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Alarms on PMR Information Sheet |
Purpose of this Information Sheet
There are a number of different types of alarm services which are available over land mobile radio. They are categorised as alarms on PMR, short range alarms and local authority alarms.
This information sheet sets out the new policy of the Radiocommunications Agency towards alarms on PMR. Previously applications for alarm services on PMR channels have been allowed on single frequency channels with on-site PMR conditions and with a requirement for carrier sense.
What is an alarm on PMR?
The alarms on PMR to which this information sheet relates are portable, mobile or transportable alarm equipment which, when activated, automatically transmits a message on a PMR (private mobile radio) channel.
It should be noted that PMR assignments on shared channels do not have any guarantee of certain communication with regard to safety of life in an emergency. This is because a number of users share the same channel and it is possible that an alarm alert signal may not be received by its base station. Applicants who have a need for safety of life operation should bear this in mind when planning the installation of their alarm system.
What are the equipment and operating requirements?
With the introduction of this new policy alarms may be used on all shared PMR channels. They may also be used on exclusive channels where appropriate. However it is not envisaged that an alarm system will be sole user of an exclusive channel.
It is important to note the following conditions for all alarms on PMR.
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Standard PMR approval will apply to all equipment. |
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The message transmitted when the alarm is triggered shall be limited to a maximum of 10 seconds. |
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The number of repeats before the alarm resets shall be limited to two. That is, there will be no more than three transmissions in total before the equipment resets. |
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On reception of an alarm message the base station may transmit an acknowledgement signal in the form of a tone or tones. This signal should cause the alarm to cease transmission immediately and reset. |
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Polling for status is forbidden. |
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The alarm shall not be allowed to act as a receiver for any type of message. The only receive capability shall be that associated with the use of carrier sense and the reception of an acknowledgement signal from the base station after transmission of an alarm message. |
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An alarm unit shall be allowed to transmit a status message not more than once in an eight hour period. The message duration shall not be of greater length than the alarm message and shall not be transmitted more than three times. During all transmissions the callsign detailed on the licence schedule must be contained in the message in line with section 6 of the licence terms provisions and limitations. |
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Alarms may be activated either manually or by automatic devices, for example, by infrared motion detector burglar alarms or smoke detectors. |
What conditions apply to alarms on PMR speech dominant channels?
The conditions for the use of PMR are given in the information sheet RA 126. All the normal PMR conditions must be adhered to and the equipment must meet the requirements of the relevant specification for approval. The licensee must ensure that accurate and up to date records of alarm locations are kept. The Agency should be advised of an efficient method of closing down the alarm system at any time in the event of interference being caused.
The Agency is prepared to consider on a case by case basis use of the following additional facilities for alarm stations utilising Private Mobile Radio.
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Use of a three element directional antenna set to provide maximum radiation in the direction of the central control point. Effective Radiated Power must not exceed 2 watts (This may be increased up to 5 if it can be demonstrated that 2 watts ERP will not provide a satisfactory signal at the central control point). |
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Height of alarm station antenna above ground level must not exceed 10 metres. |
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Equipment comprising the above must conform to the relevant Interface Requirement (IR) or be type approved for use as a fixed station if placed on the UK market before 8 April 2000. |
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Use of this facility must not cause interference to other radio users, and may be withdrawn by the Agency at any time. It is anticipated that such cases will occur only where local topography makes "normal" line of site communication difficult. Requests to use equipment in line with the above conditions should be made to the operations manager of the Agency's local office in which the installation will take place. |
What conditions apply to alarms on data dominant PMR channels.
The details of data on PMR are given in Information sheet RA 254. The alarm must conform with all the current service requirements.
What about alarms licensed before this policy came into force?
Under the Agency's previous policy non-fixed alarms were generally allowed on single frequency channels with on-site PMR conditions and with a requirement for carrier sense. Type approval was that for standard PMR.
Systems licensed under the previous policy are allowed to remain with customers for their operational lifetime on a non-interference basis.
What other types of radio alarms are available?
Provisions exist for other types of radio alarm systems. Applicants requiring a radio alarm system should check carefully their requirements before selecting the type of alarm most appropriate to their needs.
Channels currently available for alarm applications are:
a) Local Authority (emergency alarm) radio systems, Information Sheet RA 209;
b) Short Range Alarms, Information Sheet RA 114;
Applications and Enquiries
Applications for licences and frequency assignments for alarms on PMR should be made to your local Agency office using form RA1. Enquiries should also be directed to your local Agency office. The address and telephone number are available from our Enquiry Point on 020-7211-0211.
Radiocommunications
Agency,
Wyndham House
189 Marsh Wall
London
E14 9SX
RA
284 (Rev 4)
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