Says Fine ,"it is a known fact that communicators via telephone lines are the preferred method of communications because they offer two-way or bi-directional interaction.The availiable methods,namely radio alarm transmitters,telephone line communicators and lately GSM modems,all have limitationsand drawbacks."This disscusion looks at how CellSecure GSM brings something innovative and compelling to the market.
The alarm transmitter
The alarm transmitter is a transmitter only (with no two-way data capability) that transmits the critical data from a security system blindly into the ether, repeating the signal three times in the hope that one gets through to the control room.
As more and more radio frequency ( RF) alarm transmitters are used, especially those with low cost aerials, RF noise in the urban areas has reached such proportions that thousands of signals are ‘lost’ on a daily basis.
The telephone line communicator
The communicator is a little more reliable. However, being telephone line based, they are subject to easy tampering (lines can be cut) and excessive maintenance due to potential lightning damage etc.
The communicator also makes a normal telephone call, the cost of which can range from 45 c to R1,50 (as some companies monitor customers in rural or outlying areas).
Each communicator needs to establish a dial up line to the base station. If there are numerous alarms, or open and lock signals that occur simultaneously, it can take a long time for the communicator to get through with that all important panic signal.
GSM modem
GSM modems have also reared their heads in some instances and although extremely reliable they use normal GSM contracts that can be quite expensive, as any cell phone user will attest. A further problem with the GSM modem is that it must also first establish a dial-up line to the control room and at peak times this can be very difficult as many cell phone users already know. The degree of successful first-time calls is also directly proportional to the availability of landlines to the control room.
CellSecure
According to Fine, “after many years of head scratching and dabbling in two-way radio for more reliable communications, the CellSecure was developed utilising the Ultra Reliable Priority SMS messaging facility of a GSM network.” Says Fine, “At its simplest level, SMS gives the GSM network switch the ability to send and receive alphanumeric short messages between a Short Message Service Centre (SMSC) and a mobile subscriber over the appropriate air interface.”
“When the SMSC receives a message originated from a user, it processes the message by a software module. The message may pass through several phases of access management validation, including address translation, blacklist checking, class-of-service controls, and the validation of source and destination addresses against the subscriber database,” he says.
“To ensure optimum SMS reliability, received messages are stored in a relational database, a step that prevents loss of in-transit messages and which also supports powerful SMS analysis and reporting functions.
“Messages are then routed to a receiver software module as dictated by the receiver address. Stored messages are delivered to the appropriate network interface, and powerful retry mechanisms, including the network initiated retry, are used to re-send messages in the case of failed deliveries.”
Adds Fine, “Network operators can enhance their SMS products by also offering a number of message parameter options, including priority messaging, deferred delivery and time-based messaging. SMS systems can now provide delivery receipts in the form of a short message notification to the originator of the message.”
SMS – mobile originated mode
There are two basic modes of SMS: those originated by the mobile terminal, and those terminated at the mobile device. However CellSecure only uses the following mobile originated mode.
In a mobile originated situation, a short message is created by a mobile terminal and submitted to its mobile serving network switch. A serving SMSC may be selected based on the calling or called number, and the message is routed to the SMSC where it is stored and acknowledged. The message is then delivered to the appropriate destination using a mobile terminated SMS procedure. Finally, the switch delivers an automated acknowledgement to the originating mobile.
Says Fine, “As can be seen from the above when the CellSecure unit sends a message it receives an acknowledgement that the message has been delivered and vice versa when the customer or control room send the CellSecure a message it is also acknowledged.”
With the addition of a roaming SIM card the SMS message can be sent from anywhere in the world to anywhere in the world where there is a GSM 900 system operating.
A SMS messaging system is a true packet switched short data system. This allows one base unit with a GSM engine to receive multiple messages simultaneously with virtually no delay unlike a communicator or GSM modem that need to establish a dial up link in order to communicate.
CellSecure inputs
The CellSecure unit has nine fully programmable and fully protected digital inputs (or 7x digital and 2x RS232 inputs) much like an alarm transmitter, with the difference being that each input has two states (high and low) and the message transmitted is in plain alphanumeric numerals such as ‘mains on’ or ‘mains off’ that can be read on any receiving cell phone.
A total of 16 characters can be used such as ‘ALARM MAIN BDRM’.
After the data message, an address message is added so that the full customers information can be displayed on any receiving cell phone. For example, ‘ALARM MAIN BDRM At Mr P. Breedt 142 Botha Avenue Lyttelton Centurion Key holder 0824925294’.
In addition to this, four alphanumeric digits are added for base station software decoding, giving a total of 9999 different types of signals that can be sent from more sophisticated control panels using CellSecure’s telephone communicator interface.
Adds Fine, “The above message (in plain text) is firstly routed to a control room, and then to up to three additional cellphones (such as the customer, his key holder and in some cases direct to the armed response officer’s cellphone).
“Selected messages can then also be automatically rerouted to up to three additional cellphones from our base station software.”
Says Fine, “The necessity of customers monitoring their own security systems has been brought about by the degree of user initiated false alarms and the failure of monitoring control rooms to be able to offer a more reliable method of communicating problems direct to the customer.”
The CellSecure also has a built-in battery low facility that will send a battery low signal and a battery OK signal automatically. A 24 h test signal is automatically sent to ensure that the unit is on-line. This 24 h signal can be disabled if deemed unnecessary.
Outputs
From any cellphone using the correct codes, up to four latching or nonlatching outputs can be selected for controlling various functions such as alarm on or off, switching lights or opening gates or doors. Says Fine, “This makes CellSecure by far the longest distance gate remote control operator in the world!”
Each output is a high power open collector transistor output enabling the unit to be connected to various relays. The output can be activated to nonlatch (2 s) or latch until an unlatch message is sent.
Information request
The CellSecure is also capable of sending various information back to the requesting cell phone. Upon request the CellSecure will send back the status of all the inputs to the requesting cell phone for verification of ie ALARM ON, MAINS ON BATTERY OK etc.
Programming information
Upon request the CellSecure will send back the following information for verification:
1. Base station number.
2. Alternative base station number.
3. SMSC number.
4. Alternative SMSC number.
5. Cellphone 1 number.
6. Cellphone 2 number.
7. Cellphone 3 number.
Special Information
Upon request the CellSecure will send back to the requesting cellphone the following special information:
1. Signal strength of the CellSecure. This is very useful when the CellSecure is used in rural areas to ensure that contact with the nearest cell tower is maintained.
2. Area information. The CellSecure can send back information as to which cell tower it is connected to as well as the nearest five other cell towers that can be used should the one tower go off air.
3. Additional serial information from any serial device such as machinery temperature controllers etc.
Conclusion
As GSM systems become more and more sophisticated, with video messages etc soon to be introduced, it is envisioned that by the year 2002 any security or control system still using the old methods of communicating information will be totally outdated.
With the new generation of WAP-enabled (wireless application protocol) cellphones that will allow the user full access via a WAP browser (much like an Internet browser) to products containing the new Bluetooth communications protocol or to any connected item such as home or business computers, video machines, security systems and televisions, future applications for CellSecures are assured.
For details contact Eagle Wireless Security on tel: (012) 664 6688 or fax: (012) 664 8213.
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