scope:

This ETS applies to equipment designed to operate within the professional mobile radio service and to the associated frequency planning.

This ETS applies to equipment for the transmission of data on shared channels; it also contains two methods of measurement used for the assessment of receiver timing parameters.

This ETS specifies an access protocol and occupation rules for data communications on radio channels shared by different users. It may be used for data communications over channels originally intended for speech use. This ETS gives freedom for the use of any bit rate, any constant envelope modulation or any type of protocol which fulfills the normative parameters of this ETS to access a shared radio channel.

The access protocol specified in this ETS also permits the sharing of speech and data communication.

This access protocol applies to single frequency simplex operation (and two frequency repeater operations with the repeater in duplex mode and the mobile units in simplex mode). This access protocol is applicable for:

- multiple data only users, independent of each other, which do not share a common central control facility, but may share a common single or two frequency radio channel;

- multiple mixed analogue speech and data users, independent from each other, which do not share a common central control facility, but may share a common single, or two frequency, radio channel and where speech is to have priority over data transmissions.

This access protocol is not applicable for data users with common central control facilities or for trunked systems operating on dedicated non shared channels.

In the case of analogue transmissions, the corresponding access protocol is known as the "radio-discipline" of the users.

Within the limits set out in this ETS, each group of users may use its own communication protocol.