Type 0 Extension 0 - mattpascoe135/dab GitHub Wiki

#Extension 0 - Ensemble information
The ensemble information contains SI and control mechanisms which are common to all services contained in the ensemble. It is specifically used to provide an alarm flag and CIF counter (24 ms increments) for use with the management of a multiplex re-configuration. Three different levels of multiplex re-configuration are distinguished:

  • a) change of sub-channel organization only (see clause 6.2);
  • b) change of service organization only (see clause 6.3);
  • c) change of sub-channel and service organization.

The ensemble information is coded in Extension 0 of FIG type 0 (FIG 0/0) as shown in figure 29.

Ext. 0

The following definitions apply:

###EId (Ensemble Identifier): a unique 16-bit code, shall be allocated to the ensemble and allows unambiguous identification of the ensemble when associated with the Ensemble ECC (see clause 8.1.3).

  • Country Id (Country Identification): see clause 6.3.1.
  • Ensemble reference: this 12-bit field shall indicate the number of the Ensemble allocated for use within a national area.

###Change flag: this 2-bit field shall be used to indicate whether there is to be a change in the sub-channel or service organization, or both, as follows:

`b_15 - b_14`

`0 0: no change, no occurrence change field present;`

`0 1: sub-channel organization only;`

`1 0: service organization only;`

`1 1: sub-channel organization and service organization.`

###AL flag (Alarm flag): this 1-bit flag shall be used to signal that alarm messages are accessible within the ensemble, as follows:

`0: alarm messages not accessible;`

`1: alarm messages accessible.`

The alarm messages are presented as an alarm announcement which interrupts the reception of programme services carried in the ensemble (see clause 8.1.6.1).

###CIF count: this modulo-5 000 binary counter shall be arranged in two parts and is incremented by one at each successive CIF. The higher part is a modulo-20 counter (0 to 19) and the lower part is a modulo-250 counter (0 to 249).

###Occurrence change: this 8-bit field shall indicate the value of the lower part of the CIF counter from which the new configuration applies.

NOTE: In any 96 ms period, the FIG 0/0 should be transmitted in a fixed time position. In transmission mode I, this should be the first FIB (of the three) associated with the first CIF (of the four) in the transmission frame (see clause 5.1). In transmission modes II and III, this should be the first FIB of every fourth transmission frame. In transmission mode IV, this should be the first FIB (of the three) associated with the first CIF (of the two) in every alternate transmission frame (see clause 5.1).