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Use of Talkthrough Facilities By Wide Area and On-Site Private Business Systems Licensees. |
What is talkthrough?
Most Private Mobile Radio (PMR) systems operate using two separate frequencies. Base stations transmit to mobile stations on frequency A, and mobile stations transmit back to base stations on frequency B.
This mode of operation does not allow mobiles to talk directly to other mobiles, as each one is transmitting frequency B and receiving frequency A. Normally a dispatcher or controller acts as a focal point for communications, relaying messages from mobile to mobile as required.
Talkthrough facilitates automatic communication between mobiles through base stations. If a base station is set to talkthrough mode, signals received at the base station from mobile stations are immediately re-transmitted to all the other mobile units monitoring the base station's output. In this way PMR systems can operate without a dispatcher to verbally relay messages.
Benefits and usage
Talkthrough can increase the benefits of PMR to some types of business user and is permitted only under the control of the licensee. PMR channels are crowded and the Agency may restrict use of talkthrough to certain times of day and/or days of the week in order to minimise the effect of its use on other users of the radio channel. In some cases the use of talkthrough will be authorised only in the event of an emergency.
A suitable method of control must be implemented to select and deselect talkthrough as necessary. These methods include:
Uncontrolled use of talkthrough, or operation of a system without sub-audible tones and without a suitable method of control implemented to select and deselect talkthrough, is not permitted.
The use of "Store and Forward" equipment to achieve talkthrough must use Carrier Sense on the frequency on which the relayed message is transmitted. Recorded messages must not exceed 30 seconds in length. Again there must be a suitable method of selecting and deselecting talkthrough.
Private Mobile Radio (PMR) is intended for communicating business messages. If talkthrough encourages or facilitates use of a PMR radio system for non-business purposes (e.g. personal messages) the Agency may withdraw the talkthrough facility from that licensee.
Applications for talkthrough
Both new and existing applicants should submit a business case to the Agency detailing their requirement for talkthrough and the operational times between which they expect to use the facility. Upon receipt of applications, the Agency will consider each business case on its merits and assess the likely impact of talkthrough on the assigned frequency's existing users.
New systems
Potential licensees planning to install new PMR systems can apply for talkthrough when completing and submitting their initial application form RA1.
Existing systems
Licensees may ask us to consider authorising the addition of talkthrough as and when business need arises. Applications for the addition of talkthrough to existing systems should be made using form RA1A, or by letter, fax or e-mail, giving full details of the existing licence, the business case and the expected operational times required.
Equipment
Talkthrough equipment should not be purchased or installed before receipt of a licence schedule authorising the use of talkthrough. The radio equipment used must comply with Interface Requirement (IR) 2001.
Enquiries
Any questions you may have on talkthrough should be directed to your radio supplier or to your normal point of contact within the Agency, either your Local Office or Headquarters as appropriate. Local Office addresses are available on our information sheet RA 206 or from our Enquiry Point on 020 7211 0211.
Radiocommunications
Agency
Wyndham
House
189 Marsh Wall
London
E14 9SX
Website: www.radio.gov.uk
| RA 359 (Rev 1) April 2002 |
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