GB2299431A - Radio linked detector/transmitter and reciever/alarm apparatus - Google Patents

Abstract

An alarm system comprising two or more free standing units. Some units are equipped with sensors and a transmitter; other units contain a receiver together with visual and audible alarms. The two unit types are capable of remote operation at sufficient distance to allow deployment in two or more neighbouring or nearby premises. The method of transmission between transmitting and receiving units is such as to be both secure and so arranged as to obviate the need for individual installation licensing. The system is protected from misuse by a coded arming sequence.

Description

THE RADIO LINKED DETECTOR/TRANSMITTER AND RECEIVER/ALARM APPARATUS This invention relates to a set of units which together form an alarm to operate between nearby properties.

There are currently available commercially a number of alarm systems which give a visual and/or audible indication of an intrusion into, or smoke at,domestic premises. Such alarms which give an indication at the actual premises have an inherent weakness. The warning given is nonspecific and relies on a third party both observing the signal and alerting the appropriate authorities, sometimes with long delays after alarm initiation. Other alarms currently available which give a remote signal, for instance by telephone line, suffer from lack of flexibility, being fixed, relatively high installation costs and significant running costs.

The object of this invention is to combine the use of appropriate detection sensors with a low power radio transmitter into an integral unit, this to be used in conjunction with a further unit containing a receiver and alarm system. The transmitting unit is set up in the premises to be protected whilst the receiving unit is deployed at nearby, occupied, premises. On detecting an alarm condition the transmitting unit, when armed, will transmit an encoded signal to the receiving unit. No audible or visual signal is given by the transmitting unit, thus leaving an intruder in ignorance of detection, but the remote receiving unit will give appropriate announcement.

Both units are portable and are ideally suited for use by cooperating neighbours.

A more detailed technical description of the apparatus follows in three parts: (i) Theory of Operation and system set up; (ii) The transmitter Unit; (iii) The receiver Unit.

Theory of Operation and system set up: A system comprises a minimum of two units, a detector/transmitter and a receiver/alarm indicator. The detector/ transmitter unit, which is installed in a disguised housing, is placed in the area to be protected.

When armed, see below, the unit will transmit signals at any time that movement or other cause for alarm is registered by its sensors. Further signals are also transmitted at regular intervals to indicate continued operation. A means is incorporated in the detector/transmitter unit by use of which the user may indicate that the signals should be considered inactive, to enable system set up and close down, or active.

The receiver/alarm indicator unit processes the signals transmitted by the detector transmitter unit and, if an alarm condition is determined will indicate with both an audible and a visual signal.

The units are powered using internal batteries and/or mains supply.The two types of unit are linked by encoded signals transmitted at radio frequencies. The system allows different code choices such that several systems may be employed in the same general location without interference.

The overall system is set up as follows. Initially, the detector /transmitter is switched on and the disarmed state selected. The receiver/alarm unit is also switched on and placed in the selected neighbouring property; a check is made that a signal is being received using the signal strength indicator. Reception may be enhanced by use of appropriate external antenna, such as the property's TV antenna.

When ready, the system is armed. The detector/transmitter unit will give an indication that this has been correctly accomplished. The user then has a predetermined time to leave the area before the detectors become operational.

The system is disarmed by the user, it being necessary to do this within a predetermined period of time after entering the protected area to avoid activating the remote alarm. The detector/transmitter unit gives an indication that the system is now disarmed.

The system described above allows the occupant(s) of the neighbouring property to be aware that an alarm condition exists without intruder(s) in the protected property having any knowledge of their detection. A visual check may then be carried out by neighbours to help verify the cause for alarm; signs of smoke, for instance, or any change of status before deciding to summon assistance from the appropriate authorities. This human element is seen as a vital step in the overall operation of the alarm system in that it greatly increases the probability of genuine, as opposed to false, alarms being reported through to the responsible authorities.

The Transmitter Unit: The detector/transmitter comprises a single unit, the size being similar to that of a domestic radio receiver. Incorporated within the unit are appropriate detectors and means of indicating system and unit status to the operator. A power input socket, for external power and an on/off key switch are included.

The whole unit is mounted within a disguised housing to avoid recognition by an unauthorised intruder.

The Receiver Unit: The receiver/alarm unit is again a single unit having the following external features: A signal strength indicator to aid system set up, together with appropriate displays for indicating transmission received, error conditions, alarm states detected by the detector/receiver unit and no transmissions. Also provided are a power input socket, an external antenna socket, antenna and on/off switches.

A integral antenna is incorporated within the unit as is a source of audible alarm.

Circuitry within the unit allows for interpretation of a number of different signals emanating from the paired detector/transmitter allowing the unit to display or otherwise indicate the overall status of the system to the operator.

Claims (5)

THE CLAIMS

1: The detection and remote alarm system comprises two types of separate unit, both types being free standing and fully transportable.The units are linked by an encoded signal transmitted at radio frequency. The first, transmitting, unit is equipped with detectors to sense the presence of an intruder or similar causes for concern such as smoke but without any local audible or visible sign of detection. The second unit is capable of decoding signals transmitted by the first unit and giving both audible and visual indication of an alarm condition to an operator in a remote location.

2. Use of transmission frequencies, as claimed in 1 above, in conjunction with ariel requirements as laid down in appropriate specifications, ensures that the system may be used without individual installation licenses.

3. That the alarm incorporated within the receiver/alarm unit, once activated by signal from the remote detector/transmitter unit cannot be disabled by an intruder within the protected premises.

4. Use of a system as claimed in 1 above allows for the operator, having the receiving unit, to make visual or other suitable inspection of the protected premises before contacting the appropriate authorities thus substantially increasing the probability of a valid call for assistance, as opposed other systems not allowing such checking of a detected alarm condition.

5. That the range of the transmission between the units described in 1 above may be enhance by using an external receiving antenna, with or without additional amplification, the domestic television antenna being an example of this.