U.S. patent number 3,806,872 [Application Number 05/358,862] was granted by the patent office on 1974-04-23 for address interrupt and current status display.
This patent grant is currently assigned to Avco Corporation. Invention is credited to James T. Odom.
United States Patent |
3,806,872 |
Odom |
April 23, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
ADDRESS INTERRUPT AND CURRENT STATUS DISPLAY
Abstract
A signaling system located at a central station sequentially
interrogates a plurality of remotely located transponders. Means
are provided for interrupting the normal addressing sequence and
for interrogating any particular remote station, and for then
displaying the current status of such station.
Inventors: |
Odom; James T. (Huntsville,
AL) |
Assignee: |
Avco Corporation (Huntsville,
AL)
|
Family
ID: |
23411349 |
Appl.
No.: |
05/358,862 |
Filed: |
May 10, 1973 |
Current U.S.
Class: |
340/3.51;
340/505; 340/521; 340/518; 340/10.6; 340/10.31; 340/3.7; 340/3.62;
340/12.1 |
Current CPC
Class: |
G08B
26/002 (20130101); H04Q 9/14 (20130101) |
Current International
Class: |
H04Q
9/14 (20060101); G08B 26/00 (20060101); H04q
009/00 (); G08b 029/00 () |
Field of
Search: |
;340/152T,147R,163,167A,167R,409 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Yusko; Donald J.
Attorney, Agent or Firm: Hogan; Charles M. Garfinkle; Irwin
P.
Claims
I claim:
1. In a signaling system having a central station and a plurality
of remote stations, said central station having means for
sequentially transmitting time coded address signals to each of
said remote stations in a pre-established sequence, each of said
remote stations transponding to said central station upon receipt
of a respective time coded address signal, the combination
comprising:
a fixed frequency oscillator having a fixed frequency output;
a gate having an output terminal and first and second input
terminals, said fixed frequency output being applied to the first
input terminal, said fixed frequency output being coupled to said
remote stations through the output terminal of said gate when said
gate is enabled, said gate being enabled when an enabling pulse is
applied to said second terminal, the duration of each enabling
pulse establishing said time coded address signals;
enabling pulse generating means for sequentially generating
enabling pulses of different durations, the output of said enabling
pulse generating means being applied to said second terminal;
a first plurality of duration determining means connectable into
said enabling pulse generating means for establishing the duration
of said enabling pulse;
sequential switching means for sequentially connecting each of said
duration determining means into said enabling pulse generating
means for establishing the durations of said enabling pulse in said
pre-established sequence;
a second plurality of selectable duration determining means;
means for interrupting said sequential switching means and for
substituting one of said selectable duration determining means for
transmitting a selected new time coded address signal; and
means after receiving a signal from a remote station transponding
to said selected new time coded address signal for continuing the
operation of said sequential switching means.
2. The invention as defined in claim 1 wherein said enabling pulse
generating means is a one-shot multivibrator.
3. The invention as defined in claim 2 wherein said first and
second pluralities of duration determining means are first and
second pluralities of resistors, said resistors being connectable
into the R-C network of said one-shot multivibrator for
establishing the duration of its output pulse.
4. The invention as defined in claim 3 wherein said sequential
switching means is an electronic switch having a stage for each of
said first plurality of resistors, each of said stages of said
switch sequentially establishing one of said connections in
response to an update pulse, said switch recycling to the first
stage after the last stage is disconnected.
5. The invention as defined in claim 4, and a second one-shot
multivibrator for generating an update pulse, the trailing edge of
the output of said first one-shot multivibrator triggering said
second one-shot multivibrator, said update pulse being connected to
said sequential circuit means for updating said switch.
6. The invention as defined in claim 5 wherein said means for
interrupting the updating of said sequential switching means and
for substituting one of said selectable duration determinging means
comprises:
a first normally closed switch for connecting the output from said
second one-shot multivibrator to said sequential switching means
for updating said sequential switching means;
a second normally closed switch connecting sequentially selected
ones of said first duration determining means into the R-C network
of said first one-shot multivibrator;
a third switch for connecting a selected one of said second
plurality of duration determining means, said second switch being
normally open;
means for opening said first and second switches and for closing
said third switch; and
means for subsequently closing said first and second switches and
for opening said third switch.
7. The invention as defined in claim 6 wherein an addressed remote
station transponds during the period of said update pulse;
and means during the period of said update pulse for displaying a
received signal from a remote station.
8. The invention as defined in claim 7 wherein said means for
displaying a received signal includes a gate having an output
terminal and first and second input terminals, said first input
terminal being supplied with decoded received signals, said second
terminal enabling said gate when supplied with a comparator
output;
a comparator having first and second inputs, said first input being
a manually selected numerically coded address, said second input
being supplied with a numerical coded address representing a
selected new time coded address signal, the output of said address
comparator being applied to said terminal of said gate and enabling
said gate when the numerical addresses in said comparator are in
coincidence.
9. In a signaling system having a central station and a plurality
of remote stations, said central station having means for
sequentially transmitting time coded address signals to each of
said remote stations in a pre-established sequence, each of said
remote stations transponding to said central station upon receipt
of a respective time coded address signal, said time coded address
comprising the combination including a fixed frequency signal
having a duration T1 followed by a space having a duration T2, in
turn followed by a fixed frequency signal having a duration T3,
durations T1 and T2 being variable in accordance with a program to
generate said time coded signals in said pre-established sequence,
said duration T3 being constant, the combination comprising:
a fixed frequency oscillator having a fixed frequency output;
a gate having an output terminal and first and second input
terminals, said fixed frequency output being applied to said first
input terminal, said fixed frequency output being coupled to said
remote stations through the output terminal of said gate when said
gate is enabled, said gate being enabled when an enabling pulse is
applied to said second terminal;
first, second, third and fourth serially connected one-shot
multivibrators, the trailing edge of the output pulse of each of
said multivibrators triggering a succeeding multivibrator, the
trailing edge of the output of said fourth multivibrator triggering
said first multivibrator, each of said multivibrators having an R-C
network, the duration of the output pulse of each multivibrator
being a function of the parameters of a respective R-C network, the
parameters of said third and fourth multivibrators being fixed, the
parameters of said first and second one-shot multivibrators being
sequentially alterable in accordance with said program, the
duration of the outputs of said first, second, and third one-shot
multivibrators being equal to T1, T2, and T3, respectively, the
output of the fourth one-shot multivibrator having a fixed duration
T4;
a first plurality of duration determining means connectable into
the R-C network of said first one-shot multivibrator for
establishing the durations of the output pulses therefrom;
a second plurality of duration determining means connectable into
the R-C network of said second one-shot multivibrator for
selectively re-establishing the durations of the output pulses
therefrom;
sequential switching means for sequentially connecting each of said
duration determining means of said first and second pluralities
into the R-C networks of said first and second one-shot
multivibrators in accordance with said program, said sequential
switching means being updated by said fourth one-shot
multivibrator;
a third and fourth plurality of selectable duration determining
means;
means for interrupting the updating of said sequential switching
means and for substituting one of said selectable duration
determining means of each of said third and fourth pluralities for
re-establishing a selected new time coded address signal;
means during the generation of the output pulse of said fourth
one-shot multivibrator for displaying a received signal from a
remote station; and
means after receiving a signal from said remote station
transponding to said selected new time coded address signal for
continuing the operation of said sequential switching means.
10. The invention as defined in claim 9 wherein said means for
interrupting the updating of said sequential switching means and
for substituting one of said selectable duration determining means
comprises;
a first normally closed switch for connecting the output from said
second one-shot multivibrator to said sequential switching means
for updating said sequential switching means;
a second normally closed switch connecting sequentially selected
ones of said first duration determining means into the R-C network
of said first one-shot multivibrator;
a third switch for connecting a selected one of said second
plurality of duration determining means, said second switch being
normally open;
means for opening said first and second switches and for closing
said third switch; and
means for subsequently closing said first and second switches and
for opening said third switch.
11. The invention as defined in claim 10 wherein an addressed
remote station transponds during the period of said update
pulse;
and means during the period of said update pulse for displaying a
received signal from a remote station.
12. The invention as defined in claim 11 wherein said means for
displaying a received signal includes a gate having an output
termianl and first and second input terminals, said first input
terminal being supplied with decoded received signals, said second
terminal enabling said gate when supplied with a comparator
output;
a comparator having first and second inputs, said first input being
a manually selected numerically coded address, said second input
being supplied with a numerically coded address representing a
selected new time coded address signal, the output of said address
comparator being applied to said terminal of said gate and enabling
said gate when the numerical addresses in said comparator are in
coincidence.
Description
BACKGROUND OF THE INVENTION
The invention involves a transponder security system of the type
disclosed in U.S. Pat. No. 3,634,824 and which includes a signaling
system having a plurality of remote stations and a central station.
The central station has the capability of interrogating the remote
stations in sequence, the address of the remote stations being time
coded into the interrogating pulse transmissions. In a practical
system, the time required to transmit 25 separate interrogations
requires 39 seconds. This invention provides means for interrupting
the normal sequence and interrogating a selected station,
displaying the response from the selected station, and then
continuing with the normal interrogating sequence.
THE DRAWINGS
FIG. 1 is a block diagram showing a transponder system in which the
disclosed invention is utilized;
FIG. 2 is a curve showing the nature of the coded transmitted
signal;
FIG. 3 is a curve showing the nature of the coded transpondered
signal;
FIG. 4 is a block diagram showing the interrupter system utilized
in accordance with this invention;
FIG. 5 is a schematic drawing showing certain of the details of the
interrupter circuits and the address selector circuits;
FIG. 6 is a series of curves showing the time relationships
occurring within the interrupt circuit; and
FIG. 7 is a block diagram showing the processing of the coded
transponded signals from the remote stations.
The overall system is shown schematically in FIG. 1. A central
station 10 sends to the remote station address. Each of the
particular remote stations 12 (of which there may be any number
within the time capabilities of the system) responds to a
particular interrogation by transmitting back to the central
station tone pulses of lengths that are determined by the status
and changes of status of the respective monitors 14 connected to
it. Having received the responses from the remote station, the
central station decodes the response, processes the information and
displays it in displays 16 in a manner described in U.S. Pat. No.
3,634,824.
The addresses of the remote stations are contained in a fixed
frequency signal of the type shown in FIG. 2. As shown, the central
station transmits a first fixed frequency signal having a duration
T1. This is followed by a space which occurs for a period T2. The
space T2 is then followed by another signal of the same fixed
frequency and having a time period T3 which is then followed by a
space having a period T4. The address of the remote station is
coded into the transmission by varying each of the time periods T1,
T2, and T3. The time period T4 is a fixed period during which the
remote station transponds. Theoretically the number of addresses
may be multiplied by adding additional time periods, all of which
may be variable. In a practical system, only the times T1 and T2
were variable to provide a combination of 25 addresses.
As indicated in FIG. 1, each of the remote stations may contain a
number of monitors. Certain of the monitors may, for example, be
arranged to detect the opening of a window, the breaking of a
window, the walking on a floor, a fire, or the opening of a door.
Each of these conditions is given a priority level. As shown in
FIG. 3, a remote station transmits a single frequency back to the
central station and it will have a duration determined by the
highest level alarm that is causing a transmission. The first
period t.sub.m of the transmission occurs at every interrogation to
give a positive indication that the transponder is operative. A
level 0 priority alarm has a duration t.sub.0, a level 1 priority
alarm will have a duration t.sub.1, and so forth, so that the
highest level alarm signal will dominate all transponded
signals.
When an indication appears at the central station that an alarm is
being transmitted by the remote station, it is desirable to
interrupt the normal sequence, and re-interrogate the station from
which an alarm is indicated and then display or otherwise read out
the particular cause of the alarm. The block diagram in FIG. 4
shows schematically how the addresses to the remote stations are
sequentially coded and transmitted, and also how the normal
sequence is interrupted.
The system includes a fixed frequency oscillator 20 which transmits
a signal to the remote stations whenever its associated AND gate 22
is enabled. The AND gate 22 is enabled only when it receives the
output from an OR gate 24 in addition to the output signal from the
oscillator 20.
To control the output from the OR gate 24, and therefore to permit
the introduction of the appropriate addresses for the remote
stations, a plurality of one-shots 26, 28, 30, and 32 are connected
in series, that is, the one-shots are arranged so that the trailing
edge of one triggers the next. The output of each of the one-shots
is a square wave having a duration determined by the time constants
which are set in. The one-shot 32, referred to as the response
one-shot, has a fixed time constant so that the duration T4 of its
output remains fixed. The time constants of the one-shots 26, 28,
and 30 are alterable, sequentially or manually, and the durations
of the outputs from these one-shots determine the time periods T1,
T2, and T3 shown in FIG. 2.
Under normal conditions, the time constants of the one-shots 26,
28, and 30 are changed by sequentially and cyclically introducing
different values of resistance into their respective R-C circuits.
This is accomplished by means of conventional sequential switching
circuits 34, 35, and 36.
The sequential switching circuits 34, 35, and 36 have a number of
stages, each one of which sequentially connects a different
resistor value into a respective one-shot R-C network through an
associated address selector circuit 38, 40, and 42. The update
clock for the sequential switching circuit 34 is the output pulse
from the response one-shot 32. After the last stage of the
switching circuit 34 is activated, the next update pulse resets it
to the first stage and updates sequential switching circuit 35.
Similarly, the resetting of the sequential switching circuit 35
updates the switching circuit 36. This means that if there are five
stations in each switching circuit, there is a possibility of
having 125 different addresses. In a system as reduced to practice,
there were five stages in the circuit 34 and five stages in the
circuit 35 and only a single stage in the circuit 36, so that a
total of 25 addresses were possible. The particular resistor
selected by the switching circuit 34 is connected into the one shot
26 through address selector 38, the resistor selected by the
circuit 35 is connected to one-shot 28 through the address selector
40, and the resistor selected by the switching circuit 36 is
connected into the one-shot 30 by the address selector 42.
The response one-shot 32 provides the update pulse for the
sequential switching circuit 34 through an interrupt circuit 44
hereinafter to be described along with the address selectors 38-42.
A particular address is manually set into the address selectors 38,
40, and 42 through address interrupt terminals 46, 48, and 50. The
interrupt circuit 44 and the address selectors 38, 40, and 42 are
shown in more detail in FIG. 5, to which reference is now made.
The address selectors 38, 40, and 42 are identical so that only
selector 38 and its associated switching circuit 34 are described.
Each of the address selectors includes an AND gate 52 having one
input terminal connected to the resistors R1-R5 selected by its
respective sequential switching cirucit 34, 35, and 36 for
connection into the R-C network of a selected one-shot. The other
terminal of AND gate 52 is connected to the Q output of a latch 54.
Under normal sequential operation the AND gate 52 is enabled by a
logical 1 on the Q output of latch 54, and an output is provided to
the associated one-shot through an OR gate 56.
The address selectors each includes a second AND gate 58 having one
input connected to the manually selected resistors R6-R10, any one
of which may be manually switched into the R-C circuit of its
associated one-shot. The other input terminal of of the gate 58 is
connected to the Q output terminal of the latch 54. Under normal
sequential operating conditions the Q output of latch 54 is at
logical 0, and the AND gate 58 is disabled. The latch 54 is a part
of the interrupt circuit 44 which also includes latches 60 and 62,
each of which has a Q output terminal. Under sequential operating
conditions the Q output of all the latches are set to a logical 0,
while the Q output of latch 54 is set to a logical 1. The pulse
from the response one-shot 32 is applied to the sequential
switching circuit 34 through a delay 64 and through the first
terminal of AND gate 66, the other terminal of which is enabled bt
the logical 1 appearing at the Q output of latch 54.
When it is desired to interrupt the sequential updating of the
switching circuit 34, an interrupt pulse is generated by the
circuit which includes a capacitor C1, resistors R11 and R12, and
an interrupt switch 68. The pulse generated by the discharging of
capacitor C1 sets the Q output of latch 60 to a logical 1
condition. The logical 1 at the Q output of the latch 60 enables
AND gate 70 for passing the output pulses from the response
one-shot 32 to a capacitor C2 which serves to provide a spike on
the trailing edge of the one-shot pulse for setting the Q output of
the latch 54 to a logical 1 and for setting its Q output to a
logical 0. The condition of the Q and Q outputs of latch 54
disables AND gate 52 and enables AND gate 58 so that one of the
manually preselected resistors R6-R10 is connected through the AND
gate 58 and the OR gate 56 to its respective one-shot 26.
The Q output of latch 54 is also applied through a delay 72 to
reset the Q output of latch 60 to a logical 0 and to set the Q
output of latch 62 to a logical 1. The output from latch 62 is used
to enable an AND gate 74 so that the pulse from the response
one-shot 32 resets latches 54 and 62 through a capacitor C3, which
serve to provide a pulse on the trailing edge of the next response
one-shot pulse. The resetting of the latches 54 and 62 returns the
central station to its normal addressing sequence beginning again
at the point where it was interrupted. The delay 64 is a short time
delay which is used for the purpose of preventing the pulse
generated by the response one-shot 32 from passing through gate 66
while latch 54 is being set.
The operation of the interrupt and address selector circuits is
summarized as follows: Momentary closing of the switch 68 causes
the discharge of capacitor C1 to generate a pulse which is used to
set the Q output of latch 60 to a logical 1. The Q output of latch
60 is gated with the pulse from the response one-shot 32 to set the
Q output of latch 54 to a logical 1 and its Q output to a logical
0. The capacitor C2 assures that the setting and resetting of latch
54 is on the trailing edge of the response one-shot pulse. This
interrupts the normal addressing sequence of the central station in
time for the generation of a manually selected address, and the Q
output of latch 54 is used to prevent the sequential switching
circuits from being updated by disabling gate 66.
The Q output of latch 54 is used to enable the manually selected
address through gates 58 and 56 while the Q output of latch 54
disables the normal address line at gate 52. The output at gate 56
represents the manually selected address and is used to control the
timing of the one-shot 26.
The Q output of latch 54 is applied through delay 72 to reset the Q
output of latch 60 back to a logical 0 and to set the Q output of
latch 62 to a logical 1. The Q output from latch 62 is used to
enable the AND gate 74 so that the next pulse from the response
one-shot resets latches 54 and 62 on the trailing edge. This means
that the normal sequencing circuits have been interrupted for one
complete cycle but are then free to return to their normal
sequencing.
The timing frequencies for the various latches are shown in FIG. 6.
It will be seen that the interrupt occurs during the period
T.sub.int, i.e., from the trailing edge of one response one-shot
pulse to the trailing edge of a succeeding one response one-shot
pulse.
Referring now to FIG. 7, the transponded signals from each selected
remote station are applied to a response receiving and decoding
circuit 80 which serves to provide a logical 1 or a logical 0
output on a particular line, depending on the code level
transponded by the remote station. Thus, if no signal is received
from the selected remote station, a logical 1 would appear on the
line labeled "missing;" otherwise if a signal of a duration
t.sub.m, as shown in FIG. 3 is decoded, a logical 1 would appear on
the "level 0" line, and so on through the "level n" line.
Each of the level lines m through n is connected to a first input
terminal of a respective one of a plurality of AND gates 82, 84,
86, and 88. The current status of the received signals from the
remote stations is determined by sequentially scanning these AND
gates. For this purpose a "missing status" one-shot 90, triggered
on the leading edge of the response one-shot pulse, is used to
enable AND gate 82. A "non-missing status" one-shot 92, triggered
on the trailing edge of the response one-shot pulse plus an
additional signal from a status level switching circuit 94 enables
AND gate 84. The status level switching circuit 94, enabled by the
leading edge of the output pulse of the one-shot 92 and updated
from level 0 through level n by means of a system clock 96,
sequentially enables AND gates 84, 86, and 88. The time for
generation of the current status output must, of course, occur
within one complete cycle of the transmitted and received
signals.
The current status appearing at the outputs of the AND gates 82-88
is applied to an output display 98 through an AND gate 100. The AND
gate 100 is enabled by an address-comparator 102 which develops an
enabling output signal whenever its two inputs, one from the
address selectors 38, 40, and 42 and the other manually selected
addresses set in at the terminals 104, 106, and 108 are identical.
The address-comparator may comprise two logic circuits, one which
is set by the outputs of the address selectors 38-42, and one which
is manually set in at the display. The comparator provides an
output when there is coincidence between the logic circuits.
As previously noted in connection with FIGS. 4 and 5, the output
from each address selector 38, 40, and 42 is a resistor R1-R5 or a
resistor R6-R10, depending on whether the sequencing is to be
interrupted. Thus, the AND gate 100 is enabled when the address
appearing in the address selectors coincides with that set in at
the terminals 104, 106, and 108. The display 98 is enabled when the
output from an information and coding circuit 110 is applied. The
information and coding circuit 110 sets up the timing for current
status which is displayed.
It will be apparent to persons skilled in the art that the
disclosed system is subject to various modifications and
adaptations, all within the scope of the invention. For example,
while three address selectors are shown, it is apparent that the
system will work with any number, depending on the number of
addresses required by the system and the amount of time sharing
which is permitted. In certain circumstances only one address
selector may be required.
Furthermore, while the system shown utilizes only four alarm levels
including a missing level, it is apparent that any number may be
used. While reference is made to a practical system having 25
addresses, it will be understood that in the embodiment as reduced
to practice, four remote stations at the same address are
transponded simultaneously but at different frequencies and that
the system has capabilities, not a part of this invention, for
separating and processing the information from four transponders
simultaneously.
* * * * *