Trend AuroraPlus User Guide
1-16 429850
Layer 1 (BRI)
Layer 1, at the S/T reference point, transfers information bits
in frames between the terminals and the NT1.
Each layer 1 frame is 48 bits long and lasts for 250
microseconds—its structure depends on the direction of
transmission. It contains two 8 bit groups of channel B1,
two 8 bit groups of channel B2, 4 bits of channel D and 12
bits used for other functions.
D Channel Contention
If two TEs attempt to make a call simultaneously, a
procedure known as D Channel Contention Resolution
prevents a collision.
Activation and deactivation
TEs and NTs can be deactivated in order to reduce power
consumption, then reactivated to normal power. Both the TE
and NT can receive activation messages, but only an NT can
instruct a TE to deactivate.
‘Info’ signals
Activation and Deactivation messages are transmitted using
‘Info’ signals.
Info 0 idle state—neither the TEs or the NT are operating.
Info 1 TE to NT—requests activation.
Info 2 NT to TE—requests activation/responds to
Info 1.
Info 3 TE to NT—contains operational data.
Info 4 NT to TE—contains operational data.
Chap01.P65 30/04/01, 16:2716
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