U.S. patent number 3,628,153 [Application Number 04/885,401] was granted by the patent office on 1971-12-14 for receiving device for control information.
Invention is credited to Masayuki Fukata.
United States Patent |
3,628,153 |
Fukata |
December 14, 1971 |
RECEIVING DEVICE FOR CONTROL INFORMATION
Abstract
A receiving device for control information formed by a first
control signal and a second control signal transmitted after the
first signal and having a duration less than the duration of the
first signal, where the durations of received signals having the
same frequency as the control signals are measured to generate a
first output when the duration exceeds a predetermined time Ts and
to generate a second output when the duration exceeds predetermined
time Tc less than the time Ts. The duration of the first control
signal is longer than the time Ts, and the duration of the second
control signal is less than the time Ts and more than the time Tc.
A controlled circuit is triggered to and self-held in the
switching-in state in response to the first output and restored in
response to the second output.
Inventors: |
Fukata; Masayuki (Tokyo,
JA) |
Family
ID: |
14080714 |
Appl.
No.: |
04/885,401 |
Filed: |
December 16, 1969 |
Foreign Application Priority Data
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Dec 19, 1968 [JA] |
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43/93381 |
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Current U.S.
Class: |
455/231;
358/908 |
Current CPC
Class: |
H04H
20/89 (20130101); H04H 20/59 (20130101); H03G
3/005 (20130101); Y10S 358/908 (20130101) |
Current International
Class: |
H03G
3/00 (20060101); H04b 001/16 () |
Field of
Search: |
;325/55,392,64,395,364,478 ;343/225,228 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Richardson; Robert L.
Claims
What I claim is:
1. A receiving device for control information formed by a first
signal and a second signal transmitted after the first signal and
having a duration less than the duration of the first signal,
comprising:
selection means for selecting the control information from a
transmitted signal to convert it to at least one DC signal;
time-measuring means coupled to the output of the selection means
for generating a first output when the duration of the DC signal
exceeds a predetermined time Ts and for generating a second output
when the duration of the DC signal exceeds a predetermined time Tc
less than the time Ts, the duration of said first signal being
longer than the time Ts, the duration of said second signal being
longer than the time Tc and less than the time Ts;
first control means coupled to the output of the time-measuring
means for triggering a control circuit to the switching-in state
thereof in response to the first output and for holding the
switching-in state of the control circuit;
second control means coupled to the time-measuring means for
releasing the hold state of the first control means in response to
the second output; and
third control means coupled to the first and second control means
for checking the application to the first control means of the
second output until completion of said hold state of the first
control means.
2. A receiving device for control information according to claim 1,
in which the time-measuring means comprises two capacitors
respectively having a charging time constant corresponding to the
time Ts and a charging time constant corresponding to the time
Tc.
3. A receiving device for control information according to claim 1,
in which the time-measuring means comprises a capacitor, first
detecting means for generating the first output when the charged
voltage of the capacitor reaches a predetermined first voltage
after the time Ts starting from the start of the first control
signal, and second detecting means for generating the second output
when the charged voltage of the capacitor reaches a predetermined
second voltage less than the first voltage after the time Tc
starting from the start of each of the first and second control
signals.
Description
BACKGROUND OF THE INVENTION
This invention relates to receiving devices used in a system for
controlling, from the sending side, the receiving side in a
broadcast system, such as (1) an emergency broadcast system for
transmitting emergency information, such as information of a
natural disaster etc., from the broadcast station to the receivers,
(2) a recorder-control broadcast system for causing recorders of
the receivers, such as tape recorders, to record the broadcast
information in accordance with the control of the broadcast
station, or (3) a broadcast system for a control signal transmitted
to control the switch operation of each of various kinds of
apparatus at the receiving side.
In these prior art system, a device at the receiving side is
automatically triggered by a control signal transmitted from the
sending side. However, restoration to the standby condition on the
device of the receiving side is usually performed by manual
operation (hereinafter referred as "semicontrol system"). If the
customer of the receiving set is absent, the receiving set of the
semicontrol system remains in an unmuted condition after completion
of a desired operation. This will cause unnecessary power
consumption or unnecessary loud noise from the speaker which is
uncomfortable to the neighborhood. This defect tends to prevent
popularization of the broadcast system of this type.
To eliminate the above difficulty, another prior art system has
been proposed in which the triggered device of the receiving side
is automatically restored by the control from the sending side
(hereinafter referred as "full-control system"). In this
full-control system, two control signals having different
frequencies from each other are employed. Two control signals A and
B are simultaneously transmitted to the receiving side. The
received control signals a and b are applied to an AND gate, so
that a desired control is effected at the output of the AND gate.
Thereafter, one of the two control signals a and b is ceased while
the other is further transmitted without interruption to hold the
triggered condition of the controlled device. When the other of the
two control signals a and b is ceased, the controlled device is
restored to the initial condition. However, if this full-control
system is applied to an emergency broadcast system, coexistence of
the broadcast program and one of the signals a and b is offensive
to the ear. To avoid such discomfort, the modulation rate of the
carrier in transmitting the two control signals a and b is reduced
as low as possible. This causes deterioration of the reliability of
the control operation of this full-control system. With respect to
some of receiving sets, normal triggering and normal restoration in
these receiving sets will not be performed at all.
An object of this invention is to provide receiving devices free
from the above defects.
The principle of this invention will be understood from the
following detailed discussion taken in conjunction with the
accompanying drawings, in which the same or equivalent parts are
designated by the same reference numerals, characters, and
symbols.
BRIEF DESCRIPTION OF THE DRAWINGS:
FIG. 1 is a block diagram for illustrating an example of
conventional receiving devices used in the broadcast system for
control information;
FIG. 2 is a block diagram for illustrating an example of
conventional sending devices used in the broadcast system for
control information;
FIG. 3 is a block diagram for illustrating the theory of operation
of this invention;
FIG. 4 shows time charts explanatory of the operation of some
embodiments of a control device; and
FIG. 5 and 6 are each block diagram for illustrating an actual
embodiment of one control receiving device.
To afford a better understanding of this invention, a conventional
broadcast system for control information will first be
described.
FIG. 1 is an example of a receiving set which comprises a receiving
antenna 1, receiver 2 receiving a transmitted signal from the
antenna 1 and amplifying the received signal and further
demodulating the received signal, a control signal detector 5 for
detecting a transmitted control signal from the received and
demodulated signal, a switch 6 controlled by the output of the
control signal detector 5, an amplifier 3 amplifying the
demodulated signal obtained at the output of the receiver 2, and a
speaker connected to the output of the amplifier 3. In this
receiving set, the switch 6 is opened in the normal case, so that
the speaker 4 is muted. When a control signal is transmitted from
the sending side of the broadcast system, it is detected by the
control signal detector 5, so that the switch 6 is closed and the
broadcast program transmitted after the control signal can be heard
from the speaker 4.
FIG. 2 is an example of the sending side of the broadcast system to
control the receiving sets as shown in FIG. 1. Broadcast program
signals are applied from a terminal 13. A control signal generator
14 generates a predetermined control signal. The control signal
generated from the control signal generator 14 is applied to the
transmitter 11. The output of an amplifier 12 amplifying the
broadcast programs supplied from the terminal 13 is also applied to
the transmitter 11. The output of the transmitter 11 is connected
to an sending antenna 15. When a program is to be transmitted to
the receiving sets, the control signal is at first transmitted to
unmut the receiving sets and then the broadcast program is
thereafter transmitted.
With reference to FIGS. 3 and 4, the principle of this invention
will be described. Means 1, 2, 3, 4 and 6 other than the control
signal detector 5 are the same as those in the receiving set shown
in FIG. 1. The control signal detector 5 comprises three means A, B
and C in accordance with this invention. The means A comprises a
narrow band pass filter BPF for selecting a signal of a
predetermined single frequency from the output W.sub.1 of the
receiver 2 and a recifying circuit RECT for converting them to a DC
pulse signal W.sub.2. The means B comprises a time-counting circuit
TM.sub.1 and a time-counting circuit TM.sub.2. The time-counting
circuit TM.sub.1 measures the duration of the DC pulse signal
W.sub.2 obtained from the means A so that a first output W.sub.3 is
present when the duration of the DC pulse signal W.sub.2 exceeds a
predetermined time Ts. The time-counting circuit TM.sub.2 measures
the duration of the pg,6 DC pulse signal w.sub.2 obtained from the
means A so that a second output w.sub.4 is present when the
duration of the DC pulse signal w.sub.2 exceeds a predetermined
time Tc less than the time Ts. The means C is a control circuit for
switching-in the switch 6 in response to the first output w.sub.3
and for switching-off the switch 6 in response to the second output
w.sub.4 generated after the termination of the first output
w.sub.3. Accordingly, the switch 6 is held in the ON-state in a
time from the termination of the first output w.sub.3 to the start
of the second output w.sub.4.
The operation of the control signal detector 5 shown in FIG. 3 will
be further described with reference to FIG. 4. A first mark
w.sub.11 of the signal w.sub.1 is transmitted to switch-in the
switch 6, and a second mark w.sub.12 of the signal w.sub.1 is
transmitted to switch-off the switch 6. The mark w.sub.11 for
switching-on the switch 6 has a duration longer than a
predetermined time Ts. The mark w.sub.12 for switching-off the
switch 6 has a duration longer than a predetermined time Tc but
shorter than a predetermined time Ts which is longer than the time
Tc. As understood from FIG. 4, when the first mark w.sub.11 is
transmitted, the time-counting circuit TM.sub.2 generates the
second output w.sub.41 after the time Tc from the start of the
first mark w.sub.11. However, the control circuit is designed so
that the switch 6 is not switched-off in response to the second
output w.sub.41. This will be clear from actual embodiment
described below.
With reference to FIG. 5, an example of the control signal detector
5 is described. The above-mentioned means A, B and C are designated
by dotted enclosures. The operation of this example is as follows.
When the first mark w.sub.11 is transmitted to cut off a transistor
TR.sub.2 and the duration of the output w.sub.2 of the means A
exceeds the time Ts determined in accordance with a product of
values of a resistor R.sub.2 and a capacitor C, a voltage charged
in the capacitor C through the resistor R.sub.2 from a source +Vc
is discharged through a path comprising a resistor R.sub.3 and a
transistor Tr.sub.3. Accordingly, a relay RY is energized so that
contacts ry.sub.1 and ry.sub.2 are closed. In response to the close
of the contact ry.sub.2, the receiver 2 and the amplifier 3 are
connected to each other. Accordingly, program information
transmitted after the control signal (w.sub.11) can be heard from
the speaker 4. On the other hand, the charging time constant of a
capacitor Ca determined in accordance with a product of values of a
resistor R.sub.2a and the capacitor Ca is smaller than the charging
time constant Tc of the capacitor C. Accordingly, transistors
Tr.sub.4 and Tr.sub.5 are respectively turned on and off before the
above-mentioned turn on of the transistor TR.sub.3. This means that
the hold of the relay RY is maintained through the turned-on
transistor TR.sub.3 since the transistor TR.sub.5 is cut off.
However, when the first mark w.sub.11 is terminated, the charged
voltage of the capacitor Ca is suddenly discharged through a
turned-off transistor TR.sub.2a so that the hold circuit of the
relay RY is maintained by a path through the contact ry.sub.1 and
the transistor TR.sub.5. In this case, the charged voltage of the
capacitor C is also discharged through a resistor R.sub.5 and a
transistor TR.sub.2. However, since the discharging time constant
of the capacitor substantially determined in accordance with a
product of values of the capacitor C and the resistor R.sub.5 is
larger than the discharging time constant of the capacitor Ca
determined in accordance with a product of values of the capacitor
Ca and the transistor TR.sub.2a, the transistor TR.sub.5 becomes
conductive before turnoff of the transistor TR.sub.3. Accordingly,
the hold of the relay RY are continuously maintained. This hold of
the relay RY can be maintained by the use of a slow-releasing relay
as the relay RY.
When the second mark w.sub.12 more than the time Tc and less than
the time Ts is transmitted and received, the transistor TR.sub.4
becomes conductive after the time Tc starting from the start of the
second mark w.sub.12 while the transistor TR.sub.3 is remained in
the cutoff state. Therefore, the transistor TR.sub.5 is turned off
so that the seld-hold of the relay RY is released. In response to
this release of the relay RY, connection between the receiver 2 and
the amplifier 3 are cut off. This is the standby condition for
receiving a next control signal.
With reference to FIG. 6, another actural example of the control
signal detector 5 is described. In this example, the means B
comprises a single time-counting circuit. However, the start to
turn on of the transistor TR.sub.3 is determined so that the turn
on of the transistor TR.sub.3 starts when the charged voltage of
the capacitor C reaches a voltage v.sub.1, while the start to turn
on of the transistor TR.sub.4 is determined so that the turn on of
the transistor TR.sub.4 starts when the charged voltage of the
capacitor C reaches a voltage v.sub.2. In this case, the voltage
v.sub.1 corresponds a voltage charged in the capacitor C in the
time Ts starting from the start of the first mark w.sub.11. The
voltage v.sub.2 corresponds to a voltage charged in the capacitor C
in the time Tc starting from the start of the first mark w.sub.11
or the second mark w.sub.12.
In addition to the above-mentioned analogue technique, digital
technique or mechanical relays may be adopted to form the means B.
Moreover, the relay RY of the means C may be replaced by an
electronic circuit, such as flip-flop circuit, or by another
electronic switching circuit.
In the above examples, it is assumed that the control signal
consisting of two mark signals w.sub.11 and w.sub.12 has the same
frequency. However, these two mark signals w.sub.11 and w.sub.12
may have respectively different frequencies from each other. In
this case, the means A must be provided two combinations each
comprising the filter BPF and the recifying circuit RECT. Moreover,
the means B is designed as shown in FIGS. 3 and 5.
As mentioned above, correct triggering for a controlled circuit,
such as the switch 6, an amplifier 3 and the speaker 4 shown in
FIG. 3, and restoration to the standby state for control
information of the control circuit can be performed without
spurious operation in accordance with this invention.
If false signals similar to the control signal and included in the
transmitted broadcast program signal are eliminated by the use of
technique proposed in my U.S. application for patent, Ser. No.
701,031 filed on Jan. 4, 1968, and now U.S. Pat. No. 3,566,270,
reliability of in transmitting the control signal will be risen
further.
The above examples relate to receiving devices used in an emergency
broadcast system. However, it will be readily understood that the
devices of this invention can be applied to other control systems,
such as control of a tape recorder connected to a receiver or
control of a switch or switches of a device provided at the
receiving side.
* * * * *