GB2278701A

GB2278701A - Identifying individual communicating devices

Info

Publication number: GB2278701A
Application number: GB9404008A
Authority: GB
Inventors: Alan Roberts-Carlson; Keith Frederick Roberts
Original assignee: ROBERTS CARLSON ALAN
Current assignee: ROBERTS CARLSON ALAN
Priority date: 1993-06-04
Filing date: 1994-03-02
Publication date: 1994-12-07
Also published as: GB9404008D0; GB9311572D0

Abstract

The Described invention enables communication between nodes on a common channel signalling system without erroneous identification of one device for another. The transmitting device sends an individual code (the RNC) which is learnt by the receive equipment and stored in non-volatile RAM. This sequence is only necessary on initialisation. Subsequent communications use the RNC known to both devices to distinguish the source of the transmission from another signal of similar structure but different RNC. Many devices (receivers or transmitters) can use the same channel without miss operation of any of the devices. The advantage of this system over the traditional method of transmitting one of several pre-determined codes is that the likelihood of coincident settings is reduced to a negligible level. Additionally the end user of the equipment is not required to set up complex codes or work on small electrical switches, which could present problems for the elderly and infirm. The codes used are secret to the systems using them thus avoiding the necessity of remembering code numbers or the security risk of writing them down. It is a simple matter to change the RNC code, the teach/learn system can be re-activated by a couple of switches, thus setting new codes into the system easily. <IMAGE>

Description

An Invention for Identifying Individual Communicating Devices SPECIFICATION 1.1 The invention described in this paper, allows the assignment of individual identifying codes within remote communicating devices. This allows communication between many devices on a common channel without erroneously communicating to other devices. The devices exploiting the invention may be in particular (but not exclusively) devices connected by a common radio, infra red or other medium. The invention embodies special coding techniques which allocates a Random Number Code (RNC) to each specific device.

1.2 The sending device may typically consist of a transmitter suitable for the medium (such as radio), some hardware logic an input device such as a manually operated switch, sensor or the like. In addition a power supply such as a battery will be required. The hardware in this invention is capable of generating a RNC under special circumstances, such as when the device is powered up, or initialised. This initial code is transmitted from device 'A' to the receiving device 'B', and subsequently used as a unique identification for the transmitting device. If required the receiving device 'B' above can instigate a further transmission which is used to signal back to the first device 'A', thus creating a secure two way communication.Transmissions between the devices would usually carry additional information besides the RNC to indicate a status signal such as the operation of a switch or the state of a battery voltage detected by the logic circuitry. A simple use of this system would be for a radio controlled garage door opener where wordy the RNC need be transmitted upon the actuation of a manually operated switch. A more sophisticated use would be in a radio controlled security system where RNC and status information such as door opening switch and battery level are transmitted as a single message.

1.3 The logic can generate the RNC by several methods, typically by counting the time interval between initial power up and an externally generated event. If the time counter is arranged to count 16 binary bits for example, there would be 65,536 individual possible combinations for the RNC. The probability of two similar devices which are within communicating range generating the same code is very remote. The RNC generator can use a short or long code depending on the level of security required and is only limited by the amount of logic installed and the length of time available for transmission. This invention has also been developed using a microprocessor and a time counter implemented in a software algorithm.

2 A practical application of the devise incorporated into a radio linked security system is described below: 2.1 Diagram 1 shows the layout of a radio linked security system. This system is expandable by commissioning new transmitter modules and operating a process of teaching the central control unit the unique RNC, which is thereafter used to identify the source of transmission.

The transmitter module is associated with a sensor which may take the form of Magnetic reed switches, Vibration detectors, Passive Infra Red personnel detectors or similar devices.

2.2 An activated sensor is detected by a microprocessor which powers up the Data Transmission Module. After a delay to allow the transmitter to stabilise, the microprocessor generates a serial data stream to the transmitter which includes : a/ The RNC b/ The status of the sensor.

The status of peripheral circuits , such as battery condition 2.2 The main unit contains the receiver which is connected to a microprocessor which decodes the information and performs appropriate commands such as starting an alarm or displaying a battery low indication. The master unit would be able to identity which device transmitted a signal and the reason for generating that signal.

2.3 Initialisation is achieved after power-up of the device, from each transmitter module by using a teach button. A micro-processor associated with each sensor and transmitter, detects that the button has been operated and if this is the first operation since initial power-up of the device the microprocessor stops a counter which is implemented in software. The number that exists in the counter is then used as a unique code to identify the device and called the Random Number Code. This code is then transmitted to the Main Unit receiver & microprocessor which identifies the code for use in future communications. An alternative way of generating the code is to run the counter while the button is depressed or for a period between two depressions of the button.In all cases the objective is to produce an unpredictable time period, in which to run an electronic or software counter. Other scrambling and coding techniques may be used in addition to the system above. Another method is to transmit the real time and use this as a distinct identifier.

2.4 The teach cycle may be re-set and/or initiated by a power-down' power-up cycle, followed by the operation of the Teach Button. This operation assumes that the main unit has been made ready to accept the transmitted code.

2.5 The transmission uses a 16 bit code to convey the RNC and further bits as required to indicate status and parity signals. Using a 16 bit binary code ensures that there are 65,536 possible combinations for use by the immediate system and any other adjacent system ( which has sufficient power to generate a received signal in the main unit receiver).

2.6 At the receive node, in this example the alarms main unit, there would be an associated learn button . When the learn button was set the receive unit would be enabled to look for a received signal pattern which is transmitted from a remote transmitter node (when the teach button is actuated). Upon receipt of the identifying RNC the receive node microprocessor would store the code in non-volatile memory, simultaneously recording the identifier code with that specific sensor. The process would be repeated for each sensor in turn, until all sensor/transmitter nodes are recorded.

2.7 The main unit (the receive node) is fitted with a battery reserve power- pack to enable it to function during power interruptions. However in the event of a total loss of power the system may be re-activated by use of the individual sensor teach/learn sequences preceded by a power down. When completely re-activated the system codes are virtually guaranteed to be different numbers by virtue of the RNC numbers re-generated.

3 Other Applications 3.1 The embedding of the RNC within the processor of any microchip or the hardwired logic RNC generator, associated with an operational function integral or separate to a communication channel makes the concept a powerful identifier for other applications. These applications are specially useful for security devices working within radio communication proximity to other, separately targeted security devices working on the same channel thereby being recognised as being specific to one particular system. Further applications include interference free remote control power sockets, which may be used by parents for example to prevent children's over use of computer games, or invalids to enhance difficult access.

3.2 This application is therefore to include the assignment of an identifying code, randomly generated, to any system which uses the concept to discriminate specific nodes/devices via a teach/learn procedure.

3.3 In this sense the previous submission (patent file No:9311572, filed 4/6/93) of a PIN number generator and exploitation of a PIN barred mains power output associated with this idea is associated with this request.

4 Detail of method s used to generate the RNC 4.1 Software Implementation Flow Chart

Starts I tuated 3\ No Yes L ad Prim,ing,N,umber,( (Increment I cot - No tore Virtual RandomNumber i 4.2 Hardware Implementation Diagram

Contro110gic | n ' Run , Reset l 1 Store Key-Sxvitch i l Orcillai ,Couna J Resulting code Operators Sequence required to set up the RNC between transmit & receive nodes.

1/ Switch Remote Receiver to 'Learn Mode'.

2/ Switch Transmitter unit to 'Generate Code Mode'.

3/ Actuate key to set counter running.

4/ Release key to stop counter. This data is Automatically Transmitted to the Remote Receiver.

5/ Switch remote Receiver and Transmitter back to 'Normal Mode'.

6/ Units can now communicate.

7/ The sequence may be repeated for other units, or the first unit re-programmed with a new code.

Claims

1/ This invention enables individual nodes in a common channel signalling system to take an individual identity during communication to other nodes whilst maintaining a very high immunity from other nodes taking an identical identity. The individual identity is called the RNC (Random Number Code) in this paper.

2/ This invention enables the RNC (Claim 1) to be generated easily by measuring the time between two separate time events. The time events come from external stimulus such as power-up of equipment, the actuating of a switch or other external event.

3/ The system is initialised by setting the transmit node to a teach mode and the receiving node to learn mode. The RNC is then transferred from the transmit node to the receive mode. This RNC is then stored in the receive nodes non-volatile memory. Subsequent communication then uses the RNC to discriminate between the particular transmitting node and any other known or unknown codes.

4/ The code can be re-set or re-learnt at any time by repeating the learn/teach procedure.

5/ The system is easily expanded to serve many pairs of RX/TX's or multiple operation of several units. Other systems (within signalling range) may use the same technique, without causing erroneous identification of nodes, as all transmission nodes will generate an individual RNC.

6/ Additional diversity from erroneous identification is provided by frequency and data speed and data format variations.

7/ The users of the equipment do not know the RNC, nor are they required to record it or risk a third party easily identifying it.

Amendments to the claims have been filed as follows 1. A monitoring system comprising a remote unit, a master unit and means for transmitting a signal from the remote omit to the master unit, the remote unit oomprising moans for originotisly an identifying signal to be associated with the remote unit and transmitting the original identifying signal to the master unit and the master unit oomprising means for receiving the initially-transmitted original signal and thereafter recognising the signal, whn received subsequently, as originating from the remote unit.

2. A system as claimed in claim 1, wherein the remote unit comprises means for generating a coded signal.

3. A system ao claimed in claim 2, wherein the coded signal is a bistary coded signal.

4. A system as claimed in claim 2 or claim 3, wherein information is transmitted in addition to the code, 5. A system as claimed in any of the preceding claims, wherein the remote unit comprisos means for switching it into a code-originating and transmitting mode and the master unit comprises means for switching it into a learning modr to store a newly-originated code.

6. A system as claimed in any of the preceding claims, wherein the remote unit. comprises an electronic counter and means for stopping the counter at a number which becomes the originating sedge.

7. A system as claimed in claim 6, wherein the means tor Stopping the counter comprises a switch.

8. A system as claimed in claim 7, wherein subsequent to the transmission of the original identifying signal, actuation of the switch results in transmission of a tost signal.

9. A system as claimed in any of claim 6 to 8, further comprising means for commencing counting by the counter.

10. A system as claimed in claim 9, wherein the counter is started when the remote unit is switched on.

11. A system ao claimed in any of the preceding claims, wherein the remote unit comprises a random number code generator.

12. A system as claimed in any of the preceding claims, comprising a plurality of remote units.

13. A system as claimed in any of the preceding claims, comprising a plurality of master units.

14. A system as claimed in any of the preceding claims, wherein the remote unit and the master unit cosnnunicate in a wireless manner.

15. A system as claimed in any of the preceding claims, further comprising meano for replacing an existing identifying signal with a new identifying signal.

16. A monltoring system substantially as herein described, with reference to, and as illustrated in, the accompanying drawings.

17. An intruder detection system comprising a system as claimed in any of the preceding claims, comprising a plurality of remote units would wherein each remote unit comprises a detector which transmtts a signal to the master unit upon actuation.