Note: Descriptions are shown in the official language in which they were submitted.
21 92759
"A Co nication-system and ~ethod for Alarm Signal~
~ACKGROUND OF THE INvENTION
Field o~ the Invention
The in~e~tion relate~ to a communication system for
communication of alar~ information from subscriber alarm
systems to monitoring ~tations.
Prior Art Discussion
In many presently a~ailahle subscriber alarm systems
various sensor~ are conneeted to a control unit which
activates audio and visual outputs and transmits an aLarm
~ignal to a ~onitoring station when an alarm condition
arises. The signal is either a land-based or a wireless
telephony signal. The format u~ed depends on the nature
of the subscriber alarm system and also on the nature of
the monitoring station. In any one country there are
generally man~ different types of subscriber alarm sy~tems
and central monit~ring stations. Accordingly, ~any
different formats are used for data transfer to the
monitoring stations.
A basic problem which arise~ when the telephony signal is
transmitted via a land-based PSTN network is that burglars
can often gain access to the cables and cut them, thu~
breaking the ~onnection to the monitoring ~tation. The
obvious ~olution to overcome this problem is to uxe
~5 ~ireles~ communication ~uch a~ a cellular mobile telephone
network to communicate with the ~onitoring station.
Indeed, such an approach has been proposed in ~e~eral
documents including EP632635, US5004999, JP6253042 and
US4993059. In the sys~em described in VS4993059 there is
a conventional dial-up land-ba~ed path for communication
2 1 ~ 2 7 ~ 9
with a monitoring ~tation. The alarm ~ystem incl~des
detection circuitry which detects a failure of this path
and then uses a redundant path via a cellular tran~eiver.
The first outgoing transmi~sion includes only the mobile
identification num~er (MIN) and a serial number for the
transceiver. This establishes ~i-directional
communication with the monitoring station via the cellular
system in the conventional manner for voice communication.
Howe~er, with both land-ba~ed and ~ireless communication,
the alarm system may have difficulty in establishing an
ef fective telephony connec~ion to the monitorin~ station
becau~e the telephony network or the monitoring station
may be excessively busy or becau~e of a fault in the
telephony net~ork. A still further problem i~ the delay
often associated with establishing telephony connections.
Thus, with increasing sophistication of alarm sen~ors and
subscriber alarm systems it is increasingly the ca~e that
the telephony connection to the monitoring station is the
~weakest link" in the alarm system.
A further problem is that existing alarms ~y~te~s which
are de~igned for land-based communication may not be
easily modified for wireless communication. Further, the
system described in US~9930S9 requires use of detection
circuitry to monitor all stage~ of the land-based
communication path and activate the cellular c~mmunication
if this path fails. This cir~uitry adds to complexity
Indeed, in general, provi~ion of wireles~ co~munication
circuits in the subscriber alarm system is expensive, thus
limiting spread of their u6e.
Ob~ect6 of the Inventlon
The invention i~ therefore directed toward~ providing a
communication ~y~tem and method for wireless communication
21 9275't
bet~een suh~criber alarm sy~tems and monitoring stations
in a manner which avoids the abo~e-mentioned proble~s.
Summary of the In~ention
The invention provides a comm~nication ~ystem comprising:-
a plurality of sub~criber alarm system interfaces, each
c~mpri~ing:-
control means for detecting an alarm condition in a
subscriber alarm ~stem; and
a wirele~s transmitter comprising means for
automatically trans~itting an alan~ trigger signal when
an alarm condition is detected, said trigger signal
including an alarm ~ystem identifier;
a message processing center associated with a plurality of
interfaces and comprising:-
a recei~er for receiving trigger alarm signals,
a tran~mitter for transmitting telephony signals, and
a controller compri~ing:-
means for reading a received trigger slgnal, means
for generating an emulation telephony signal which
an as~o~iated monitoring station expects to
receive directly from the alanm sy~tèm, and means
for directing the tran~mitter to transmit the
emulation telephony s ignal to ~aid monitoring
station.
21 92759
The invention also provides a method of co~munic~ting an
alarm signal from a subscriber alarm system to a
~onitoring station, the method compri~ing the ~teps of:-
detecting an alarm condition at the subscriber alarm
S system;
transmitting an alarm trigger signal in response to
detection of an alarm condition, said trigger signnl
including an identifier for the s~bscriber alarm
system;
receiving the trigger ~ignal and, in response,
generating an emulation telephony signal which the
monitoring station expects to receive directly from the
subsc~iber alarm system; and
transmitting said emulation telephony signal to said
monitorinq station.
The invention therefore pro~ides a very simple solution to
the problem of applying wireles~ communication technology
to existing alarm systems and monitoring stations. The
monitoring station recei~es the sign~l it expects to
receive, namely a conventional telephony signal. However,
at the subscriber end there is no need to generate a
telephony signal. All that i~ reyuired is a trigger
~ignal containing an alarm ~y~tem identifier. This avoid~
the expen~e and possible delay and congestion problems
which can arise if a telephony ~ignal is generated at the
~ub~ribers' end.
n one embodiment, said controller comprises a stored
~atabase of records each s~oring emul~tion data for an
associated alarm system, and means for generating said
telephony ~ignal ac~ording to ~aid emulation data. The
2l ~275q
-- 5 --
databa~e record may store an address of the monitoring
station associated with the alarm system. These features
allo~ centralified updating, ~ithout the need for
programming emula~ion data at the subscriber's end -
either initially or for subsequent updates. It also
allo~s the trigger signal to be very short.
In one e~bodiment, said wireles~ tran~mitter is a cellular
transceiver comprising means for transmltting the trigger
signal in an overhead control channel. This is a very
well e~tabli~hed and effective ~echanism, which may be
easily applied to transmission of a t~igger signal
Preferably, the interface control mean~ comprises means
for detecting an alanm condition status and for directing
transmission of condition status data in the ESN frame of
the overhead control channel, and said message proces~ing
center ~ontroller comprises means for representing said
status data in the telephony ~ignal. This allows
comprehensive information to be received by the monitoring
station - although ~nly a trigger 6ignal is transmitted
from the subs~riber~s end.
Preferably, the message processing center comprise~ means
for transmitting an acknowledgement signal to the
interface in response to receipt of an acknowledge~ent
signal fro~ the monitoring station. This allows
validation by the interface and re-transmission if
necessary
In one embodiment, the wirele~ tra~smitter is a cellular
tran~cei~er, and the message pr~cessing ~enter compri~es
means for causing 8 cellular paging signal to be
transmitt~d to the tr~n~ceiver as an acknowledgement.
Thi~ is a very si~ple way of tran~mitting an
acknowledgement signal.
21 92759
-- 6 --
In one embodiment:-
the interface control mean~ comprises means for
directing the wireless transmi~ter to 1nclude emulation
data in the trigger signal, and
the mes~age processing ~enter ~ontroller comprise~
means ~or reading the emulati~n data in a received
trigger signal and generating the telephony ~ignal
according to ~aid emulation data. In the latter
embodiment, said interface control meang may comprl~e
means for directing the wirele~ transmitter to include
the associated monitoring station address in the
trigger signal, and the me~sage processing center
compri~es means for reading ~aid address
In a preferred embodiment, the me~sage processing center
controller comprises means for crea~ing an in-process
event record when a trigger signal is received, for
writing emulation data to said event record, and for using
contents of the event record to generate the emulation
signal.
According to another aspect, the invention pro~ides an
alarm c~mmunication system comprising:-
a plurality of subscriber alarm ~y~tem interfaces, each
compri~ing:-
control means for detecting an alarm condition in
a subscriber alarm sy~tem; and
a wireless transmitter compri~ing mean~ for
automatically tran~mitting an alarm trigger ~ignal
w~en an alarm c~ndition i~ detected, said trigger
signal including an alarm ~y~tem identifier; and
21 ~27Sq
a message processing center associated with a pl~rality
of interfaces and comprising:-
a recei~er for receiving trigger alarm signals,
a tran~mitter for transmittin~ telephony signals,
S and
a controller comprising:-
means for reading a received trigger signal to
determine the alarm system identifier;
means for retrie~ing a database record associated
with said alar~ sy6tem using baid identifier as an
address;
means for reading emulation data in the retrieved
database record and for using fiaid emulation data
to generate an emulation telephony signal which an
associated monitoring station expects to receive
directly from the alarm 8y6tem; and
means for reading the data~ase record to determine
the associated monitoring station address and
transmitting the emulation telephony signal to
said monitoring station.
Ideally, the interface further compri~es a wireless
recei~er and means for recognising an acknowledgement
signal from the message processing center, and the message
processing center controller comprises means for directing
transfer of said ackno~ledgement signal to the interface
after receipt cf an acknowledgement from Lhe monitoring
station. In one embodiment, the interface comprises means
21 92 759
-- 8 --
for recognising a dial-~ack (attempted communication)
within a pre-set time period as an acknowledge~ent signal.
This is a very simple way of receiving an acknowledgement
because it eliminate~ the need to process an
S acknowledgement signal and the circuitry required to do
so .
~he interface preferably comprises a wlreless transceiver
such as a cellular transceiver, which items are readily
a~ailable and inexpensive and allow use of a ceLlular
system to be used to transmit the ala~m trigger signal to
the message processing center.
Pre~erably, the ~ireless tran~mitter comprises means for
trans~itting the trigger signal in an overhead control
channel of a mobile teleco. Inication6 network. Such
channels are not sub~ect to net~ork delays and congestion,
and the need for voice channel capability in the
transceiver is avoided. This al~o allows very fa~t
transmission of the trigger signal.
Ideally~ the detecting means of the interface comprises
input ports for connection to alarm si~nal conductors of
an existing alanm system whereby the interface may ~e
easily retro-fitted to an exi~ting alarm system. Ideally,
the detecting means comprise~ a number of di~ferent types
of input ports to allow retro-fitting t~ one of a range of
di~ferent types of alarm syatems. Thu~, a ~ingle
univer~al inter~ace may be developed which may be used
with different types of ~u~scriber alarms systems
different input ports being used in different cases.
In one embod~ment, the interface comprise~- means for
capturing status data relating to the alarm condition and
~or transmitting said status data in the trigger signa~,
and wherein said message proce~ing center cont~oller
21 ~2759
comprises means for representing said ~tatus data in the
emulation telephony signal. Preferably, the wireless
transmitter comprises a cellular tran6cei~er, and the
control means compri~e~ means for directing insertion of
said ~tatus data in the ~SN frame of an o~erhead control
channel trigger s iynal.
In one embodiment, the me~sage processing center compri~es
means for creating a database record for an interface,
being addressable by an identifier o~ the interface, means
for receiving emulation data from an installer via a
telecomm~nications network and for wri~ing the emulation
data to the record, and means for tran~mitting an
activation signal to the interface after wrLting the
emulation data. Thi~ allows initialisation of a
particular interface in a ~ery simple manner in which the
integrity of the database record is also assured.
In one embodiment, the controller comprises means for
creating an in-process event record when a trigyer signal
is received, for writing the emulation data to the event
2~ record, and for using content~ of the e~ent record to
direct generation of the e~ulation sign~l. Use of an
event record in this way allows simplified control of a
particular alarm signal.
In one emhodiment, the interface compri~es a mean~ for
transmitting alarm ~tatus data with the additional alarm
signal and the controller comprises a means for writing
the alarm status data to the e~ent record.
In one embodiment, the c~ntroller comprises a gateway
processox controlling the receiver, a dialling processor
controlling the tranæmitter, and a main processor, each
proces~or comprising means for perfon~ing an action with
reference to the event record and passing control over to
2 ! 92759
-- 10 --
a next processor. Thi~ mechanism allows distribution of
the proces~ing tasks at the message processing center in
a simple and effective ~anner to achieve a very fast
message transfer rate in real time.
Pre~erably, the processors pa88 control over to a next
processor by updating an owner field in the event record.
This is a very simple way of passing control and allo~s a
large degree of processor-independence.
In one embodiment, the controller comprises a main
processor, a plu~ali~y of modular gateway processors
connected ~o as~ociated communication de~ices in the
receiver, and a plurality of modular dialler processors
connected to as~ociated cc. Inication devices in the
trans~itter. Thi~ allow~ very simple growth of the
message processing center without affecting the current
capability of the center. It also allows redundancy -
very important for alarm communication.
Preferably, the gateway and dialler processors update a
watchdog field in a table to indicate current status, and
the ~ain controller re-assigns processors upon failure by
reference to the watchdog field. ThiS is a very simple
way of maintaining controller integrity.
According to another embodLment, the invention provides an
alarm communications mes~age proce~sing center
comprising:-
a gateway process~r comprising ~eans for receiving an
alarm trigger signal including an i~entif ier of an
associated sub~criber alarm syste~;
2 1 92 I Sq
~eans for creating an in-process e~ent record uniquely
associated with the received trigger signal and means
for writing ~aid identifier to said event record;
a main processor comprising means for reading the
identifier from the event record, for ~etrieving a
database record addressed by the identifier, and
writing emulation data and a monitoring station address
read from the database record to th~ in-proce5s event
record and
a dialling processor comprising mean~ for reading the
emulation data and the monitoring ~tation identifier
from the in-process event record and for automatically
generating an emulation telephony signal which the
monitoring station expects to receive directly from
the subscriber alarm system, and for transmitting said
emulation ~ignal to the monitoring station.
According to a furthe~ aspect, the invention provides an
alarm communication sy~tem compri~ing:-
a subscriber alarm ~ystem interface comprising:-
control means for detecting an alarm condition in
a subscriber alarm system, and
a cellular transceiver connected to the control
means and comprising means for automatically
transmitting an alarm trigger ~ignal including an
2S alarm system identifier when an alarm condition i~
detected, said trigger signal being transmitted in
an overhead control channel; and
a mes~age proce~ing center as~ociated with a plurality
~f interfaces and comprising:-
21 ~2159
- 12 -
a receiver having means for receiving alarm
trigger signals from a cellular system;
a transmitter for transmitting telephony signals;
and
a controller comprising:-
means for reading a rece~ved trigger signal
to determine the alarm syRtem identifier;
means for retrieving a database record
associated with said alarm system using ~ai~
identifier as an address;
means for reading em~lation data in the
retrieved record and for using said emulation
data to generate an emulation telephony
signal which an associated monitoring station
expects to receive directly from the alarm
system; and
means for reading the record to determine the
associated monitoring station addre~s and for
transmitting the emulation telephony signal
to said monitoring station
According to another aspect, the invention providex an
ala~m communication system comprising:-
a plurality of subscriber alarm system interfaces, each
comprising: -
a wireles~ transmitter and
. ~
21 92759
control ~eans comprising means for detecting an
alarm condition in a subscriber alarm syste~,
storage means for storing telephony emulation data
and an address of an ass~ciated monitoring
S station, and mean~ for directing the wireless
transmitter to transmit a trigger ~ignal including
an alarm system identifier, the emulation data,
and the monitoring station add~ess; and
a message processing center associated w~th a plurality
of interfaces, and comprising:-
a receiver for receiving alarm trigger signals;
a transmitter for transmitting telephony signals;
and
a controller comprising means for reading a
received trigger signal, for using the emulation
data to generate an emulation telephony ~ignal
which the addressed monitoring station expects to
recei~e directly from the alarm sy~tem, an~ for
directing the tran~mitter to trans~it the
~0 telephony to the addres~ed monitoring station
address.
In another aspect, the invention provides a method of
communicating an alarm signal from a subscriber alarm
system to a monitoring station, the method comprising the
steps of:-
detecting an alarm condition at the su~scriber alarm
system;
transmitting an alarm trigger signal in response to
detection o~ an alarm condition, said trigger signal
21 9275~
including an identifier for the subscriber alarm
sy~tem, telephony em~lation datar and monitoring
station address;
recei~ing the triyger signal and, in response, using
the emulation data to generate an emulation telephony
signal which the addressed monitorin~ station expects
to receive from the alarm system, and transmitting the
telephony signal to the addre66ed moni~oring ~tAt3on.
DETAILE~ DESCRIPTION OF THE INVEN~ION
Brief descri~tion of the drawings
The in~ention will ~e more clearly understood from the
following de~cription of ~ome embodiments thereof, gi~en
by way of example only with reference to the accompanying
drawing~ in which:-
Fig 1 i~ schematic overview of a communication ~yste~
of the invention;
Figs 2a and 2b are a ~chematic representation of an
interface of the communication system;
Fig 3 is a diagram illustrating a me~sage processing
center of the system in more detail; and
Fig 4a and 4b are toyether a flow chart illustratingoperati~n of the system.
- 15 -
Detailed description of the emdodiments
Renferring initially to Fig 1, there id shown a
communication system 1 of the invention. The system 1 is
shown for use with a particular subscriber alarm system 2
which communicates via a PSTN network 3 with a monitoring
station 4 administered by the alarm company of which the
subscriber is a client. For simplicity, the system 1 is
shown for use with a single subscriber alarm system 2 and
a single monitoring station 4, however, in practice it
will be used for in the range of tens of thousands to
millions of subscriber alarm systems 2 and with up to
thousands of monitoring stations 4. Indeed, and advantage
of the system 1 is that it can be used for any subscriber
alarm system and with any monitoring station.
The conventional path for transmission of an alarm signal
is indicated by the letter A in Fig 1. The communication
system 1 of the invention provides an additional path B
which is always used, irrespective of success of the
conventional path. The additional path is started by an
interface 5 which detects an alarm condition in the
subscriber alarm system 2.
The interface 5 transmits a radio trigger signal which is
picked up by a mobile telecommunications network 6 and
relayed via gateway computers and a PSTN network 7 to a
message processing center 8. The trigger signal is not a
telephony signal. In general, it is any signal which can
alert the center 8 and need only include an identifier for
the subscriber alarm system 2. This avoids the problems
which may arise when a telephony signal is used, namely
possible faults, congestion-related delays, and slow
speed. Indeed, it may be generated in as little as 100 ms
- much quicker than a telephony signal. The network 6
2 1 92759
does not form part of the sy~tem, but is utilised by the
interface 5 and the message processing center ~ of the
system l to transfer messages in one ~'leg~ of the path B.
The network used is the Cellemetry Sy~tem described in
United States Patent Specification Nos. US 5546444 and US
5526401 (BellSouth Corporation) in which forward and
re~erse control channel~ are used.
The message processing center 8 emulat~s the fiubscrlber
alarm system 2 and generates emulation signals which are
identical to those which are transmitted on path ~, and
transmits them via the PSTN 9 to the ~onitoring station 4.
Thi6 is performed by retrieving emulation data from a
database record (pennanent record) u~ing the subscriber
alarm system identifier in the trigger signal to index the
record.
Thus, the monitoring station 4 "~ees" identical signal~ to
those which are received via the conventional route, and
because they are received within a pre-set time period
they are regarded as relating to the same alarm condition.
The additional path i~ alway~ used ~o that the monitoring
station 4 al~ays receives a signal, even if the dial-up
path A ha~ failed by, for example, a burglar cutting
telephone wlres, or communicatlons problems. Thus, the
monitoring station 4 either receives two identical signals
from the two ro~tes, or only receives the ~ignal from the
path B, this being the signal which it expects to receive
from path A.
Of cour~e, the ~ubscriber alarm system's circuits for the
conventional path may be disabled ~o that path B alone is
relied upon. Indeed, the system 2 need not include any
land-based communication circuits, the invention allowing
a tamper-proof path to be used without the need for
21 9275~
transmission of telephony signals f~om the subscriber's
end in a manner transparent to the monitoring station.
The ~essage processing center 8 receives an
acknowledgement ~ignal from the monitoring station, and in
turn send~ an acknowledgement to the interface 5. This
acknowledgement is a page signal which is simply
recognised by the interface, not proces~ed.
Because the message processing ~enter 8 emulates
conventional telephony signals, there i8 no need for any
modification of the monitoring station 4. Further,
because the interface 5 merely detect~ an alarm condit~on
in the su~scriber alarm system 2, it may be easily retro-
fitted to the alarm system 2. Updates such as changes in
monitoring stations may be made centrally at the center 8.
Referring again to Fig 1, the ~e~sage processing center 8
comprises a receiver 10 compriRing a number of modular
gateway modem bays for receiving signals from the
Celle~etry System gateway computer~. A transmitter 12 for
trans~ission of telephony ~ignals has a number of modular
dialler mode~ bays. The center 8 also compri~es a
controller which is in three parts, namely a main
processor for primary control and coordination, a gateway
processor for control of the receiver 10, and a dialler
processor for control of the trans~itter 12.
Referring now to Fig~ 2a and 2b, there i~ illustrated an
interface circu-t 20 forming part of the interface 5. The
interface circuit 20 has te inAls 22 and 23 for
connectlon in parallel with the sounder of a subscriber
alarm system, usually an electronic siren or bell. The
optically isolated output of these terminals i~ connected
to an interrupt input of a microprocessor 34 for analysis
of the nature of the signals. This allows the interface
2 ! 92 75~
- 18 -
5 to distinguish between burglary and fire alerts. ~n
addition, the interface circuit 20 includes terminals 25,
26 and 27 for connection to trip channels or analog
inputs. An interface chip 24 interfaces eight inputs to
one output selected by a three-way address and it allows
~ an analog to digital con~erter circuit 29 to be used. The
circuit 29 is connected to a port on the microprocessor
34. This allow~ detailed information to be captured, such
as hold-up medical alarm conditions. Terminal~ 2~
connected to the transceiver receive analog ~perating
information such a~ control channel signal strength. The
circuit 20 also comprises æerial interface terminals 35
for capture of comprehensive information from a subscriber
alarm system which has a ~erial link. The circuit 29
comprises ports P00 to P07 conne~ted to the microprocessor
34, used to generate voltages for analog to digital
con~ersion~
The circui~ 20 is connected to a cellemetry transceiver
using the CMM RXD and CMM Txn terminals, also indicated by
the numerals 31 and 32, The tran6ceiver i~ of the type
marketed a~ a Cellemetry Radio Transceiver - a cellular
radio unit with only control channel circuitry. A CMM RTS
terminal 33 is u~ed for handshake/flow control. These
~erminal~ are ~onnected to the microprocessor 34 which
controls interfacing. LEDs 1 - 7 display system status
to the installing technician in order to verify correct
system operation.
The transceiver connected to the terminal~ 31 doe~ not
include ~oice channels - only circuits sufficient to
transmit a trigger signal on a forward or reverse overhead
control channel ~hich i~ conventionally used for mobile
telephone roamer registration. It i~ thus inexpensive and
compact.
21 92759
-- 19 --
It will be apparent from the description of the interface
5 that it may be easily retro-fitted to existing
subscrl~er alarm systems by simply connecting up the
relevant terminals, depending on the nature of the
subscriber alarm syste~. An example is a ~imple 4-~ire
connection having two wires for power and two for an alarm
output conductor. The interface chip 24 is programmed to
recognise a wide ~ariety o~ inputs and to in t~rn cause
the microprocessor 34 to i.nitiate an additlonal alnrm
s~gnal transmitted over-the air to be picked up by the
Celle~etry System.
Referring now to Fig 3, the message proces~ing center B i~
illustrated in more detail. The center 8 comprises a
local area network 40 which interconnecta various
processing devices. ~he receiver 10 comprises a numbe~
of modular bays of modems progra~med for communication
with gateway computers of a cellular system. Each bay lO
is controlled by a gateway control proces~or (GCP) 41
forming part of the controller 11. The transmitter 12
comprises a number of modular dialler bays, each of which
is controlled by a dialler control processor (DCP) 42~
al~o forming part of the controller ll. The controller 11
is completed ~y a main control processor (MCP) 43 ~nd a
backup MCP 44. A database is provided by a primary NT
server 45 mirrored by a back-up NT 46, each of which is
connected to the network 40. Finally, the center ~
comprises a set of dialogue line interfaces 47, each
controlled by an IVR PC 48.
In operation, interfaces 5 a~e tested and assigned unique
mobile identity numbers (MIN), which are recorded on a
database on the server 45. ~his record is indexed by the
MIN number. Each interface i8 then connected to a
subscriber alarm ~y~tem by connection of the re}e~ant
21 92759
- 20 -
terminal~, depending on the nature of the alarm system.
This is a ~ery si~ple operation.
The interface i8 then activ~ted in real time by one of the
I~R computer~ 48. The installer dials in to the IVR PC 48
S and transmits data needed by the CMPC 8 to send emulation
signals. This is perfor~ed interactively ~y keying data
in respon~e to IVR PC prompts using D~MF tones. The
emulation data includes details of the mapping of digital
dialler messages to send in the case of each activation
l~ report type. These are identical to the messages which
are conventionally transmitted by the alar~ ~ystem to the
monitoring station ~ia the dial-up path. The IVR PC
writes this information t~ the per~anent re~ord.
~he interface ~ then tran~mits a trigger signal (fir~t
time activation registration) t~ confirm radio
functionality and pro~ides de~ails of operations and
program status to the center 8. ~he permanent record i~
~pdated when this registration is received. ~he in~taller
then trigger~ a test alarm and the center relays the alarm
to the monitoring ~t~tion and verifies this to indicate
successful completion of the installation.
An i~portant aspect of the ~nvention i~ the fact that the
interface 5 tran8mits only a trigger - not a telephony
. signal. In this embodiment, the trigger uses a
conventional forward or rever~e cellular overhead control
channel for registration of a mobile telephone to register
its location This channel is not ~ubject to delays or
congeStion, unlike the telephony ~hannels.
Referring now to ~ig~ 4a and 4b, operation of the system
l to handle an alarm æignal is now deæcri~ed. This method
is indicated generally by the numeral 60. In step 61, an
alarm condition i~ detected by an interface S and ~his
21 92759
- 21 -
causes the transmitter of the interface 5 to emit a
trigger signal ~cellular regifitration signal). This
includes the MIN number of the interface and a 32-bit data
field ~hich inciudes the alarm status information. This
data i~ within the frame reserved for the ESN number in a
conventional regi~tration signal. The leading 3 bit~
indicate the nature of the remaining bits. The data
generally include~ codes indicating the nature of the
ala~m condition, and po~sibly diagnostic information
indicating ho~ the ~ystem 2 is operating. This signal is
picked up hy the Cellemetry System 6 and is routed via a
gateway computer to the message processing center 8. The
recei~er 10 is the only mean~ of contact ~etween the
sub~criber alarm system and the message processing center
8. In the center 8, a GCP 41 controls the gateway modem
whi~h receives the tri~ger signal and it initiates an
event wh~c~ begins with receipt of a valid trigger
(registration data packet) from the cellular system
gateway computer and ends with writing of an event record
to an event log table. Between these t~o points, the
event i~ processed by referen~e to an in-pr~cess event
(IPE) record. This record is used by the GCP 4I, t~e MCP
43 and the DCP 42. The IP~ record i~ a temporary record
which is created and e~entually logged in real time when
the ~ignals have been handled.
A~ indicated by the step 62, the gate~ay computer dials
into the message proces~ing center 8 and if the trigger
~ignal is not valid, a~ indic~ted by the step~ 63 and 64
the relevant GCP 41 generates an exception log record. It
al80 generates a respon~e to the gate~ay computer with
rele~ant error code and hang-up information.
If the trigger signal is validr in step 65 the GCP 41
creates an event by creating an IPE record in an IP~
table. This record contains all of the data supplied by
21 92759
the gateway computer for the registration and the current
time is added hy the GCP 41, ~arking a start-of-event time
stamp. Importantly, the GCP 41 also marks an OWNER field
as being the MCP 43. In more detail, the following sets
out the structure of the IPE record in full
21 9275C~
-- 2:~ --
I PE RECORD
Field Narne 7~peS~z~ EdJ't Rlmor~
(B~rcs)
1 Eventld ~ lS GCP Sequencc ~o. - Same as uscd in
his~oncal Evenl~og.
2 Event Start Tir,nc @ GCP Date/Tirne stamp on rccord creation by
3 GCP Bay Reg r 2 ~CP Bay 9~ ot GCP.
4 l(iateway I`lanle C 8 GCP ~ame o~ gatew~y rrescn~ message.
Gal~way Id ~ 2 GCP Catew3y recunl #
6 aat~way Time C 6 GCP Tunc field of actual message scllt by
galcWay
7 Gateway Ml~ C 10 GCP t ; e MlN.
8 Gateway ESr~ C 8 GCP 1~ g ESN 8 chars or he~ dig~ts
(~nns status).
9 Galcway SID C 4 GC~ 1 ' O mc~sage c ;~, " 3 SID.
10 Gateway MSC C 2 GCP l~lSC id.
11 DCPBay ~ 2 MCP DCP bag àssi~ned by l~CP to contact
3 ~) MS.
12 CSPhoneNo ~1 10 MCP Phone no. Or MS.
13 CSMa~sFvl~dt ~ 2 MCP ~ormat to use in MS ~ logu~
14 CSMsg Data C 2~ MCP ~hat to send to MS.
1~; CSRetries C 1 MC~ How many times has the MS call bcen
llied?
IG CSMsgRcsult N 2 DCP Delivered OK? PR Errot code.
17 DiallcrNo N 2 DCP Dialler # assigDcd by DCP to call CS.
21 '~275~
-- 24 --
1~ GCPBayPage 1~1 2 MCP CCP Bay N~ lo rcqucsl Ml~l page.
I9 MIMageRetr~s C 1 ~CP H~wmany lim~s h~ gatew~y Ml~l page
requc5~ bce~ ~ried ?
20 I~ JPageResulls 1`~ 2 GCP Deli-~ered OK? OR error codc.
21 GCPModeml~o N 2 GCP GCP Modcm Nc. uscd lo c~ll g~teway.
22 EYenlEndTim~ (~) MCP Date~Time slamp event pr~
cu...~!~l 1.
23 Owncr C 5 All ~he p.ocessor currently r~s
for event p~x
Note: MS - monitoring ~tation
N - numeric
C - characters (alph~n ~ric)
An important aspect of ~peration of the center 8 is that
control of the event is transferred between the different
processors by a~endment of the OWNER field in this manner.
When the MCP 43 identifies a new IPE record marked for its
attention in the IPE table, it looks up the file of
permanent records to e~tablish if the registration is to
be processed. If so, it retrieve~ emulation data from the
permanent record and writes it to the IP~ record. ~he
emulation data includes the monitoring station phone
number, message f~rmat, the ~ubscriber's account number,
the message data to transmit (e.g. ~orrelating a message
with an alarm statu~ code in the recei~ed ~SN data), and
number of retrie~. The MCP 43 then selects an appropriate
DCP bay and mark~ the record for that bay. This is a
function ~f the ~n-line ~tatu~ and num~er of idle dialler~
3~i for each bay. These ~;tep3 are indica~ed by the numerals
67 and 7t) in Fig 4a.
- 21 ~2759
- 25 -
When a DCP 42 identifies a new IPE record marked for its
attention, it assigns one of its free diallers to transmit
the mes~age to the monitoring station. This i~ achieved
~y fiimply reading the e~ulation data of the IPE record and
~uild~ng an emulation ~ignal according to this data in a
con~entional manner. ~his ~ignal includes all of the
status information deri~ed from the ESN frame and i~ thus
very comprehensive.
This step is indicated by the numeral 71 in Fig 4a (in
which the dialler ba~ is referred to as a 'Smart
Dialler" ) . In step 72, the DCP 42 update~ the monitoring
station report result field. If the deli~ery failed, the
MCP 43 moves the IPE record to the historical event log
file and generates an event error record. At thi~ point,
the current time is added b~ the MCP 43, thu~ marking the
end-of-event time stamp.
If, however, the delivery was succe6~ful, the MCP 43 marks
the IPE record for the most appropriate GCP bay as
follows:-
- If the GCP which received the regi~tration i~
still on-line, thi~ i~ u~ed. It may ~till be
connec~ed to/our receiving a new registration from
the required gateway.
- Otherwise, the GCP with the most idle modems i~
chosen.
These steps are indicated by the numeral 73 and 75 in Fig
4b.
The GCP 41 re~uests the gateway to "MIN page" the
originating interface as an acknowledgement. This iS
recognised by the interface 5 as 8 delivery confirmation.
21 92759
There is no bi-directional communication - simply
reco~nition of the paging signal. This step is indicated
by the numeral 76 and in step 77 the GCP 41 stores the
result of the MIN page request in the IPE record and
S transfers contr~l back to the MCP 43. The microproces~or
34 of the interface 5 is programmed to auto~atically re-
~ransmit the trigger signal if the acknowledgement is not
received with a pre-set time.
The MCP 43 then moves the IPE record to the hi~torical
message event log file and adds the c~rrent time to the
end-of-event time field as indicated by the step 79. The
process 60 is then ended as indicated by the step 8~. If
delivery i~ unsuccessful as indicated by step 73 or the
acknowledgement or confirmation MIN page operation is
unsuccessful, an event error is generated in step 68.
The modulàr nature of the CMPC c~ntroller 11, namely the
mod~lar GCPs 41, the MCP 43, and the modular DCPs 42 allow
for dlstribution of tasks very effectively. This helps to
achieve effective and fast throughput of messages in real
ti~e, de~pite the fact that there may be hundreds of
messages being handled simultaneously. The IPE record is
a very simple and ef~ective way o~ achieving control using
such modular processors. Another feature which helps
coordination is the fac~ that the proce~sors automatically
update a watchdog field in a table in real-time. If a
particular bay fails, the MCP 43 i -'iately re-assignS
the rele~ant task.
It will be appreciated that the invention provides a
system which once installed can be used for any subscri~er
system which dials a monitoring station to non-intrusively
and transparently pro~ide a second alarm signal path,
which is m~re secure than conventional paths. It is thus
entirely flexible and versatile and may be very easily
21 92759
- 27 -
applied by installers. The interface unit may be very
easily connected ~o the ~ubscriber alarm system, and no
modification ~hatsoever is required of the ~onitoring
station because of the emulation which take~ place. It
S will also be appreciated that message~ are handled in real
time very e~ficiently within the message processing center
8 by the manner in which an IP~ record is created and
managed. An important point is that the IPE record allows
operation of the centre 8 to be independent of any single
processor. This is very important for communication of
alarm signals. F~rther, the system may be installed very
inexpensively for sub8cribers. Thi~ i~ because a
transce~ver which only handles trigger signals such as
control channels is much le~s expensiYe than a
conventional wireless transceiver Further, the control
and detectlon circuits of the interface 5 are relati~ely
simple, inexpensive, and easy to connect to a ~ubscriber
alarm system. Tn addition, the power supply requirement
is very low.
It is envi~aged that the trigger 6ignal may include the
emulation and/or the address of the associated monitoring
station. This may be the case if a cellular system having
a control channel protocol allowing a relatively large
data frame is used, for example. In this case the ~e~age
proce~sing center need not ha~e a stored database of
permanent records storing em~lation data or monitoring
~tation addre~ses. It would ~imply read the data in the
received trigger signal and use it for emulation and
transmission of the telephony signal. S~ch a message
processing center may create and use in-process e~ent
records, much as de~cribed aboue The emulation data and
the address w~uld be written im~ediately to the e~ent
~ecord instead of being retrieved from a database.
