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Remote Control of Base Stations by Landlines |
Where a licensee operating a radio system using Private Mobile Radio frequencies chooses to have the base station installed at a remote site, the normal method of control is via a landline. This is normally obtained from a network service supplier. This can be either a 'Private Wire' which uses a point-to-point installation, or a 'Dial-up' system operating via any network service, using a conventional telephone line to connect the base station to its control point, often many miles away.
Private Wire (PW) links are only available from the major network suppliers, and can be expensive both to install and operate, with an annual rental charge of a similar level. They do however offer a high grade of service and line quality. A failure in a PW based system may render the base station inoperative until such time as the network supplier can repair the line.
A dial-up landline is one where the control point and remote base station are linked via a standard telephone line, provided either by one of the major networks, or by one of the new cable operators. Dial-up systems have the advantage that the licensee pays the standard installation charge, plus call costs when the system is in use; no costs being charged when the link is disconnected. This will allow control points, which only need to have direct access to the system on an occasional basis, to use the PSTN (Public Switched Telephone Network) or other network as the source of the line, rather than requiring a dedicated landline. Line quality may not be as good as that available on a 'PW' based system, but there is some additional benefit if the line fails; dialling out again will quickly re-establish control of the base station.
Private Mobile Radio licensees assigned with standard wide-area shared channels and/or on-site shared channels, together with those with regional and/or nationally exclusive assignments. Service Providers normally do not use landlines as a method of controlling base stations, however they may be permitted to do so after consultation with the Agency's Public Telecommunications Networks Section.
Where modifications to the radio apparatus comprising part, or all of the system are necessary to accommodate this facility, then advice as to the effect on type approval that this may have must be sought from the Radiocommunications Agency's Type Approvals Unit. It may be necessary for manufacturers and suppliers of these systems to have the equipment re-approved prior to it being used as part of a licensed PMR system utilising the dial-up facility.
The apparatus used to connect to the landline part of the system must be British Approvals Board of Telecommunications (BABT) approved and installed in accordance with the requirements of the network operator. No third party traffic may be carried and it must be made impossible for members of the public to gain access to the system.
The following requirements must be met by the licensee before use of dial-up landline control will be granted by the Radiocommunications Agency.
Any licensee wishing to take advantage of dial-up control must make an application to the Radiocommunications Agency on form RA1. Location of the remote site and its associated control point must be supplied at the time of application, together with the appropriate telephone numbers.
The method of establishing the link between the control point and its associated base station shall not take place over any part of the radio system. Mobiles will not be able to initiate the setting up of the landline link.
The Agency requires a security system involving the use of a PIN (Private Identification Number) and dial-back routine to be used by the base station end of the landline. Typically the remote control point will initiate the setting up of the link by the licensee dialling the base station. Upon answering, the base station's landline unit will request the PIN, and having received the correct PIN will disconnect the line. Dial-back will then occur automatically, recalling the number stored within the unit, the connection is then made. Only after this procedure has been completed will the base station be controllable by landline from the remote control point.
On completion of the message, a signal must be sent to the base unit which instructs it to disconnect the call. Similarly if the base station control unit detects a line failure condition, the connection will be automatically terminated.
In order to prevent the base station from being triggered accidentally for example by a crossed line, an in band control tone must be generated from the calling remote control unit. This tone should be inaudible to the system operators and radio users and must be sent during the transmit period. In all cases a three minute automatic cut-out timer must be fitted to the base station transmitter. This timing circuit will automatically switch off the transmitter at the end of the three minute period, if no transmissions have been made or if a fault condition occurs and will not allow any further transmissions until the fault condition is cleared.
Licensees will only be permitted one control point plus an additional one for emergency, or out of hours use, unless they can present an acceptable case to the Agency, detailing why additional control points should be granted. All control points must be shown on the licence schedule(s).
Details can be obtained from your local office, the address of which is contained in Agency Information Sheet RA206 which is available from:
Library and Information ServiceAlternatively the phone number and address of your Local Office can be obtained by contacting the Agency's Enquiry Point on 020 7211 0211.
website: www.radio.gov.uk
| RA 327 (Rev 1) June 1999 |
