. has the potential L).
At the arrival of the 1st signal 3 or 4, the difference tim
measuring stage 24 is started by the priority logic 21 whereby
counting pulses of clock signal line 2, leading from the clock
counter 40 to the difference time measuring stage 24 and to the
correcting stage 27, are counted and determine the resolution of
the time measuring stage for the rate of the clock 49. The differ-
ence time measuring is then ended by the last arriving signal 4
or 5 via the path of priority logic 21. The signal 7 of the clock
counter 40 then interlocks the time mark 3, 5 via OR-gate 41,
_ g _
I 1 67~9
1 flip-flop 47, and OR-gate 46. The next output 8 of the clock
counter 40 turns off the time-signal receiver 45 via OR-gate 35,
flip-flop 43, and OR-gate 44, and with the same signal 8 trans-
mits the measuring values from priority logic 21 and difference
time measuring stage 24, via the OR-gates 22, 25 into the memory
for sign 23 and the memory for difference time 26. When these
data are stable at the correction stage 27 and have been evaluat-
ed, the correction can be initiated from the clock counter 40 via
the signalling line 9. The indication correction is performed by
means of the pulse stage (1) 29, pulse stage (2) 33, and the OR-
gate 37 in a way that the rate values stored in the memory for
sign 23 and the memory for difference time 26 are cancelled. Here-
by the pulse stage (1) 29 converts clock signal 1 (FIG. 3a) of the
oscillator 30 into a square-wave of the impulse ratio 4 (FIG. 3b).
In normal operation, this square-wave reaches the clock 49 as a
clock signal via the OR-gate 37 and the noise filter 42. If,
according to the measurement result, the clock 49 is fast, the
latter clock signal is inhibited by the correction stage 27 via
the OR-gate 28 in the pulse stage (1) 29, until the measured rate
is compensated. If, according to the measurement result, the
clock is slow, a center pulse relative to the clock signal (FIG.
3c) is released by the correction stage 27 via the OR-gate 32, in
the pulse stage ~2) 33 whereby the aggregate signal with the im-
pulse ratio 2 (FIG. 3d) reaches the clock 49 via the OR-gate 37
until the measured rate is compensated. Parallel to the indica-
tion correction it is advisable to perform the oscillator correc-
tion, e.g. the digital correction, as described by Dipl.-Ing.
Gollinger, Wolfgang, in: "Elektronische ~uarzuhr mit integrieten
Schaltungen" in published patent application (Offenlegungsschrift)
DE-OS 2,362,470 of December 15, 1973 and schematically illustrated
-- 1 0
~ ~ 67~-~9
1 in FIG. 5. The correction stage calculatingly counteracts to
the rate of the clock 49 in this oscillator path, so that there
is a closed control loop. The end of all correction processes
is :indicated by the correction stage 27 by means of a signal 10
which effects the reset of the clock counter 40 and the flip-
flop 38 via the OR-gate 36. In the event of a missin~ time mark,
the counter in the difference time measuring stage 24 reaches its
maximum value and sets the flip-flop 34 with its output or over-
flow 6. By this, the carry pulse 8 has no effect, so that the
following indication correction is performed on the basis of the
values lastly stored in the memory for sign 23 and the memory for
difference time 26. The oscillator correction is inhibited by
the flip-flop 34, so the automatic control system is interrupted
in order to preserve the high backup time. The signalling line
DST (daylight saving time) from the clock 49 to the adjusting
logic 31 presupposes a computer-regulated date clock. H-potential
corresponds e.g. to summer time, L-potential to winter time. The
potential variation on this signalling line produces the aimed
adjusting process of one hour respectively by means of the afore-
described method for indication correction. As this adjustingprocess takes a relatively long time, and the indication informa-
tion is incorrect during this time, the display resolution should
be one second in any case in order to make visually noticeable
the following information: the clock is too fast, or the clock is
not in operation. This signalling is sufficient for outsiders,
even without operating instructions, to disregard the display.
Pronest to interference is the time mark 3, 5, whose
signal line is subjected to a closer study. Interference pulses
outside the lock-in range (FIG. 1) have no effect whatsoever.
Interference pulses within the lock-in range only have an effect
-- 11 --
I ~ 67649
1 if they arise before the arrival of the time mark 3 or 5. In
this case, there is a high probability of a continuous interfer-
ence, i.e. a high probability of an interference impulse sequence
ranging over the whole lock-in range. ~ere, only the first in-
terference pulse being nearest to the bottom limit (FIG. 1) has
an effect. Hence it is simulated that the clock is slow. If,
during the automatic oscillator alignment, provisions are made for
the clock to be really slow, then the lock-in range -- in spite of
misinterpreted time marks -- will not shift too far even after re-
peated interferences. In other words: the time mark 3 is expect-
ed within the first half of the lock-in range; whereby the inter-
ference pulse has only little action time. It must be regarded
that the lock-in range with the periodic pulse 4 from the clock
counter 40 changes in relat~on to the time mark 3, 5, whereas the
time mark itself 3, 5 can be regarded as stationary.
FIG. 4 shows a detailed block diagram of the time-signal
receiver 45. The radio tuner 61 -- as described before -- has a
simple design. The transmitter tuning is controlled by voltage.
The receiver-microcomputer 68 automatically sets the radio tuner
61 to the transmitter of the highest field intensity after the
switching-on by the OR-gate 44 and the switchinq-on stage 64.
This is e.g. done by evaluating the AGC voltage supplied to the
receiver-microcomputer 68 via the amplifier 62 and via the A/D-
converter 66. First the computer program checks the whole receiv-
ed frequency range by means of the tuning voltage transformed by
the D/A-converter 65 and stores the respective AGC voltage values.
Then it locks the radio tuner 61 at the transmitter having the
highest field intensity in order to increase the probability of a
trouble-free reception. If, as is done now, the time-signal is
transmitted at nearly each full hour by all transmitters, there
- 12 -
t J ~64g
1 is the possibility -- in time information border areas -- of re-
ceiving an adjacent transmitter outside the time information
border, which is not possible with transmitted coded signals. The
receiver-microcomputer 68 can simply register a repeated missing
time mark, as it also has to perform the time mark decoding. In
this case, it searches the transmitter of the second highest field
intensity.
If the radio tuner 61 is to be used as a clock radio at
the same time, a changeover to manual tuning by means of the switch
g is advisable. The then tuned-in transmitter is now used as a
time mark transmitter as well. In this operating mode, the start-
automatic 48 must be interlocked via the OR-gate 69, and the re-
ceiver-microcomputer 68 must be changed over to a different soft-
ware loop. There may be the necessity of selecting the time mark
transmitter by manually tuning-in a certain transmitter (e.g. time
code transmitter). This transmitter selection can then be stored
by actuating the pushbutton h which ensures that the receiver-
microcomputer 68 will then automatically select this transmitter.
Pushbutton i can cancel this operatimg mode: if the program re-
gisters a 0 when sensing the memory location for the given trans-
mitter, it then selects the transmitter of the highest field in-
tensity. The time-signal LF to be decoded (FIG. 9) is amplified
by the amplifier 63 and becomes high enough to be used as square-
wave with defined logic levels. The flip-flop 67 improves the
decodability, as it halves the mark frequency, and provides an
exact impulse ratio of 2.
The application of the method of this invention for
clock installations is as follows:
The most simple and least expensive embodiment of a
clock installation according to this method includes a master
_ 13 ~
t 1 675.~9
1 clock according to FIG. 5, and quasi-analog indicating slave
clocks with stepp motors 82. The controlling of the slave clocks
is done by a single signalling line that leads the second step
with correction to each slave clock. So the installation of the
slave clocks is restricted to one twin wire -- without power
supply --, which recommends this method for applications where ex-
plosion hazards exist.
Similarly simpl~ is the embodiment of a clock installa-
tion according to FIG. 7. The master clock is worked out as in
FIG. 5, and so are the slave clocks; the latter, however, have no
time-signal receiver 45. The controlling of the slave clocks in
this embodiment is done by means of the time mark. As a conse-
quence, the slave clocks work trouble-free, need no adjustment
after a master clock failure (exploitation of high backup time)
and can be equipped with a digital display 81. Very often slave
clocks are installed in places hard to get at and exposed to ex-
treme environmental influences; so the service should be easy for
this type of clock in particular. As the method of this invention
presupposes a computer-directed clock anyway, it is possible, with-
out any additional elaboration, to provide for outputs for thedata exchange (the indicated value) via standardized interfaces
between master clock and slave clocks. FIG. 8 shows an example,
where the controlling of the slave clocks is done again by means
of the time mark, resulting in trouble-free operation with a high
backup time; moreover, there is the additional possibility of in-
dicating, in a central control station, the defective operation
of a slave clock by the cyclic checking of all slave clocks.
After a preformed service, a precision adjusting process derived
from the master clock is also possible. The requisite condition
for this process is the possibility of addressing each slave clock
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1 J 67649
1 from the master clock, and the simple setting and recognition of
the specific addresses in the slave clock. In accordance with
this invention, this problem can be solved comparatively easily
by means of thumbwheel switches 91 (FIG. 8). Then there is the
possibility of performing adjusting process for DST coming from
the master clock.
Adjustment at the transmitter end:
Automatic timing controls or readjustment steps for the
self-contained radio-clocks must be designed and dimensioned for
10 functioning under the worst operational conditions. A wide lock-
in range, however, means a susceptibility to disturbances and a
high amount of energy consumed by the clock, because the time-
signal receiver is turned on for a longer period of time. At the
present level of technology, excellent resonators can be produced
to keep the daily rate deviations of a clock low. The highest de-
viation arises at a time scale jump, i.e., at leap or switchover
seconds which a radio-clock must constantly take into account lest
they degrade the whole conception. Hence it is advisable to part-
ly depart from the method of leap seconds and to perform the
adaptation of the mean solar time to the average atomic time in
smaller time scale jumps. Advantageous is the splitting of the
leap into 8 (23) equal parts, that is 0.125 second steps which are
taken into consideration on 8 successive days before the calculat-
ed moment, the last calendar days of a UTC-month (UTC = Coordinat-
ed Universal Time), preferably at the end of June or December.
Here the general principle of the leap second internationally
agreed upon is kept up. If more than one time-signal is trans-
mitted per day (there should be 2 at least, displaced by 12 hours),
then a time scale jump in each time-signal of a time interval
(e.g. of one day) must be taken into consideration in the same way.
- 15-
I 1 6~tfi~9
1 Practical experience shows that one correction of the clock per
day is sufficient. In order to tune out periodically interfer-
ing transmitters regularly interfering at the same time of the
day it is advisable to fall back to a second time-signal. An-
other advantage of this is the independence of one particular
time of the day when putting the clock into operation for the
first time, or after a service. Hence all radio stations should
oblige to always transmit the uniform time-signal at two fixed
moments of the day displaced by 12 hours. From the various possi-
bilities for an appropriate time-signal granting an automatic
evaluation one solution has been worked out permitting the layout
of simple time mark decoders and coders, being acoustically notice-
able and having a duration of only 3 seconds (FIG. 9). The LF-
modulation frequency of 1000 Hz was chosen because in communica-
tion engineering it serves as reference frequency for many para-
meters, and moreover can be made audible. The chosen duration of
3 seconds in all is an advantageous compromise between unnecessar-
ily long (which means interference-prone) and too short (which
means insufficient selection from an optional LF-signal). It must
further be stressed that all decisive time intervals can be deriv-
ed by binary dividers from a usual "clock frequency", e.g. 215 Hz
or 222 Hz, for which sufficient resonators are available. This
advantage is valid for both the time mark coder and decoder cir-
cuits. The equally selected time intervals cooperate to a comput-
er evaluation, because then software loops or subroutines can be
applied.
It will be understood that each of the elements describ-
ed above may also find a useful application in other types of con-
structions differing from the types described above.
- 16 -
